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Sample records for slm

  1. A Centrifugal Microfluidic Platform Using SLM Extraction

    DEFF Research Database (Denmark)

    Andreasen, Sune Zoëga; Burger, Robert; Emnéus, Jenny

    2016-01-01

    Here we present a pump-less microfluidic pla>orm which performs sample clean-up and enrichment in a single step, by integraAng Supported Liquid Membrane (SLM) extracAon. Our pla>orm offers a simple, yet very efficient, method for achieving sample pre-treatment and enrichment of rare analytes, in ...

  2. Convolving optically addressed VLSI liquid crystal SLM

    Science.gov (United States)

    Jared, David A.; Stirk, Charles W.

    1994-03-01

    We designed, fabricated, and tested an optically addressed spatial light modulator (SLM) that performs a 3 X 3 kernel image convolution using ferroelectric liquid crystal on VLSI technology. The chip contains a 16 X 16 array of current-mirror-based convolvers with a fixed kernel for finding edges. The pixels are located on 75 micron centers, and the modulators are 20 microns on a side. The array successfully enhanced edges in illumination patterns. We developed a high-level simulation tool (CON) for analyzing the performance of convolving SLM designs. CON has a graphical interface and simulates SLM functions using SPICE-like device models. The user specifies the pixel function along with the device parameters and nonuniformities. We discovered through analysis, simulation and experiment that the operation of current-mirror-based convolver pixels is degraded at low light levels by the variation of transistor threshold voltages inherent to CMOS chips. To function acceptable, the test SLM required the input image to have an minimum irradiance of 10 (mu) W/cm2. The minimum required irradiance can be further reduced by adding a photodarlington near the photodetector or by increasing the size of the transistors used to calculate the convolution.

  3. Development of a predictive system for SLM product quality

    Science.gov (United States)

    Park, H. S.; Tran, N. H.; Nguyen, D. S.

    2017-08-01

    Recently, layer by layer manufacturing or additive manufacturing (AM) has been used in many application fields. Selective laser melting (SLM) is the most attractive method for building layer by layer from metallic powders. However, applications of AM in general and SLM in particular to industry have some barriers due to the quality of the manufactured parts which are affected by the high residual stresses and large deformation. SLM process is characterized by high heat source and fast solidification which lead to large thermal stress. The aim of this research is to develop a system for predicting the printed part quality during SLM process by simulation in consideration of the temperature distribution on the workpiece. For carrying out the system, model for predicting the temperature distribution was established. From this model, influences of process parameters to temperature distribution were analysed. The thermal model in consideration of relationship among printing parameters with temperature distribution is used for optimizing printing process parameters. Then, these results are used for calculating residual stress and predicting the workpiece deformation. The functionality of the proposed predictive system is proven through a case study on aluminium material manufactured on a MetalSys150 - SLM machine.

  4. Melt pool modelling, simulation and experimental validation for SLM

    NARCIS (Netherlands)

    Wits, Wessel

    2017-01-01

    SLM parts are built by successively melting layers of powder in a powder bed. Process parameters are often optimized experimentally by laser scanning a number of single tracks and subsequently determining which settings lead to a good compromise between quality and build speed. However,

  5. Requirements of Slm proteins for proper eisosome organization ...

    Indian Academy of Sciences (India)

    Eisosomes are large immobile assemblies at the cortex of a cell under the membrane ... microscopic analysis of Abp1-RFP revealed that the actin defect in slmts cells was not ... Our data provide evidence for the requirement of Slm proteins in eisosome ..... with a bandwidth of 10 nm, and emission was measured at. 680 nm ...

  6. Requirements of Slm proteins for proper eisosome organization ...

    Indian Academy of Sciences (India)

    Eisosomes are large immobile assemblies at the cortex of a cell under the membrane compartment of Can1 (MCC) in yeast. Slm1 has recently been identified as an MCC component that acts downstream of Mss4 in a pathway that regulates actin cytoskeleton organization in response to stress. In this study, we showed that ...

  7. Integration of Fast Predictive Model and SLM Process Development Chamber, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This STTR project seeks to develop a fast predictive model for selective laser melting (SLM) processes and then integrate that model with an SLM chamber that allows...

  8. Microstructural Characterization and Modeling of SLM Superalloy 718

    Science.gov (United States)

    Smith, Tim M.; Sudbrack, Chantal K.; Bonacuse, Pete; Rogers, Richard

    2017-01-01

    Superalloy 718 is an excellent candidate for selective laser melting (SLM) fabrication due to a combination of excellent mechanical properties and workability. Predicting and validating the microstructure of SLM-fabricated Superalloy 718 after potential post heat-treatment paths is an important step towards producing components comparable to those made using conventional methods. At present, obtaining accurate volume fraction and size measurements of gamma-double-prime, gamma-prime and delta precipitates has been challenging due to their size, low volume fractions, and similar chemistries. A technique combining high resolution distortion corrected SEM imaging and with x-ray energy dispersive spectroscopy has been developed to accurately and independently measure the size and volume fractions of the three precipitates. These results were further validated using x-ray diffraction and phase extraction methods and compared to the precipitation kinetics predicted by PANDAT and JMatPro. Discrepancies are discussed in context of materials properties, model assumptions, sampling, and experimental errors.

  9. Metal waste (Cu and Ni) prevention by SLM and MED

    Energy Technology Data Exchange (ETDEWEB)

    Van de Voorde, I.; Vander Linden, J.; De Ketelaere, R. F. [Chemical and Biochemical Research Centre KaHo Sint-Lieven (CBOK), Ghent (Belgium)

    2001-07-01

    Results of an investigation into implementing supported liquid membranes (SLM) and modified electrodialysis (MED) technology for the recovery of copper and nickel from electroplating effluents in order to prevent metal waste, are discussed. To date, the study of the influence of the individual parameters and their aggregate effect on mass transfer has been completed on laboratory scale equipment. The SLM pilot plant has also been tested extensively, confirming the feasibility of the technique for use with solutions containing up to 500 ppm of metal, as well as for use with other solutions with low metal concentrations originating in other than plating shops. A modified electrodialysis unit also has been designed and constructed using solid ion exchangers. Although development of the technique of electrolytic regeneration and simultaneous conditioning of solid ion exchangers has been successfully completed, the PARCOM 0.5 ppm level envisaged for the deionisation of nickel salts, has not been achieved. Development of the entire control system for SLM and more experiments for MED to replace the ion exchanger membranes, and the effective nickel ion exchanger, by one simple ceramic cell of variable porosity, are the next steps. 7 refs., 3 tabs.

  10. ON THE PAPR REDUCTION IN OFDM SYSTEMS: A NOVEL ZCT PRECODING BASED SLM TECHNIQUE

    Directory of Open Access Journals (Sweden)

    VARUN JEOTI

    2011-06-01

    Full Text Available High Peak to Average Power Ratio (PAPR reduction is still an important challenge in Orthogonal Frequency Division Multiplexing (OFDM systems. In this paper, we propose a novel Zadoff-Chu matrix Transform (ZCT precoding based Selected Mapping (SLM technique for PAPR reduction in OFDM systems. This technique is based on precoding the constellation symbols with ZCT precoder after the multiplication of phase rotation factor and before the Inverse Fast Fourier Transform (IFFT in the SLM based OFDM (SLM-OFDM Systems. Computer simulation results show that, the proposed technique can reduce PAPR up to 5.2 dB for N=64 (System subcarriers and V=16 (Dissimilar phase sequences, at clip rate of 10-3. Additionally, ZCT based SLM-OFDM (ZCT-SLM-OFDM systems also take advantage of frequency variations of the communication channel and can also offer substantial performance gain in fading multipath channels.

  11. Evaluating Acoustic Emission Signals as an in situ process monitoring technique for Selective Laser Melting (SLM)

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, Karl A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Candy, Jim V. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Guss, Gabe [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Mathews, M. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-14

    In situ real-time monitoring of the Selective Laser Melting (SLM) process has significant implications for the AM community. The ability to adjust the SLM process parameters during a build (in real-time) can save time, money and eliminate expensive material waste. Having a feedback loop in the process would allow the system to potentially ‘fix’ problem regions before a next powder layer is added. In this study we have investigated acoustic emission (AE) phenomena generated during the SLM process, and evaluated the results in terms of a single process parameter, of an in situ process monitoring technique.

  12. Sustainable land management (SLM) practices in drylands: how do they address desertification threats?

    Science.gov (United States)

    Schwilch, G; Liniger, H P; Hurni, H

    2014-11-01

    Managing land sustainably is a huge challenge, especially under harsh climatic conditions such as those found in drylands. The socio-economic situation can also pose challenges, as dryland regions are often characterized by remoteness, marginality, low-productive farming, weak institutions, and even conflict. With threats from climate change, disputes over water, competing claims on land, and migration increasing worldwide, the demands for sustainable land management (SLM) measures will only increase in the future. Within the EU-funded DESIRE project, researchers and stakeholders jointly identified existing SLM technologies and approaches in 17 dryland study sites located in the Mediterranean and around the world. In order to evaluate and share this valuable SLM experience, local researchers documented the SLM technologies and approaches in collaboration with land users, utilizing the internationally recognized WOCAT questionnaires. This article provides an analysis of 30 technologies and 8 approaches, enabling an initial evaluation of how SLM addresses prevalent dryland threats, such as water scarcity, soil degradation, vegetation degradation and low production, climate change, resource use conflicts, and migration. Among the impacts attributed to the documented technologies, those mentioned most were diversified and enhanced production and better management of water and soil degradation, whether through water harvesting, improving soil moisture, or reducing runoff. Favorable local-scale cost-benefit relationships were mainly found when considered over the long term. Nevertheless, SLM was found to improve people's livelihoods and prevent further outmigration. More field research is needed to reinforce expert assessments of SLM impacts and provide the necessary evidence-based rationale for investing in SLM.

  13. Sustainable Land Management (SLM) Practices in Drylands: How Do They Address Desertification Threats?

    Science.gov (United States)

    Schwilch, G.; Liniger, H. P.; Hurni, H.

    2014-11-01

    Managing land sustainably is a huge challenge, especially under harsh climatic conditions such as those found in drylands. The socio-economic situation can also pose challenges, as dryland regions are often characterized by remoteness, marginality, low-productive farming, weak institutions, and even conflict. With threats from climate change, disputes over water, competing claims on land, and migration increasing worldwide, the demands for sustainable land management (SLM) measures will only increase in the future. Within the EU-funded DESIRE project, researchers and stakeholders jointly identified existing SLM technologies and approaches in 17 dryland study sites located in the Mediterranean and around the world. In order to evaluate and share this valuable SLM experience, local researchers documented the SLM technologies and approaches in collaboration with land users, utilizing the internationally recognized WOCAT questionnaires. This article provides an analysis of 30 technologies and 8 approaches, enabling an initial evaluation of how SLM addresses prevalent dryland threats, such as water scarcity, soil degradation, vegetation degradation and low production, climate change, resource use conflicts, and migration. Among the impacts attributed to the documented technologies, those mentioned most were diversified and enhanced production and better management of water and soil degradation, whether through water harvesting, improving soil moisture, or reducing runoff. Favorable local-scale cost-benefit relationships were mainly found when considered over the long term. Nevertheless, SLM was found to improve people's livelihoods and prevent further outmigration. More field research is needed to reinforce expert assessments of SLM impacts and provide the necessary evidence-based rationale for investing in SLM.

  14. PERANCANGAN DAN IMPLEMENTASI SOUND LEVEL METER (SLM DALAM SKALA LABORATORIUM SEBAGAI ALAT UKUR INTENSITAS BUNYI

    Directory of Open Access Journals (Sweden)

    Jamaludin Jamaludin

    2016-11-01

    Keywords  : Sound Level Meter, Wave Mechanics Penelitian yang berbasis laboratorium merupakan implementasi dari Gelombang Mekanik (GM. Pada peristtiwa fisis ini akan diteliti tentang Gelombang Mekanik dalam mengukur Intensitas Bunyi. Guna untuk mengetahui SLM yang relevan menggunakan mic condenser serta menentukan kebisingan bunyi dalam tingkat frekuensi yang berbeda dalam skala Laboratorium. Pengujian intensitas bunyi dilakukan dalam kondisi ruang yang kedap suara serta perbandingan intensitas bunyi dengan SLM rancangan industri. Dalam penelitian ini juga membandingkan antara SLM Rancangan dengan SLM Nor-118. Sehingga data yang diperoleh adalah hasil dari pengambilan data yang kami lakukan antara SLM Rancangan dengan SLM Nor-118 bisa dikatakan relevan namun ada perbedaan selisih sebesar ±5.0 %. Dan pada saat frekuensi tertentu dia akan menurun yang disebabkan oleh beberapa faktor internal dan eksternal. Kesimpulan yang diambil adalah dalam setiap pengambilan data harus dalam kondisi ruang yang kedap suara sehingga ketika dalam pengambilan data tidak ada faktor yang mempengaruhi baik eksternal maupun internal. Kata Kunci : Sound Level Meter, Gelombang Mekanik

  15. PERANCANGAN DAN IMPLEMENTASI SOUND LEVEL METER (SLM DALAM SKALA LABORATORIUM SEBAGAI ALAT UKUR INTENSITAS BUNYI

    Directory of Open Access Journals (Sweden)

    Jamaludin .

    2014-09-01

    Full Text Available Laboratory based research is the implementation of Wave Mechanics ( GM . In this physical peristtiwa will be examined on Wave Mechanics in measuring the intensity of sound . In order to determine the relevant SLM using a condenser mic as well as determine the level of noise in the sound of different frequencies in the laboratory scale . Tests carried out under conditions of sound intensity soundproof space and sound intensity comparison with SLM industrial design . In this study also compares the design of the SLM SLM Nor- 118 . So that the data obtained is the result of data collection we did the design of the SLM SLM Nor- 118 can be said to be relevant , but there is a difference is a difference of ± 5.0 % . And at a certain frequency when he would decline due to several internal and external factors . The conclusions drawn are in any retrieval of data must be in the soundproof room so that when the data collection is no factor that affects both external and internal.

  16. Increasing reconstruction quality of diffractive optical elements displayed with LC SLM

    Science.gov (United States)

    Cheremkhin, Pavel A.; Evtikhiev, Nikolay N.; Krasnov, Vitaly V.; Rodin, Vladislav G.; Starikov, Sergey N.

    2015-03-01

    Phase liquid crystal (LC) spatial light modulators (SLM) are actively used in various applications. However, majority of scientific applications require stable phase modulation which might be hard to achieve with commercially available SLM due to its consumer origin. The use of digital voltage addressing scheme leads to phase temporal fluctuations, which results in lower diffraction efficiency and reconstruction quality of displayed diffractive optical elements (DOE). Due to high periodicity of fluctuations it should be possible to use knowledge of these fluctuations during DOE synthesis to minimize negative effect. We synthesized DOE using accurately measured phase fluctuations of phase LC SLM "HoloEye PLUTO VIS" to minimize its negative impact on displayed DOE reconstruction. Synthesis was conducted with versatile direct search with random trajectory (DSRT) method in the following way. Before DOE synthesis begun, two-dimensional dependency of SLM phase shift on addressed signal level and time from frame start was obtained. Then synthesis begins. First, initial phase distribution is created. Second, random trajectory of consecutive processing of all DOE elements is generated. Then iterative process begins. Each DOE element sequentially has its value changed to one that provides better value of objective criterion, e.g. lower deviation of reconstructed image from original one. If current element value provides best objective criterion value then it left unchanged. After all elements are processed, iteration repeats until stagnation is reached. It is demonstrated that application of SLM phase fluctuations knowledge in DOE synthesis with DSRT method leads to noticeable increase of DOE reconstruction quality.

  17. The influence of cellular structures on flow stress of high strength components manufactured using SLM

    DEFF Research Database (Denmark)

    Mahshid, Rasoul; Hansen, Hans Nørgaard; Loft Højbjerre, Klaus

    2016-01-01

    Additive manufacturing has shown significant improvement in material and machines for high-quality solid freeform fabrication processes such as selective laser melting (SLM). In particular, manufacturing lattice structures using the SLM procedure is of interest. This research examines the effect...... of cellular materials on compression strength. The specimens are manufactured additively using industrial 3D printing systems from high-strength alloy. The material has the right mechanical properties for manufacturing tool components. This includes samples with solid and lattice structures. The Compression...

  18. Plasma membrane proteins Slm1 and Slm2 mediate activation of the AGC kinase Ypk1 by TORC2 and sphingolipids in S. cerevisiae.

    Science.gov (United States)

    Niles, Brad J; Powers, Ted

    2012-10-15

    The PH domain-containing proteins Slm1 and Slm2 were originally identified as substrates of the rapamycin-insensitive TOR complex 2 (TORC2) and as mediators of signaling by the lipid second messenger phosphatidyl-inositol-4,5-bisphosphate (PI4,5P2) in budding yeast S. cerevisiae. More recently, these proteins have been identified as critical effectors that facilitate phosphorylation and activation of the AGC kinases Ypk1 and Ypk2 by TORC2. Here, we review the molecular basis for this regulation as well as place it within the context of recent findings that have revealed Slm1/2 and TORC2-dependent phosphorylation of Ypk1 is coupled to the biosynthesis of complex sphingolipids and to their levels within the plasma membrane (PM) as well as other forms of PM stress. Together, these studies reveal the existence of an intricate homeostatic feedback mechanism, whereby the activity of these signaling components is linked to the biosynthesis of PM lipids according to cellular need.

  19. Dimensional Accuracy and Surface Roughness Analysis for AlSi10Mg Produced by Selective Laser Melting (SLM

    Directory of Open Access Journals (Sweden)

    Kamarudin K.

    2016-01-01

    Full Text Available Selective Laser Melting (SLM is an Additive Manufacturing (AM technique that built 3D part in a layer-by-layer method by melting the top surface layer of a powder bed with a high intensity laser according to sliced 3D CAD data. AlSi10Mg alloy is a traditional cast alloy that is broadly used for die-casting process and used in automotive industry due its good mechanical properties. This paper seeks to investigate the requirement SLM in rapid tooling application. The feasibility study is done by examining the surface roughness and dimensional accuracy as compared to the benchmark part produced through the SLM process with constant parameters. The benchmark produced by SLM shows the potential of SLM in a manufacturing application particularly in moulds.

  20. The effect of spatial light modulator (SLM) dependent dispersion on spatial beam shaping

    CSIR Research Space (South Africa)

    Spangenberg, D-M

    2013-08-01

    Full Text Available on the pixels between zero and two pi for a specific wavelength. It is therefore unavoidable when using the same SLM, to do beam shaping of a source which emits multiple wavelengths or a wide bandwidth, that the device will not modulate all wavelengths between...

  1. Additive Manufacturing Thermal Performance Testing of Single Channel GRCop-84 SLM Components

    Science.gov (United States)

    Garcia, Chance P.; Cross, Matthew

    2014-01-01

    The surface finish found on components manufactured by sinter laser manufacturing (SLM) is rougher (0.013 - 0.0006 inches) than parts made using traditional fabrication methods. Internal features and passages built into SLM components do not readily allow for roughness reduction processes. Alternatively, engineering literature suggests that the roughness of a surface can enhance thermal performance within a pressure drop regime. To further investigate the thermal performance of SLM fabricated pieces, several GRCop-84 SLM single channel components were tested using a thermal conduction rig at MSFC. A 20 kW power source running at 25% duty cycle and 25% power level applied heat to each component while varying water flow rates between 2.1 - 6.2 gallons/min (GPM) at a supply pressure of 550 to 700 psi. Each test was allowed to reach quasi-steady state conditions where pressure, temperature, and thermal imaging data were recorded. Presented in this work are the heat transfer responses compared to a traditional machined OHFC Copper test section. An analytical thermal model was constructed to anchor theoretical models with the empirical data.

  2. Fabrication of SLM NiTi Shape Memory Alloy via Repetitive Laser Scanning

    Science.gov (United States)

    Khoo, Zhong Xun; Liu, Yong; Low, Zhi Hong; An, Jia; Chua, Chee Kai; Leong, Kah Fai

    2018-01-01

    Additive manufacturing has the potential to overcome the poor machinability of NiTi shape-memory alloy in fabricating smart structures of complex geometry. In recent years, a number of research activities on selective laser melting (SLM) of NiTi have been carried out to explore the optimal parameters for producing SLM NiTi with the desired phase transformation characteristics and shape-memory properties. Different effects of energy density and processing parameters on the properties of SLM NiTi were reported. In this research, a new approach—repetitive laser scanning—is introduced to meet these objectives as well. The results suggested that the laser absorptivity and heat conductivity of materials before and after the first scan significantly influence the final properties of SLM NiTi. With carefully controlled repetitive scanning process, the fabricated samples have demonstrated shape-memory effect of as high as 5.11% (with an average value of 4.61%) and exhibited comparable transformation characteristics as the NiTi powder used. These results suggest the potential for fabricating complex NiTi structures with similar properties to that of the conventionally produced NiTi parts.

  3. Fabrication of SLM NiTi Shape Memory Alloy via Repetitive Laser Scanning

    Science.gov (United States)

    Khoo, Zhong Xun; Liu, Yong; Low, Zhi Hong; An, Jia; Chua, Chee Kai; Leong, Kah Fai

    2018-03-01

    Additive manufacturing has the potential to overcome the poor machinability of NiTi shape-memory alloy in fabricating smart structures of complex geometry. In recent years, a number of research activities on selective laser melting (SLM) of NiTi have been carried out to explore the optimal parameters for producing SLM NiTi with the desired phase transformation characteristics and shape-memory properties. Different effects of energy density and processing parameters on the properties of SLM NiTi were reported. In this research, a new approach—repetitive laser scanning—is introduced to meet these objectives as well. The results suggested that the laser absorptivity and heat conductivity of materials before and after the first scan significantly influence the final properties of SLM NiTi. With carefully controlled repetitive scanning process, the fabricated samples have demonstrated shape-memory effect of as high as 5.11% (with an average value of 4.61%) and exhibited comparable transformation characteristics as the NiTi powder used. These results suggest the potential for fabricating complex NiTi structures with similar properties to that of the conventionally produced NiTi parts.

  4. Comparison of Dental Prostheses Cast and Sintered by SLM from Co-Cr-Mo-W Alloy

    Directory of Open Access Journals (Sweden)

    Myszka D.

    2016-12-01

    Full Text Available The article presents the results of a comparative analysis of the metal substructure for dental prosthesis made from a Co-Cr-Mo-W alloy by two techniques, i.e. precision investment casting and selective laser melting (SLM. It was found that the roughness of the raw surface of the SLM sinter is higher than the roughness of the cast surface, which is compensated by the process of blast cleaning during metal preparation for the application of a layer of porcelain. Castings have a dendritic structure, while SLM sinters are characterized by a compact, fine-grain microstructure of the hardness higher by about 100 HV units. High performance and high costs of implementation the SLM technology are the cause to use it for the purpose of many dental manufacturers under outsourcing rules. The result is a reduction in manufacturing costs of the product associated with dental work time necessary to scan, designing and treatment of sinter compared with the time needed to develop a substructure in wax, absorption in the refractory mass, casting, sand blasting and finishing. As a result of market competition and low cost of materials, sinter costs decrease which brings the total costs related to the construction unit making using the traditional method of casting, at far less commitment of time and greater predictability and consistent sinter quality.

  5. GEOMETRIC COMPLEXITY ANALYSIS IN AN INTEGRATIVE TECHNOLOGY EVALUATION MODEL (ITEM FOR SELECTIVE LASER MELTING (SLM#

    Directory of Open Access Journals (Sweden)

    S. Merkt

    2012-01-01

    Full Text Available

    ENGLISH ABSTRACT: Selective laser melting (SLM is becoming an economically viable choice for manufacturing complex serial parts. This paper focuses on a geometric complexity analysis as part of the integrative technology evaluation model (ITEM presented here. In contrast to conventional evaluation methodologies, the ITEM considers interactions between product and process innovations generated by SLM. The evaluation of manufacturing processes that compete with SLM is the main goal of ITEM. The paper includes a complexity analysis of a test part from Festo AG. The paper closes with a discussion of how the expanded design freedom of SLM can be used to improve company operations, and how the complexity analysis presented here can be seen as a starting point for feature-based complexity analysis..

    AFRIKAANSE OPSOMMING: Selektiewe lasersmelting word geleidelik ’n gangbare ekonomiese keuse vir die vervaar-diging van opeenvolgende komplekse onderdele. Die navorsing is toegespits op die ontleding van meetkundige kompleksiteit as ’n gedeelte van ’n integrerende tegnologiese evalueringsmodel. Gemeet teen konvensionele evalueringsmodelle behandel die genoemde metode interaksies tussen produkte- en prosesinnovasies wat gegenereer word. Die navorsing behandel ’n kompleksiteitsontleding van ’n toetsonderdeel van die firma FESTO AG. Die resultaat toon hoe kompleksiteits-analise gebruik kan word as die vertrekpunt vir eienskapsgebaseerde analise.

  6. Semi-Blind Error Resilient SLM for PAPR Reduction in OFDM Using Spread Spectrum Codes

    Science.gov (United States)

    Elhelw, Amr M.; Badran, Ehab F.

    2015-01-01

    High peak to average power ratio (PAPR) is one of the major problems of OFDM systems. Selected mapping (SLM) is a promising choice that can elegantly tackle this problem. Nevertheless, side information (SI) index is required to be transmitted which reduces the overall throughput. This paper proposes a semi-blind error resilient SLM system that utilizes spread spectrum codes for embedding the SI index in the transmitted symbols. The codes are embedded in an innovative manner which does not increase the average energy per symbol. The use of such codes allows the correction of probable errors in the SI index detection. A new receiver, which does not require perfect channel state information (CSI) for the detection of the SI index and has relatively low computational complexity, is proposed. Simulations results show that the proposed system performs well both in terms SI index detection error and bit error rate. PMID:26018504

  7. Long-Term Effects of Temperature Exposure on SLM 304L Stainless Steel

    Science.gov (United States)

    Amine, Tarak; Kriewall, Caitlin S.; Newkirk, Joseph W.

    2018-03-01

    Austenitic stainless steel is extensively used in industries that operate at elevated temperatures. This work investigates the high-temperature microstructure stability as well as elevated-temperature properties of 304L stainless steel fabricated using the selective laser melting (SLM) process. Significant microstructural changes were seen after a 400°C aging process for as little as 25 h. This dramatic change in microstructure would not be expected based on the ferrite decomposition studied in conventional 304L materials. The as-built additively manufactured alloy has much faster kinetic response to heat treatment at 400°C. An investigation of the structures which occur, the kinetics of the various transformations, and the mechanical properties is presented. The impact of this on the application of SLM 304L is discussed.

  8. Optimization and Simulation of SLM Process for High Density H13 Tool Steel Parts

    Science.gov (United States)

    Laakso, Petri; Riipinen, Tuomas; Laukkanen, Anssi; Andersson, Tom; Jokinen, Antero; Revuelta, Alejandro; Ruusuvuori, Kimmo

    This paper demonstrates the successful printing and optimization of processing parameters of high-strength H13 tool steel by Selective Laser Melting (SLM). D-Optimal Design of Experiments (DOE) approach is used for parameter optimization of laser power, scanning speed and hatch width. With 50 test samples (1×1×1cm) we establish parameter windows for these three parameters in relation to part density. The calculated numerical model is found to be in good agreement with the density data obtained from the samples using image analysis. A thermomechanical finite element simulation model is constructed of the SLM process and validated by comparing the calculated densities retrieved from the model with the experimentally determined densities. With the simulation tool one can explore the effect of different parameters on density before making any printed samples. Establishing a parameter window provides the user with freedom for parameter selection such as choosing parameters that result in fastest print speed.

  9. Semi-Blind Error Resilient SLM for PAPR Reduction in OFDM Using Spread Spectrum Codes.

    Directory of Open Access Journals (Sweden)

    Amr M Elhelw

    Full Text Available High peak to average power ratio (PAPR is one of the major problems of OFDM systems. Selected mapping (SLM is a promising choice that can elegantly tackle this problem. Nevertheless, side information (SI index is required to be transmitted which reduces the overall throughput. This paper proposes a semi-blind error resilient SLM system that utilizes spread spectrum codes for embedding the SI index in the transmitted symbols. The codes are embedded in an innovative manner which does not increase the average energy per symbol. The use of such codes allows the correction of probable errors in the SI index detection. A new receiver, which does not require perfect channel state information (CSI for the detection of the SI index and has relatively low computational complexity, is proposed. Simulations results show that the proposed system performs well both in terms SI index detection error and bit error rate.

  10. Phase-only SLM Generating Variable Patterns Applied in Optical Connection

    International Nuclear Information System (INIS)

    Liu, B H; Wu, L Y; Zhang, J

    2006-01-01

    An adaptive optical communication system is proposed. The system sends spatial information by emitting multiple variable laser beams generated from a programmable diffractive optical element (DOE): phase-only liquid crystal Spatial Light Modulator (SLM). Laser beams carrying signals are programmable by an optimal algorithm based on an iterative Fourier transformation algorithm. The system has the advantage in redundancy of signal by the means of broadcast. It can adaptively seek position and transmit information in parallel

  11. Influence of SLM on compressive response of NiTi scaffolds

    Science.gov (United States)

    Shayesteh Moghaddam, Narges; Saedi, Soheil; Amerinatanzi, Amirhesam; Jahadakbar, Ahmadreza; Saghaian, Ehsan; Karaca, Haluk; Elahinia, Mohammad

    2018-03-01

    Porous Nickel-Titanium shape memory alloys (NiTi-SMAs) have attracted much attention in biomedical applications due to their high range of pure elastic deformability (i.e., superelasticity) as well as their bone-level modulus of elasticity (E≈12-20 GPa). In recent years, Selective Laser Melting (SLM) has been used to produce complex NiTi components. The focus of this study is to investigate the superelasticity and compressive properties of SLM NiTi-SMAs. To this aim, several NiTi components with different level of porosities (32- 58%) were fabricated from Ni50.8Ti (at. %) powder via SLM PXM by Phenix/3D Systems, using optimum processing parameter (Laser power-P=250 W, scanning speed-v=1250mm/s, hatch spacing-h=120μm, layer thickness-t=30μm). To tailor the superelasticity behavior at body temperature, the samples were solution annealed and aged for 15 min at 350°C. Then, transformation temperatures (TTs), superelastic response, and cyclic behavior of NiTi samples were studied. As the porosity was increased, the irrecoverable strain was observed to be higher in the samples. At the first superelastic cycle, 3.5%, 3.5%, and 2.7% strain recovery were observed for the porosity levels of 32%, 45%, and 58%, respectively. However, after 10 cycles, the superelastic response of the samples was stabilized and full strain recovery was observed. Finally, the modulus of elasticity of dense SLM NiTi was decreased from 47 GPa to 9 GPa in the first cycle by adding 58% porosity.

  12. Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need

    Directory of Open Access Journals (Sweden)

    Albert E. Patterson

    2017-04-01

    Full Text Available A useful and increasingly common additive manufacturing (AM process is the selective laser melting (SLM or direct metal laser sintering (DMLS process. SLM/DMLS can produce full-density metal parts from difficult materials, but it tends to suffer from severe residual stresses introduced during processing. This limits the usefulness and applicability of the process, particularly in the fabrication of parts with delicate overhanging and protruding features. The purpose of this study was to examine the current insight and progress made toward understanding and eliminating the problem in overhanging and protruding structures. To accomplish this, a survey of the literature was undertaken, focusing on process modeling (general, heat transfer, stress and distortion and material models, direct process control (input and environmental control, hardware-in-the-loop monitoring, parameter optimization and post-processing, experiment development (methods for evaluation, optical and mechanical process monitoring, imaging and design-of-experiments, support structure optimization and overhang feature design; approximately 143 published works were examined. The major findings of this study were that a small minority of the literature on SLM/DMLS deals explicitly with the overhanging stress problem, but some fundamental work has been done on the problem. Implications, needs and potential future research directions are discussed in-depth in light of the present review.

  13. An Assessment of Subsurface Residual Stress Analysis in SLM Ti-6Al-4V

    Directory of Open Access Journals (Sweden)

    Tatiana Mishurova

    2017-03-01

    Full Text Available Ti-6Al-4V bridges were additively fabricated by selective laser melting (SLM under different scanning speed conditions, to compare the effect of process energy density on the residual stress state. Subsurface lattice strain characterization was conducted by means of synchrotron diffraction in energy dispersive mode. High tensile strain gradients were found at the frontal surface for samples in an as-built condition. The geometry of the samples promotes increasing strains towards the pillar of the bridges. We observed that the higher the laser energy density during fabrication, the lower the lattice strains. A relief of lattice strains takes place after heat treatment.

  14. Discrete Optimization of Internal Part Structure via SLM Unit Structure-Performance Database

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    Li Tang

    2018-01-01

    Full Text Available The structural optimization of the internal structure of parts based on three-dimensional (3D printing has been recognized as being important in the field of mechanical design. The purpose of this paper is to present a creation of a unit structure-performance database based on the selective laser melting (SLM, which contains various structural units with different functions and records their structure and performance characteristics so that we can optimize the internal structure of parts directly, according to the database. The method of creating the unit structure-performance database was introduced in this paper and several structural units of the unit structure-performance database were introduced. The bow structure unit was used to show how to create the structure-performance database of the unit as an example. Some samples of the bow structure unit were designed and manufactured by SLM. These samples were tested in the WDW-100 compression testing machine to obtain their performance characteristics. After this, the paper collected all data regarding unit structure parameters, weight, performance characteristics, and other data; and, established a complete set of data from the bow structure unit for the unit structure-performance database. Furthermore, an aircraft part was reconstructed conveniently to be more lightweight according to the unit structure-performance database. Its weight was reduced by 36.8% when compared with the original structure, while the strength far exceeded the requirements.

  15. Finite element modeling of deposition of ceramic material during SLM additive manufacturing

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    Chen Qiang

    2016-01-01

    Full Text Available A three dimensional model for material deposition in Selective Laser Melting (SLM with application to Al2O3-ZrO2 eutectic ceramic is presented. As the material is transparent to laser, dopants are added to increase the heat absorption efficiency. Based on Beer-Lambert law, a volumetric heat source model taking into account the material absorption is derived. The Level Set method with multiphase homogenization is used to track the shape of deposed bead and the thermodynamic is coupled to calculate the melting-solidification path. The shrinkage during consolidation from powder to compact medium is modeled by a compressible Newtonian constitutive law. A semi-implicit formulation of surface tension is used, which permits a stable resolution to capture the gas-liquid interface. The formation of droplets is obtained and slight waves of melt pool are observed. The influence of different process parameters on temperature distribution, melt pool profiles and bead shapes is discussed.

  16. INVESTIGATION THE FITTING ACCURACY OF CAST AND SLM CO-CR DENTAL BRIDGES USING CAD SOFTWARE

    Directory of Open Access Journals (Sweden)

    Tsanka Dikova

    2017-09-01

    Full Text Available The aim of the present paper is to investigate the fitting accuracy of Co-Cr dental bridges, manufactured by three technologies, with the newly developed method using CAD software. The four-part dental bridges of Co-Cr alloys were produced by conventional casting of wax models, casting with 3D printed patterns and selective laser melting. The marginal and internal fit of dental bridges was studied out by two methods – silicone replica test and CAD software. As the silicone replica test characterizes with comparatively low accuracy, a new methodology for investigating the fitting accuracy of dental bridges was developed based on the SolidWorks CAD software. The newly developed method allows the study of the marginal and internal adaptation in unlimited directions and high accuracy. Investigation the marginal fit and internal adaptation of Co-Cr four-part dental bridges by the two methods show that the technological process strongly influences the fitting accuracy of dental restorations. The fitting accuracy of the bridges, cast with 3D printed patterns, is the highest, followed by the SLM and conventionally cast bridges. The marginal fit of the three groups of bridges is in the clinically acceptable range. The internal gap values vary in different regions – it is highest on the occlusal surfaces, followed by that in the marginal and axial areas. The higher fitting accuracy of the bridges, manufactured by casting with 3D printed patterns and SLM, compared to the conventionally cast bridges is a good precondition for their successful implementation in the dental offices and laboratories.

  17. Beam shaping by using small-aperture SLM and DM in a high power laser

    Science.gov (United States)

    Li, Sensen; Lu, Zhiwei; Du, Pengyuan; Wang, Yulei; Ding, Lei; Yan, Xiusheng

    2018-03-01

    High-power laser plays an important role in many fields, such as directed energy weapon, optoelectronic contermeasures, inertial confinement fusion, industrial processing and scientific research. The uniform nearfield and wavefront are the important part of the beam quality for high power lasers, which is conducive to maintaining the high spatial beam quality in propagation. We demonstrate experimentally that the spatial intensity and wavefront distribution at the output is well compensated in the complex high-power solid-state laser system by using the small-aperture spatial light modulator (SLM) and deformable mirror (DM) in the front stage. The experimental setup is a hundred-Joule-level Nd:glass laser system operating at three wavelengths at 1053 nm (1ω), 527 nm (2ω) and 351 nm (3ω) with 3 ns pulse duration with the final output beam aperture of 60 mm. While the clear arperture of the electrically addressable SLM is less than 20 mm and the effective diameter of the 52-actuators DM is about 15 mm. In the beam shaping system, the key point is that the two front-stage beam shaping devices needs to precompensate the gain nonuniform and wavefront distortion of the laser system. The details of the iterative algorithm for improving the beam quality are presented. Experimental results show that output nearfield and wavefont are both nearly flat-topped with the nearfield modulation of 1.26:1 and wavefront peak-to-valley value of 0.29 λ at 1053nm after beam shaping.

  18. Design and Fabrication of a Precision Template for Spine Surgery Using Selective Laser Melting (SLM

    Directory of Open Access Journals (Sweden)

    Di Wang

    2016-07-01

    Full Text Available In order to meet the clinical requirements of spine surgery, this paper proposes the fabrication of the customized template for spine surgery through computer-aided design. A 3D metal printing-selective laser melting (SLM technique was employed to directly fabricate the 316L stainless steel template, and the metal template with tiny locating holes was used as an auxiliary tool to insert spinal screws inside the patient’s body. To guarantee accurate fabrication of the template for cervical vertebra operation, the contact face was placed upwards to improve the joint quality between the template and the cervical vertebra. The joint surface of the printed template had a roughness of Ra = 13 ± 2 μm. After abrasive blasting, the surface roughness was Ra = 7 ± 0.5 μm. The surgical metal template was bound with the 3D-printed Acrylonitrile Butadiene Styrene (ABS plastic model. The micro-hardness values determined at the cross-sections of SLM-processed samples varied from HV0.3 250 to HV0.3 280, and the measured tensile strength was in the range of 450 MPa to 560 MPa, which showed that the template had requisite strength. Finally, the metal template was clinically used in the patient’s surgical operation, and the screws were inserted precisely as the result of using the auxiliary template. The geometrical parameters of the template hole (e.g., diameter and wall thickness were optimized, and measures were taken to optimize the key geometrical units (e.g., hole units in metal 3D printing. Compared to the traditional technology of screw insertion, the use of the surgical metal template enabled the screws to be inserted more easily and accurately during spinal surgery. However, the design of the high-quality template should fully take into account the clinical demands of surgeons, as well as the advice of the designing engineers and operating technicians.

  19. Design and Fabrication of a Precision Template for Spine Surgery Using Selective Laser Melting (SLM).

    Science.gov (United States)

    Wang, Di; Wang, Yimeng; Wang, Jianhua; Song, Changhui; Yang, Yongqiang; Zhang, Zimian; Lin, Hui; Zhen, Yongqiang; Liao, Suixiang

    2016-07-22

    In order to meet the clinical requirements of spine surgery, this paper proposes the fabrication of the customized template for spine surgery through computer-aided design. A 3D metal printing-selective laser melting (SLM) technique was employed to directly fabricate the 316L stainless steel template, and the metal template with tiny locating holes was used as an auxiliary tool to insert spinal screws inside the patient's body. To guarantee accurate fabrication of the template for cervical vertebra operation, the contact face was placed upwards to improve the joint quality between the template and the cervical vertebra. The joint surface of the printed template had a roughness of Ra = 13 ± 2 μm. After abrasive blasting, the surface roughness was Ra = 7 ± 0.5 μm. The surgical metal template was bound with the 3D-printed Acrylonitrile Butadiene Styrene (ABS) plastic model. The micro-hardness values determined at the cross-sections of SLM-processed samples varied from HV0.3 250 to HV0.3 280, and the measured tensile strength was in the range of 450 MPa to 560 MPa, which showed that the template had requisite strength. Finally, the metal template was clinically used in the patient's surgical operation, and the screws were inserted precisely as the result of using the auxiliary template. The geometrical parameters of the template hole (e.g., diameter and wall thickness) were optimized, and measures were taken to optimize the key geometrical units (e.g., hole units) in metal 3D printing. Compared to the traditional technology of screw insertion, the use of the surgical metal template enabled the screws to be inserted more easily and accurately during spinal surgery. However, the design of the high-quality template should fully take into account the clinical demands of surgeons, as well as the advice of the designing engineers and operating technicians.

  20. Fatigue behaviour of NiTi shape memory alloy scaffolds produced by SLM, a unit cell design comparison.

    Science.gov (United States)

    Speirs, M; Van Hooreweder, B; Van Humbeeck, J; Kruth, J-P

    2017-06-01

    Selective laser melting (SLM) is an additive manufacturing technique able to produce complex functional parts via successively melting layers of metal powder. This process grants the freedom to design highly complex scaffold components to allow bone ingrowth and aid mechanical anchorage. This paper investigates the compression fatigue behaviour of three different unit cells (octahedron, cellular gyroid and sheet gyroid) of SLM nitinol scaffolds. It was found that triply periodic minimal surfaces display superior static mechanical properties in comparison to conventional octahedron beam lattice structures at identical volume fractions. Fatigue resistance was also found to be highly geometry dependent due to the effects of AM processing techniques on the surface topography and notch sensitivity. Geometries minimising nodal points and the staircase effect displayed the greatest fatigue resistance when normalized to yield strength. Furthermore oxygen analysis showed a large oxygen uptake during SLM processing which must be altered to meet ASTM medical grade standards and may significantly reduce fatigue life. These achieved fatigue properties indicate that NiTi scaffolds produced via SLM can provide sufficient mechanical support over an implants lifetime within stress range values experienced in real life. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The Influence of Selective Laser Melting (SLM) Process Parameters on In-Vitro Cell Response.

    Science.gov (United States)

    Wysocki, Bartłomiej; Idaszek, Joanna; Zdunek, Joanna; Rożniatowski, Krzysztof; Pisarek, Marcin; Yamamoto, Akiko; Święszkowski, Wojciech

    2018-05-30

    The use of laser 3D printers is very perspective in the fabrication of solid and porous implants made of various polymers, metals, and its alloys. The Selective Laser Melting (SLM) process, in which consolidated powders are fully melted on each layer, gives the possibility of fabrication personalized implants based on the Computer Aid Design (CAD) model. During SLM fabrication on a 3D printer, depending on the system applied, there is a possibility for setting the amount of energy density (J/mm³) transferred to the consolidated powders, thus controlling its porosity, contact angle and roughness. In this study, we have controlled energy density in a range 8⁻45 J/mm³ delivered to titanium powder by setting various levels of laser power (25⁻45 W), exposure time (20⁻80 µs) and distance between exposure points (20⁻60 µm). The growing energy density within studied range increased from 63 to 90% and decreased from 31 to 13 µm samples density and Ra parameter, respectively. The surface energy 55⁻466 mN/m was achieved with contact angles in range 72⁻128° and 53⁻105° for water and formamide, respectively. The human mesenchymal stem cells (hMSCs) adhesion after 4 h decreased with increasing energy density delivered during processing within each parameter group. The differences in cells proliferation were clearly seen after a 7-day incubation. We have observed that proliferation was decreasing with increasing density of energy delivered to the samples. This phenomenon was explained by chemical composition of oxide layers affecting surface energy and internal stresses. We have noticed that TiO₂, which is the main oxide of raw titanium powder, disintegrated during selective laser melting process and oxygen was transferred into metallic titanium. The typical for 3D printed parts post-processing methods such as chemical polishing in hydrofluoric (HF) or hydrofluoric/nitric (HF/HNO₃) acid solutions and thermal treatments were used to restore surface

  2. The Influence of Selective Laser Melting (SLM Process Parameters on In-Vitro Cell Response

    Directory of Open Access Journals (Sweden)

    Bartłomiej Wysocki

    2018-05-01

    Full Text Available The use of laser 3D printers is very perspective in the fabrication of solid and porous implants made of various polymers, metals, and its alloys. The Selective Laser Melting (SLM process, in which consolidated powders are fully melted on each layer, gives the possibility of fabrication personalized implants based on the Computer Aid Design (CAD model. During SLM fabrication on a 3D printer, depending on the system applied, there is a possibility for setting the amount of energy density (J/mm3 transferred to the consolidated powders, thus controlling its porosity, contact angle and roughness. In this study, we have controlled energy density in a range 8–45 J/mm3 delivered to titanium powder by setting various levels of laser power (25–45 W, exposure time (20–80 µs and distance between exposure points (20–60 µm. The growing energy density within studied range increased from 63 to 90% and decreased from 31 to 13 µm samples density and Ra parameter, respectively. The surface energy 55–466 mN/m was achieved with contact angles in range 72–128° and 53–105° for water and formamide, respectively. The human mesenchymal stem cells (hMSCs adhesion after 4 h decreased with increasing energy density delivered during processing within each parameter group. The differences in cells proliferation were clearly seen after a 7-day incubation. We have observed that proliferation was decreasing with increasing density of energy delivered to the samples. This phenomenon was explained by chemical composition of oxide layers affecting surface energy and internal stresses. We have noticed that TiO2, which is the main oxide of raw titanium powder, disintegrated during selective laser melting process and oxygen was transferred into metallic titanium. The typical for 3D printed parts post-processing methods such as chemical polishing in hydrofluoric (HF or hydrofluoric/nitric (HF/HNO3 acid solutions and thermal treatments were used to restore surface

  3. Observation of melting conditions in selective laser melting of metals (SLM)

    Science.gov (United States)

    Thombansen, U.; Abels, Peter

    2016-03-01

    Process observation in 3D printing of metals currently is one of the central challenges. Many companies strive to employ this additive manufacturing process in their production chains in order to gain competitive advantages through added flexibility in product design and embedded features. The new degrees of freedom are accompanied with the challenge to manufacture every detail of the product to the predefined specifications. Products with filigree internal structures for example require a perfect build to deliver the performance that was designed into these structures. Melting conditions determine properties such as grain structure and density of the finished part before it is sent to post processing steps. Monitoring of such melting conditions is still a challenge where the use of photodiodes, pyrometry and camera systems contribute to an overall picture that might identify errors or deviations during the build process. Additional considerations must be made to decide if these sensors are applied coaxially or from a lateral perspective. Furthermore, setting parameters of focal plane array (FPA) sensors are discussed and events that are seen in the machine vision image are compared against the pyrometry data. The resume of the experiments suggests the application of multiple sensors to the selective laser melting process (SLM) as they jointly contribute to an identification of events. These events need to be understood in order to establish cause effect relationships in the future.

  4. SLM Produced Porous Titanium Implant Improvements for Enhanced Vascularization and Osteoblast Seeding

    Science.gov (United States)

    Matena, Julia; Petersen, Svea; Gieseke, Matthias; Kampmann, Andreas; Teske, Michael; Beyerbach, Martin; Murua Escobar, Hugo; Haferkamp, Heinz; Gellrich, Nils-Claudius; Nolte, Ingo

    2015-01-01

    To improve well-known titanium implants, pores can be used for increasing bone formation and close bone-implant interface. Selective Laser Melting (SLM) enables the production of any geometry and was used for implant production with 250-µm pore size. The used pore size supports vessel ingrowth, as bone formation is strongly dependent on fast vascularization. Additionally, proangiogenic factors promote implant vascularization. To functionalize the titanium with proangiogenic factors, polycaprolactone (PCL) coating can be used. The following proangiogenic factors were examined: vascular endothelial growth factor (VEGF), high mobility group box 1 (HMGB1) and chemokine (C-X-C motif) ligand 12 (CXCL12). As different surfaces lead to different cell reactions, titanium and PCL coating were compared. The growing into the porous titanium structure of primary osteoblasts was examined by cross sections. Primary osteoblasts seeded on the different surfaces were compared using Live Cell Imaging (LCI). Cross sections showed cells had proliferated, but not migrated after seven days. Although the cell count was lower on titanium PCL implants in LCI, the cell count and cell spreading area development showed promising results for titanium PCL implants. HMGB1 showed the highest migration capacity for stimulating the endothelial cell line. Future perspective would be the incorporation of HMGB1 into PCL polymer for the realization of a slow factor release. PMID:25849656

  5. SLM Produced Porous Titanium Implant Improvements for Enhanced Vascularization and Osteoblast Seeding

    Directory of Open Access Journals (Sweden)

    Julia Matena

    2015-04-01

    Full Text Available To improve well-known titanium implants, pores can be used for increasing bone formation and close bone-implant interface. Selective Laser Melting (SLM enables the production of any geometry and was used for implant production with 250-µm pore size. The used pore size supports vessel ingrowth, as bone formation is strongly dependent on fast vascularization. Additionally, proangiogenic factors promote implant vascularization. To functionalize the titanium with proangiogenic factors, polycaprolactone (PCL coating can be used. The following proangiogenic factors were examined: vascular endothelial growth factor (VEGF, high mobility group box 1 (HMGB1 and chemokine (C-X-C motif ligand 12 (CXCL12. As different surfaces lead to different cell reactions, titanium and PCL coating were compared. The growing into the porous titanium structure of primary osteoblasts was examined by cross sections. Primary osteoblasts seeded on the different surfaces were compared using Live Cell Imaging (LCI. Cross sections showed cells had proliferated, but not migrated after seven days. Although the cell count was lower on titanium PCL implants in LCI, the cell count and cell spreading area development showed promising results for titanium PCL implants. HMGB1 showed the highest migration capacity for stimulating the endothelial cell line. Future perspective would be the incorporation of HMGB1 into PCL polymer for the realization of a slow factor release.

  6. A Review of the As-Built SLM Ti-6Al-4V Mechanical Properties towards Achieving Fatigue Resistant Designs

    Directory of Open Access Journals (Sweden)

    Dylan Agius

    2018-01-01

    Full Text Available Ti-6Al-4V has been widely used in both the biomedical and aerospace industry, due to its high strength, corrosion resistance, high fracture toughness and light weight. Additive manufacturing (AM is an attractive method of Ti-6Al-4V parts’ fabrication, as it provides a low waste alternative for complex geometries. With continued progress being made in SLM technology, the influence of build layers, grain boundaries and defects can be combined to improve further the design process and allow the fabrication of components with improved static and fatigue strength in critical loading directions. To initiate this possibility, the mechanical properties, including monotonic, low and high cycle fatigue and fracture mechanical behaviour, of machined as-built SLM Ti-6Al-4V, have been critically reviewed in order to inform the research community. The corresponding crystallographic phases, defects and layer orientations have been analysed to determine the influence of these features on the mechanical behaviour. This review paper intends to enhance our understanding of how these features can be manipulated and utilised to improve the fatigue resistance of components fabricated from Ti-6Al-4V using the SLM technology.

  7. On the Selective Laser Melting (SLM of the AlSi10Mg Alloy: Process, Microstructure, and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Francesco Trevisan

    2017-01-01

    Full Text Available The aim of this review is to analyze and to summarize the state of the art of the processing of aluminum alloys, and in particular of the AlSi10Mg alloy, obtained by means of the Additive Manufacturing (AM technique known as Selective Laser Melting (SLM. This process is gaining interest worldwide, thanks to the possibility of obtaining a freeform fabrication coupled with high mechanical properties related to a very fine microstructure. However, SLM is very complex, from a physical point of view, due to the interaction between a concentrated laser source and metallic powders, and to the extremely rapid melting and the subsequent fast solidification. The effects of the main process variables on the properties of the final parts are analyzed in this review: from the starting powder properties, such as shape and powder size distribution, to the main process parameters, such as laser power and speed, layer thickness, and scanning strategy. Furthermore, a detailed overview on the microstructure of the AlSi10Mg material, with the related tensile and fatigue properties of the final SLM parts, in some cases after different heat treatments, is presented.

  8. Influence of Powder Bed Preheating on Microstructure and Mechanical Properties of H13 Tool Steel SLM Parts

    Science.gov (United States)

    Mertens, R.; Vrancken, B.; Holmstock, N.; Kinds, Y.; Kruth, J.-P.; Van Humbeeck, J.

    Powder bed preheating is a promising development in selective laser melting (SLM), mainly applied to avoid large thermal stresses in the material. This study analyses the effect of in-process preheating on microstructure, mechanical properties and residual stresses during SLM of H13 tool steel. Sample parts are produced without any preheating and are compared to the corresponding parts made with preheating at 100°, 200°, 300°, and 400°C. Interestingly, internal stresses at the top surface of the parts evolve from compressive (-324MPa) without preheating to tensile stresses (371MPa) with preheating at 400°C. Nevertheless, application of powder bed preheating results in a more homogeneous microstructure with better mechanical properties compared to H13 SLM parts produced without preheating. The fine bainitic microstructure leads to hardness values of 650-700Hv and ultimate tensile strength of 1965MPa, which are comparable to or even better than those of conventionally made and heat treated H13 tool steel.

  9. On the Selective Laser Melting (SLM) of the AlSi10Mg Alloy: Process, Microstructure, and Mechanical Properties.

    Science.gov (United States)

    Trevisan, Francesco; Calignano, Flaviana; Lorusso, Massimo; Pakkanen, Jukka; Aversa, Alberta; Ambrosio, Elisa Paola; Lombardi, Mariangela; Fino, Paolo; Manfredi, Diego

    2017-01-18

    The aim of this review is to analyze and to summarize the state of the art of the processing of aluminum alloys, and in particular of the AlSi10Mg alloy, obtained by means of the Additive Manufacturing (AM) technique known as Selective Laser Melting (SLM). This process is gaining interest worldwide, thanks to the possibility of obtaining a freeform fabrication coupled with high mechanical properties related to a very fine microstructure. However, SLM is very complex, from a physical point of view, due to the interaction between a concentrated laser source and metallic powders, and to the extremely rapid melting and the subsequent fast solidification. The effects of the main process variables on the properties of the final parts are analyzed in this review: from the starting powder properties, such as shape and powder size distribution, to the main process parameters, such as laser power and speed, layer thickness, and scanning strategy. Furthermore, a detailed overview on the microstructure of the AlSi10Mg material, with the related tensile and fatigue properties of the final SLM parts, in some cases after different heat treatments, is presented.

  10. Mechanické vlastnosti slitiny AlSi9Cu3 zpracovaného technologií SLM

    OpenAIRE

    Koutný, Filip

    2017-01-01

    Tato bakalářská práce se zabývá porovnáním mechanických vlastností hliníkové slitiny AlSi9Cu3 v odlitém stavu se stavem po zpracování technologií selective laser melting (SLM). Rešeršní část práce pojednává o problematice hliníkových slitin, především o jejich rozdělení, mechanických vlastnostech, tepelné úpravě a zpracování technologií SLM. V diskuzi je řešen návrh optimálního rozsahu procesních parametrů SLM tisku a jsou porovnány mechanické vlastnosti konvenčně odlité slitiny AlSi9Cu3 se s...

  11. Technology of stable, prolonged-release eye-drops containing Cyclosporine A, distributed between lipid matrix and surface of the solid lipid microspheres (SLM).

    Science.gov (United States)

    Wolska, Eliza; Sznitowska, Małgorzata

    2013-01-30

    The aim of this study was to prepare solid lipid microspheres (SLM) with incorporated Cyclosporine A (Cs), suitable for ocular application. For this purpose, SLM were formulated by using different lipids and three different nonionic surfactants. The SLM were produced using a hot emulsification method. The SLM dispersions contained 10, 20 or 30% of lipid (w/w) and up to 2% (w/w) of Cs. The size of the microspheres with Cs ranged from 1 to 15 μm. Physically stable SLM with Cs were prepared using Compritol, as a lipid matrix, and Tween 80, as a surfactant. In contrast, dispersion with Precirol alone, formed semi-solid gels during storage, while in formulations with Precirol and Miglyol, crystals of Cs were observed. In vitro release profile of Compritol formulations showed that 40% of Cs is released within 1h, while the release of the following 40% takes more time, depending on lipid content in the formulations. The large part of Cs, added to SLM formulations (from 45 to 80%), was found on the surface of microparticles, but no drug crystallization occurred during a long-term storage. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Dimensional accuracy of internal cooling channel made by selective laser melting (SLM And direct metal laser sintering (DMLS processes in fabrication of internally cooled cutting tools

    Directory of Open Access Journals (Sweden)

    Ghani S. A. C.

    2017-01-01

    Full Text Available Selective laser melting(SLM and direct metal laser sintering(DMLS are preferred additive manufacturing processes in producing complex physical products directly from CAD computer data, nowadays. The advancement of additive manufacturing promotes the design of internally cooled cutting tool for effectively used in removing generated heat in metal machining. Despite the utilisation of SLM and DMLS in a fabrication of internally cooled cutting tool, the level of accuracy of the parts produced remains uncertain. This paper aims at comparing the dimensional accuracy of SLM and DMLS in machining internally cooled cutting tool with a special focus on geometrical dimensions such as hole diameter. The surface roughness produced by the two processes are measured with contact perthometer. To achieve the objectives, geometrical dimensions of identical tool holders for internally cooled cutting tools fabricated by SLM and DMLS have been determined by using digital vernier calliper and various magnification of a portable microscope. In the current study, comparing internally cooled cutting tools made of SLM and DMLS showed that generally the higher degree of accuracy could be obtained with DMLS process. However, the observed differences in surface roughness between SLM and DMLS in this study were not significant. The most obvious finding to emerge from this study is that the additive manufacturing processes selected for fabricating the tool holders for internally cooled cutting tool in this research are capable of producing the desired internal channel shape of internally cooled cutting tool.

  13. Implementation of PSF engineering in high-resolution 3D microscopy imaging with a LCoS (reflective) SLM

    Science.gov (United States)

    King, Sharon V.; Doblas, Ana; Patwary, Nurmohammed; Saavedra, Genaro; Martínez-Corral, Manuel; Preza, Chrysanthe

    2014-03-01

    Wavefront coding techniques are currently used to engineer unique point spread functions (PSFs) that enhance existing microscope modalities or create new ones. Previous work in this field demonstrated that simulated intensity PSFs encoded with a generalized cubic phase mask (GCPM) are invariant to spherical aberration or misfocus; dependent on parameter selection. Additional work demonstrated that simulated PSFs encoded with a squared cubic phase mask (SQUBIC) produce a depth invariant focal spot for application in confocal scanning microscopy. Implementation of PSF engineering theory with a liquid crystal on silicon (LCoS) spatial light modulator (SLM) enables validation of WFC phase mask designs and parameters by manipulating optical wavefront properties with a programmable diffractive element. To validate and investigate parameters of the GCPM and SQUBIC WFC masks, we implemented PSF engineering in an upright microscope modified with a dual camera port and a LCoS SLM. We present measured WFC PSFs and compare them to simulated PSFs through analysis of their effect on the microscope imaging system properties. Experimentally acquired PSFs show the same intensity distribution as simulation for the GCPM phase mask, the SQUBIC-mask and the well-known and characterized cubic-phase mask (CPM), first applied to high NA microscopy by Arnison et al.10, for extending depth of field. These measurements provide experimental validation of new WFC masks and demonstrate the use of the LCoS SLM as a WFC design tool. Although efficiency improvements are needed, this application of LCoS technology renders the microscope capable of switching among multiple WFC modes.

  14. Ghost imaging and ghost diffraction with pseudo-thermal light generated by means of a programmable SLM

    International Nuclear Information System (INIS)

    Capeluto, M G; Schmiegelow, C T; Francisco, D; Ledesma, S; Iemmi, C; Duisterwinkel, H

    2011-01-01

    Ghost imaging and ghost diffraction are techniques in which information about the object or about its diffraction pattern is extracted by measuring the correlation between a reference beam and a beam that passes through the object. Although first experiments were carried on by using entangled photons, it was demonstrated that this technique can be performed by splitting incoherent pseudo-thermal radiation such as that obtained with a laser passing through a moving diffuser. In this work we implemented the use of a programmable phase spatial light modulator (SLM) in order to replace the rotating ground glass. In this way the random phase distributions obtained from the moving diffuser can be emulated by displaying onto the SLM different realizations of a random function with uniform distribution. Based on the programmability of the modulator we have studied the influence of diverse parameters such as speckle size or phase distributions in the final image quality. We carry on the experiment for two different cases ghost imaging and far field ghost diffraction.

  15. Influence of Process Parameters on the Quality of Aluminium Alloy EN AW 7075 Using Selective Laser Melting (SLM)

    Science.gov (United States)

    Kaufmann, N.; Imran, M.; Wischeropp, T. M.; Emmelmann, C.; Siddique, S.; Walther, F.

    Selective laser melting (SLM) is an additive manufacturing process, forming the desired geometry by selective layer fusion of powder material. Unlike conventional manufacturing processes, highly complex parts can be manufactured with high accuracy and little post processing. Currently, different steel, aluminium, titanium and nickel-based alloys have been successfully processed; however, high strength aluminium alloy EN AW 7075 has not been processed with satisfying quality. The main focus of the investigation is to develop the SLM process for the wide used aluminium alloy EN AW 7075. Before process development, the gas-atomized powder material was characterized in terms of statistical distribution: size and shape. A wide range of process parameters were selected to optimize the process in terms of optimum volume density. The investigations resulted in a relative density of over 99%. However, all laser-melted parts exhibit hot cracks which typically appear in aluminium alloy EN AW 7075 during the welding process. Furthermore the influence of processing parameters on the chemical composition of the selected alloy was determined.

  16. Fabrication of friction-reducing texture surface by selective laser melting of ink-printed (SLM-IP) copper (Cu) nanoparticles(NPs)

    Science.gov (United States)

    Wang, Xinjian; Liu, Junyan; Wang, Yang; Fu, Yanan

    2017-02-01

    This paper reports a process of selective laser melting of ink-printed (SLM-IP) copper (Cu) nanoparticles(NPs) for the fabrication of full dense Cu friction-reducing texture on the metallic surface in ambient condition. This technique synthesizes pure Cu by chemical reduction route using an organic solvent during laser melting in the atmosphere environment, and provides a flexible additive manufacture approach to form complex friction-reduction texture on the metallic surface. Microtextures of ring and disc arrays have been fabricated on the stainless steel surface by SLM-IP Cu NPs. The friction coefficient has been measured under the lubricating condition of the oil. Disc texture surface (DTS) has a relatively low friction coefficient compared with ring texture surface (RTS), Cu film surface (Cu-FS) and the untreated substrate. The study suggests a further research on SLM-IP approach for complex microstructure or texture manufacturing, possibly realizing its advantage of flexibility.

  17. Effect of the build orientation on the mechanical properties and fracture modes of SLM Ti–6Al–4V

    Energy Technology Data Exchange (ETDEWEB)

    Simonelli, M., E-mail: M.Simonelli@lboro.ac.uk [Department of Materials, Loughborough University, Loughborough LE11 3TU (United Kingdom); Tse, Y.Y. [Department of Materials, Loughborough University, Loughborough LE11 3TU (United Kingdom); Tuck, C. [Additive Manufacturing and 3D Printing Research Group, Faculty of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2014-10-20

    Recent research on the additive manufacturing (AM) of Ti alloys has shown that the mechanical properties of the parts are affected by the characteristic microstructure that originates from the AM process. To understand the effect of the microstructure on the tensile properties, selective laser melted (SLM) Ti–6Al–4V samples built in three different orientations were tensile tested. The investigated samples were near fully dense, in two distinct conditions, as-built and stress relieved. It was found that the build orientation affects the tensile properties, and in particular the ductility of the samples. The mechanical anisotropy of the parts was discussed in relation to the crystallographic texture, phase composition and the predominant fracture mechanisms. Fractography and electron backscatter diffraction (EBSD) results indicate that the predominant fracture mechanism is intergranular fracture present along the grain boundaries and thus provide and explain the typical fracture surface features observed in fracture AM Ti–6Al–4V.

  18. Effect of the build orientation on the mechanical properties and fracture modes of SLM Ti–6Al–4V

    International Nuclear Information System (INIS)

    Simonelli, M.; Tse, Y.Y.; Tuck, C.

    2014-01-01

    Recent research on the additive manufacturing (AM) of Ti alloys has shown that the mechanical properties of the parts are affected by the characteristic microstructure that originates from the AM process. To understand the effect of the microstructure on the tensile properties, selective laser melted (SLM) Ti–6Al–4V samples built in three different orientations were tensile tested. The investigated samples were near fully dense, in two distinct conditions, as-built and stress relieved. It was found that the build orientation affects the tensile properties, and in particular the ductility of the samples. The mechanical anisotropy of the parts was discussed in relation to the crystallographic texture, phase composition and the predominant fracture mechanisms. Fractography and electron backscatter diffraction (EBSD) results indicate that the predominant fracture mechanism is intergranular fracture present along the grain boundaries and thus provide and explain the typical fracture surface features observed in fracture AM Ti–6Al–4V

  19. The effect of a lipid composition and a surfactant on the characteristics of the solid lipid microspheres and nanospheres (SLM and SLN).

    Science.gov (United States)

    Sznitowska, Malgorzata; Wolska, Eliza; Baranska, Helena; Cal, Krzysztof; Pietkiewicz, Justyna

    2017-01-01

    Solid lipid microparticles (SLM) were produced by a two-step process that, firstly, involved the emulsification of the molten lipid phase in a heated aqueous phase and, secondly, the system cooling. Compritol 888 ATO and Precirol ATO 5, including their mixtures with Miglyol 812 or Witepsol H15 were used as lipid components (10-30% w/w). The average size of the SLM prepared with Compritol and Tween 80 as an emulsifier was 3-7μm and the influence of lipid concentration and thermal sterilization was not large. Dispersions of SLM with Precirol (10-20% w/w) gellified upon storage. SLM stabilized with another surfactant, Tego Care 450, were larger in size and measured 40μm on average. The use of the sonication step (5-15min) in hot formulations containing 5% w/w of Compritol resulted in the formation of the solid lipid nanoparticles (SLN) with average size 200-300nm. The smallest SLN size (below 100nm on average) was obtained in SLN that contained Tego Care and an antimicrobial agent Euxyl PE 9010; such combination evoked synergism between the surfactant and Euxyl components. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. The analysis of the mechanical properties of F75 Co-Cr alloy for use in selective laser melting (SLM manufacturing of removable partial dentures (RPD

    Directory of Open Access Journals (Sweden)

    D. Jevremovic

    2012-04-01

    Full Text Available The presented work discusses the applicability of the selective laser melting technique (SLM in manufacture of removable partial denture (RPD frameworks with the emphasis on material properties. The paper presents initial results of a conducted test of the mechanical properties of the F75 Co-Cr dental alloy used with selective laser melting.

  1. Interfacial characterization of SLM parts in multi-material processing: Metallurgical diffusion between 316L stainless steel and C18400 copper alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Z.H., E-mail: AZHLIU@ntu.edu.sg; Zhang, D.Q., E-mail: ZHANGDQ@ntu.edu.sg; Sing, S.L., E-mail: SING0011@e.ntu.edu.sg; Chua, C.K., E-mail: MCKCHUA@ntu.edu.sg; Loh, L.E., E-mail: LELOH1@e.ntu.edu.sg

    2014-08-15

    Multi-material processing in selective laser melting using a novel approach, by the separation of two different materials within a single dispensing coating system was investigated. 316L stainless steel and UNS C18400 Cu alloy multi-material samples were produced using selective laser melting and their interfacial characteristics were analyzed using focused ion beam, scanning electron microscopy, energy dispersive spectroscopy and electron back scattered diffraction techniques. A substantial amount of Fe and Cu element diffusion was observed at the bond interface suggesting good metallurgical bonding. Quantitative evidence of good bonding at the interface was also obtained from the tensile tests where the fracture was initiated at the copper region. Nevertheless, the tensile strength of steel/Cu SLM parts was evaluated to be 310 ± 18 MPa and the variation in microhardness values was found to be gradual along the bonding interface from the steel region (256 ± 7 HV{sub 0.1}) to the copper region (72 ± 3 HV{sub 0.1}). - Highlights: • Multi-material processing was successfully implemented and demonstrated in SLM. • Bi-metallic laminates of steel/Cu were successfully produced with the SLM process. • A substantial amount of Fe and Cu diffusion was observed at the bond interface. • Good metallurgical bonding was obtained at the interface of the steel/Cu laminates. • Highly refined microstructure was obtained due to rapid solidification in SLM.

  2. Sangivamycin-Like Molecule 6 (SLM6) exhibits potent anti-multiple myeloma activity through inhibition of cyclin-dependent kinase-9 (CDK9)

    Science.gov (United States)

    Dolloff, Nathan G.; Allen, Joshua E.; Dicker, David T.; Aqui, Nicole; Vogl, Dan; Malysz, Jozef; Talamo, Giampaolo; El-Deiry, Wafik S.

    2012-01-01

    Despite significant treatment advances over the past decade, multiple myeloma (MM) remains largely incurable. In this study we found that MM cells were remarkably sensitive to the death-inducing effects of a new class of sangivamycin-like molecules (SLMs). A panel of structurally related SLMs selectively induced apoptosis in MM cells but not other tumor or non-malignant cell lines at sub-micromolar concentrations. SLM6 was the most active compound in vivo, where it was well-tolerated and significantly inhibited growth and induced apoptosis of MM tumors. We determined that the anti-MM activity of SLM6 was mediated by direct inhibition of cyclin-dependent kinase 9 (CDK9), which resulted in transcriptional repression of oncogenes that are known to drive MM progression (c-Maf, cyclin D1, and c-Myc). Furthermore, SLM6 demonstrated superior in vivo anti-MM activity over the CDK inhibitor flavopiridol, which is currently in clinical trials for MM. These findings demonstrate that SLM6 is a novel CDK9 inhibitor with promising preclinical activity as an anti-MM agent. PMID:22964485

  3. Evaluation of the Effect of Surface Finish on High-Cycle Fatigue of SLM-IN718

    Science.gov (United States)

    Lambert, D. M.

    2016-01-01

    The surface finish of parts produced by additive manufacturing processes is much rougher than the surface finish generated by machining processes, and a rougher surface can reduce the fatigue strength of a part. This paper discusses an effort to quantify that reduction of strength in high-cycle fatigue for selective laser melt (SLM) coupons. A high-cycle fatigue (HCF) knockdown factor was estimated for Inconel 718, manufactured with the SLM process. This factor is the percentage reduction from the maximum stress in fatigue for low-stress ground (LSG) specimens to the maximum stress of those left with the original surface condition at the same fatigue life. Specimens were provided by a number of vendors, free to use their "best practice"; only one heat treat condition was considered; and several test temperatures were characterized, including room temperature, 800F, 1000F, and 1200F. The 1000F data had a large variance, and was omitted from consideration in this document. A first method used linear approximations extracted from the graphs, and only where data was available for both. A recommended knockdown factor of the as-built surface condition (average roughness of approximately 245 micro-inches/inch) versus low-stress ground condition (roughness no more than 4 micro-inches/inch) was established at approximately 1/3 or 33%. This is to say that for the as-built surface condition, a maximum stress of 2/3 of the stress for LSG can be expected to produce a similar life in the as-built surface condition. In this first evaluation, the knockdown factor did not appear to be a function of temperature. A second approach, the "KP method", incorporated the surface finish measure into a new parameter termed the pseudo-stress intensity factor, Kp, which was formulated to be similar to the fracture mechanics stress intensity factor. Using Kp, the variance seemed to be reduced across all sources, and knockdown factors were estimated using Kp over the range where data occurred. A

  4. The use of rainfall simulations to assess land degradation and soil erosion produced by an SLM technology, Portugal

    Science.gov (United States)

    Soares, J.; Coelho, C.; Carvalho, T.; Oliveira, E.; Valente, S.

    2012-04-01

    Forest fires represent the main threat to sustainable forest management in Portugal. During the last fifty years, a massive depopulation took place at rural areas, developing a landscape more prone to fire. The expansion of forest and shrubland into former agricultural areas, as well as, the rapid regeneration of vegetation after fire in some areas, highlighted the need to implement several measures to protect forest and rural areas against fires. Mação municipality suffered massive fires in 2003 and 2005, where more than 70% of the municipality area has been burnt. The implementation of a forest fire prevention and mitigation technology as well as the vegetation regeneration rate was assessed at this location, under the framework of DESIRE project1. Forest is the dominant land use at Mação municipality, consisting of Pinus pinaster, with some Eucalyptus globulus and residual oak forest and shrubland. An important part was burned recently and gave way to regeneration of stands and shrubs. In 2009, the municipality started to implement an SLM (Sustainable Land Management) technology, Primary Strips Network System for Fuel Management (RPFGC). This technology is integrated in the National System to Prevent and Protect Forest against Fires and it is defined by the National Forest Authority (AFN). The RPFGC are linear strips, strategically located in areas where total or partial removal of the forest biomass is possible. This technology contributes to prevent the occurrence and spread of large forest fires and to reduce their consequences for the environment, people, infrastructures, etc . However, the removal of vegetation tends to expose bare soil to the erosive effects of rainfall. Rainfall simulations were used to assess erosive processes, such as runoff and sediment loss, in three types of land cover: pine, eucalyptus and shrubland. The results from rainfall simulations on areas inside the RPFGC showed higher results for all studied parameters, while whether or

  5. Tailoring the texture of IN738LC processed by selective laser melting (SLM) by specific scanning strategies

    Energy Technology Data Exchange (ETDEWEB)

    Geiger, Fabian [General Electric Switzerland GmbH – GE Power, CH-5401 Baden (Switzerland); Kunze, Karsten, E-mail: karsten.kunze@scopem.ethz.ch [ETH Zurich, Scientific Center of Optical and Electron Microscopy (ScopeM), CH-8093 Zürich (Switzerland); Etter, Thomas [General Electric Switzerland GmbH – GE Power, CH-5401 Baden (Switzerland)

    2016-04-20

    Selective laser melting (SLM) is an emerging technology of additive manufacturing, which is used to directly produce metallic parts from thin powder layers. This study aims at correlating laser scanning strategies with the resulting textures and corresponding anisotropy of the elastic behavior of bulk materials. Tensile test specimens made of the γ’-containing Ni-base superalloy IN738LC were built with the loading direction oriented either parallel (z-specimens) or perpendicular to the build-up direction (xy-specimens). Their bulk mechanical properties were determined at room temperature and at 850 °C. Specimens were investigated in the ‘as-built’ condition and after recrystallization heat treatment. SEM-based electron backscatter diffraction (EBSD) was applied to measure their crystallographic preferred orientations (texture) and to correlate the anisotropy of Young's modulus with the texture of the material. It is shown that the applied laser scanning strategies allow to tailor the crystallographic texture locally. The possibility to switch from transverse anisotropic to transverse isotropic properties and reverse is demonstrated for triple layered tensile samples. A recrystallization heat treatment reduces the degree of crystallographic texture and thus the elastic anisotropy by abundant annealing twinning. Predictions of Young's modulus calculated from the measured textures compare well with the data from tensile tests.

  6. Reducing the PAPR in FBMC-OQAM systems with low-latency trellis-based SLM technique

    Science.gov (United States)

    Bulusu, S. S. Krishna Chaitanya; Shaiek, Hmaied; Roviras, Daniel

    2016-12-01

    Filter-bank multi-carrier (FBMC) modulations, and more specifically FBMC-offset quadrature amplitude modulation (OQAM), are seen as an interesting alternative to orthogonal frequency division multiplexing (OFDM) for the 5th generation radio access technology. In this paper, we investigate the problem of peak-to-average power ratio (PAPR) reduction for FBMC-OQAM signals. Recently, it has been shown that FBMC-OQAM with trellis-based selected mapping (TSLM) scheme not only is superior to any scheme based on symbol-by-symbol approach but also outperforms that of the OFDM with classical SLM scheme. This paper is an extension of that work, where we analyze the TSLM in terms of computational complexity, required hardware memory, and latency issues. We have proposed an improvement to the TSLM, which requires very less hardware memory, compared to the originally proposed TSLM, and also have low latency. Additionally, the impact of the time duration of partial PAPR on the performance of TSLM is studied, and its lower bound has been identified by proposing a suitable time duration. Also, a thorough and fair comparison of performance has been done with an existing trellis-based scheme proposed in literature. The simulation results show that the proposed low-latency TSLM yields better PAPR reduction performance with relatively less hardware memory requirements.

  7. Integration of LCoS-SLM and LabVIEW based software to simulate fundamental optics, wave optics, and Fourier optics

    Science.gov (United States)

    Lyu, Bo-Han; Wang, Chen; Tsai, Chun-Wei

    2017-08-01

    Jasper Display Corp. (JDC) offer high reflectivity, high resolution Liquid Crystal on Silicon - Spatial Light Modulator (LCoS-SLM) which include an associated controller ASIC and LabVIEW based modulation software. Based on this LCoS-SLM, also called Education Kit (EDK), we provide a training platform which includes a series of optical theory and experiments to university students. This EDK not only provides a LabVIEW based operation software to produce Computer Generated Holograms (CGH) to generate some basic diffraction image or holographic image, but also provides simulation software to verity the experiment results simultaneously. However, we believe that a robust LCoSSLM, operation software, simulation software, training system, and training course can help students to study the fundamental optics, wave optics, and Fourier optics more easily. Based on these fundamental knowledges, they could develop their unique skills and create their new innovations on the optoelectronic application in the future.

  8. Country report: Vietnam. Setting Up of a 90Sr/90Y Generator System Based on Supported Liquid Membrane (SLM) Technique and Radiolabeling of Eluted 90Y with Biomolecules

    International Nuclear Information System (INIS)

    Nguyen Thi Thu; Duong Van Dong; Bui Van Cuong; Chu Van Khoa

    2010-01-01

    In the course of participating in the IAEA-CRP during the last two years, Vietnam has achieved the goal of setting up a 90 Sr/ 90 Y generator system based on Supported Liquid Membrane (SLM) technique and also radiolabeling of the eluted 90 Y with antibody, peptides and albumin. A two stage SLM based 90 Sr- 90 Y generator was set up in-house to generate carrier-free 90 Y at different activity levels viz. 5, 20, 50 mCi. The generator system was operated in sequential mode in which 2-ethylhexyl 2-ethylhexyl phosphonic acid (PC88A) based SLM was used in the first stage for the transport 90 Y in 4.0 M nitric acid from source phase where 90 Sr- 90 Y equilibrium mixture is placed in nitric acid medium at pH to 1-2. In the second stage, octyl (phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) based SLM was used for the transport of 90 Y selectively to 1.0 M acetic acid which is the best medium for radiolebeling. The eluted 90 Y from the generator was tested for the presence of any traces of 90 Sr using the Extraction Paper Chromatography (EPC) and was found suitable for radiolabeling. The generator system could be upgraded to 100 mCi level successfully due to an expert mission from India through IAEA. The 90 Y product obtained from the generator system was used for radiolabeling of antibody and peptides viz. Rituximab, DOTATATE and albumin particles under different experimental conditions. A new chromatography system could be developed for analyzing 90 Y labeled albumin using the TAE buffer as mobile phase in PC and ITLC

  9. Development of 90Sr/90Y Generator Systems Based on SLM Techniques for Radiolabelling of Therapeutic Biomolecules with 90Y. Chapter 14

    International Nuclear Information System (INIS)

    Thu, N.T.; Van Dong, D.; Van Cuong, B.; Van Khoa, C.; Cam Hoa, V.T.

    2015-01-01

    Yttrium-90 is one of the most useful radionuclides for radioimmunotherapeutic applications, especially for labelling peptides and antibodies. Studies were carried out to develop a 90 Sr/ 90 Y generator system based on the SLM technique. Two stages of 90 Sr/ 90 Y generator systems were developed at different activity levels of 5, 20, 50 and 100 mCi and operated with semiautomation in sequential mode. In the first stage of the system, PC88A based SLM was used, which transported 90 Y from a nitric acid medium containing 0.01–4M HNO 3 . In the second stage, the 90 Y from the first stage was transferred to the first compartment of the second stage using carbamoylmethyl phosphine oxide (CMPO) based SLM where 1M acetic acid was used as the receiving phase for 90 Y. Quality control was carried out for the products of 90 Y using EPC with paper chromatography and Tec control chromatography. Peptides and antibodies were labelled using the 90 Y product obtained from the generator developed in house. (author)

  10. Comparison of mechanical properties and microstructural characterization of CoCrMo alloy obtained via selective laser melting (SLM) and casting techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mergulhao, Marcello Vertamatti; Podesta, Carlos Eduardo; Neves, Mauricio David Martins das, E-mail: marcellovertamatti@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2016-07-01

    Full text: Advances in processes using the powder metallurgy techniques are making this technology competitive compared to the other traditional manufacturing processes, especially in medicine area. The additive manufacturing technique - selective laser melting (SLM) was applied in a biomaterial of CoCrMo alloy (ASTM F75), to study the mechanical properties and microstructural characterization in comparison between the conventional technique - lost wax casting. The gas atomized powder was investigated by their physical (as apparent density, bulk density and flow rate) and the chemical properties (SEM-EDS and X-ray fluorescence). Specimens of standard samples were manufactured using these techniques to evaluate the mechanical properties as yield strength, maximum tensile, rupture tensile, elongation, elastic modulus, transverse rupture strength and the Vickers hardness. Before the mechanical tests the microstructure of specimens were examined using optical microscope (OM) and SEM-EDS. The results of mechanical properties showed a higher values in the SLM specimens compared with the obtained in the cast specimens. The micrographs revealed a typical morphology of consolidation process, like as the characterized by selected layer used in the SLM technique and the primary and secondary dendrites arms in the casting technique. (author)

  11. Microstructure, mechanical property and metal release of As-SLM CoCrW alloy under different solution treatment conditions.

    Science.gov (United States)

    Lu, Yanjin; Wu, Songquan; Gan, Yiliang; Zhang, Shuyuan; Guo, Sai; Lin, Junjie; Lin, Jinxin

    2015-03-01

    In the study, the microstructure, mechanical property and metal release behavior of selective laser melted CoCrW alloys under different solution treatment conditions were systemically investigated to assess their potential use in orthopedic implants. The effects of the solution treatment on the microstructure, mechanical properties and metal release were systematically studied by OM, SEM, XRD, tensile test, and ICP-AES, respectively. The XRD indicated that during the solution treatment the alloy underwent the transformation of γ-fcc to ε-hcp phase; the ε-hcp phase nearly dominated in the alloy when treated at 1200°C following the water quenching; the results from OM, SEM showed that the microstructural change was occurred under different solution treatments; solution at 1150°C with furnace cooling contributed to the formation of larger precipitates at the grain boundary regions, while the size and number of the precipitates was decreased as heated above 1100°C with the water quenching; moreover, the diamond-like structure was invisible at higher solution temperature over 1150°C following water quenching; compared with the furnace cooling, the alloy quenched by water showed excellent mechanical properties and low amount of metal release; as the alloy heated at 1200°C, the mechanical properties of the alloy reached their optimum combination at UTS=1113.6MPa, 0.2%YS=639.5MPa, and E%=20.1%, whilst showed the lower total quantity of metal release. It is suggested that a proper solution treatment is an efficient strategy for improving the mechanical properties and corrosion resistance of As-SLM CoCrW alloy that show acceptable tensile ductility. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Recovery Of Chromium Metal (VI) Using Supported Liquid Membrane (SLM) Method, A study of Influence of NaCl and pH in Receiving Phase on Transport

    Science.gov (United States)

    Cholid Djunaidi, Muhammad; Lusiana, Retno A.; Rahayu, Maya D.

    2017-06-01

    Chromium metal(VI) is a valuable metal but in contrary has high toxicity, so the separation and recovery from waste are very important. One method that can be used for the separation and recovery of chromium (VI) is a Supported Liquid Membrane (SLM). SLM system contains of three main components: a supporting membrane, organic solvents and carrier compounds. The supported Membrane used in this research is Polytetrafluoroethylene (PTFE), organic solvent is kerosene, and the carrier compound used is aliquat 336. The supported liquid membrane is placed between two phases, namely, feed phase as the source of analyte (Cr(VI)) and the receiving phase as the result of separation. Feed phase is the electroplating waste which contains of chromium metal with pH variation about 4, 6 and 9. Whereas the receiving phase are the solution of HCl, NaOH, HCl-NaCl and NaOH-NaCl with pH variation about 1, 3, 5 and 7. The efficiency separation is determined by measurement of chromium in the feed and the receiving phase using AAS (Atomic Absorption Spectrophotometry). The experiment results show that transport of Chrom (VI) by Supported Liquid membrane (SLM) is influenced by pH solution in feed phase and receiving phase as well as NaCl in receiving phase. The highest chromium metal is transported from feed phase about 97,78%, whereas in receiving phase shows about 58,09%. The highest chromium metal transport happens on pH 6 in feed phase, pH 7 in receiving phase with the mixture of NaOH and NaCl using carrier compound aliquat 336.

  13. Trinary arithmetic and logic unit (TALU) using savart plate and spatial light modulator (SLM) suitable for optical computation in multivalued logic

    Science.gov (United States)

    Ghosh, Amal K.; Bhattacharya, Animesh; Raul, Moumita; Basuray, Amitabha

    2012-07-01

    Arithmetic logic unit (ALU) is the most important unit in any computing system. Optical computing is becoming popular day-by-day because of its ultrahigh processing speed and huge data handling capability. Obviously for the fast processing we need the optical TALU compatible with the multivalued logic. In this regard we are communicating the trinary arithmetic and logic unit (TALU) in modified trinary number (MTN) system, which is suitable for the optical computation and other applications in multivalued logic system. Here the savart plate and spatial light modulator (SLM) based optoelectronic circuits have been used to exploit the optical tree architecture (OTA) in optical interconnection network.

  14. A flexible method for residual stress measurement of spray coated layers by laser made hole drilling and SLM based beam steering

    Science.gov (United States)

    Osten, W.; Pedrini, G.; Weidmann, P.; Gadow, R.

    2015-08-01

    A minimum invasive but high resolution method for residual stress analysis of ceramic coatings made by thermal spraycoating using a pulsed laser for flexible hole drilling is described. The residual stresses are retrieved by applying the measured surface data for a model-based reconstruction procedure. While the 3D deformations and the profile of the machined area are measured with digital holography, the residual stresses are calculated by FE analysis. To improve the sensitivity of the method, a SLM is applied to control the distribution and the shape of the holes. The paper presents the complete measurement and reconstruction procedure and discusses the advantages and challenges of the new technology.

  15. Tunable and switchable dual-wavelength single polarization narrow linewidth SLM erbium-doped fiber laser based on a PM-CMFBG filter.

    Science.gov (United States)

    Yin, Bin; Feng, Suchun; Liu, Zhibo; Bai, Yunlong; Jian, Shuisheng

    2014-09-22

    A tunable and switchable dual-wavelength single polarization narrow linewidth single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser based on polarization-maintaining chirped moiré fiber Bragg grating (PM-CMFBG) filter is proposed and demonstrated. For the first time as we know, the CMFBG inscribed on the PM fiber is applied for the wavelength-tunable and-switchable dual-wavelength laser. The PM-CMFBG filter with ultra-narrow transmission band (0.1 pm) and a uniform polarization-maintaining fiber Bragg grating (PM-FBG) are used to select the laser longitudinal mode. The stable single polarization SLM operation is guaranteed by the PM-CMFBG filter and polarization controller. A tuning range of about 0.25 nm with about 0.075 nm step is achieved by stretching the uniform PM-FBG. Meanwhile, the linewidth of the fiber laser for each wavelength is approximate 6.5 and 7.1 kHz with a 20 dB linewidth, which indicates the laser linewidth is approximate 325 Hz and 355 Hz FWHM.

  16. Study on Topology Optimization Design, Manufacturability, and Performance Evaluation of Ti-6Al-4V Porous Structures Fabricated by Selective Laser Melting (SLM).

    Science.gov (United States)

    Xu, Yangli; Zhang, Dongyun; Zhou, Yan; Wang, Weidong; Cao, Xuanyang

    2017-09-07

    The combination of topology optimization (TOP) and selective laser melting (SLM) provides the possibility of fabricating the complex, lightweight and high performance geometries overcoming the traditional manufacturing "bottleneck". This paper evaluates the biomechanical properties of porous structures with porosity from 40% to 80% and unit cell size from 2 to 8 mm, which are designed by TOP and manufactured by SLM. During manufacturability exploration, three typical structures including spiral structure, arched bridge structure and structures with thin walls and small holes are abstracted and investigated, analyzing their manufacturing limits and forming reason. The property tests show that dynamic elastic modulus and compressive strength of porous structures decreases with increases of porosity (constant unit cell size) or unit cell size (constant porosity). Based on the Gibson-Ashby model, three failure models are proposed to describe their compressive behavior, and the structural parameter λ is used to evaluate the stability of the porous structure. Finally, a numerical model for the correlation between porous structural parameters (unit cell size and porosity) and elastic modulus is established, which provides a theoretical reference for matching the elastic modulus of human bones from different age, gender and skeletal sites during innovative medical implant design and manufacturing.

  17. Structural Properties of EB-Welded AlSi10Mg Thin-Walled Pressure Vessels Produced by AM-SLM Technology

    Science.gov (United States)

    Nahmany, Moshe; Stern, Adin; Aghion, Eli; Frage, Nachum

    2017-10-01

    Additive manufacturing of metals by selective laser melting (AM-SLM) is hampered by significant limitations in product size due to the limited dimensions of printing trays. Electron beam welding (EBW) is a well-established process that results in relatively minor metallurgical modifications in workpieces due to the ability of EBW to pass high-density energy to the related substance. The present study aims to evaluate structural properties of EB-welded AlSi10Mg thin-walled pressure vessels produced from components prepared by SLM technology. Following the EB welding process, leak and burst tests were conducted, as was fractography analysis. The welded vessels showed an acceptable holding pressure of 30 MPa, with a reasonable residual deformation up to 2.3% and a leak rate better than 1 × 10-8 std-cc s-1 helium. The failures that occurred under longitudinal stresses reflected the presence of two weak locations in the vessels, i.e., the welded joint region and the transition zone between the vessel base and wall. Fractographic analysis of the fracture surfaces of broken vessels displayed the ductile mode of the rupture, with dimples of various sizes, depending on the failure location.

  18. Development and optimisation of process parameters for recovery of uranium from calcia slag and lining material (SLM) by leaching process and subsequent recovery of uranium from the leach liquor generated

    International Nuclear Information System (INIS)

    Verma, Dinesh Kumar; Srivastava, Praveen Kumar; Das, Santanu; Kumar, Raj; Roy, S.B.

    2014-01-01

    Presently uranium value is recovered by nitric acid dissolution of the SLM, to get uranyl nitrate solution (UNS) and subsequent solvent extraction process. UNS generated After SLM dissolution is very lean in uranium content and create difficulty in solvent extraction. Moreover, NO X is also generated during SLM dissolution in nitric acid. An alternate process was developed where nitric acid is not being used and uranium is being recovered by leaching out the SLM using acetic acid. The process was also optimised for recovery and overall economics of the process by using process effluent AALL (Acetic Acid Leach Liquor) as a leaching agent. The uranium value in the leach liquor was precipitated by using sodium hydroxide. The precipitate was dissolved in nitric acid and the Uranyl Nitrate Solution generated was having Uranium concentration of 15-30 g/l. The alternate process developed will have less effluent generation, less NO X generation and will produce more concentrated UNS in comparison to the nitric acid dissolution process

  19. 90Y and 90Sr separation from hydrochloric acid solutions using TODGA as the extractant by solvent extraction and SLM methods

    International Nuclear Information System (INIS)

    Dutta, S.; Raut, D.R.; Mohapatra, P.K.; Manchanda, V.K.

    2010-01-01

    Yttrium-90 is an important radionuclide known for its therapeutic application in nuclear medicine. It is a pure β-emitter with no associated gamma rays and decays to stable daughter 90 Zr. Suitability of this isotope is because of its short half-life (t 1/2 = 64.2 hrs) and high β emissions (E max = 2.28 MeV. An important source of 90 Y is through the decay of 90 Sr, which produces carrier free isotope. 90 Sr (t 1/2 28 yrs) attains secular equilibrium with 90 Y in a short period and can serve as a long term source for the latter isotope because of relatively long half-life of the parent isotope. Solvent extraction studies with N,N,N',N'-tetra-octyldiglycolamide (TODGA) has shown that Y(III) is well extracted in 6 M HCI while at the same time, extraction of Sr(II) is very low leading to a separation factor (D Y /D Sr = 60,000). This property of TODGA can be exploited for the separation of Y from Sr. In the present work, Supported Liquid Membrane (SLM) based separation of Y and Sr has been explored using TODGA as the carrier

  20. Country report: Vietnam. Setting Up of a {sup 90}Sr/{sup 90}Y Generator System Based on Supported Liquid Membrane (SLM) Technique and Radiolabeling of Eluted {sup 90}Y with Biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Thu, Nguyen Thi; Dong, Duong Van; Cuong, Bui Van; Khoa, Chu Van [Vietnam Atomic Energy Commission (VAEC), Nuclear Research Institute, Dalat (Viet Nam)

    2010-07-01

    In the course of participating in the IAEA-CRP during the last two years, Vietnam has achieved the goal of setting up a {sup 90}Sr/{sup 90}Y generator system based on Supported Liquid Membrane (SLM) technique and also radiolabeling of the eluted {sup 90}Y with antibody, peptides and albumin. A two stage SLM based {sup 90}Sr-{sup 90}Y generator was set up in-house to generate carrier-free {sup 90}Y at different activity levels viz. 5, 20, 50 mCi. The generator system was operated in sequential mode in which 2-ethylhexyl 2-ethylhexyl phosphonic acid (PC88A) based SLM was used in the first stage for the transport {sup 90}Y in 4.0 M nitric acid from source phase where {sup 90}Sr-{sup 90}Y equilibrium mixture is placed in nitric acid medium at pH to 1-2. In the second stage, octyl (phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) based SLM was used for the transport of {sup 90}Y selectively to 1.0 M acetic acid which is the best medium for radiolebeling. The eluted {sup 90}Y from the generator was tested for the presence of any traces of {sup 90}Sr using the Extraction Paper Chromatography (EPC) and was found suitable for radiolabeling. The generator system could be upgraded to 100 mCi level successfully due to an expert mission from India through IAEA. The {sup 90}Y product obtained from the generator system was used for radiolabeling of antibody and peptides viz. Rituximab, DOTATATE and albumin particles under different experimental conditions. A new chromatography system could be developed for analyzing {sup 90}Y labeled albumin using the TAE buffer as mobile phase in PC and ITLC.

  1. The potential for SLM, facing human constraints, the case of the semi-arid agro-pastoral lands in the Atlantic plateaus, Morocco

    Science.gov (United States)

    Laouina, A.; Chaker, M.; Aderghal, M.; Machouri, N.; Alkarkouri, J.

    2012-04-01

    The agro-pastoral activity through its evolution, in the Atlantic plateaus of Morocco, led to unsuitable forms of resources use, which carried damage in the balance of water and the stability of land. It was thus necessary to start a revision of these practices and to set up improved forms of land use. The research made in the framework of the DESIRE project concerns the Sehoul commune, which presents a high rate of poverty and illiteracy, in spite of its location near Rabat, the capital of the country. Farming has as main objective to feed the livestock. The rain-based cereal cultivations, which still occupy more than 80% of the agricultural surface, reveals the stagnation of the techniques adopted and of the local knowledge. In collaboration with various stakeholders, technicians and farmers, the assessment with the WOCAT approach permitted to identify the main factors of constraints, responsible of the current spreading of land degradation mechanisms (forest clearing, shrubs cutting on the pastoral slopes, soil erosion, constitution of rills in the recently ploughed fields, incision of gullies and channels, mass movements on the banks of the deepest channels). These constraints derive from social evolution of the population during the last 60 years and mainly the rapid transformation of the rural structure of families to a new kind of farmers, more interested by what they can earn during their frequent movements to the city than by their own traditional agriculture. Due to the penetration of urban investment, direct overgrazing and indirect effect related to mismanagement of land for fodder production, operate massive damages to the vegetation cover and to the soil. It is why the SLM behavior, approaches and techniques have a very low rate of chance for success, without a deep change in term of land ownership, law constraints, agrarian structures, relations between the city and its vicinity, etc. Scenarios were built, based on various rates of land management

  2. Electropolishing of Re-melted SLM Stainless Steel 316L Parts Using Deep Eutectic Solvents: 3 × 3 Full Factorial Design

    Science.gov (United States)

    Alrbaey, K.; Wimpenny, D. I.; Al-Barzinjy, A. A.; Moroz, A.

    2016-07-01

    This three-level three-factor full factorial study describes the effects of electropolishing using deep eutectic solvents on the surface roughness of re-melted 316L stainless steel samples produced by the selective laser melting (SLM) powder bed fusion additive manufacturing method. An improvement in the surface finish of re-melted stainless steel 316L parts was achieved by optimizing the processing parameters for a relatively environmentally friendly (`green') electropolishing process using a Choline Chloride ionic electrolyte. The results show that further improvement of the response value-average surface roughness ( Ra) can be obtained by electropolishing after re-melting to yield a 75% improvement compared to the as-built Ra. The best Ra value was less than 0.5 μm, obtained with a potential of 4 V, maintained for 30 min at 40 °C. Electropolishing has been shown to be effective at removing the residual oxide film formed during the re-melting process. The material dissolution during the process is not homogenous and is directed preferentially toward the iron and nickel, leaving the surface rich in chromium with potentially enhanced properties. The re-melted and polished surface of the samples gave an approximately 20% improvement in fatigue life at low stresses (approximately 570 MPa). The results of the study demonstrate that a combination of re-melting and electropolishing provides a flexible method for surface texture improvement which is capable of delivering a significant improvement in surface finish while holding the dimensional accuracy of parts within an acceptable range.

  3. Digital mode selection using an intracavity SLM

    CSIR Research Space (South Africa)

    Burger, L

    2012-07-01

    Full Text Available stream_source_info Burger_2012.pdf.txt stream_content_type text/plain stream_size 6646 Content-Encoding ISO-8859-1 stream_name Burger_2012.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Digital mode selection using... HoloEye HEO1080P as well as with the newer generation Hamamatsu X10468 SLMs. See comparison in Table 1. Nevertheless, we have demonstrated that this device can be used to digitally select for a number of transverse and radial modes. The advantage...

  4. Development of scanning holographic display using MEMS SLM

    Science.gov (United States)

    Takaki, Yasuhiro

    2016-10-01

    Holography is an ideal three-dimensional (3D) display technique, because it produces 3D images that naturally satisfy human 3D perception including physiological and psychological factors. However, its electronic implementation is quite challenging because ultra-high resolution is required for display devices to provide sufficient screen size and viewing zone. We have developed holographic display techniques to enlarge the screen size and the viewing zone by use of microelectromechanical systems spatial light modulators (MEMS-SLMs). Because MEMS-SLMs can generate hologram patterns at a high frame rate, the time-multiplexing technique is utilized to virtually increase the resolution. Three kinds of scanning systems have been combined with MEMS-SLMs; the screen scanning system, the viewing-zone scanning system, and the 360-degree scanning system. The screen scanning system reduces the hologram size to enlarge the viewing zone and the reduced hologram patterns are scanned on the screen to increase the screen size: the color display system with a screen size of 6.2 in. and a viewing zone angle of 11° was demonstrated. The viewing-zone scanning system increases the screen size and the reduced viewing zone is scanned to enlarge the viewing zone: a screen size of 2.0 in. and a viewing zone angle of 40° were achieved. The two-channel system increased the screen size to 7.4 in. The 360-degree scanning increases the screen size and the reduced viewing zone is scanned circularly: the display system having a flat screen with a diameter of 100 mm was demonstrated, which generates 3D images viewed from any direction around the flat screen.

  5. Eigenmode multiplexing with SLM for volume holographic data storage

    Science.gov (United States)

    Chen, Guanghao; Miller, Bo E.; Takashima, Yuzuru

    2017-08-01

    The cavity supports the orthogonal reference beam families as its eigenmodes while enhancing the reference beam power. Such orthogonal eigenmodes are used as additional degree of freedom to multiplex data pages, consequently increase storage densities for volume Holographic Data Storage Systems (HDSS) when the maximum number of multiplexed data page is limited by geometrical factor. Image bearing holograms are multiplexed by orthogonal phase code multiplexing via Hermite-Gaussian eigenmodes in a Fe:LiNbO3 medium with a 532 nm laser at multiple Bragg angles by using Liquid Crystal on Silicon (LCOS) spatial light modulators (SLMs) in reference arms. Total of nine holograms are recorded with three angular and three eigenmode.

  6. An efficient architecture for LVQ-SLM for PAPR reduction

    International Nuclear Information System (INIS)

    Khalid, S.; Yasin, M.

    2010-01-01

    In this paper we propose an efficient architecture for the implementation of a LVQ (Learning Vector Quantization)NN (Neural Network), used as a classifier, for PAPR (Peak to Average Power Ratio) reduction. A special feature of the implementation is a combinatorial module for nearest neighbor search that allows online execution of this important operation during classification. The LVQ classifier is programmed in Verilog and the entire circuit is synthesized on FPGAs (Field Programmable Gate Arrays) using Xilinx at the rate ISE (Integrated Software Environment) 8.1i. The model is implemented with 64 sub carriers, considering the parametric values of WLANs standard IEEE 802.11a. Using the architecture, efficient on-line classification is achieved. (author)

  7. Using stochastic language models (SLM) to map lexical, syntactic, and phonological information processing in the brain.

    Science.gov (United States)

    Lopopolo, Alessandro; Frank, Stefan L; van den Bosch, Antal; Willems, Roel M

    2017-01-01

    Language comprehension involves the simultaneous processing of information at the phonological, syntactic, and lexical level. We track these three distinct streams of information in the brain by using stochastic measures derived from computational language models to detect neural correlates of phoneme, part-of-speech, and word processing in an fMRI experiment. Probabilistic language models have proven to be useful tools for studying how language is processed as a sequence of symbols unfolding in time. Conditional probabilities between sequences of words are at the basis of probabilistic measures such as surprisal and perplexity which have been successfully used as predictors of several behavioural and neural correlates of sentence processing. Here we computed perplexity from sequences of words and their parts of speech, and their phonemic transcriptions. Brain activity time-locked to each word is regressed on the three model-derived measures. We observe that the brain keeps track of the statistical structure of lexical, syntactic and phonological information in distinct areas.

  8. Studies on the transport of actinides and lanthanides through DHDECMPO based supported liquid membranes (SLM)

    Energy Technology Data Exchange (ETDEWEB)

    Dudwadkar, N.L.; Tripathi, S.C.; Gandhi, P.M. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Fuel Reprocessing Div.

    2013-07-01

    This paper describes our studies on the partitioning of actinides from high level liquid waste of PUREX origin employing a supported liquid membrane technique. The process uses a solution of DHDECMPO in n-dodecane as a carrier with poly tetra fluoro ethylene support and a mixture of citric acid, formic acid and hydrazine hydrate as a receiving phase. Transport studies are carried out for {sup 241}Am under different experimental conditions to optimize the transport parameters such as feed acidity, carrier concentration and effect of uranium, Nd(III) and salt concentration in the feed. Studies indicated good transport of neptunium, americium and plutonium across the membrane from a nitric acid medium. Under the optimized conditions the transport of {sup 241}Am has been studied for uranium depleted synthetic PHWR-HLW and finally the technique is used for the partitioning of alpha emitters from an actual HLW after reprocessing. A high concentration of uranium in the feed is found to retard the transport of americium, suggesting the need of prior removal of uranium from the waste. Separation of actinides from uranium-lean simulated as well as actual HLW has been found to be feasible using the above described technique. (orig.)

  9. Design and Manufacture of Customised Denture Frameworks Using Magics®/Autofab® and SLM

    OpenAIRE

    Kutiyal, S.; Moroz, Adam; Attenborough, E.; Alrbaey, K.

    2013-01-01

    Layer additive manufacturing technologies are progressing from rapid prototyping and rapid tooling. The development of finished parts made of metal powders without post processing is especially suitable for creation of precision part/object from small to mass customized fabrication; hence is the key application of these technologies. Laser based layer manufacturing techniques are mostly preferred in medical industry, particularly in the manufacture of denture frameworks; since these need to g...

  10. SLM processing-microstructure-mechanical property correlation in an aluminum alloy produced by additive manufacturing

    Science.gov (United States)

    Alejos, Martin Fernando

    Additive manufacturing has become a highly researched topic in recent years all over the world. The current research evaluates the merits of additive manufacturing based on the mechanical, microstructural, and fracture properties of additive manufactured AlSi10Mg test specimens. The additive manufactured build plates consisted of tensile and fatigue test specimens. They were printed in the 0°, 30°, 60°, and 90° orientations relative to the build platform. Tensile and dynamic fatigue tests were conducted followed by microstructural characterization and fracture analysis. A wrought 6061 T6 aluminum alloy was also tested for comparison. Tensile tests revealed similar ultimate tensile strengths for all aluminum tensile specimens (350-380 MPa). Fatigue strength was greatest for wrought 6061 T6 aluminum (175 MPa). The fatigue behavior was a strong function of build orientation for the additive manufactured specimens. The 0°, 30°, and 60° orientations had fatigue strengths close to 104 MPa while the 90° orientation had a fatigue strength of 125 MPa. All test specimens failed primarily in a ductile manner. The effect of laser power, hatch spacing, and scan speed were also studied using microstructural analysis. Increasing laser power decreased grain size and void size. Increasing scan speed led to the formation of columnar grains. Increasing hatch spacing decreased grain size and the amount of voids present in the microstructure.

  11. Studies of magnetic properties of permalloy (Fe-30%Ni) prepared by SLM technology

    International Nuclear Information System (INIS)

    Zhang Baicheng; Fenineche, Nour-Eddine; Zhu Lin; Liao Hanlin; Coddet, Christian

    2012-01-01

    In the present study, a high permeability induction Fe-30%Ni alloy cubic bulk was prepared by the selective laser melting process. In order to reveal the microstructure effect on soft magnetic properties, the microstructure and magnetic properties of the Fe-30%Ni alloy were carefully investigated by scanning electron microscopy, X-ray diffraction and hysteresis measurements. The bcc-Fe (Ni) phase formation is identified by X-ray diffraction. Meanwhile, it was found that low bcc lattice parameter and high grain size could be obtained when high laser scanning velocity and low laser power were used. Moreover, the lowest value of coercivity is 88 A/m, and the highest value of saturation magnetization is 565 Am 2 /kg, which can be obtained at a low laser scanning velocity of 0.4 m/s and high laser power input at 110 W. - Highlights: → Proper Fe-30%Ni alloy (permalloy) using selective laser melting technology. → Microstructure of Fe-30%Ni alloy exhibits fine cellular structure of approximately 100 nm. → Magnetic properties can be controlled by laser parameter. → Lowest coercivity is 88 A/m and highest saturation magnetization is 565 Am 2 /kg.

  12. Quantification of a bacterial secondary metabolite by SERS combined with SLM extraction for bioprocess monitoring

    DEFF Research Database (Denmark)

    Morelli, Lidia; Andreasen, Sune Zoëga; Jendresen, Christian Bille

    2017-01-01

    and combined it with surface enhanced Raman scattering (SERS) sensing for the screening of a biological process, namely for the quantification of a bacterial secondary metabolite, p-coumaric acid (pHCA), produced by Escherichia coli. The microfluidic device proved to be robust and reusable, enabling efficient...... removal of interfering compounds from the real samples, reaching more than 13-fold up-concentration of the donor at 10 μL min-1 flow rate. With this method, we quantified pHCA directly from the bacterial supernatant, distinguishing between various culture conditions based on the pHCA production yield...

  13. Physics-based selection of SLM process parameters to mitigate defects and to control deposit microstructure, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The research objectives of this proposal are to: (1) To adapt the thermal-fluid science procedures for the prediction of weld defects to the prediction and control...

  14. Control of Variability in the Performance of Selective Laser Melting (SLM) Parts through Microstructure Control and Design

    Data.gov (United States)

    National Aeronautics and Space Administration — The high variability and low repeatability of metal parts produced using Additive Manufacturing (AM) represent a major barrier in getting AM into the mainstream....

  15. Refractive microlensarray made of silver-halide sensitized gelatin (SHSG) etched by enzyme with SLM-based lithography

    Science.gov (United States)

    Guo, Xiaowei; Chen, Mingyong; Zhu, Jianhua; Ma, Yanqin; Du, Jinglei; Guo, Yongkang; Du, Chunlei

    2006-01-01

    A novel method for the fabrication of continuous micro-optical components is presented in this paper. It employs a computer controlled digital-micromirror-device(DMD TM) as a switchable projection mask and silver-halide sensitized gelatin (SHSG) as recording material. By etching SHSG with enzyme solution, the micro-optical components with relief modulation can be generated through special processing procedures. The principles of etching SHSG with enzyme and theoretical analysis for deep etching are also discussed in detail, and the detailed quantitative experiments on the processing procedures are conducted to determine optimum technique parameters. A good linear relationship within a depth range of 4μm was experimentally obtained between exposure dose and relief depth. At last, the microlensarray with 256.8μm radius and 2.572μm depth was achieved. This method is simple, cheap and the aberration in processing procedures can be corrected in the step of designing mask, so it is a practical method to fabricate good continuous profile for low-volume production.

  16. A Low-Cost Method for Coating of Selective Laser Melting (SLM) Manufacturing of Complex High-Precision Components for Spaceflight Applications Using Atomic Layer Deposition (ALD), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is intended to perform basic research using Atomic Layer Deposition (ALD) as a means of coating various substrate materials with a variety of metallic...

  17. Surface chemistry of Ti6Al4V components fabricated using selective laser melting for biomedical applications.

    Science.gov (United States)

    Vaithilingam, Jayasheelan; Prina, Elisabetta; Goodridge, Ruth D; Hague, Richard J M; Edmondson, Steve; Rose, Felicity R A J; Christie, Steven D R

    2016-10-01

    Selective laser melting (SLM) has previously been shown to be a viable method for fabricating biomedical implants; however, the surface chemistry of SLM fabricated parts is poorly understood. In this study, X-ray photoelectron spectroscopy (XPS) was used to determine the surface chemistries of (a) SLM as-fabricated (SLM-AF) Ti6Al4V and (b) SLM fabricated and mechanically polished (SLM-MP) Ti6Al4V samples and compared with (c) traditionally manufactured (forged) and mechanically polished Ti6Al4V samples. The SLM-AF surface was observed to be porous with an average surface roughness (Ra) of 17.6±3.7μm. The surface chemistry of the SLM-AF was significantly different to the FGD-MP surface with respect to elemental distribution and their existence on the outermost surface. Sintered particles on the SLM-AF surface were observed to affect depth profiling of the sample due to a shadowing effect during argon ion sputtering. Surface heterogeneity was observed for all three surfaces; however, vanadium was witnessed only on the mechanically polished (SLM-MP and FGD-MP) surfaces. The direct and indirect 3T3 cell cytotoxicity studies revealed that the cells were viable on the SLM fabricated Ti6Al4V parts. The varied surface chemistry of the SLM-AF and SLM-MP did not influence the cell behaviour. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  18. Devolution: A mechanism for scaling adoption of sustainable land ...

    African Journals Online (AJOL)

    Sustainable Land Management (SLM) technologies are known to improve food ... mechanisms for mitigation of this land degradation have been developed, but ... of SLM innovations is a crucial aspect for evaluating the devolution process.

  19. Some thoughts on policy and desertification: what key contributions ...

    African Journals Online (AJOL)

    This paper uses practical examples of important desertification policy processes and measures that integrate critical science information, including examples on setting sustainable land management (SLM) standards, developing land-use planning frameworks, and establishing SLM monitoring and evaluation systems.

  20. Solidified reverse micellar solutions (SRMS): A novel approach for ...

    African Journals Online (AJOL)

    AMARA

    The types of SRMS-based drug delivery systems include solid lipid nanoparticles (SLN), solid lipid microparticles (SLM), tablets and suppositories amongst others. The work ..... based SLM for intramuscular administration of gentamicin.

  1. 75 FR 6233 - Self-Regulatory Organizations; NASDAQ OMX PHLX, Inc.; Notice of Filing and Immediate...

    Science.gov (United States)

    2010-02-08

    ... Holdings Airlines Inc. Corp. 211 CF CF Industries 175 SLM SLM Corp. Holdings Inc. 142 CMCSA Comcast Corp... Kraft Foods Inc. 2. Statutory Basis The Exchange believes that its proposal is consistent with Section 6...

  2. 75 FR 6239 - Self-Regulatory Organizations; The NASDAQ Stock Market LLC; Notice of Filing and Immediate...

    Science.gov (United States)

    2010-02-08

    ... SHLD Sears Holdings Airlines Inc Corp. 211 CF CF Industries 175 SLM SLM Corp. Holdings Inc 142 CMCSA... Inc 148 XTO XTO Energy Inc. 213 JWN Nordstrom Inc 130 YRCW YRC Worldwide Inc. 137 KFT Kraft Foods Inc...

  3. Surface chemistry of Ti6Al4V components fabricated using selective laser melting for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Vaithilingam, Jayasheelan, E-mail: Jayasheelan.Vaithilingam@nottingham.ac.uk [Additive Manufacturing and 3D Printing Research Group, EPSRC Centre for Innovative Manufacturing in Additive Manufacturing, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Prina, Elisabetta [School of Pharmacy, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Goodridge, Ruth D.; Hague, Richard J.M. [Additive Manufacturing and 3D Printing Research Group, EPSRC Centre for Innovative Manufacturing in Additive Manufacturing, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Edmondson, Steve [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Rose, Felicity R.A.J. [School of Pharmacy, Centre for Biomolecular Sciences, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Christie, Steven D.R. [Department of Chemistry, Loughborough University, Loughborough LE11 3TU (United Kingdom)

    2016-10-01

    Selective laser melting (SLM) has previously been shown to be a viable method for fabricating biomedical implants; however, the surface chemistry of SLM fabricated parts is poorly understood. In this study, X-ray photoelectron spectroscopy (XPS) was used to determine the surface chemistries of (a) SLM as-fabricated (SLM-AF) Ti6Al4V and (b) SLM fabricated and mechanically polished (SLM-MP) Ti6Al4V samples and compared with (c) traditionally manufactured (forged) and mechanically polished Ti6Al4V samples. The SLM–AF surface was observed to be porous with an average surface roughness (Ra) of 17.6 ± 3.7 μm. The surface chemistry of the SLM-AF was significantly different to the FGD-MP surface with respect to elemental distribution and their existence on the outermost surface. Sintered particles on the SLM-AF surface were observed to affect depth profiling of the sample due to a shadowing effect during argon ion sputtering. Surface heterogeneity was observed for all three surfaces; however, vanadium was witnessed only on the mechanically polished (SLM-MP and FGD-MP) surfaces. The direct and indirect 3T3 cell cytotoxicity studies revealed that the cells were viable on the SLM fabricated Ti6Al4V parts. The varied surface chemistry of the SLM-AF and SLM-MP did not influence the cell behaviour. - Highlights: • Surface chemistry of selective laser melted (SLM) Ti6Al4V parts was compared with conventionally forged Ti6Al4V parts. • The surface elemental compositions of the SLM as-fabricated surfaces were significantly different to the forged surface. • Surface oxide-layer of the SLM as-fabricated was thicker than the polished SLM surfaces and the forged Ti6Al4V surfaces.

  4. Sustainable land management contribution to successful land-based climate change adaptation and mitigation : a report of the Science-Policy Interface

    OpenAIRE

    Sanz, M.J.; De Vente, J.L.; Chotte, Jean-Luc; Bernoux, Martial; Kust, G.; Ruiz, I.; Almagro, M.; Alloza, J.A.; Vallejo, R.; Castillo, V.; Hebel, A.; Akhtar-Schuster, M.

    2017-01-01

    Sustainable Land Management (SLM) represents a holistic approach to achieving long-term productive ecosystems by integrating biophysical, socio-cultural and economic needs and values. SLM is one of the main mechanisms to achieve Land Degradation Neutrality (LDN).To foster and facilitate the adoption of SLM practices that address DLDD while mitigating climate change and enhancing climate change adaptation, this report assesses the synergistic potential of SLM practices while als...

  5. Surface Quality Research for Selective Laser Melting of Ti-6Al-4V Alloy

    Directory of Open Access Journals (Sweden)

    Król M.

    2016-09-01

    Full Text Available One of the innovative technology of producing the components is Selective Laser Melting (SLM belongs to additive manufacturing techniques. SLM technology has already been successfully applied in the automotive, aerospace and medical industries. Despite progress in material flexibility and mechanical performances, relatively poor surface finish still presents a significant weakness in the SLM process.

  6. Computationally efficient thermal-mechanical modelling of selective laser melting

    NARCIS (Netherlands)

    Yang, Y.; Ayas, C.; Brabazon, Dermot; Naher, Sumsun; Ul Ahad, Inam

    2017-01-01

    The Selective laser melting (SLM) is a powder based additive manufacturing (AM) method to produce high density metal parts with complex topology. However, part distortions and accompanying residual stresses deteriorates the mechanical reliability of SLM products. Modelling of the SLM process is

  7. The impact of particle preparation methods and polymorphic stability of lipid excipients on protein distribution in microparticles

    DEFF Research Database (Denmark)

    Liu, Jingying; Christophersen, Philip C; Yang, Mingshi

    2017-01-01

    OBJECTIVE: The present study aimed at elucidating the influence of polymorphic stability of lipid excipients on the physicochemical characters of different solid lipid microparticles (SLM), with the focus on the alteration of protein distribution in SLM. METHODS: Labeled lysozyme was incorporated...... provides updated knowledge for rational development of lipid-based formulations for oral delivery of peptide or protein drugs.......OBJECTIVE: The present study aimed at elucidating the influence of polymorphic stability of lipid excipients on the physicochemical characters of different solid lipid microparticles (SLM), with the focus on the alteration of protein distribution in SLM. METHODS: Labeled lysozyme was incorporated...... into SLM prepared with different excipients, i.e. trimyristin (TG14), glyceryl distearate (GDS), and glyceryl monostearate (GMS), by water-oil-water (w/o/w) or solid-oil-water (s/o/w) method. The distribution of lysozyme in SLM and the release of the protein from SLM were evaluated by confocal laser...

  8. Review of selective laser melting: Materials and applications

    Energy Technology Data Exchange (ETDEWEB)

    Yap, C. Y., E-mail: cyap001@e.ntu.edu.sg [Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Block N3.1 - B2c - 01, Singapore 639798 (Singapore); Energy Research Institute @ NTU, Interdisciplinary Graduate School, Nanyang Technological University, 50 Nanyang Avenue, Block S2 - B3a - 01, Singapore 639798 (Singapore); Chua, C. K., E-mail: mckchua@ntu.edu.sg; Liu, Z. H., E-mail: azhliu@ntu.edu.sg; Zhang, D. Q., E-mail: zhangdq@ntu.edu.sg; Loh, L. E., E-mail: leloh1@e.ntu.edu.sg; Sing, S. L., E-mail: sing0011@e.ntu.edu.sg [Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Block N3.1 - B2c - 01, Singapore 639798 (Singapore); Dong, Z. L., E-mail: zldong@ntu.edu.sg [School of Materials Science & Engineering, Nanyang Technological University, 50 Nanyang Avenue, Block N4.1, Singapore 639798 (Singapore)

    2015-12-15

    Selective Laser Melting (SLM) is a particular rapid prototyping, 3D printing, or Additive Manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders. A component is built by selectively melting and fusing powders within and between layers. The SLM technique is also commonly known as direct selective laser sintering, LaserCusing, and direct metal laser sintering, and this technique has been proven to produce near net-shape parts up to 99.9% relative density. This enables the process to build near full density functional parts and has viable economic benefits. Recent developments of fibre optics and high-power laser have also enabled SLM to process different metallic materials, such as copper, aluminium, and tungsten. Similarly, this has also opened up research opportunities in SLM of ceramic and composite materials. The review presents the SLM process and some of the common physical phenomena associated with this AM technology. It then focuses on the following areas: (a) applications of SLM materials and (b) mechanical properties of SLM parts achieved in research publications. The review is not meant to put a ceiling on the capabilities of the SLM process but to enable readers to have an overview on the material properties achieved by the SLM process so far. Trends in research of SLM are also elaborated in the last section.

  9. Review of selective laser melting: Materials and applications

    Science.gov (United States)

    Yap, C. Y.; Chua, C. K.; Dong, Z. L.; Liu, Z. H.; Zhang, D. Q.; Loh, L. E.; Sing, S. L.

    2015-12-01

    Selective Laser Melting (SLM) is a particular rapid prototyping, 3D printing, or Additive Manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders. A component is built by selectively melting and fusing powders within and between layers. The SLM technique is also commonly known as direct selective laser sintering, LaserCusing, and direct metal laser sintering, and this technique has been proven to produce near net-shape parts up to 99.9% relative density. This enables the process to build near full density functional parts and has viable economic benefits. Recent developments of fibre optics and high-power laser have also enabled SLM to process different metallic materials, such as copper, aluminium, and tungsten. Similarly, this has also opened up research opportunities in SLM of ceramic and composite materials. The review presents the SLM process and some of the common physical phenomena associated with this AM technology. It then focuses on the following areas: (a) applications of SLM materials and (b) mechanical properties of SLM parts achieved in research publications. The review is not meant to put a ceiling on the capabilities of the SLM process but to enable readers to have an overview on the material properties achieved by the SLM process so far. Trends in research of SLM are also elaborated in the last section.

  10. Review of selective laser melting: Materials and applications

    International Nuclear Information System (INIS)

    Yap, C. Y.; Chua, C. K.; Liu, Z. H.; Zhang, D. Q.; Loh, L. E.; Sing, S. L.; Dong, Z. L.

    2015-01-01

    Selective Laser Melting (SLM) is a particular rapid prototyping, 3D printing, or Additive Manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders. A component is built by selectively melting and fusing powders within and between layers. The SLM technique is also commonly known as direct selective laser sintering, LaserCusing, and direct metal laser sintering, and this technique has been proven to produce near net-shape parts up to 99.9% relative density. This enables the process to build near full density functional parts and has viable economic benefits. Recent developments of fibre optics and high-power laser have also enabled SLM to process different metallic materials, such as copper, aluminium, and tungsten. Similarly, this has also opened up research opportunities in SLM of ceramic and composite materials. The review presents the SLM process and some of the common physical phenomena associated with this AM technology. It then focuses on the following areas: (a) applications of SLM materials and (b) mechanical properties of SLM parts achieved in research publications. The review is not meant to put a ceiling on the capabilities of the SLM process but to enable readers to have an overview on the material properties achieved by the SLM process so far. Trends in research of SLM are also elaborated in the last section

  11. HALÃŽL B. AHMED'İN KİTBÜ'L-AYN ADLI ESERİNDE YER ALAN TIBBÃŽ TERİMLER IŞIĞINDA ERKEN DÖNEM İSLM TIP TARİHİNE YENİDEN BİR BAKIŞ

    Directory of Open Access Journals (Sweden)

    Levent ÖZTÜRK

    2004-12-01

    Full Text Available Apparently, our knowledge about the development of the Early Islamic Medicine is notsufficient considering the current knowledge. Since researches on that period areinadequate and writing documents does not carry on until today completely. Somedocuments regarding medicine are translated to Arabic since Umayyad period, under thereign of Mervan b. el-Hakem (64-65/684-685 and these efforts continue until the reignof Memun, who was Abbasid caliphate. However, contents of these translations are notso clear. Khalil b. Ahmad (d. 175/791, who lived in the end of the Umayyad period andin the beginning of the Abbasid period, was very prominent philologist. He has Kitabü'l-Ayn that is very early study on the Arabic Literature. In this work, Khalil b. Ahmad,explained over hundred words regarding the medicine, and sometimes investigatesetymologic roots of these words and from where they came. His explanations on thesewords and information, which he presented, reflect medical culture of that time. Thisessay will analyze medical terms given by Khalil b. Ahmad and meanwhile emphasize theimportant points from the point of history of medicine.

  12. Bioactive treatment promotes osteoblast differentiation on titanium materials fabricated by selective laser melting technology.

    Science.gov (United States)

    Tsukanaka, Masako; Fujibayashi, Shunsuke; Takemoto, Mitsuru; Matsushita, Tomiharu; Kokubo, Tadashi; Nakamura, Takashi; Sasaki, Kiyoyuki; Matsuda, Shuichi

    2016-01-01

    Selective laser melting (SLM) technology is useful for the fabrication of porous titanium implants with complex shapes and structures. The materials fabricated by SLM characteristically have a very rough surface (average surface roughness, Ra=24.58 µm). In this study, we evaluated morphologically and biochemically the specific effects of this very rough surface and the additional effects of a bioactive treatment on osteoblast proliferation and differentiation. Flat-rolled titanium materials (Ra=1.02 µm) were used as the controls. On the treated materials fabricated by SLM, we observed enhanced osteoblast differentiation compared with the flat-rolled materials and the untreated materials fabricated by SLM. No significant differences were observed between the flat-rolled materials and the untreated materials fabricated by SLM in their effects on osteoblast differentiation. We concluded that the very rough surface fabricated by SLM had to undergo a bioactive treatment to obtain a positive effect on osteoblast differentiation.

  13. A novel coping metal material CoCrCu alloy fabricated by selective laser melting with antimicrobial and antibiofilm properties

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Ling [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Memarzadeh, Kaveh [Institute of Dentistry, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, Newark Street, London E1 2AT (United Kingdom); Zhang, Shuyuan; Sun, Ziqing; Yang, Chunguang [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Ren, Guogang [University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); Allaker, Robert P., E-mail: r.p.allaker@qmul.ac.uk [Institute of Dentistry, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, Newark Street, London E1 2AT (United Kingdom); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2016-10-01

    Objective: The aim of this study was to fabricate a novel coping metal CoCrCu alloy using a selective laser melting (SLM) technique with antimicrobial and antibiofilm activities and to investigate its microstructure, mechanical properties, corrosion resistance and biocompatibility. Methods: Novel CoCrCu alloy was fabricated using SLM from a mixture of commercial CoCr based alloy and elemental Cu powders. SLM CoCr without Cu served as control. Antibacterial activity was analyzed using standard antimicrobial tests, and antibiofilm properties were investigated using confocal laser scanning microscope. Cu distribution and microstructure were determined using scanning electron microscope, optical microscopy and X-ray diffraction. Corrosion resistance was evaluated by potential dynamic polarization and biocompatibility measured using an MTT assay. Results: SLM CoCrCu alloys were found to be bactericidal and able to inhibit biofilm formation. Other factors such as microstructure, mechanical properties, corrosion resistance and biocompatibility were similar to those of SLM CoCr alloys. Significance: The addition of appropriate amounts of Cu not only maintains normal beneficial properties of CoCr based alloys, but also provides SLM CoCrCu alloys with excellent antibacterial and antibiofilm capabilities. This material has the potential to be used as a coping metal for dental applications. - Highlights: • Novel CoCrCu alloys were fabricated by using selective laser melting (SLM). • SLM CoCrCu alloys showed satisfied antimicrobial and antibiofilm activities. • SLM CoCrCu alloys have no cytotoxic effect on normal cells. • Other properties of SLM CoCrCu alloys were similar to SLM CoCr alloys. • SLM CoCrCu alloys have the potential to be used as coping metals.

  14. A novel coping metal material CoCrCu alloy fabricated by selective laser melting with antimicrobial and antibiofilm properties

    International Nuclear Information System (INIS)

    Ren, Ling; Memarzadeh, Kaveh; Zhang, Shuyuan; Sun, Ziqing; Yang, Chunguang; Ren, Guogang; Allaker, Robert P.; Yang, Ke

    2016-01-01

    Objective: The aim of this study was to fabricate a novel coping metal CoCrCu alloy using a selective laser melting (SLM) technique with antimicrobial and antibiofilm activities and to investigate its microstructure, mechanical properties, corrosion resistance and biocompatibility. Methods: Novel CoCrCu alloy was fabricated using SLM from a mixture of commercial CoCr based alloy and elemental Cu powders. SLM CoCr without Cu served as control. Antibacterial activity was analyzed using standard antimicrobial tests, and antibiofilm properties were investigated using confocal laser scanning microscope. Cu distribution and microstructure were determined using scanning electron microscope, optical microscopy and X-ray diffraction. Corrosion resistance was evaluated by potential dynamic polarization and biocompatibility measured using an MTT assay. Results: SLM CoCrCu alloys were found to be bactericidal and able to inhibit biofilm formation. Other factors such as microstructure, mechanical properties, corrosion resistance and biocompatibility were similar to those of SLM CoCr alloys. Significance: The addition of appropriate amounts of Cu not only maintains normal beneficial properties of CoCr based alloys, but also provides SLM CoCrCu alloys with excellent antibacterial and antibiofilm capabilities. This material has the potential to be used as a coping metal for dental applications. - Highlights: • Novel CoCrCu alloys were fabricated by using selective laser melting (SLM). • SLM CoCrCu alloys showed satisfied antimicrobial and antibiofilm activities. • SLM CoCrCu alloys have no cytotoxic effect on normal cells. • Other properties of SLM CoCrCu alloys were similar to SLM CoCr alloys. • SLM CoCrCu alloys have the potential to be used as coping metals.

  15. Participatory Evaluation of Monitoring and Modeling of Sustainable Land Management Technologies in Areas Prone to Land Degradation

    Science.gov (United States)

    Stringer, L. C.; Fleskens, L.; Reed, M. S.; de Vente, J.; Zengin, M.

    2014-11-01

    Examples of sustainable land management (SLM) exist throughout the world. In many cases, SLM has largely evolved through local traditional practices and incremental experimentation rather than being adopted on the basis of scientific evidence. This means that SLM technologies are often only adopted across small areas. The DESIRE (DESertIfication mitigation and REmediation of degraded land) project combined local traditional knowledge on SLM with empirical evaluation of SLM technologies. The purpose of this was to evaluate and select options for dissemination in 16 sites across 12 countries. It involved (i) an initial workshop to evaluate stakeholder priorities (reported elsewhere), (ii) field trials/empirical modeling, and then, (iii) further stakeholder evaluation workshops. This paper focuses on workshops in which stakeholders evaluated the performance of SLM technologies based on the scientific monitoring and modeling results from 15 study sites. It analyses workshop outcomes to evaluate how scientific results affected stakeholders' perceptions of local SLM technologies. It also assessed the potential of this participatory approach in facilitating wider acceptance and implementation of SLM. In several sites, stakeholder preferences for SLM technologies changed as a consequence of empirical measurements and modeling assessments of each technology. Two workshop examples are presented in depth to: (a) explore the scientific results that triggered stakeholders to change their views; and (b) discuss stakeholders' suggestions on how the adoption of SLM technologies could be up-scaled. The overall multi-stakeholder participatory approach taken is then evaluated. It is concluded that to facilitate broad-scale adoption of SLM technologies, de-contextualized, scientific generalisations must be given local context; scientific findings must be viewed alongside traditional beliefs and both scrutinized with equal rigor; and the knowledge of all kinds of experts must be

  16. Osseointegration of three-dimensional designed titanium implants manufactured by selective laser melting.

    Science.gov (United States)

    Shaoki, Algabri; Xu, Jia-Yun; Sun, Haipeng; Chen, Xian-Shuai; Ouyang, Jianglin; Zhuang, Xiu-Mei; Deng, Fei-Long

    2016-10-27

    The selective laser melting (SLM) technique is a recent additive manufacturing (AM) technique. Several studies have reported success in the SLM-based production of biocompatible orthopaedic implants and three-dimensional bone defect constructs. In this study, we evaluated the surface properties and biocompatibility of an SLM titanium implant in vitro and compared them with those of a machined (MA) titanium control surface. In addition, we evaluated the osseointegration capability of the SLM implants in vivo and compared it with those of MA and Nobel-speedy (Nobel-S) implants. SLM microtopographical surface analysis revealed porous and high roughness with varied geometry compared with a smooth surface in MA Ti samples but with similar favourable wettability. Osteoblast proliferation and alkaline phosphatase activity were significantly enhanced on the SLM surface. Histological analysis of the bone-implant contact ratio revealed no significant difference among SLM, MA, and Nobel-S implants. Micro-CT assessment indicated that there was no significant difference in bone volume fraction around the implant among SLM implants and other types of surface modification implants. The removal torque value measurement of SLM implants was significantly lower that of than Nobel-S implants P manufacturing technique.

  17. Prediction and Control of Selective Laser Melting Product Microstructure, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Despite the rapid commercialization of additive manufacturing technology such as selective laser melting, SLM, there are gaps in models for material microstructure...

  18. Multiple High-Fidelity Modeling Tools for Metal Additive Manufacturing Process Development, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Despite the rapid commercialization of additive manufacturing technology such as selective laser melting, SLM, there are gaps in process modeling and material...

  19. A Comparison of Biocompatibility of a Titanium Alloy Fabricated by Electron Beam Melting and Selective Laser Melting.

    Science.gov (United States)

    Wang, Hong; Zhao, Bingjing; Liu, Changkui; Wang, Chao; Tan, Xinying; Hu, Min

    2016-01-01

    Electron beam melting (EBM) and selective laser melting (SLM) are two advanced rapid prototyping manufacturing technologies capable of fabricating complex structures and geometric shapes from metallic materials using computer tomography (CT) and Computer-aided Design (CAD) data. Compared to traditional technologies used for metallic products, EBM and SLM alter the mechanical, physical and chemical properties, which are closely related to the biocompatibility of metallic products. In this study, we evaluate and compare the biocompatibility, including cytocompatibility, haemocompatibility, skin irritation and skin sensitivity of Ti6Al4V fabricated by EBM and SLM. The results were analysed using one-way ANOVA and Tukey's multiple comparison test. Both the EBM and SLM Ti6Al4V exhibited good cytobiocompatibility. The haemolytic ratios of the SLM and EBM were 2.24% and 2.46%, respectively, which demonstrated good haemocompatibility. The EBM and SLM Ti6Al4V samples showed no dermal irritation when exposed to rabbits. In a delayed hypersensitivity test, no skin allergic reaction from the EBM or the SLM Ti6Al4V was observed in guinea pigs. Based on these results, Ti6Al4V fabricated by EBM and SLM were good cytobiocompatible, haemocompatible, non-irritant and non-sensitizing materials. Although the data for cell adhesion, proliferation, ALP activity and the haemolytic ratio was higher for the SLM group, there were no significant differences between the different manufacturing methods.

  20. Multiple High-Fidelity Modeling Tools for Metal Additive Manufacturing Process Development, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Despite the rapid commercialization of additive manufacturing technology such as selective laser melting, SLM, there are gaps in process modeling and material...

  1. Silymarin prevents acetaminophen-induced hepatotoxicity in mice.

    Directory of Open Access Journals (Sweden)

    Zuzana Papackova

    Full Text Available Acetaminophen or paracetamol (APAP overdose is a common cause of liver injury. Silymarin (SLM is a hepatoprotective agent widely used for treating liver injury of different origin. In order to evaluate the possible beneficial effects of SLM, Balb/c mice were pretreated with SLM (100 mg/kg b.wt. per os once daily for three days. Two hours after the last SLM dose, the mice were administered APAP (300 mg/kg b.wt. i.p. and killed 6 (T6, 12 (T12 and 24 (T24 hours later. SLM-treated mice exhibited a significant reduction in APAP-induced liver injury, assessed according to AST and ALT release and histological examination. SLM treatment significantly reduced superoxide production, as indicated by lower GSSG content, lower HO-1 induction, alleviated nitrosative stress, decreased p-JNK activation and direct measurement of mitochondrial superoxide production in vitro. SLM did not affect the APAP-induced decrease in CYP2E1 activity and expression during the first 12 hrs. Neutrophil infiltration and enhanced expression of inflammatory markers were first detected at T12 in both groups. Inflammation progressed in the APAP group at T24 but became attenuated in SLM-treated animals. Histological examination suggests that necrosis the dominant cell death pathway in APAP intoxication, which is partially preventable by SLM pretreatment. We demonstrate that SLM significantly protects against APAP-induced liver damage through the scavenger activity of SLM and the reduction of superoxide and peroxynitrite content. Neutrophil-induced damage is probably secondary to necrosis development.

  2. Ionospheric correction for spaceborne single-frequency GPS based ...

    Indian Academy of Sciences (India)

    A modified ionospheric correction method and the corresponding approximate algorithm for spaceborne single-frequency Global Positioning System (GPS) users are proposed in this study. Single Layer Model (SLM) mapping function for spaceborne GPS was analyzed. SLM mapping functions at different altitudes were ...

  3. Taking on Inquiry in Iowa

    Science.gov (United States)

    Carruthers, Cheryl; Lampe, Karen

    2011-01-01

    Over the last year, "School Library Monthly" ("SLM") has challenged school librarians to "nudge toward inquiry" through the "SLM" blog-driven submissions compiled by Kristin Fontichiaro. Iowa took up the challenge! This article describes how teacher librarians across Iowa teamed with classroom teachers to…

  4. Highly selective and sensitive methanol gas sensor based on molecular imprinted silver-doped LaFeO3 core-shell and cage structures

    Science.gov (United States)

    Rong, Qian; Zhang, Yumin; Lv, Tianping; Shen, Kaiyuan; Zi, Baoye; Zhu, Zhongqi; Zhang, Jin; Liu, Qingju

    2018-04-01

    Silver-doped LaFeO3 molecularly imprinted polymers (SLMIPs) were synthesized by a sol-gel method combined with molecularly imprinted technology as precursors. The precursors were then used to prepare SLMIPs cage (SLM-cage) and SLMIPs core-shell (SLM-core-shell) structures by using a carbon sphere as the template and hydrothermal synthesis, respectively. The structures, morphologies, and surface areas of these materials were determined, as well as their gas-sensing properties and related mechanisms. The SLM-cage and SLM-core-shell samples exhibited good responses to methanol gas, with excellent selectivity. The response and optimum working temperature were 16.98 °C and 215 °C, 33.7 °C and 195 °C, respectively, with corresponding response and recovery times of 45 and 50 s (SLM-cage) and 42 and 57 s (SLM-core-shell) for 5 ppm methanol gas. Notably, the SLM-cage and SLM-core-shell samples exhibited lower responses (≤5 and ≤7, respectively) to other gases, including ethanol, ammonia, benzene, acetone, and toluene. Thus, these materials show potential as practical methanol detectors.

  5. Exploring co-investments in sustainable land management in the Central Rift Valley of Ethiopia

    NARCIS (Netherlands)

    Adimassu Teferi, Z.; Kessler, A.; Stroosnijder, L.

    2013-01-01

    In Ethiopia, not only farmers but also the public and private sector partners are still hesitant to invest in sustainable land management (SLM). This study focuses on the Central Rift Valley and explores the potential for co-investments in SLM, where public and private sector partners support

  6. Electrode properties of Sr-doped LaMnO3 on yttria-stabilized zirconia. I. Three-phase boundary area

    NARCIS (Netherlands)

    van Heuveln, F.H.; van Heuveln, F.H.; Bouwmeester, Henricus J.M.; van Berkel, F.P.F.

    1997-01-01

    The interface microstructure of the state-of-the-art cathode material for solid oxide fuel cells, SrxLa1–xMnO3 (SLM), was investigated with respect to its electrochemical performance. The interface microstructure was characterized by grain size and coverage of SLM on the electrolyte surface.

  7. Effectiveness of sustainable land management measures in West Usambara highlands, Tanzania

    NARCIS (Netherlands)

    Wickama, Juma; Okoba, Barrack; Sterk, Geert|info:eu-repo/dai/nl/157276465

    2014-01-01

    Soil erosion is a serious problem that affects food security and social livelihoods in the highlands of East Africa. Sustainable land management (SLM) measures have been widely promoted to reduce erosion and increase crop yield, but the adoption of SLM measures has remained low. In order to

  8. Direct plasma NOx reduction using single surface dielectric barrier discharge

    DEFF Research Database (Denmark)

    Kroushawi, Feisal; Stamate, Eugen

    2014-01-01

    NOx reduction using direct atmospheric barrier discharge in air-NO mixture at different voltages and flow rates is inversigated. Reduction rate of 80% is achieved at 3.18 W/cm2 power density and gas mixture of 20 slm air and 0.006 slm NO. The ozone for NO reduction is produced by a honeycomb stru...

  9. On-chip electro membrane extraction with online ultraviolet and mass spectrometric detection

    DEFF Research Database (Denmark)

    Petersen, Nickolaj Jacob; Foss, Sunniva Taule; Jensen, Henrik

    2011-01-01

    (SLM) consisted of 2-nitrophenyl octyl ether (NPOE) immobilized in the pores of the membrane. The driving force for the extraction was a 15 V direct current (DC) electrical potential applied across the SLM. Samples containing the basic drugs pethidine, nortriptyline, methadone, haloperidol, loperamide...

  10. The Development and Evaluation of Speaking Learning Model by Cooperative Approach

    Science.gov (United States)

    Darmuki, Agus; Andayani; Nurkamto, Joko; Saddhono, Kundharu

    2018-01-01

    A cooperative approach-based Speaking Learning Model (SLM) has been developed to improve speaking skill of Higher Education students. This research aimed at evaluating the effectiveness of cooperative-based SLM viewed from the development of student's speaking ability and its effectiveness on speaking activity. This mixed method study combined…

  11. Design and implementation of an automated liquid-phase microextraction-chip system coupled on-line with high performance liquid chromatography

    DEFF Research Database (Denmark)

    Li, Bin; Petersen, Nickolaj J.; Payán, María D Ramos

    2014-01-01

    . The composition of the supported liquid membrane (SLM) and carrier was optimized in order to achieve reasonable extraction performance of all the five alkaloids. With 1-octanol as SLM solvent and with 25mM sodium octanoate as anionic carrier, extraction recoveries for the different opium alkaloids ranged between...

  12. Point, surface and volumetric heat sources in the thermal modelling of selective laser melting

    NARCIS (Netherlands)

    Yang, Y.; Ayas, C.; Brabazon, Dermot; Naher, Sumsun; Ul Ahad, Inam

    2017-01-01

    Selective laser melting (SLM) is a powder based additive manufacturing technique suitable for producing high precision metal parts. However, distortions and residual stresses within products arise during SLM because of the high temperature gradients created by the laser heating. Residual stresses

  13. Fabricating High-Quality 3D-Printed Alloys for Dental Applications

    Directory of Open Access Journals (Sweden)

    Min-Ho Hong

    2017-07-01

    Full Text Available Metal additive manufacturing (AM, especially selective laser melting (SLM, has been receiving particular attention because metallic functional structures with complicated configurations can be effectively fabricated using the technique. However, there still exist some future challenges for the fabrication of high-quality SLM products for dental applications. First, the surface quality of SLM products should be further improved by standardizing the laser process parameters or by appropriately post-treating the surface. Second, it should be guaranteed that dental SLM restorations have good dimensional accuracy and, in particular, a good marginal fit. Third, a definitive standard regarding building and scanning strategies, which affect the anisotropy, should be established to optimize the mechanical properties and fatigue resistance of SLM dental structures. Fourth, the SLM substructure’s bonding and support to veneering ceramic should be further studied to facilitate the use of esthetic dental restorations. Finally, the biocompatibility of SLM dental alloys should be carefully examined and improved to minimize the potential release of toxic metal ions from the alloys. Future research of SLM should focus on solving the above challenges, as well as on fabricating dental structures with “controlled” porosity.

  14. Binding Mechanisms in Selective Laser Sintering and Selective Laser Melting

    NARCIS (Netherlands)

    Kruth, J.P.; Mercelis, P.; Van Vaerenbergh, J.; van Vaerenbergh, J.; Froyen, L.; Rombouts, M.

    2005-01-01

    Purpose – This paper provides an overview of the different binding mechanisms in selective laser sintering (SLS) and selective laser melting (SLM), thus improving the understanding of these processes. Design/methodology/approach – A classification of SLS/SLM processes was developed, based on the

  15. A semi-analytical thermal modelling approach for selective laser melting

    NARCIS (Netherlands)

    Yang, Y.; van Keulen, A.; Ayas, C.

    2018-01-01

    Selective laser melting (SLM) wherein a metal part is built in a layer-by-layer manner in a powder bed is a promising and versatile way for manufacturing components with complex geometry. However, components built by SLM suffer from substantial deformation of the part and residual stresses.

  16. Key-socio economic factors influencing sustainable land management investments in the West Usambara Highlands, Tanzania

    NARCIS (Netherlands)

    Nyanga, A.W.; Kessler, C.A.; Tenge, A.J.M.

    2016-01-01

    Low investments in sustainable land management (SLM) limit agricultural production in the East African Highlands, leading to increased soil erosion, low productivity of land and food insecurity. Recent studies in the region show that different socio-economic factors influence SLM investments by

  17. Physics and technology of tunable pulsed single longitudinal mode ...

    Indian Academy of Sciences (India)

    Design and technology demonstration of compact, narrow bandwidth, high repetition rate, tunable SLM dye lasers in two different configurations, namely Littrow and grazing incidence grating (GIG), were carried out in our lab at BARC, India. The single longitudinal mode (SLM) dye laser generates single-mode laser beams ...

  18. Significance of social networks in sustainable land management in ...

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    multi-stakeholder Innovation Platforms (IPs) necessary for catalysing wide adoption of SLM innovations. This paper analyses the significance of SNs in sustainable land management (SLM), focusing on stakeholders' characteristics and their association among agricultural rural communities in central Ethiopia and eastern ...

  19. Influence of small particles inclusion on selective laser melting of Ti-6Al-4V powder

    Science.gov (United States)

    Gong, Haijun; Dilip, J. J. S.; Yang, Li; Teng, Chong; Stucker, Brent

    2017-12-01

    The particle size distribution and powder morphology of metallic powders have an important effect on powder bed fusion based additive manufacturing processes, such as selective laser melting (SLM). The process development and parameter optimization require a fundamental understanding of the influence of powder on SLM. This study introduces a pre-alloyed titanium alloy Ti-6Al-4V powder, which has a certain amount of small particles, for SLM. The influence of small particle inclusion is investigated through microscopy of surface topography, elemental and microstructural analysis, and mechanical testing, compared to the Ti-6Al-4V powder provided by SLM machine vendor. It is found that the small particles inclusion in Ti-6Al-4V powder has a noticeable effect on extra laser energy absorption, which may develop imperfections and deteriorate the SLM fatigue performance.

  20. ITIL Based Service Level Management if SLAs Cover Security

    Directory of Open Access Journals (Sweden)

    Tomas Feglar

    2005-08-01

    Full Text Available Current level of information technology creates new perspectives for more IT service oriented market. Quality of these services requires slightly different approach then was applied for products including software. No IT services are delivered and supported in risk free environment. Risks would be considered consistently with IT services quality gaps from Service Level Management (SLM perspective. SLM is one of ITIL modules that are widely used within the IT service industry. We identified some weaknesses in how SLM is developed in ITIL environment if service level agreement (SLA has cover Security. We argue that in such cases Architecture modeling and risk assessment approach let us effectively control analytical effort that relates to risks identification and understanding. Risk driven countermeasures designed in a next step (Risk treatment have significant impact to the SLM especially from responsibility perspective. To demonstrate SLM's importance in real practice we analyze SLA synthesize process in CCI (Cyber Critical Infrastructure environment.

  1. A structured multi-stakeholder learning process for Sustainable Land Management.

    Science.gov (United States)

    Schwilch, Gudrun; Bachmann, Felicitas; Valente, Sandra; Coelho, Celeste; Moreira, Jorge; Laouina, Abdellah; Chaker, Miloud; Aderghal, Mohamed; Santos, Patricia; Reed, Mark S

    2012-09-30

    There are many, often competing, options for Sustainable Land Management (SLM). Each must be assessed - and sometimes negotiated - prior to implementation. Participatory, multi-stakeholder approaches to identification and selection of SLM options are increasingly popular, often motivated by social learning and empowerment goals. Yet there are few practical tools for facilitating processes in which land managers may share, select, and decide on the most appropriate SLM options. The research presented here aims to close the gap between the theory and the practice of stakeholder participation/learning in SLM decision-making processes. The paper describes a three-part participatory methodology for selecting SLM options that was tested in 14 desertification-prone study sites within the EU-DESIRE project. Cross-site analysis and in-depth evaluation of the Moroccan and Portuguese sites were used to evaluate how well the proposed process facilitated stakeholder learning and selection of appropriate SLM options for local implementation. The structured nature of the process - starting with SLM goal setting - was found to facilitate mutual understanding and collaboration between stakeholders. The deliberation process led to a high degree of consensus over the outcome and, though not an initial aim, it fostered social learning in many cases. This solution-oriented methodology is applicable in a wide range of contexts and may be implemented with limited time and resources. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Quantification of genistein and daidzein in two endemic Genista species and their antioxidant activity

    Directory of Open Access Journals (Sweden)

    DANIMIR JEVREMOVIĆ

    2011-01-01

    Full Text Available The aim of this study was to determine the cytotoxicity of a Co–Cr alloy used for the rapid manufacture of removable partial denture frameworks using murine fibroblasts L929 cell lines and three test methods: the MTT (3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide, a yellow tetrazole assay, the agar diffusion test (ADT and the dye exclusion test (DET. Two groups of disc specimens (5 mm diameter, 1 mm thick were fabricated. The first group was cast using a conventional method (CM in a Nautilus CC casting. The second group was fabricated using selective laser melting (SLM in SLM Realiser The total cell number and viability of cells pre-incubated with CM and SLM alloys were comparable to the control sample. Differences between the growth inhibitory effects of the CM and SLM alloys in the MTT assay were below 30 %. Results of two independent agar diffusion tests with CM and SLM alloys showed neither detectable discoloration around or under the discs nor a detectable difference in staining intensity. As the cell response for both CM and SLM alloys was 0/0, the discs can be rated as non-cytotoxic. The results suggested that the F75 Co–Cr alloy used for the SLM process did not release harmful material that could cause acute effects against L929 cells under the given experimental conditions.

  3. A Review of Selective Laser Melted NiTi Shape Memory Alloy

    Science.gov (United States)

    Khoo, Zhong Xun; Shen, Yu Fang

    2018-01-01

    NiTi shape memory alloys (SMAs) have the best combination of properties among the different SMAs. However, the limitations of conventional manufacturing processes and the poor manufacturability of NiTi have critically limited its full potential applicability. Thus, additive manufacturing, commonly known as 3D printing, has the potential to be a solution in fabricating complex NiTi smart structures. Recently, a number of studies on Selective Laser Melting (SLM) of NiTi were conducted to explore the various aspects of SLM-produced NiTi. Compared to producing conventional metals through the SLM process, the fabrication of NiTi SMA is much more challenging. Not only do the produced parts require a high density that leads to good mechanical properties, strict composition control is needed as well for the SLM NiTi to possess suitable phase transformation characteristics. Additionally, obtaining a good shape memory effect from the SLM NiTi samples is another challenging task that requires further understanding. This paper presents the results of the effects of energy density and SLM process parameters on the properties of SLM NiTi. Its shape memory properties and potential applications were then reviewed and discussed. PMID:29596320

  4. Laser post-processing of Inconel 625 made by selective laser melting

    Science.gov (United States)

    Witkin, David; Helvajian, Henry; Steffeney, Lee; Hansen, William

    2016-04-01

    The effect of laser remelting of surfaces of as-built Selective Laser Melted (SLM) Inconel 625 was evaluated for its potential to improve the surface roughness of SLM parts. Many alloys made by SLM have properties similar to their wrought counterparts, but surface roughness of SLM-made parts is much higher than found in standard machine shop operations. This has implications for mechanical properties of SLM materials, such as a large debit in fatigue properties, and in applications of SLM, where surface roughness can alter fluid flow characteristics. Because complexity and netshape fabrication are fundamental advantages of Additive Manufacturing (AM), post-processing by mechanical means to reduce surface roughness detracts from the potential utility of AM. Use of a laser to improve surface roughness by targeted remelting or annealing offers the possibility of in-situ surface polishing of AM surfaces- the same laser used to melt the powder could be amplitude modulated to smooth the part during the build. The effects of remelting the surfaces of SLM Inconel 625 were demonstrated using a CW fiber laser (IPG: 1064 nm, 2-50 W) that is amplitude modulated with a pulse profile to induce remelting without spallation or ablation. The process achieved uniform depth of melting and improved surface roughness. The results show that with an appropriate pulse profile that meters the heat-load, surface features such as partially sintered powder particles and surface connected porosity can be mitigated via a secondary remelting/annealing event.

  5. Additive manufacturing of ITER first wall panel parts by two approaches: Selective laser melting and electron beam melting

    International Nuclear Information System (INIS)

    Zhong, Yuan; Rännar, Lars-Erik; Wikman, Stefan; Koptyug, Andrey; Liu, Leifeng; Cui, Daqing; Shen, Zhijian

    2017-01-01

    Highlights: • A novel way using additive manufacturing to fabricated ITER First Wall Panel parts is proposed. • ITER First Wall Panel parts successfully manufactured by both SLM and EBM are compared. • Physical and mechanical properties of SLM and EBM SS316L are clearly compared. • Problems encountered for large scale part building were discussed and possible solutions are given. - Abstract: Fabrication of ITER First Wall (FW) Panel parts by two additive manufacturing (AM) technologies, selective laser melting (SLM) and electron beam melting (EBM), was supported by Fusion for Energy (F4E). For the first time, AM is applied to manufacture ITER In-Vessel parts with complex design. Fully dense SS316L was prepared by both SLM and EBM after developing optimized laser/electron beam parameters. Characterizations on the density, magnetic permeability, microstructure, defects and inclusions were carried out. Tensile properties, Charpy-impact properties and fatigue properties of SLM and EBM SS316L were also compared. ITER FW Panel parts were successfully fabricated by both SLM and EBM in a one-step building process. The SLM part has smoother surface, better size accuracy while the EBM part takes much less time to build. Issues with removing support structures might be solved by slightly changing the design of the internal cooling system. Further investigation of the influence of neutron irradiation on materials properties between the two AM technologies is needed.

  6. Additive manufacturing of ITER first wall panel parts by two approaches: Selective laser melting and electron beam melting

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Yuan [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm (Sweden); Rännar, Lars-Erik [Department of Quality Technology, Mechanical Engineering and Mathematics, Sports Tech Research Centre, Mid Sweden University, SE-831 25 Östersund (Sweden); Wikman, Stefan [Fusion for Energy, Torres Diagonal Litoral B3, Josep Pla 2, 08019 Barcelona (Spain); Koptyug, Andrey [Department of Quality Technology, Mechanical Engineering and Mathematics, Sports Tech Research Centre, Mid Sweden University, SE-831 25 Östersund (Sweden); Liu, Leifeng; Cui, Daqing [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm (Sweden); Shen, Zhijian, E-mail: shen@mmk.su.se [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm (Sweden)

    2017-03-15

    Highlights: • A novel way using additive manufacturing to fabricated ITER First Wall Panel parts is proposed. • ITER First Wall Panel parts successfully manufactured by both SLM and EBM are compared. • Physical and mechanical properties of SLM and EBM SS316L are clearly compared. • Problems encountered for large scale part building were discussed and possible solutions are given. - Abstract: Fabrication of ITER First Wall (FW) Panel parts by two additive manufacturing (AM) technologies, selective laser melting (SLM) and electron beam melting (EBM), was supported by Fusion for Energy (F4E). For the first time, AM is applied to manufacture ITER In-Vessel parts with complex design. Fully dense SS316L was prepared by both SLM and EBM after developing optimized laser/electron beam parameters. Characterizations on the density, magnetic permeability, microstructure, defects and inclusions were carried out. Tensile properties, Charpy-impact properties and fatigue properties of SLM and EBM SS316L were also compared. ITER FW Panel parts were successfully fabricated by both SLM and EBM in a one-step building process. The SLM part has smoother surface, better size accuracy while the EBM part takes much less time to build. Issues with removing support structures might be solved by slightly changing the design of the internal cooling system. Further investigation of the influence of neutron irradiation on materials properties between the two AM technologies is needed.

  7. Sliding Wear Characteristics and Corrosion Behaviour of Selective Laser Melted 316L Stainless Steel

    Science.gov (United States)

    Sun, Y.; Moroz, A.; Alrbaey, K.

    2014-02-01

    Stainless steel is one of the most popular materials used for selective laser melting (SLM) processing to produce nearly fully dense components from 3D CAD models. The tribological and corrosion properties of stainless steel components are important in many engineering applications. In this work, the wear behaviour of SLM 316L stainless steel was investigated under dry sliding conditions, and the corrosion properties were measured electrochemically in a chloride containing solution. The results show that as compared to the standard bulk 316L steel, the SLM 316L steel exhibits deteriorated dry sliding wear resistance. The wear rate of SLM steel is dependent on the vol.% porosity in the steel and by obtaining full density it is possible achieve wear resistance similar to that of the standard bulk 316L steel. In the tested chloride containing solution, the general corrosion behaviour of the SLM steel is similar to that of the standard bulk 316L steel, but the SLM steel suffers from a reduced breakdown potential and is more susceptible to pitting corrosion. Efforts have been made to correlate the obtained results with porosity in the SLM steel.

  8. A Multiscale Understanding of the Thermodynamic and Kinetic Mechanisms of Laser Additive Manufacturing

    Directory of Open Access Journals (Sweden)

    Dongdong Gu

    2017-10-01

    Full Text Available Selective laser melting (SLM additive manufacturing (AM technology has become an important option for the precise manufacturing of complex-shaped metallic parts with high performance. The SLM AM process involves complicated physicochemical phenomena, thermodynamic behavior, and phase transformation as a high-energy laser beam melts loose powder particles. This paper provides multiscale modeling and coordinated control for the SLM of metallic materials including an aluminum (Al-based alloy (AlSi10Mg, a nickel (Ni-based super-alloy (Inconel 718, and ceramic particle-reinforced Al-based and Ni-based composites. The migration and distribution mechanisms of aluminium nitride (AlN particles in SLM-processed Al-based nanocomposites and the in situ formation of a gradient interface between the reinforcement and the matrix in SLM-processed tungsten carbide (WC/Inconel 718 composites were studied in the microscale. The laser absorption and melting/densification behaviors of AlSi10Mg and Inconel 718 alloy powder were disclosed in the mesoscale. Finally, the stress development during line-by-line localized laser scanning and the parameter-dependent control methods for the deformation of SLM-processed composites were proposed in the macroscale. Multiscale numerical simulation and experimental verification methods are beneficial in monitoring the complicated powder-laser interaction, heat and mass transfer behavior, and microstructural and mechanical properties development during the SLM AM process.

  9. The AlSi10Mg samples produced by selective laser melting: single track, densification, microstructure and mechanical behavior

    International Nuclear Information System (INIS)

    Wei, Pei; Wei, Zhengying; Chen, Zhen; Du, Jun; He, Yuyang; Li, Junfeng; Zhou, Yatong

    2017-01-01

    Highlights: • The thermal behavior of AlSi10Mg molten pool was analyzed. • The SLM-processed sample with a relatively low surface roughness was obtained. • Effects of parameters on surface topography of scan track were investigated. • Effects of parameters on microstructure of parts were investigated. • Optimum processing parameters for AlSi10Mg SLM was obtained. - Abstract: This densification behavior and attendant microstructural characteristics of the selective laser melting (SLM) processed AlSi10Mg alloy affected by the processing parameters were systematically investigated. The samples with a single track were produced by SLM to study the influences of laser power and scanning speed on the surface morphologies of scan tracks. Additionally, the bulk samples were produced to investigate the influence of the laser power, scanning speed, and hatch spacing on the densification level and the resultant microstructure. The experimental results showed that the level of porosity of the SLM-processed samples was significantly governed by energy density of laser beam and the hatch spacing. The tensile properties of SLM-processed samples and the attendant fracture surface can be enhanced by decreasing the level of porosity. The microstructure of SLM-processed samples consists of supersaturated Al-rich cellular structure along with eutectic Al/Si situated at the cellular boundaries. The Si content in the cellular boundaries increases with increasing the laser power and decreasing the scanning speed. The hardness of SLM-processed samples was significantly improved by this fine microstructure compared with the cast samples. Moreover, the hardness of SLM-processed samples at overlaps was lower than the hardness observed at track cores.

  10. The AlSi10Mg samples produced by selective laser melting: single track, densification, microstructure and mechanical behavior

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Pei; Wei, Zhengying, E-mail: zywei@mail.xjtu.edu.cn; Chen, Zhen; Du, Jun; He, Yuyang; Li, Junfeng; Zhou, Yatong

    2017-06-30

    Highlights: • The thermal behavior of AlSi10Mg molten pool was analyzed. • The SLM-processed sample with a relatively low surface roughness was obtained. • Effects of parameters on surface topography of scan track were investigated. • Effects of parameters on microstructure of parts were investigated. • Optimum processing parameters for AlSi10Mg SLM was obtained. - Abstract: This densification behavior and attendant microstructural characteristics of the selective laser melting (SLM) processed AlSi10Mg alloy affected by the processing parameters were systematically investigated. The samples with a single track were produced by SLM to study the influences of laser power and scanning speed on the surface morphologies of scan tracks. Additionally, the bulk samples were produced to investigate the influence of the laser power, scanning speed, and hatch spacing on the densification level and the resultant microstructure. The experimental results showed that the level of porosity of the SLM-processed samples was significantly governed by energy density of laser beam and the hatch spacing. The tensile properties of SLM-processed samples and the attendant fracture surface can be enhanced by decreasing the level of porosity. The microstructure of SLM-processed samples consists of supersaturated Al-rich cellular structure along with eutectic Al/Si situated at the cellular boundaries. The Si content in the cellular boundaries increases with increasing the laser power and decreasing the scanning speed. The hardness of SLM-processed samples was significantly improved by this fine microstructure compared with the cast samples. Moreover, the hardness of SLM-processed samples at overlaps was lower than the hardness observed at track cores.

  11. Molecular Method for Sex Identification of Half-Smooth Tongue Sole (Cynoglossus semilaevis Using a Novel Sex-Linked Microsatellite Marker

    Directory of Open Access Journals (Sweden)

    Xiaolin Liao

    2014-07-01

    Full Text Available Half-smooth tongue sole (Cynoglossus semilaevis is one of the most important flatfish species for aquaculture in China. To produce a monosex population, we attempted to develop a marker-assisted sex control technique in this sexually size dimorphic fish. In this study, we identified a co-dominant sex-linked marker (i.e., CyseSLM by screening genomic microsatellites and further developed a novel molecular method for sex identification in the tongue sole. CyseSLM has a sequence similarity of 73%–75% with stickleback, medaka, Fugu and Tetraodon. At this locus, two alleles (i.e., A244 and A234 were amplified from 119 tongue sole individuals with primer pairs CyseSLM-F1 and CyseSLM-R. Allele A244 was present in all individuals, while allele A234 (female-associated allele, FAA was mostly present in females with exceptions in four male individuals. Compared with the sequence of A244, A234 has a 10-bp deletion and 28 SNPs. A specific primer (CyseSLM-F2 was then designed based on the A234 sequence, which amplified a 204 bp fragment in all females and four males with primer CyseSLM-R. A time-efficient multiplex PCR program was developed using primers CyseSLM-F2, CyseSLM-R and the newly designed primer CyseSLM-F3. The multiplex PCR products with co-dominant pattern could be detected by agarose gel electrophoresis, which accurately identified the genetic sex of the tongue sole. Therefore, we have developed a rapid and reliable method for sex identification in tongue sole with a newly identified sex-linked microsatellite marker.

  12. Corrosion resistance characteristics of a Ti-6Al-4V alloy scaffold that is fabricated by electron beam melting and selective laser melting for implantation in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Bingjing; Wang, Hong [Department of Stomatology, General Hospital of the PLA, Beijing (China); Department of Stomatology, The Second Affiliated Stomatological Hospital of Liaoning Medical University (China); Qiao, Ning [College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing (China); Wang, Chao [School of Medicine, Nankai University, Tianjin 300071 (China); Hu, Min, E-mail: humin48@vip.163.com [Department of Stomatology, General Hospital of the PLA, Beijing (China)

    2017-01-01

    The purpose of this study is to determine the corrosion resistance of Ti-6Al-4V alloy fabricated with electron beam melting and selective laser melting for implantation in vivo. Ti-6Al-4V alloy specimens were fabricated with electron beam melting (EBM) and selective laser melting (SLM). A wrought form of Ti-6Al-4V alloy was used as a control. Surface morphology observation, component analysis, corrosion resistance experimental results, electrochemical impedance spectroscopy, crevice corrosion resistance experimental results, immersion test and metal ions precipitation analysis were processed, respectively. The thermal stability of EBM specimen was the worst, based on the result of open circuit potential (OCP) result. The result of electrochemical impedance spectroscopy indicated that the corrosion resistance of the SLM specimen was the best under the low electric potential. The result of potentiodynamic polarization suggested that the corrosion resistance of the SLM specimen was the best under the low electric potential (< 1.5 V) and EBM specimen was the best under the high electric potential (> 1.5 V).The crevice corrosion resistance of the EBM specimen was the best. The corrosion resistance of SLM specimen was the best, based on the result of immersion test. The content of Ti, Al and V ions of EBM, SLM and wrought specimens was very low. In general, the scaffolds that were fabricated with EBM and SLM had good corrosion resistance, and were suitable for implantation in vivo. - Highlights: • EBM and SLM Ti-6Al-4V alloy have good corrosion resistance, and both of them can be applied in vivo. • SLM Ti-6Al-4V alloy was more suitable for implantation in vivo than that of EBM Ti-6Al-4V alloy. • The crevice corrosion resistance of the EBM specimen is the best. • EBM and SLM specimens can form oxide film.

  13. Intragranular cellular segregation network structure strengthening 316L stainless steel prepared by selective laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Yuan; Liu, Leifeng [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden); Wikman, Stefan [Fusion for Energy, Torres Diagonal Litoral B3, Josep Pla 2, 08019 Barcelona (Spain); Cui, Daqing [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden); Shen, Zhijian, E-mail: shen@mmk.su.se [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden)

    2016-03-15

    A feasibility study was performed to fabricate ITER In-Vessel components by Selective Laser Melting (SLM) supported by Fusion for Energy (F4E). Almost fully dense 316L stainless steel (SS316L) components were prepared from gas-atomized powder and with optimized SLM processing parameters. Tensile tests and Charpy-V tests were carried out at 22 °C and 250 °C and the results showed that SLM SS316L fulfill the RCC-MR code. Microstructure characterization reveals the presence of hierarchical macro-, micro- and nano-structures in as-built samples that were very different from SS316L microstructures prepared by other established methods. The formation of a characteristic intragranular cellular segregation network microstructure appears to contribute to the increase of yield strength without losing ductility. Silicon oxide nano-inclusions were formed during the SLM process that generated a micro-hardness fluctuation in the building direction. The combined influence of a cellular microstructure and the nano-inclusions constraints the size of ductile dimples to nano-scale. The crack propagation is hindered by a pinning effect that improves the defect-tolerance of the SLM SS316L. This work proves that it was possible to manufacture SS316L with properties suitable for ITER First Wall panels. Further studies on irradiation properties of SLM SS316L and manufacturing of larger real-size components are needed. - Highlights: • The mechanical properties of SS316L made by selective laser melting fulfill RCC-MR. • SLM SS316L consists hierarchical structures of high heterogeneity. • Silicon rich oxide nano-inclusions are formed unexpectedly during SLM process. • Cellular structure and oxide nano-inclusions strengthen SLM SS316L.

  14. 3D Metal Printing - Additive Manufacturing Technologies for Frameworks of Implant-Borne Fixed Dental Prosthesis.

    Science.gov (United States)

    Revilla León, M; Klemm, I M; García-Arranz, J; Özcan, M

    2017-09-01

    An edentulous patient was rehabilitated with maxillary metal-ceramic and mandibular metal-resin implant-supported fixed dental prosthesis (FDP). Metal frameworks of the FDPs were fabricated using 3D additive manufacturing technologies utilizing selective laser melting (SLM) and electron beam melting (EBM) processes. Both SLM and EBM technologies were employed in combination with computer numerical control (CNC) post-machining at the implant interface. This report highlights the technical and clinical protocol for fabrication of FDPs using SLM and EBM additive technologies. Copyright© 2017 Dennis Barber Ltd.

  15. 3D printed porous stainless steel for potential use in medicine

    Science.gov (United States)

    Fousová, M.; Kubásek, J.; Vojtěch, D.; Fojt, J.; Čapek, J.

    2017-02-01

    3D printing technologies like Selective Laser Melting (SLM) or Electron Beam Melting (EBM) produce components of very complicated shapes from various kinds of materials. In this work a highly porous (porosity of almost 90 vol. %) stainless steel component was manufactured by SLM. The material was characterized in terms of structure, surface chemistry and mechanical properties. It was observed that mechanical properties of the material were similar to those of trabecular human bone. The tests realized in this work confirmed suitability of the porous material prepared by SLM for the use in medicine, for example, for scaffolds designed to repair bone defects.

  16. Additively Manufactured Main Fuel Valve Housing

    Science.gov (United States)

    Eddleman, David; Richard, Jim

    2015-01-01

    Selective Laser Melting (SLM) was utilized to fabricate a liquid hydrogen valve housing typical of those found in rocket engines and main propulsion systems. The SLM process allowed for a valve geometry that would be difficult, if not impossible to fabricate by traditional means. Several valve bodies were built by different SLM suppliers and assembled with valve internals. The assemblies were then tested with liquid nitrogen and operated as desired. One unit was also burst tested and sectioned for materials analysis. The design, test results, and planned testing are presented herein.

  17. The variable refractive index correction algorithm based on a stereo light microscope

    International Nuclear Information System (INIS)

    Pei, W; Zhu, Y Y

    2010-01-01

    Refraction occurs at least twice on both the top and the bottom surfaces of the plastic plate covering the micro channel in a microfluidic chip. The refraction and the nonlinear model of a stereo light microscope (SLM) may severely affect measurement accuracy. In this paper, we study the correlation between optical paths of the SLM and present an algorithm to adjust the refractive index based on the SLM. Our algorithm quantizes the influence of cover plate and double optical paths on the measurement accuracy, and realizes non-destructive, non-contact and precise 3D measurement of a hyaloid and closed container

  18. Evaluation of the mechanical properties and porcelain bond strength of cobalt-chromium dental alloy fabricated by selective laser melting.

    Science.gov (United States)

    Wu, Lin; Zhu, Haiting; Gai, Xiuying; Wang, Yanyan

    2014-01-01

    Limited information is available regarding the microstructure and mechanical properties of dental alloy fabricated by selective laser melting (SLM). The purpose of this study was to evaluate the mechanical properties of a cobalt-chromium (Co-Cr) dental alloy fabricated by SLM and to determine the correlation between its microstructure and mechanical properties and its porcelain bond strength. Five metal specimens and 10 metal ceramic specimens were fabricated to evaluate the mechanical properties of SLM Co-Cr dental alloy (SLM alloy) with a tensile test and its porcelain bond strength with a 3-point bending test. The relevant properties of the SLM alloy were compared with those of the currently used Co-Cr dental alloy fabricated with conventional cast technology (cast alloy). The Student t test was used to compare the results of the SLM alloy and the cast alloy (α=.05). The microstructure of the SLM alloy was analyzed with a metallographic microscope; the metal ceramic interface of the SLM porcelain bonded alloy was studied with scanning electron microscopy, energy dispersive x-ray spectroscopy, and an electron probe microanalyzer. Both the mean (standard deviation) yield strength (884.37 ± 8.96 MPa) and tensile strength (1307.50 ±10.65 MPa) of the SLM alloy were notably higher than yield strength (568.10 ± 30.94 MPa) and tensile strength (758.73 ± 25.85 MPa) of the currently used cast alloy, and the differences were significant (P.05). Microstructure analysis suggested that the SLM alloy had a dense and obviously orientated microstructure, which led to excellent mechanical properties. Analysis from scanning electron microscopy, energy dispersive x-ray spectroscopy, and the electron probe microanalyzer indicated that the SLM alloy had an intermediate layer with elemental interpenetration between the alloy and the porcelain, which resulted in an improved bonding interface. Compared with the currently used cast alloy, SLM alloy possessed improved mechanical

  19. Fabrication of titanium alloy frameworks for complete dentures by selective laser melting.

    Science.gov (United States)

    Kanazawa, Manabu; Iwaki, Maiko; Minakuchi, Shunsuke; Nomura, Naoyuki

    2014-12-01

    Casting difficulties have led to the limited use of titanium in dental prostheses. The selective laser melting system was recently developed to fabricate biomedical components from titanium alloys. However, the fabrication of a titanium alloy framework for a maxillary complete denture by selective laser melting has not yet been investigated. The purpose of the study was to fabricate thin titanium alloy frameworks for a maxillary complete denture with a selective laser melting system and to evaluate their hardness and microstructure. A cast of an edentulous maxilla was scanned with a dental 3-dimensional cone-beam computed tomography system, and standard triangulation language data were produced with the DICOM Viewer (Digital Imaging and Communications in Medicine). Two types of metal frameworks for complete dentures were designed with 3-dimensional computer-aided design software. Two titanium alloy frameworks, SLM-1 and SLM-2, were fabricated from these designs with the selective laser melting system. Plate-shaped specimens were cut from the central flat region of SLM-1, SLM-2, and as-cast Ti-6Al-4V (As-cast). Vickers hardness testing, optical microscopy, and x-ray diffraction measurements were performed. Thin titanium alloy frameworks for maxillary complete dentures could be fabricated by selective laser melting. The hardness values for SLM-1 and SLM-2 were higher than that for the as-cast specimen. Optical microscopy images of the SLM-1 and SLM-2 microstructure showed that the specimens did not exhibit pores, indicating that dense frameworks were successfully obtained with the selective laser melting process. In the x-ray diffraction patterns, only peaks associated with the α phase were observed for SLM-1 and SLM-2. In addition, the lattice parameters for SLM-1 and SLM-2 were slightly larger than those for the as-cast specimen. The mechanical properties and microstructure of the denture frameworks prepared by selective laser melting indicate that these dentures

  20. Microstructural and thermal stability of selective laser melted 316L stainless steel single tracks

    Directory of Open Access Journals (Sweden)

    Krakhmalev, P.

    2017-05-01

    Full Text Available To remove residual stresses, an as-built SLM object is usually post- treated. This treatment can affect the microstructure, changing the final mechanical characteristics. This investigation is focused on the microstructural characterisation of 316L austenitic stainless steel in as-built and annealed conditions. The SLM microstructure was relatively stable up to 900°C, when cell boundaries start to disappear. At higher temperatures, an insignificant grain coarsening was detected. These microstructural changes caused a gradual drop in the hardness. The obtained result is background for the future development of post-treatment regimens to achieve a high level in the final mechanical properties of SLM objects.

  1. Exhaustive and stable electromembrane extraction of acidic drugs from human plasma

    DEFF Research Database (Denmark)

    Huang, Chuixiu; Gjelstad, Astrid; Seip, Knut Fredrik

    2015-01-01

    The first part of the current work systematically described the screening of different types of organic solvents as the supported liquid membrane (SLM) for electromembrane extraction (EME) of acidic drugs, including different alcohols, ketones, and ethers. Seven acidic drugs with a wide logP rang......). With this SLM, exhaustive EME was performed from diluted human plasma, and the recoveries of five out of seven analytes were over 91% after 10min EME. This approach was evaluated using HPLC-UV, and the evaluation data were found to be satisfactory...... to increasing viscosity and decreasing α and π* values. The system-current during EME was found to be dependent on the type and the volume of the SLM. In contact with human plasma, an SLM of pure 1-heptanol was unstable, and to improve stability, 1-heptanol was mixed with 2-nitrophenyl octyl ether (NPOE...

  2. Microstructure and mechanical properties of direct metal laser sintered TI-6AL-4V

    Directory of Open Access Journals (Sweden)

    Becker, Thorsten Hermann

    2015-05-01

    Full Text Available Direct metal laser sintering (DMLS is a selective laser melting (SLM manufacturing process that can produce near net shape parts from metallic powders. A range of materials are suitable for SLM; they include various metals such as titanium, steel, aluminium, and cobalt-chrome alloys. This paper forms part of a research drive that aims to evaluate the material performance of the SLM-manufactured metals. It presents DMLS-produced Ti-6Al-4V, a titanium alloy often used in biomedical and aerospace applications. This paper also studies the effect of several heat treatments on the microstructure and mechanical properties of Ti-6Al-4V processed by SLM. It reports the achievable mechanical properties of the alloy, including quasi-static, crack growth behaviour, density and porosity distribution, and post-processing using various heat-treatment conditions.

  3. Tailoring Selective Laser Melting Process Parameters for NiTi Implants

    Science.gov (United States)

    Bormann, Therese; Schumacher, Ralf; Müller, Bert; Mertmann, Matthias; de Wild, Michael

    2012-12-01

    Complex-shaped NiTi constructions become more and more essential for biomedical applications especially for dental or cranio-maxillofacial implants. The additive manufacturing method of selective laser melting allows realizing complex-shaped elements with predefined porosity and three-dimensional micro-architecture directly out of the design data. We demonstrate that the intentional modification of the applied energy during the SLM-process allows tailoring the transformation temperatures of NiTi entities within the entire construction. Differential scanning calorimetry, x-ray diffraction, and metallographic analysis were employed for the thermal and structural characterizations. In particular, the phase transformation temperatures, the related crystallographic phases, and the formed microstructures of SLM constructions were determined for a series of SLM-processing parameters. The SLM-NiTi exhibits pseudoelastic behavior. In this manner, the properties of NiTi implants can be tailored to build smart implants with pre-defined micro-architecture and advanced performance.

  4. Supported liquid membrane extraction of 17β- estradiol and its ...

    African Journals Online (AJOL)

    Administrator

    2006-10-02

    Oct 2, 2006 ... respectively. For spiked water sample, the extraction efficiencies were of the order 82–96% from a 1 .... advantages of using SLM are that, the system uses very ..... electrochemical detection for the determination of chlorinated.

  5. Parameter optimization for selective laser melting of TiAl6V4 alloy by CO2 laser

    Science.gov (United States)

    Baitimerov, R. M.; Lykov, P. A.; Radionova, L. V.; Safonov, E. V.

    2017-10-01

    TiAl6V4 alloy is one of the widely used materials in powder bed fusion additive manufacturing technologies. In recent years selective laser melting (SLM) of TiAl6V4 alloy by fiber laser has been well studied, but SLM by CO2-lasers has not. SLM of TiAl6V4 powder by CO2-laser was studied in this paper. Nine 10×10×10 mm cubic specimens were fabricated using different SLM process parameters. All of the fabricated specimens have a good dense structure and a good surface finish quality without dimensional distortion. The lowest porosity that was achieved was about 0.5%.

  6. Modelling the regional application of stakeholder identified land management strategies.

    Science.gov (United States)

    Irvine, B. J.; Fleskens, L.; Kirkby, M. J.

    2012-04-01

    The DESIRE project has trialled a series of sustainable land management (SLM) technologies. These technologies have been identified as being beneficial in mitigating land degradation by local stakeholders from a range of semi-arid study sites. The field results and the qualitative WOCAT technology assessment ftom across the study sites have been used to develop the adapted PESERA SLM model. This paper considers the development of the adapted PESERA SLM model and the potential for applying locally successful SLM technologies across a wider range of climatic and environmental conditions with respect to degradation risk, biomass production and the investment cost interface (PESERA/DESMICE). The integrate PESERA/DESMICE model contributes to the policy debate by providing a biophysical and socio-economic assessment of technology and policy scenarios.

  7. Microstructure and mechanical properties of selective laser melted Ti6Al4V alloy

    Science.gov (United States)

    Losertová, M.; Kubeš, V.

    2017-11-01

    The present work was focused on the properties of porous Ti6Al4V specimens processed by selective laser melting (SLM) and tested in tension and compression before and after heat treatment. The SLM samples were annealed at 955 °C, water quenched and aged at 600 °C with following air cooling. The values of the mechanical tests showed that the samples exhibited high mechanical properties. The anisotropy of tensile and compressive strength was observed, which was related to the occurrence of voids. The plastic properties of specimens were improved by means of the heat treatment that led to the transformation of martensitic to lamellar structure composed of α + β phases. The microstructure of SLM samples were evaluated before and after the heat treatment. The brittle nature of failures of non-heat treated samples can be explained by synergy of martensite presence, microcracks and residual stresses produced by SLM.

  8. Selective Laser Melting of Hot Gas Turbine Components: Materials, Design and Manufacturing Aspects

    DEFF Research Database (Denmark)

    Goutianos, Stergios

    2017-01-01

    are built additively to nearly net shape. This allows the fabrication of arbitrary complex geometries that cannot be made by conventional manufacturing techniques. However, despite the powerful capabilities of SLM, a number of issues (e.g. part orientation, support structures, internal stresses), have......Selective Laser Melting (SLM) allows the design and manufacturing of novel parts and structures with improved performance e.g. by incorporating complex and more efficient cooling schemes in hot gas turbine parts. In contrast to conventional manufacturing of removing material, with SLM parts...... to be considered in order to manufacture cost-effective and high quality parts at an industrial scale. These issues are discussed in the present work from an engineering point of view with the aim to provide simple quidelines to produce high quality SLM parts....

  9. Laser-based additive manufacturing of metals

    CSIR Research Space (South Africa)

    Kumar, S

    2010-11-01

    Full Text Available For making metallic products through Additive Manufacturing (AM) processes, laser-based systems play very significant roles. Laser-based processes such as Selective Laser Melting (SLM) and Laser Engineered Net Shaping (LENS) are dominating processes...

  10. Additive Manufacturing of Shape Memory Alloys

    Science.gov (United States)

    Van Humbeeck, Jan

    2018-04-01

    Selective Laser Melting (SLM) is an additive manufacturing production process, also called 3D printing, in which functional, complex parts are produced by selectively melting patterns in consecutive layers of powder with a laser beam. The pattern the laser beam is following is controlled by software that calculates the pattern by slicing a 3D CAD model of the part to be constructed. Apart from SLM, also other additive manufacturing techniques such as EBM (Electron Beam Melting), FDM (Fused Deposition Modelling), WAAM (Wire Arc Additive Manufacturing), LENS (Laser Engineered Net Shaping such as Laser Cladding) and binder jetting allow to construct complete parts layer upon layer. But since more experience of AM of shape memory alloys is collected by SLM, this paper will overview the potentials, limits and problems of producing NiTi parts by SLM.

  11. Determination of bromoxynil and ioxynil in the presence of ...

    African Journals Online (AJOL)

    SLM) technique for the determination of phenolic nitrile herbicides in presence of carbamates in river water samples was investigated. The uncharged herbicide molecules from the flowing aqueous solution diffuse through an immobilized ...

  12. Actinide separations by supported liquid membranes

    International Nuclear Information System (INIS)

    Danesi, P.R.; Horwitz, E.P.; Rickert, P.; Chiarizia, R.

    1984-01-01

    The work has demonstrated that actinide removal from synthetic waste solutions using both flat-sheet and hollow-fiber SLM's is a feasible chemical process at the laboratory scale level. The process is characterized by the typical features of SLM's processes: very small quantities of extractant required; the potential for operations with high feed/strip volume ratios, resulting in a corresponding concentration factor of the actinides; and simplicity of operation. Major obstacles to the implementation of the SLM technology to the decontamination of liquid nuclear wastes are the probable low resistance of polypropylene supports to high radiation fields, which may prevent the application to high-level nuclear wastes; the unknown lifetime of the SLM; and the high Na content of the separated actinide solution

  13. Generating shaped femtosecond pulses in the far infrared using a spatial light modulator and difference frequency generation

    CSIR Research Space (South Africa)

    Botha, N

    2010-08-31

    Full Text Available Femtosecond pulse shaping can be done by different kinds of pulse shapers, such as liquid crystal spatial light modulators (LC SLM), acousto optic modulators (AOM) and deformable and movable mirrors. A few applications where pulse shaping...

  14. Pulse shaping using a spatial light modulator

    CSIR Research Space (South Africa)

    Botha, N

    2009-07-01

    Full Text Available Femtosecond pulse shaping can be done by different kinds of pulse shapers, such as liquid crystal spatial light modulators (LC SLM), acousto optic modulators (AOM) and deformable and movable mirrors. A few applications where pulse shaping...

  15. Q4 Titanium 6-4 Material Properties Development

    Science.gov (United States)

    Cooper, Kenneth; Nettles, Mindy

    2015-01-01

    This task involves development and characterization of selective laser melting (SLM) parameters for additive manufacturing of titanium-6%aluminum-4%vanadium (Ti-6Al-4V or Ti64). SLM is a relatively new manufacturing technology that fabricates complex metal components by fusing thin layers of powder with a high-powered laser beam, utilizing a 3D computer design to direct the energy and form the shape without traditional tools, dies, or molds. There are several metal SLM technologies and materials on the market today, and various efforts to quantify the mechanical properties, however, nothing consolidated or formal to date. Meanwhile, SLM material fatigue properties of Ti64 are currently highly sought after by NASA propulsion designers for rotating turbomachinery components.

  16. Structure Optimization of Porous Dental Implant Based on 3D Printing

    Science.gov (United States)

    Ji, Fangqiu; Zhang, Chunyu; Chen, Xianshuai

    2018-03-01

    In this paper, selective laser melting (SLM) technology is used to process complex structures. In combination with the theory of biomedicine, a porous implant with a porous structure is designed to induce bone cell growth. The mechanical strength advantage of SLM was discussed by observing the metallographic structure of SLM specimen with mechanical microscope and mechanical tensile test. The osseointegration of porous implants was observed and analyzed by biological experiments. By establishing a mechanical model, the mechanical properties of the bone implant combined with the jaw bone were studied by the simple mechanical analysis under static multi loading and the finite element mechanical analysis. According to the experimental observation and mechanical research, the optimization suggestions for the structure design of the implant made by SLM technology were put forward.

  17. Combined holographic-mechanical optical tweezers: Construction, optimization, and calibration

    Science.gov (United States)

    Hanes, Richard D. L.; Jenkins, Matthew C.; Egelhaaf, Stefan U.

    2009-08-01

    A spatial light modulator (SLM) and a pair of galvanometer-mounted mirrors (GMM) were combined into an optical tweezers setup. This provides great flexibility as the SLM creates an array of traps, which can be moved smoothly and quickly with the GMM. To optimize performance, the effect of the incidence angle on the SLM with respect to phase and intensity response was investigated. Although it is common to use the SLM at an incidence angle of 45°, smaller angles give a full 2π phase shift and an output intensity which is less dependent on the magnitude of the phase shift. The traps were calibrated using an active oscillatory technique and a passive probability distribution method.

  18. Combined holographic-mechanical optical tweezers: Construction, optimization, and calibration

    International Nuclear Information System (INIS)

    Hanes, Richard D. L.; Jenkins, Matthew C.; Egelhaaf, Stefan U.

    2009-01-01

    A spatial light modulator (SLM) and a pair of galvanometer-mounted mirrors (GMM) were combined into an optical tweezers setup. This provides great flexibility as the SLM creates an array of traps, which can be moved smoothly and quickly with the GMM. To optimize performance, the effect of the incidence angle on the SLM with respect to phase and intensity response was investigated. Although it is common to use the SLM at an incidence angle of 45 deg., smaller angles give a full 2π phase shift and an output intensity which is less dependent on the magnitude of the phase shift. The traps were calibrated using an active oscillatory technique and a passive probability distribution method.

  19. Altitudinal distribution of the common longeared bat Plecotus auritus (Linnaeus, 1758 and grey long-eared bat Plecotus austriacus (J. B. Fischer, 1829 (Chiroptera, Vespertilionidae in the Tatra mountains (southern Poland

    Directory of Open Access Journals (Sweden)

    Krzysztof Piksa

    2006-03-01

    Full Text Available Riassunto Distribuzione altitudinale di Orecchione bruno (Plecotus auritus e Orecchione meridionale (Plecotus austriacus nei Monti Tatra (Polonia meridionale. Vengono riportati nuovi dati relativi alla distribuzione altitudinale nei Monti Tatra (Polonia meridionale di Plecotus auritus e P. austriacus. Tali segnalazioni incrementano le conoscenze relative alla presenza di questi chirotteri a quote elevate, in particolare per la Polonia. In inverno P. auritus è stato rinvenuto a 1921 m s.l.m. mentre in estate è stato rinvenuto a 2250 m s.l.m.; in aggiunta, sono stati ritrovati resti ossei a 1929 m s.l.m. P. austriacus è stato segnalato in ibernazione a 1294 m s.l.m.

  20. Angular Accelerating White Light

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2015-08-01

    Full Text Available wavelength dependence. By digitally simulating free-space propagation on the SLM, The authors compare the effects of real and digital propagation on the angular rotation rates of the resulting optical fields for various wavelengths. The development...

  1. RESIDUAL STRESS MEASUREMENTS AND STRUCTURAL INTEGRITY IMPLICATIONS FOR SELECTIVE LASER MELTED TI-6AL-4V

    Directory of Open Access Journals (Sweden)

    Knowles, C. R.

    2012-11-01

    Full Text Available Selective laser melting (SLM of Ti-6Al-4V has significant potential in the aerospace and biotechnology industries. SLM employs a focused laser beam to melt successive layers of metallic powder into complex components. This process can result in the generation of high thermally-induced residual stresses. These residual stresses, together with micro-flaws/ pores from the inherent fabrication process, may lead to premature fatigue crack initiation and propagation at relatively low cyclic stresses. The hole-drilling strain gauge method was used to evaluate residual stresses within SLM Ti-6Al-4V specimens, with the intention of understanding the associated mechanisms for the successful application of SLM Ti-6Al-4V in industry.

  2. Additively Manufactured, Thermally Stable Telescope Mirror Substrates, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is to demonstrate the feasibility of using selective laser melting (SLM) to develop the material composition and the additive manufacturing fabrication...

  3. Low-Cost Manufacturing Technique for Advanced Regenerative Cooling for In-Space Cryogenic Engines, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the proposed effort is to use selective laser melting (SLM, an additive manufacturing technique) to manufacture a hot fire-capable, water-cooled spool...

  4. Development of Physics-Based Numerical Models for Uncertainty Quantification of Selective Laser Melting Processes

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the proposed research is to characterize the influence of process parameter variability inherent to Selective Laser Melting (SLM) and performance effect...

  5. Investigation on Porosity and Microhardness of 316L Stainless Steel Fabricated by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Shahir Mohd Yusuf

    2017-02-01

    Full Text Available This study investigates the porosity and microhardness of 316L stainless steel samples fabricated by selective laser melting (SLM. The porosity content was measured using the Archimedes method and the advanced X-ray computed tomography (XCT scan. High densification level (≥99% with a low average porosity content (~0.82% were obtained from the Archimedes method. The highest porosity content in the XCT-scanned sample was ~0.61. However, the pores in the SLM samples for both cases (optical microscopy and XCT were not uniformly distributed. The higher average microhardness values in the SLM samples compared to the wrought manufactured counterpart are attributed to the fine microstructures from the localised melting and rapid solidification rate of the SLM process.

  6. Additive Manufacturing of Telescope Mirrors, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase 1 SBIR is to demonstrate feasibility of using selective laser melting (SLM) to produce a 3-meter symmetrical radius of curvature (ROC) isogrid mirror...

  7. Low-Cost Manufacturing Technique for Advanced Regenerative Cooling for In-Space Cryogenic Engines, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the proposed effort is to demonstrate feasibility of using selective laser melting (SLM, an emerging manufacturing technique) to manufacture a subscale...

  8. Microstructure and tensile properties of Ti-6Al-4V alloys manufactured by selective laser melting with optimized processing parameters

    Science.gov (United States)

    Wang, L.; Ma, C.; Huang, J.; Ding, H. Y.; Chu, M. Q.

    2017-11-01

    Selective laser melting (SLM) is a precise additive manufacturing process that the metallic powders without binder are melted layer by layer to complex components using a high bright fiber laser. In the paper, Ti-6Al-4V alloy was fabricated by SLM and its microstructure and mechanical properties were investigated in order to evaluate the SLM process. The results show that the microstructure exists anisotropy between the horizontal and vertical section due to the occurrence of epitaxial growth, and the former microstructure seems equal-axis and the latter is column. Moreover, there is little difference in tensile test between the horizontal and vertical sections. Furthermore, the tensile properties of fabricated Ti-6Al-4V alloy by SLM are higher than the forged standard ones. However, the fatigue results show that there are some scatters, which need further investigation to define the fatigue initiation.

  9. Analysis and optimisation of vertical surface roughness in micro selective laser melting

    International Nuclear Information System (INIS)

    Abele, Eberhard; Kniepkamp, Michael

    2015-01-01

    Surface roughness is a major disadvantage of many additive manufacturing technologies like selective laser melting (SLM) compared to established processes like milling or drilling. With recent advancements the resolution of the SLM process could be increased to layer heights of less than 10 μm leading to a new process called micro selective laser melting (μSLM). The purpose of this paper is to analyze the influence of the μSLM process parameters and exposure strategies on the morphology of vertical surfaces. Contour scanning using varying process parameters was used to increase the surface quality. It is shown that it is possible to achieve average surface roughness of less than 1.7 μm using low scan speeds compared to 8–10 μm without contour scanning. Furthermore it is shown that a contour exposure prior to the core exposure leads to surface defects and thus increased roughness. (paper)

  10. profitability of soil erosion control technologies in eastern uganda

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    The lack of farmer awareness of costs and benefits associated with the use of sustainable land management (SLM) .... land under soil erosion control technologies, cost of labour and ..... and promotion of quality protein maize hybrids in Ghana.

  11. Selective laser melting of Al-12Si

    OpenAIRE

    Prashanth, Konda Gokuldoss

    2014-01-01

    Selective laser melting (SLM) is a powder-based additive manufacturing technique consisting of the exact reproduction of a three dimensional computer model (generally a computer-aided design CAD file or a computer tomography CT scan) through an additive layer-by-layer strategy. Because of the high degree of freedom offered by the additive manufacturing, parts having almost any possible geometry can be produced by SLM. More specifically, with this process it is possible to build parts with ext...

  12. SPA Adición de enmiendas a suelos contaminados

    OpenAIRE

    Madejón, Paula

    2016-01-01

    SPA Adición de enmiendas a suelos contaminados.-- Información introducida en la base de datos WOCAT es una red global de gestión sostenible de tierras (SLM) que promueve la documentación, el intercambio y el uso del conocimiento para apoyar la adaptación, la innovación y la toma de decisiones en SLM.

  13. Advanced Manufacturing Technologies (AMT): Additive Manufactured Hot Fire Planning and Testing in GRC Cell 32 Project

    Science.gov (United States)

    Fikes, John C.

    2014-01-01

    The objective of this project is to hot fire test an additively manufactured thrust chamber assembly TCA (injector and thrust chamber). GRC will install the additively manufactured Inconel 625 injector, two additively manufactured (SLM) water cooled Cu-Cr thrust chamber barrels and one additively manufactured (SLM) water cooled Cu-Cr thrust chamber nozzle on the test stand in Cell 32 and perform hot fire testing of the integrated TCA.

  14. Steady-state coupled transport of HNO3 through a hollow-fiber supported liquid membrane

    International Nuclear Information System (INIS)

    Noble, R.D.; Danesi, P.R.

    1987-01-01

    Nitric acid removal from an aqueous stream was accomplished by continuously passing the fluid through a hollow fiber supported liquid membrane (SLM). The nitric acid was extracted through the membrane wall by coupled transport. The system was modeled as a series of (SLM)-continuous stirred tank reactor (CSTR) pairs. An approximate technique was used to predict the steady state nitric acid concentration in the system. The comparison with experimental data was very good

  15. Additive manufacturing of titanium alloy for aircraft components

    OpenAIRE

    Uhlmann, E.; Kersting, R.; Klein, T.B.; Cruz, M.F.; Borille, A.V.

    2015-01-01

    Selective Laser melting (SLM) is an additive manufacturing technology that uses laser as a power source to sinter powdered metals to produce solid structures. The application of SLM permits engineers to develop and implement components with topologically optimized designs and resultant material properties in comparison to conventionally produced casting parts. Current aviation programs as ACARE 2020 (Advisory Council for Aviation Research and Innovation in the EU) and Flightpath 2050 request ...

  16. Electromembrane extraction – Recent trends and where to go

    DEFF Research Database (Denmark)

    Pedersen-Bjergaard, Stig; Huang, Chuixiu; Gjelstad, Astrid

    2017-01-01

    Electromembrane extraction (EME) is an analytical microextraction technique, where charged analytes (such as drug substances) are extracted from an aqueous sample (such as a biological fluid), through a supported liquid membrane (SLM) comprising a water immiscible organic solvent......, papers published in 2016 are reviewed and discussed with focus on (a) new SLMs, (b) new support materials for the SLM, (c) new sample additives improving extraction, (d) new technical configurations, (e) improved theoretical understanding, and (f) pharmaceutical new applications. Finally, important...

  17. The biocompatibility of dense and porous Nickel-Titanium produced by selective laser melting.

    Science.gov (United States)

    Habijan, T; Haberland, C; Meier, H; Frenzel, J; Wittsiepe, J; Wuwer, C; Greulich, C; Schildhauer, T A; Köller, M

    2013-01-01

    Nickel-Titanium shape memory alloys (NiTi-SMA) are of biomedical interest due to their unusual range of pure elastic deformability and their elastic modulus, which is closer to that of bone than any other metallic or ceramic material. Newly developed porous NiTi, produced by Selective Laser Melting (SLM), is currently under investigation as a potential carrier material for human mesenchymal stem cells (hMSC). SLM enables the production of highly complex and tailor-made implants for patients on the basis of CT data. Such implants could be used for the reconstruction of the skull, face, or pelvis. hMSC are a promising cell type for regenerative medicine and tissue engineering due to their ability to support the regeneration of critical size bone defects. Loading porous SLM-NiTi implants with autologous hMSC may enhance bone growth and healing for critical bone defects. The purpose of this study was to assess whether porous SLM-NiTi is a suitable carrier for hMSC. Specimens of varying porosity and surface structure were fabricated via SLM. hMSC were cultured for 8 days on NiTi specimens, and cell viability was analyzed using two-color fluorescence staining. Viable cells were detected on all specimens after 8 days of cell culture. Cell morphology and surface topography were analyzed by scanning electron microscopy (SEM). Cell morphology and surface topology were dependent on the orientation of the specimens during SLM production. The Nickel ion release can be reduced significantly by aligned laser processing conditions. The presented results clearly attest that both dense SLM-NiTi and porous SLM-NiTi are suitable carriers for hMSC. Nevertheless, before carrying out in vivo studies, some work on optimization of the manufacturing process and post-processing is required. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Two spatial light modulator system for laboratory simulation of random beam propagation in random media.

    Science.gov (United States)

    Wang, Fei; Toselli, Italo; Korotkova, Olga

    2016-02-10

    An optical system consisting of a laser source and two independent consecutive phase-only spatial light modulators (SLMs) is shown to accurately simulate a generated random beam (first SLM) after interaction with a stationary random medium (second SLM). To illustrate the range of possibilities, a recently introduced class of random optical frames is examined on propagation in free space and several weak turbulent channels with Kolmogorov and non-Kolmogorov statistics.

  19. From neurons to nests : nest-building behaviour as a model in behavioural and comparative neuroscience

    OpenAIRE

    Hall, Zachary Jonas; Meddle, Simone L; Healy, Susan Denise

    2015-01-01

    This work was supported by funding from the Biotechnology and Biological Sciences Research Council (BB/ I019502/1 to SDH and SLM) and the Natural Sciences and Engineering Research Council of Canada (grant number PGSD3-409582-2011 to ZJH) and Roslin Institute Strategic Grant funding from the Biotechnology and Biological Sciences Research Council (SLM). Despite centuries of observing the nest building of most extant bird species, we know surprisingly little about how birds build nests and, s...

  20. Fabrication and Thermoelectric Properties of n-Type CoSb2.85Te0.15 Using Selective Laser Melting.

    Science.gov (United States)

    Yan, Yonggao; Ke, Hongquan; Yang, Jihui; Uher, Ctirad; Tang, Xinfeng

    2018-04-25

    We report a nonequilibrium fabrication method of n-type CoSb 2.85 Te 0.15 skutterudites using selective laser melting (SLM) technology. A powder of CoSb 2.85 Te 0.15 was prepared by self-propagating high-temperature synthesis (SHS) and served as the raw material for the SLM process. The effect of SLM processing parameters such as the laser power and scanning speed on the quality of the forming CoSb 2.85 Te 0.15 thin layers was systematically analyzed, and the optimal processing window for SLM was determined. A brief postannealing at 450 °C for 4 h, following the SLM process, has resulted in a phase-pure CoSb 2.85 Te 0.15 bulk material deposited on a Ti substrate. The Seebeck coefficient of the annealed SLM prepared bulk material is close to that of the sample prepared by the traditional sintering method, and its maximum ZT value reached 0.56 at 823 K. Moreover, a Ti-Co-Sb ternary compound transition layer of about 70 μm in thickness was found at a dense interface between CoSb 2.85 Te 0.15 and the Ti substrate. The contact resistivity was measured as 37.1 μΩcm 2 . The results demonstrate that SLM, coupled with postannealing, can be used for fabrication of incongruently melting skutterudite compounds on heterogeneous substrates. This lays an important foundation for the follow-up research utilizing energy efficient SHS and SLM processes in rapid printing of thermoelectric modules.

  1. Constitutive and failure behaviour in selective laser melted stainless steel for microlattice structures

    International Nuclear Information System (INIS)

    Li, Peifeng

    2015-01-01

    The emerging selective laser melting (SLM) technology makes possible the manufacturing of metallic microlattice structures with better tailorability of properties. This work investigated the constitutive formulation of the parent material and the failure mechanism in the SLM stainless steel microlattice structure. The constitutive behaviour of SLM stainless steel was quantitatively formulated using the Johnson–Cook hardening model. A finite element model incorporating the constitutive formula was developed and experimentally validated to predict the localised stress evolution in an SLM stainless steel microlattice structure subjected to uniaxial compression. The predicted stresses were then linked to the fracture process in the SLM steel observed by scanning electron microscope. It was found that the tensile and compressive stress state is localised in the strut members of the microlattice, and determines the macroscopic cracking mode. The tensile opening and shear cracking dominate the tension and compression zones, respectively. However, the microscopic examination on the fracture surfaces reveals the formation of substantial slip bands in both the tension and compression zones, implying that the ductile fracture in the SLM stainless steel is transgranular

  2. [Comparative adaptation of crowns of selective laser melting and wax-lost-casting method].

    Science.gov (United States)

    Li, Guo-qiang; Shen, Qing-yi; Gao, Jian-hua; Wu, Xue-ying; Chen, Li; Dai, Wen-an

    2012-07-01

    To investigate the marginal adaptation of crowns fabricated by selective laser melting (SLM) and wax-lost-casting method, so as to provide an experimental basis for clinic. Co-Cr alloy full crown were fabricated by SLM and wax-lost-casting for 24 samples in each group. All crowns were cemented with zinc phosphate cement and cut along longitudinal axis by line cutting machine. The gap between crown tissue surface and die was measured by 6-point measuring method with scanning electron microscope (SEM). The marginal adaptation of crowns fabricated by SLM and wax-lost-casting were compared statistically. The gap between SLM crowns were (36.51 ± 2.94), (49.36 ± 3.31), (56.48 ± 3.35), (42.20 ± 3.60) µm, and wax-lost-casting crowns were (68.86 ± 5.41), (58.86 ± 6.10), (70.62 ± 5.79), (69.90 ± 6.00) µm. There were significant difference between two groups (P casting method and SLM method provide acceptable marginal adaptation in clinic, and the marginal adaptation of SLM is better than that of wax-lost-casting method.

  3. Laser and Electron Beam Additive Manufacturing Methods of Fabricating Titanium Bone Implants

    Directory of Open Access Journals (Sweden)

    Bartłomiej Wysocki

    2017-06-01

    Full Text Available Additive Manufacturing (AM methods are generally used to produce an early sample or near net-shape elements based on three-dimensional geometrical modules. To date, publications on AM of metal implants have mainly focused on knee and hip replacements or bone scaffolds for tissue engineering. The direct fabrication of metallic implants can be achieved by methods, such as Selective Laser Melting (SLM or Electron Beam Melting (EBM. This work compares the SLM and EBM methods used in the fabrication of titanium bone implants by analyzing the microstructure, mechanical properties and cytotoxicity. The SLM process was conducted in an environmental chamber using 0.4–0.6 vol % of oxygen to enhance the mechanical properties of a Ti-6Al-4V alloy. SLM processed material had high anisotropy of mechanical properties and superior UTS (1246–1421 MPa when compared to the EBM (972–976 MPa and the wrought material (933–942 MPa. The microstructure and phase composition depended on the used fabrication method. The AM methods caused the formation of long epitaxial grains of the prior β phase. The equilibrium phases (α + β and non-equilibrium α’ martensite was obtained after EBM and SLM, respectively. Although it was found that the heat transfer that occurs during the layer by layer generation of the component caused aluminum content deviations, neither methods generated any cytotoxic effects. Furthermore, in contrast to SLM, the EBM fabricated material met the ASTMF136 standard for surgical implant applications.

  4. Influence of Selective Laser Melting Processing Parameters of Co-Cr-W Powders on the Roughness of Exterior Surfaces

    Science.gov (United States)

    Baciu, M. A.; Baciu, E. R.; Bejinariu, C.; Toma, S. L.; Danila, A.; Baciu, C.

    2018-06-01

    Selective Laser Melting (SLM) represents an Additive Manufacturing method widely used in medical practice, mainly in dental medicine. The powder of 59% Co, 25% Cr, 2.5% W alloy (Starbond CoS Powder 55, S&S Scheftner C, Germany) was processed (SLM) on a Realizer SLM 50 device (SLM Solution, Germany). After laser processing and simple sanding with Al2O3 or two-phase sanding (Al2O3 and glass balls), measurements of surface roughness were conducted. This paper presents the influences exercised by laser power (P = 60 W, 80 W and 100 W), the scanning speed (vscan = 333 mm/s, 500 mm/s and 1000 mm/s) and exposure time (te = 20 µs, 40 µs and 60 µs) on the roughness of surfaces obtained by SLM processing. Based on the experimental results obtained for roughness (Ra), some recommendations regarding the choice of favorable combinations among the values of technological parameters under study in order to obtain the surface quality necessary for subsequent applications of the processed parts (SLM) have been made.

  5. Selective laser melting of Ti6Al4V alloy for biomedical applications: Temperature monitoring and microstructural evolution

    Energy Technology Data Exchange (ETDEWEB)

    Yadroitsev, I., E-mail: ihar.yadroitsau@enise.fr [Université de Lyon, Ecole Nationale d’Ingénieurs de Saint-Etienne, 58 rue Jean Parot, 42023 Saint-Etienne (France); Krakhmalev, P. [Karlstad University, Department of Mechanical and Materials Engineering, SE-651 88 Karlstad (Sweden); Yadroitsava, I. [Université de Lyon, Ecole Nationale d’Ingénieurs de Saint-Etienne, 58 rue Jean Parot, 42023 Saint-Etienne (France)

    2014-01-15

    Highlights: • Temperature measurements of molten pool were done using CCD camera. • Temperature of molten pool versus scanning speed and laser power was determined. • Microstructures and microhardness of SLM samples were analyzed. • Influence of heat treatment on microstructure were discussed and presented. -- Abstract: Selective laser melting (SLM) is a kind of additive manufacturing where parts are made directly from 3D CAD data layer-by-layer from powder material. SLM products are used in various industries including aerospace, automotive, electronic, chemical, biomedical and other high-tech areas. The properties of the parts produced by SLM depend strongly on the material nature, characteristics of each single track and each single layer, as well as the strength of the connections between them. Studying the temperature distribution during SLM is important because temperature gradient and heat transfer determine the microstructure and finally mechanical properties of the SLM part. In this study a CCD camera was applied for determination of the surface temperature distribution and the molten pool size of Ti6Al4V alloy. The investigation of the microstructure evolution after different heat treatments was carried out to determine the microstructure in terms of applicability for the biomedical industry.

  6. Selective laser melting porous metallic implants with immobilized silver nanoparticles kill and prevent biofilm formation by methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    van Hengel, Ingmar A J; Riool, Martijn; Fratila-Apachitei, Lidy E; Witte-Bouma, Janneke; Farrell, Eric; Zadpoor, Amir A; Zaat, Sebastian A J; Apachitei, Iulian

    2017-09-01

    Implant-associated infection and limited longevity are two major challenges that orthopedic devices need to simultaneously address. Additively manufactured porous implants have recently shown tremendous promise in improving bone regeneration and osseointegration, but, as any conventional implant, are threatened by infection. In this study, we therefore used rational design and additive manufacturing in the form of selective laser melting (SLM) to fabricate porous titanium implants with interconnected pores, resulting in a 3.75 times larger surface area than corresponding solid implants. The SLM implants were biofunctionalized by embedding silver nanoparticles in an oxide surface layer grown using plasma electrolytic oxidation (PEO) in Ca/P-based electrolytes. The PEO layer of the SLM implants released silver ions for at least 28 days. X-ray diffraction analysis detected hydroxyapatite on the SLM PEO implants but not on the corresponding solid implants. In vitro and ex vivo assays showed strong antimicrobial activity of these novel SLM PEO silver-releasing implants, without any signs of cytotoxicity. The rationally designed SLM porous implants outperformed solid implants with similar dimensions undergoing the same biofunctionalization treatment. This included four times larger amount of released silver ions, two times larger zone of inhibition, and one additional order of magnitude of reduction in numbers of CFU in an ex vivo mouse infection model. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. PHASE QUANTIZATION STUDY OF SPATIAL LIGHT MODULATOR FOR EXTREME HIGH-CONTRAST IMAGING

    Energy Technology Data Exchange (ETDEWEB)

    Dou, Jiangpei; Ren, Deqing, E-mail: jpdou@niaot.ac.cn, E-mail: jiangpeidou@gmail.com [Physics and Astronomy Department, California State University Northridge, 18111 Nordhoff Street, Northridge, CA 91330 (United States)

    2016-11-20

    Direct imaging of exoplanets by reflected starlight is extremely challenging due to the large luminosity ratio to the primary star. Wave-front control is a critical technique to attenuate the speckle noise in order to achieve an extremely high contrast. We present a phase quantization study of a spatial light modulator (SLM) for wave-front control to meet the contrast requirement of detection of a terrestrial planet in the habitable zone of a solar-type star. We perform the numerical simulation by employing the SLM with different phase accuracy and actuator numbers, which are related to the achievable contrast. We use an optimization algorithm to solve the quantization problems that is matched to the controllable phase step of the SLM. Two optical configurations are discussed with the SLM located before and after the coronagraph focal plane mask. The simulation result has constrained the specification for SLM phase accuracy in the above two optical configurations, which gives us a phase accuracy of 0.4/1000 and 1/1000 waves to achieve a contrast of 10{sup -10}. Finally, we have demonstrated that an SLM with more actuators can deliver a competitive contrast performance on the order of 10{sup -10} in comparison to that by using a deformable mirror.

  8. Intragranular cellular segregation network structure strengthening 316L stainless steel prepared by selective laser melting

    Science.gov (United States)

    Zhong, Yuan; Liu, Leifeng; Wikman, Stefan; Cui, Daqing; Shen, Zhijian

    2016-03-01

    A feasibility study was performed to fabricate ITER In-Vessel components by Selective Laser Melting (SLM) supported by Fusion for Energy (F4E). Almost fully dense 316L stainless steel (SS316L) components were prepared from gas-atomized powder and with optimized SLM processing parameters. Tensile tests and Charpy-V tests were carried out at 22 °C and 250 °C and the results showed that SLM SS316L fulfill the RCC-MR code. Microstructure characterization reveals the presence of hierarchical macro-, micro- and nano-structures in as-built samples that were very different from SS316L microstructures prepared by other established methods. The formation of a characteristic intragranular cellular segregation network microstructure appears to contribute to the increase of yield strength without losing ductility. Silicon oxide nano-inclusions were formed during the SLM process that generated a micro-hardness fluctuation in the building direction. The combined influence of a cellular microstructure and the nano-inclusions constraints the size of ductile dimples to nano-scale. The crack propagation is hindered by a pinning effect that improves the defect-tolerance of the SLM SS316L. This work proves that it was possible to manufacture SS316L with properties suitable for ITER First Wall panels. Further studies on irradiation properties of SLM SS316L and manufacturing of larger real-size components are needed.

  9. How does the surface treatment change the cytocompatibility of implants made by selective laser melting?

    Science.gov (United States)

    Matouskova, Lucie; Ackermann, Michal; Horakova, Jana; Capek, Lukas; Henys, Petr; Safka, Jiri

    2018-04-01

    The study investigates the potential for producing medical components via Selective Laser Melting technology (SLM). The material tested consisted of the biocompatible titanium alloy Ti6Al4V. The research involved the testing of laboratory specimens produced using SLM technology both in vitro and for surface roughness. The aim of the research was to clarify whether SLM technology affects the cytocompatibility of implants and, thus, whether SLM implants provide suitable candidates for medical use following zero or minimum post-fabrication treatment. Areas covered: The specimens were tested with an osteoblast cell line and, subsequently, two post-treatment processes were compared: non-treated (as-fabricated) and glass-blasted. Interactions with MG-63 cells were evaluated by means of metabolic MTT assay and microscope techniques (scanning electron microscopy, fluorescence microscopy). Surface roughness was observed on both the non-treated and glass-blasted SLM specimens. Expert Commentary: The research concluded that the glass-blasting of SLM Ti6Al4V significantly reduces surface roughness. The arithmetic mean roughness Ra was calculated at 3.4 µm for the glass-blasted and 13.3 µm for the non-treated surfaces. However, the results of in vitro testing revealed that the non-treated surface was better suited to cell growth.

  10. [Comparison of the clinical effects of selective laser melting deposition basal crowns and cobalt chromium alloy base crowns].

    Science.gov (United States)

    Li, Jing-min; Wang, Wei-qian; Ma, Jing-yuan

    2014-06-01

    To evaluate the clinical effects of selective laser melting (SLM) deposition basal crowns and cobalt chromium alloy casting base crowns. One hundred and sixty eight patients treated with either SLM deposition basal crowns (110 teeth) or cobalt chromium alloy casting basal crowns (110 teeth) were followed-up for 1 month, 6 months, 12 months and 24 months. The revised standard of American Public Health Association was used to evaluate the clinical effect of restoration, including the color of porcelain crowns, gingival inflammation, gingival margin discoloration, and crack or fracture. Data analysis was conducted with SPSS 20 software package for Student's t test and Chi-square test. Six cases were lost to follow-up. The patients who were treated with SLM deposition basal crowns (104 teeth) and cobalt chromium alloy casting base crowns (101 teeth) completed the study. Patients were more satisfied with SLM deposition cobalt chromium alloy porcelain crowns. There was 1 prosthesis with poor marginal fit after 24 months of restoration in SLM crowns. There were 6 prostheses with edge coloring and 8 with poor marginal fit in cobalt chromium alloy casting base crowns, which was significantly different between the 2 groups(P<0.05). The SLM deposition copings results in smaller edge coloring and better marginal fit than those of cobalt-chrome copings. Patients are pleased with short-term clinical results.

  11. Bone ingrowth potential of electron beam and selective laser melting produced trabecular-like implant surfaces with and without a biomimetic coating.

    Science.gov (United States)

    Biemond, J E; Hannink, G; Verdonschot, N; Buma, P

    2013-03-01

    The bone ingrowth potential of trabecular-like implant surfaces produced by either selective laser melting (SLM) or electron beam melting (EBM), with or without a biomimetic calciumphosphate coating, was examined in goats. For histological analysis and histomorphometry of bone ingrowth depth and bone implant contact specimens were implanted in the femoral condyle of goats. For mechanical push out tests to analyse mechanical implant fixation specimens were implanted in the iliac crest. The follow up periods were 4 (7 goats) and 15 weeks (7 goats). Both the SLM and EBM produced trabecular-like structures showed a variable bone ingrowth after 4 weeks. After 15 weeks good bone ingrowth was found in both implant types. Irrespective to the follow up period, and the presence of a coating, no histological differences in tissue reaction around SLM and EBM produced specimens was found. Histological no coating was detected at 4 and 15 weeks follow up. At both follow up periods the mechanical push out strength at the bone implant interface was significantly lower for the coated SLM specimens compared to the uncoated SLM specimens. The expected better ingrowth characteristics and mechanical fixation strength induced by the coating were not found. The lower mechanical strength of the coated specimens produced by SLM is a remarkable result, which might be influenced by the gross morphology of the specimens or the coating characteristics, indicating that further research is necessary.

  12. A novel coping metal material CoCrCu alloy fabricated by selective laser melting with antimicrobial and antibiofilm properties.

    Science.gov (United States)

    Ren, Ling; Memarzadeh, Kaveh; Zhang, Shuyuan; Sun, Ziqing; Yang, Chunguang; Ren, Guogang; Allaker, Robert P; Yang, Ke

    2016-10-01

    The aim of this study was to fabricate a novel coping metal CoCrCu alloy using a selective laser melting (SLM) technique with antimicrobial and antibiofilm activities and to investigate its microstructure, mechanical properties, corrosion resistance and biocompatibility. Novel CoCrCu alloy was fabricated using SLM from a mixture of commercial CoCr based alloy and elemental Cu powders. SLM CoCr without Cu served as control. Antibacterial activity was analyzed using standard antimicrobial tests, and antibiofilm properties were investigated using confocal laser scanning microscope. Cu distribution and microstructure were determined using scanning electron microscope, optical microscopy and X-ray diffraction. Corrosion resistance was evaluated by potential dynamic polarization and biocompatibility measured using an MTT assay. SLM CoCrCu alloys were found to be bactericidal and able to inhibit biofilm formation. Other factors such as microstructure, mechanical properties, corrosion resistance and biocompatibility were similar to those of SLM CoCr alloys. The addition of appropriate amounts of Cu not only maintains normal beneficial properties of CoCr based alloys, but also provides SLM CoCrCu alloys with excellent antibacterial and antibiofilm capabilities. This material has the potential to be used as a coping metal for dental applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Metal-ceramic bond strength of Co-Cr alloy fabricated by selective laser melting.

    Science.gov (United States)

    Xiang, Nan; Xin, Xian-Zhen; Chen, Jie; Wei, Bin

    2012-06-01

    This study was to evaluated the metal-ceramic bond strength of a Co-Cr dental alloy prepared using a selective laser melting (SLM) technique. Two groups comprised of twenty Co-Cr metal bars each were prepared using either a SLM or traditional lost-wax casting method. Ten bars from each group were moulded into standard ISO 9693:1999 dimensions of 25 mm × 3 mm × 0.5 mm with 1.1 mm of porcelain fused onto an 8 mm × 3 mm rectangular area in the centre of each bar. Metal-ceramic bonding was assessed using a three-point bending test. Fracture mode analysis and area fraction of adherence porcelain (AFAP) were determined by measuring Si content of specimens by SEM/EDS. Student's t-test within the groups demonstrated no significant difference for the mean bond strength between the SLM and traditional cast sample groups. While SEM/EDS analysis indicated a mixed fracture mode on the debonding interface of both the SLM and the cast groups, the SLM group showed significantly more porcelain adherence than the control group (p<0.05). The SLM metal-ceramic system exhibited a bonding strength that exceeds the requirement of ISO 9691:1999(E) and it even showed a better behaviour in porcelain adherence test comparable to traditional cast methods. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Surface properties and corrosion behavior of Co-Cr alloy fabricated with selective laser melting technique.

    Science.gov (United States)

    Xin, Xian-zhen; Chen, Jie; Xiang, Nan; Wei, Bin

    2013-01-01

    We sought to study the corrosion behavior and surface properties of a commercial cobalt-chromium (Co-Cr) alloy which was fabricated with selective laser melting (SLM) technique. For this purpose, specimens were fabricated using different techniques, such as SLM system and casting methods. Surface hardness testing, microstructure observation, surface analysis using X-ray photoelectron spectroscopy (XPS) and electrochemical corrosion test were carried out to evaluate the corrosion properties and surface properties of the specimens. We found that microstructure of SLM specimens was more homogeneous than that of cast specimens. The mean surface hardness values of SLM and cast specimens were 458.3 and 384.8, respectively; SLM specimens showed higher values than cast ones in hardness. Both specimens exhibited no differences in their electrochemical corrosion properties in the artificial saliva through potentiodynamic curves and EIS, and no significant difference via XPS. Therefore, we concluded that within the scope of this study, SLM-fabricated restorations revealed good surface properties, such as proper hardness, homogeneous microstructure, and also showed sufficient corrosion resistance which could meet the needs of dental clinics.

  15. Corrosion resistance characteristics of a Ti-6Al-4V alloy scaffold that is fabricated by electron beam melting and selective laser melting for implantation in vivo.

    Science.gov (United States)

    Zhao, Bingjing; Wang, Hong; Qiao, Ning; Wang, Chao; Hu, Min

    2017-01-01

    The purpose of this study is to determine the corrosion resistance of Ti-6Al-4V alloy fabricated with electron beam melting and selective laser melting for implantation in vivo. Ti-6Al-4V alloy specimens were fabricated with electron beam melting (EBM) and selective laser melting (SLM). A wrought form of Ti-6Al-4V alloy was used as a control. Surface morphology observation, component analysis, corrosion resistance experimental results, electrochemical impedance spectroscopy, crevice corrosion resistance experimental results, immersion test and metal ions precipitation analysis were processed, respectively. The thermal stability of EBM specimen was the worst, based on the result of open circuit potential (OCP) result. The result of electrochemical impedance spectroscopy indicated that the corrosion resistance of the SLM specimen was the best under the low electric potential. The result of potentiodynamic polarization suggested that the corrosion resistance of the SLM specimen was the best under the low electric potential (1.5V).The crevice corrosion resistance of the EBM specimen was the best. The corrosion resistance of SLM specimen was the best, based on the result of immersion test. The content of Ti, Al and V ions of EBM, SLM and wrought specimens was very low. In general, the scaffolds that were fabricated with EBM and SLM had good corrosion resistance, and were suitable for implantation in vivo. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Point, surface and volumetric heat sources in the thermal modelling of selective laser melting

    Science.gov (United States)

    Yang, Yabin; Ayas, Can

    2017-10-01

    Selective laser melting (SLM) is a powder based additive manufacturing technique suitable for producing high precision metal parts. However, distortions and residual stresses within products arise during SLM because of the high temperature gradients created by the laser heating. Residual stresses limit the load resistance of the product and may even lead to fracture during the built process. It is therefore of paramount importance to predict the level of part distortion and residual stress as a function of SLM process parameters which requires a reliable thermal modelling of the SLM process. Consequently, a key question arises which is how to describe the laser source appropriately. Reasonable simplification of the laser representation is crucial for the computational efficiency of the thermal model of the SLM process. In this paper, first a semi-analytical thermal modelling approach is described. Subsequently, the laser heating is modelled using point, surface and volumetric sources, in order to compare the influence of different laser source geometries on the thermal history prediction of the thermal model. The present work provides guidelines on appropriate representation of the laser source in the thermal modelling of the SLM process.

  17. Sharing evidence of sustainable land management impacts

    Science.gov (United States)

    Schwilch, Gudrun; Mekdaschi Studer, Rima; Providoli, Isabelle; Liniger, Hanspeter

    2015-04-01

    Ensuring sustainable use of natural resources is crucial for maintaining the basis for our livelihoods. With threats from climate change, disputes over water, biodiversity loss, competing claims on land, and migration increasing worldwide, the demands for sustainable land management (SLM) practices will only increase in the future. For years already, various national and international organizations (GOs, NGOs, donors, research institutes, etc.) have been working on alternative forms of land management. And numerous land users worldwide - especially small farmers - have been testing, adapting, and refining new and better ways of managing land. All too often, however, the resulting SLM knowledge has not been sufficiently evaluated, documented and shared. Among other things, this has often prevented valuable SLM knowledge from being channelled into evidence-based decision-making processes. Indeed, proper knowledge management is crucial for SLM to reach its full potential. Since more than 20 years, the international WOCAT network documents and promotes SLM through its global platform. As a whole, the WOCAT methodology comprises tools for documenting, evaluating, and assessing the impact of SLM practices, as well as for knowledge sharing, analysis and use for decision support in the field, at the planning level, and in scaling up identified good practices. In early 2014, WOCAT's growth and ongoing improvement culminated in its being officially recognized by the UNCCD as the primary recommended database for SLM best practices. Over the years, the WOCAT network confirmed that SLM helps to prevent desertification, to increase biodiversity, enhance food security and to make people less vulnerable to the effects of climate variability and change. In addition, it plays an important role in mitigating climate change through improving soil organic matter and increasing vegetation cover. In-depth assessments of SLM practices from desertification sites enabled an evaluation of

  18. The biocompatibility of dense and porous Nickel-Titanium produced by selective laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Habijan, T., E-mail: Tim.Habijan@rub.de [Surgical Research, Department of Surgery, BG Kliniken Bergmannsheil, Ruhr-University Bochum, Buerkle-de-la-Camp-Platz 1, 44789 Bochum (Germany); Haberland, C.; Meier, H. [Institute Product and Service Engineering, Ruhr-University Bochum (Germany); Frenzel, J. [Institute for Materials, Ruhr-University Bochum (Germany); Wittsiepe, J. [Department of Hygiene, Social and Environmental Medicine, Ruhr-University Bochum (Germany); Wuwer, C.; Greulich, C.; Schildhauer, T.A.; Koeller, M. [Surgical Research, Department of Surgery, BG Kliniken Bergmannsheil, Ruhr-University Bochum, Buerkle-de-la-Camp-Platz 1, 44789 Bochum (Germany)

    2013-01-01

    Nickel-Titanium shape memory alloys (NiTi-SMA) are of biomedical interest due to their unusual range of pure elastic deformability and their elastic modulus, which is closer to that of bone than any other metallic or ceramic material. Newly developed porous NiTi, produced by Selective Laser Melting (SLM), is currently under investigation as a potential carrier material for human mesenchymal stem cells (hMSC). SLM enables the production of highly complex and tailor-made implants for patients on the basis of CT data. Such implants could be used for the reconstruction of the skull, face, or pelvis. hMSC are a promising cell type for regenerative medicine and tissue engineering due to their ability to support the regeneration of critical size bone defects. Loading porous SLM-NiTi implants with autologous hMSC may enhance bone growth and healing for critical bone defects. The purpose of this study was to assess whether porous SLM-NiTi is a suitable carrier for hMSC. Specimens of varying porosity and surface structure were fabricated via SLM. hMSC were cultured for 8 days on NiTi specimens, and cell viability was analyzed using two-color fluorescence staining. Viable cells were detected on all specimens after 8 days of cell culture. Cell morphology and surface topography were analyzed by scanning electron microscopy (SEM). Cell morphology and surface topology were dependent on the orientation of the specimens during SLM production. The Nickel ion release can be reduced significantly by aligned laser processing conditions. The presented results clearly attest that both dense SLM-NiTi and porous SLM-NiTi are suitable carriers for hMSC. Nevertheless, before carrying out in vivo studies, some work on optimization of the manufacturing process and post-processing is required. - Highlights: Black-Right-Pointing-Pointer Specimens, varying in porosity and surface structure were produced via SLM. Black-Right-Pointing-Pointer Biocompatibility of these specimens was analyzed. Black

  19. The biocompatibility of dense and porous Nickel–Titanium produced by selective laser melting

    International Nuclear Information System (INIS)

    Habijan, T.; Haberland, C.; Meier, H.; Frenzel, J.; Wittsiepe, J.; Wuwer, C.; Greulich, C.; Schildhauer, T.A.; Köller, M.

    2013-01-01

    Nickel–Titanium shape memory alloys (NiTi-SMA) are of biomedical interest due to their unusual range of pure elastic deformability and their elastic modulus, which is closer to that of bone than any other metallic or ceramic material. Newly developed porous NiTi, produced by Selective Laser Melting (SLM), is currently under investigation as a potential carrier material for human mesenchymal stem cells (hMSC). SLM enables the production of highly complex and tailor-made implants for patients on the basis of CT data. Such implants could be used for the reconstruction of the skull, face, or pelvis. hMSC are a promising cell type for regenerative medicine and tissue engineering due to their ability to support the regeneration of critical size bone defects. Loading porous SLM-NiTi implants with autologous hMSC may enhance bone growth and healing for critical bone defects. The purpose of this study was to assess whether porous SLM-NiTi is a suitable carrier for hMSC. Specimens of varying porosity and surface structure were fabricated via SLM. hMSC were cultured for 8 days on NiTi specimens, and cell viability was analyzed using two-color fluorescence staining. Viable cells were detected on all specimens after 8 days of cell culture. Cell morphology and surface topography were analyzed by scanning electron microscopy (SEM). Cell morphology and surface topology were dependent on the orientation of the specimens during SLM production. The Nickel ion release can be reduced significantly by aligned laser processing conditions. The presented results clearly attest that both dense SLM-NiTi and porous SLM-NiTi are suitable carriers for hMSC. Nevertheless, before carrying out in vivo studies, some work on optimization of the manufacturing process and post-processing is required. - Highlights: ► Specimens, varying in porosity and surface structure were produced via SLM. ► Biocompatibility of these specimens was analyzed. ► All specimens were completely coated with a layer

  20. Physical evaluations of Co-Cr-Mo parts processed using different additive manufacturing techniques

    Science.gov (United States)

    Ghani, Saiful Anwar Che; Mohamed, Siti Rohaida; Harun, Wan Sharuzi Wan; Noar, Nor Aida Zuraimi Md

    2017-12-01

    In recent years, additive manufacturing with highly design customization has gained an important technique for fabrication in aerospace and medical fields. Despite the ability of the process to produce complex components with highly controlled architecture geometrical features, maintaining the part's accuracy, ability to fabricate fully functional high density components and inferior surfaces quality are the major obstacles in producing final parts using additive manufacturing for any selected application. This study aims to evaluate the physical properties of cobalt chrome molybdenum (Co-Cr-Mo) alloys parts fabricated by different additive manufacturing techniques. The full dense Co-Cr-Mo parts were produced by Selective Laser Melting (SLM) and Direct Metal Laser Sintering (DMLS) with default process parameters. The density and relative density of samples were calculated using Archimedes' principle while the surface roughness on the top and side surface was measured using surface profiler. The roughness average (Ra) for top surface for SLM produced parts is 3.4 µm while 2.83 µm for DMLS produced parts. The Ra for side surfaces for SLM produced parts is 4.57 µm while 9.0 µm for DMLS produced parts. The higher Ra values on side surfaces compared to the top faces for both manufacturing techniques was due to the balling effect phenomenon. The yield relative density for both Co-Cr-Mo parts produced by SLM and DMLS are 99.3%. Higher energy density has influence the higher density of produced samples by SLM and DMLS processes. The findings of this work demonstrated that SLM and DMLS process with default process parameters have effectively produced full dense parts of Co-Cr-Mo with high density, good agreement of geometrical accuracy and better surface finish. Despite of both manufacturing process yield that produced components with higher density, the current finding shows that SLM technique could produce components with smoother surface quality compared to DMLS

  1. Selective Laser Melting Technique of Co-Cr Dental Alloys: A Review of Structure and Properties and Comparative Analysis with Other Available Techniques.

    Science.gov (United States)

    Koutsoukis, Theodoros; Zinelis, Spiros; Eliades, George; Al-Wazzan, Khalid; Rifaiy, Mohammed Al; Al Jabbari, Youssef S

    2015-06-01

    The aim of this study was to review the effect of selective laser melting (SLM) procedure on the properties of dental structures made of Co-Cr alloys and to evaluate its quality and compare it to those produced by conventional casting and milling fabrication techniques. A computerized database search using PubMed and Scopus was conducted for peer-reviewed scientific research studies regarding the use of SLM in Co-Cr dental alloys with no restrictions for publication years. The search engines provided hundreds of results, and only 48 scientific research papers, case studies, or literature reviews were considered relevant for this review. The innovative manufacturing concept of SLM offers many advantages compared with casting and milling fabrication techniques. SLM provides different microstructure from casting and milling with minimal internal porosity and internal fitting, marginal adaptation, and comparable bond strength to porcelain. Mechanical and electrochemical properties of SLM structures are enhanced compared to cast, while clinical longevity of single-metal ceramic crowns is comparable to Au-Pt dental alloy. The SLM technique provides dental prosthetic restorations more quickly and less expensively without compromising their quality compared with restorations prepared by casting and milling techniques. The current SLM devices provide metallic restorations made of Co-Cr alloys for removable and fixed partial dentures without compromising the alloy or restoration properties at a fraction of the time and cost, showing great potential to replace the aforementioned fabrication techniques in the long term; however, further clinical studies are essential to increase the acceptance of this technology by the worldwide dental community. © 2015 by the American College of Prosthodontists.

  2. Replacement of alfalfa hay (Medicago sativa L.) with subabul (Leucaena leucocephala) leaf meal in diets of Najdi goats: effect on digestion activity of rumen microorganisms.

    Science.gov (United States)

    Mohammadabadi, Tahereh; Jolazadeh, Alireza

    2017-08-01

    This study investigated the effect of replacing alfalfa hay by subabul leaf meal (SLM) on digestion, fermentation parameters and rumen bacteria and fungi activity of Najdi goats. Six Najdi goats (150 ± 15 days of age and initial body weight of 35 ± 1.1 kg) were randomly assigned to one of two dietary treatments in a balanced completely randomized design (three goats per treatment) for 56 days. Experimental treatments included alfalfa hay as control group and diet containing SLM (SLM replacing alfalfa hay at 50% level). Bacterial and fungi activity and rumen fermentation parameters of animals fed experimental diets were determined. Dry matter disappearance (DMD) was unaffected by replacing SLM with alfalfa hay for both rumen bacteria and fungi in different incubation times, except for 48 h of incubation in specific culture medium of mixed rumen bacteria, which decreased for SLM group (P > 0.05). NDF disappearance (NDFD) and ADF disappearance (ADFD) after 24 and 48 h of incubation in specific culture medium of mixed rumen bacteria was not affected by experimental diets (P > 0.05). However, 72 h after incubation, NDFD in SLM treatment decreased (P > 0.05). Gas production parameters of rumen bacteria were similar for both experimental diets, but partitioning factor (PF), efficiency microbial biomass production (EMBP), microbial protein production (MP), and organic matter truly digested (OMTD) decreased (p alfalfa hay by SLM had no major effect on rumen microorganisms' activity of Najdi goats, so it may be used as an alternative for alfalfa (at 50% level) in susceptible areas.

  3. Land-based approach to evaluate sustainable land management and adaptive capacity of ecosystems/lands

    Science.gov (United States)

    Kust, German; Andreeva, Olga

    2015-04-01

    A number of new concepts and paradigms appeared during last decades, such as sustainable land management (SLM), climate change (CC) adaptation, environmental services, ecosystem health, and others. All of these initiatives still not having the common scientific platform although some agreements in terminology were reached, schemes of links and feedback loops created, and some models developed. Nevertheless, in spite of all these scientific achievements, the land related issues are still not in the focus of CC adaptation and mitigation. The last did not grow much beyond the "greenhouse gases" (GHG) concept, which makes land degradation as the "forgotten side of climate change" The possible decision to integrate concepts of climate and desertification/land degradation could be consideration of the "GHG" approach providing global solution, and "land" approach providing local solution covering other "locally manifesting" issues of global importance (biodiversity conservation, food security, disasters and risks, etc.) to serve as a central concept among those. SLM concept is a land-based approach, which includes the concepts of both ecosystem-based approach (EbA) and community-based approach (CbA). SLM can serve as in integral CC adaptation strategy, being based on the statement "the more healthy and resilient the system is, the less vulnerable and more adaptive it will be to any external changes and forces, including climate" The biggest scientific issue is the methods to evaluate the SLM and results of the SLM investments. We suggest using the approach based on the understanding of the balance or equilibrium of the land and nature components as the major sign of the sustainable system. Prom this point of view it is easier to understand the state of the ecosystem stress, size of the "health", range of adaptive capacity, drivers of degradation and SLM nature, as well as the extended land use, and the concept of environmental land management as the improved SLM approach

  4. Effect of fluoride content on ion release from cast and selective laser melting-processed Co-Cr-Mo alloys.

    Science.gov (United States)

    Yang, Xu; Xiang, Nan; Wei, Bin

    2014-11-01

    Selective laser melting (SLM) alloy is gaining popularity in prosthetic dentistry. However, its biocompatibility has been of some concern because of long-term exposure to fluoride in the oral environment. The purpose of this study was to examine the effect of fluoride concentration on ion release from Co-Cr-Mo alloy specimens fabricated using either SLM or lost-wax casting when immersed in an artificial saliva solution containing fluoride. Specimens were prepared with either a SLM system for the SLM alloy or conventional lost-wax techniques for the cast alloy. The specimen surfaces were wet ground with silicon carbide paper (400, 800, and 1200 grit) and immersed in modified artificial saliva solutions, the pH of which had been adjusted to 5.0 with lactic acid and which contained NaF at concentrations of 0.00%, 0.05%, 0.1%, or 0.2%. The metal ion content of the solution was determined with an inductively coupled plasma mass spectrometer. The results were submitted to 2-way ANOVA and regression analysis (α=.05). Fluoride concentration significantly influenced the elemental ion release from both the SLM and cast alloys. The quantity of ions released increased significantly with increasing fluoride concentration. The ion release from the cast specimens was significantly greater than that from the SLM specimens. The performance of the SLM alloy in immersion tests demonstrates that this new technique is a superior choice because of its good biocompatibility. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  5. Computationally efficient thermal-mechanical modelling of selective laser melting

    Science.gov (United States)

    Yang, Yabin; Ayas, Can

    2017-10-01

    The Selective laser melting (SLM) is a powder based additive manufacturing (AM) method to produce high density metal parts with complex topology. However, part distortions and accompanying residual stresses deteriorates the mechanical reliability of SLM products. Modelling of the SLM process is anticipated to be instrumental for understanding and predicting the development of residual stress field during the build process. However, SLM process modelling requires determination of the heat transients within the part being built which is coupled to a mechanical boundary value problem to calculate displacement and residual stress fields. Thermal models associated with SLM are typically complex and computationally demanding. In this paper, we present a simple semi-analytical thermal-mechanical model, developed for SLM that represents the effect of laser scanning vectors with line heat sources. The temperature field within the part being build is attained by superposition of temperature field associated with line heat sources in a semi-infinite medium and a complimentary temperature field which accounts for the actual boundary conditions. An analytical solution of a line heat source in a semi-infinite medium is first described followed by the numerical procedure used for finding the complimentary temperature field. This analytical description of the line heat sources is able to capture the steep temperature gradients in the vicinity of the laser spot which is typically tens of micrometers. In turn, semi-analytical thermal model allows for having a relatively coarse discretisation of the complimentary temperature field. The temperature history determined is used to calculate the thermal strain induced on the SLM part. Finally, a mechanical model governed by elastic-plastic constitutive rule having isotropic hardening is used to predict the residual stresses.

  6. Manipulating femtosecond laser interactions in bulk glass and thin-film with spatial light modulation (Conference Presentation)

    Science.gov (United States)

    Alimohammadian, Ehsan; Ho, Stephen; Ertorer, Erden; Gherghe, Sebastian; Li, Jianzhao; Herman, Peter R.

    2017-03-01

    Spatial Light Modulators (SLM) are emerging as a power tool for laser beam shaping whereby digitally addressed phase shifts can impose computer-generated hologram patterns on incoming laser light. SLM provide several additional advantages with ultrashort-pulsed lasers in controlling the shape of both surface and internal interactions with materials. Inside transparent materials, nonlinear optical effects can confine strong absorption only to the focal volume, extend dissipation over long filament tracks, or reach below diffraction-limited spot sizes. Hence, SLM beam shaping has been widely adopted for laser material processing applications that include parallel structuring, filamentation, fiber Bragg grating formation and optical aberration correction. This paper reports on a range of SLM applications we have studied in femtosecond processing of transparent glasses and thin films. Laser phase-fronts were tailored by the SLM to compensate for spherical surface aberration, and to further address the nonlinear interactions that interplay between Kerr-lens self-focusing and plasma defocusing effects over shallow and deep focusing inside the glass. Limits of strong and weak focusing were examined around the respective formation of low-loss optical waveguides and long uniform filament tracks. Further, we have employed the SLM for beam patterning inside thin film, exploring the limits of phase noise, resolution and fringe contrast during interferometric intra-film structuring. Femtosecond laser pulses of 200 fs pulse duration and 515 nm wavelength were shaped by a phase-only LCOS-SLM (Hamamatsu X10468-04). By imposing radial phase profiles, axicon, grating and beam splitting gratings, volume shape control of filament diameter, length, and uniformity as well as simultaneous formation of multiple filaments has been demonstrated. Similarly, competing effects of spherical surface aberration, self-focusing, and plasma de-focusing were studied and delineated to enable formation

  7. Effects of Salinity on Yield and Component Characters in Canola (Brassica napus L. Cultivars

    Directory of Open Access Journals (Sweden)

    Ahmad BYBORDI

    2010-03-01

    Full Text Available Cultivars �Okapi�, �SLM046�, �Elite�, �Fornax� and �Licord� Brassica napus were tested for yield and component characters under different levels of salinity. The variations due to salinity levels, cultivars and cultivarxsalinity (interaction were significant for different characters. The variable degrees of increase and decrease of regression coefficient estimate mates (curve estimation showed the performance as influenced by different salinity levels. The performance of Brassica napus variety in plant height and days to first flowering was the best for �SLM046�, �Okapi� �SLM046� and �Okapi� cultivars. �SLM046� showed the best performance in days to maturity, followed by �Licord� and �Elite�. �Okapi� performed better than others regarding the increased number of seeds per plant and seed yield per plant, followed by �Fornax�. Considering all characters, the most tolerance ability was found in �SLM046� and �Okapi�, against different levels of salinity.

  8. Effect of Heat Treatment on the Properties of CoCrMo Alloy Manufactured by Selective Laser Melting

    Science.gov (United States)

    Guoqing, Zhang; Junxin, Li; Xiaoyu, Zhou; Jin, Li; Anmin, Wang

    2018-05-01

    To obtain medical implants with better mechanical properties, it is necessary to conduct studies on the heat treatment process of the selective laser melting (SLM) manufacturing parts. The differential scanning calorimetry method was used to study the heat treatment process of the phase transition of SLM CoCrMo alloy parts. The tensile properties were tested with a tensile test machine, the quantity of carbide precipitated after heat treatment was measured by energy-dispersive x-ray spectroscopy, and the tensile fracture morphology of the parts was investigated using SEM. The obtained results were: Mechanical properties in terms of elongation and tensile strength of CoCrMo alloy manufactured by SLM that had been heat-treated at 1200 °C for 2 h followed by cooling with water were not only higher than the national standard but also higher than the experimental results of the same batch of castings. The mechanism of fracture of parts manufactured by SLM without heat treatment was brittle fracture, whereas parts which had been heat-treated at 1200 °C for 2 h combined with water cooling and at 1200 °C for 1 h with furnace cooling suffered ductile fracture. This study provides the basis for defining the applications for which CoCrMo alloys manufactured by SLM are suitable within the field of medical implants.

  9. Combining Sustainable Land Management Technologies to Combat Land Degradation and Improve Rural Livelihoods in Semi-arid Lands in Kenya.

    Science.gov (United States)

    Mganga, K Z; Musimba, N K R; Nyariki, D M

    2015-12-01

    Drylands occupy more than 80% of Kenya's total land mass and contribute immensely to the national economy and society through agriculture, livestock production, tourism, and wild product harvesting. Dryland ecosystems are areas of high climate variability making them vulnerable to the threats of land degradation. Consequently, agropastoralists inhabiting these ecosystems develop mechanisms and technologies to cope with the impacts of climate variability. This study is aimed to; (1) determine what agropastoralists inhabiting a semi-arid ecosystem in Kenya attribute to be the causes and indicators of land degradation, (2) document sustainable land management (SLM) technologies being undertaken to combat land degradation, and (3) identify the factors that influence the choice of these SLM technologies. Vegetation change from preferred indigenous forage grass species to woody vegetation was cited as the main indicator of land degradation. Land degradation was attributed to recurrent droughts and low amounts of rainfall, overgrazing, and unsustainable harvesting of trees for fuelwood production. However, despite the challenges posed by climate variability and recurrent droughts, the local community is engaging in simple SLM technologies including grass reseeding, rainwater harvesting and soil conservation, and dryland agroforestry as a holistic approach combating land degradation and improving their rural livelihoods. The choice of these SLM technologies was mainly driven by their additional benefits to combating land degradation. In conclusion, promoting such simple SLM technologies can help reverse the land degradation trend, improve agricultural production, food security including access to food, and subsequently improve livelihoods of communities inhabiting dryland ecosystems.

  10. Fabrication of TBMs cooling structures demonstrators using additive manufacturing (AM) technology and HIP

    Energy Technology Data Exchange (ETDEWEB)

    Ordás, Nerea, E-mail: nordas@ceit.es [CEIT-IK4 and Tecnun (University of Navarra), Donostia-San Sebastián (Spain); Ardila, Luis Carlos [IK4-LORTEK Joining Research Institute, Ordizia (Spain); Iturriza, Iñigo [CEIT-IK4 and Tecnun (University of Navarra), Donostia-San Sebastián (Spain); Garcianda, Fermín; Álvarez, Pedro [IK4-LORTEK Joining Research Institute, Ordizia (Spain); García-Rosales, Carmen [CEIT-IK4 and Tecnun (University of Navarra), Donostia-San Sebastián (Spain)

    2015-10-15

    Highlights: • TBM geometrically relevant component components were obtained by addtive manufacturing. • P91, a ferritic–martensitic steel metallurgically similar to EUROFER was used. • Dense core walls were obtained by SLM, though contour of cooling channel walls are slightly porous. • HIP after SLM is effective in removing the porosity and homogenizing the microstructure. • After HIP + normalizing + tempering mechanical behavior is similar to P91 as received. - Abstract: Several mock-ups, each of them consisting of six rectangular channels with dimensions according to the EU Test Blanket Modules (TBMs) specifications, were manufactured by selective laser melting (SLM) technology using P91, a ferritic–martensitic 9%Cr–1%Mo–V steel with a metallurgical behavior similar to EUROFER, the reference structural material for DEMO blanket concepts. SLM parameters led to an as-built density of 99.35% Theoretical Density (TD) that increased up to 99.74% after hot isostatic pressing (HIP). Dimensional control showed that the differences between the original design and the component are below 100 μm. By the appropriate selection of normalization and tempering parameters it was possible to obtain a material fulfilling P91 specification. The microstructure was investigated after SLM, HIP and normalizing and tempering treatments. In all cases, it consisted of thin martensitic laths. Subsize tensile samples were extracted from the mock-ups to measure the mechanical tensile properties after each step of the manufacturing process. The effect of thermal treatments on hardness was also evaluated.

  11. Effect of heat treatment on the microstructure, texture and elastic anisotropy of the nickel-based superalloy CM247LC processed by selective laser melting

    International Nuclear Information System (INIS)

    Muñoz-Moreno, R.; Divya, V.D.; Driver, S.L.; Messé, O.M.D.M.; Illston, T.; Baker, S.; Carpenter, M.A.; Stone, H.J.

    2016-01-01

    Selective laser melting (SLM) of nickel-based superalloys is of great interest for the aerospace industry due to its capability for producing components with complex geometries. However, an improved understanding of the effect of SLM and subsequent post deposition heat treatments on the microstructure and mechanical properties is required to ensure that components with good structural integrity are produced. In this study, the microstructure, texture and elastic anisotropy of the nickel-based superalloy, CM247LC, in the as-SLM and heat-treated states have been analysed. The as-SLM microstructure showed fine elongated cells with a preferential alignment of <001> along the build direction and a significant intercellular misorientation. Heat treatments at temperatures below 1230 °C resulted in a progressive recovery of the microstructure, whilst heat treatments above this temperature gave rise to a recrystallised microstructure. The extent to which nucleation and growth of the γ′ precipitates and secondary particles were affected by increasing the heat treatment temperature was also characterised. The bulk elastic anisotropy of all samples was measured by resonant ultrasound spectroscopy (RUS) and was found to be consistent with the local textures obtained by electron backscatter diffraction (EBSD). It was observed that the initially strong elastic anisotropy exhibited by the as-SLM material was significantly reduced in the recrystallised samples, although some anisotropy was retained as a result of their elongated grain microstructures.

  12. Combining Sustainable Land Management Technologies to Combat Land Degradation and Improve Rural Livelihoods in Semi-arid Lands in Kenya

    Science.gov (United States)

    Mganga, K. Z.; Musimba, N. K. R.; Nyariki, D. M.

    2015-12-01

    Drylands occupy more than 80 % of Kenya's total land mass and contribute immensely to the national economy and society through agriculture, livestock production, tourism, and wild product harvesting. Dryland ecosystems are areas of high climate variability making them vulnerable to the threats of land degradation. Consequently, agropastoralists inhabiting these ecosystems develop mechanisms and technologies to cope with the impacts of climate variability. This study is aimed to; (1) determine what agropastoralists inhabiting a semi-arid ecosystem in Kenya attribute to be the causes and indicators of land degradation, (2) document sustainable land management (SLM) technologies being undertaken to combat land degradation, and (3) identify the factors that influence the choice of these SLM technologies. Vegetation change from preferred indigenous forage grass species to woody vegetation was cited as the main indicator of land degradation. Land degradation was attributed to recurrent droughts and low amounts of rainfall, overgrazing, and unsustainable harvesting of trees for fuelwood production. However, despite the challenges posed by climate variability and recurrent droughts, the local community is engaging in simple SLM technologies including grass reseeding, rainwater harvesting and soil conservation, and dryland agroforestry as a holistic approach combating land degradation and improving their rural livelihoods. The choice of these SLM technologies was mainly driven by their additional benefits to combating land degradation. In conclusion, promoting such simple SLM technologies can help reverse the land degradation trend, improve agricultural production, food security including access to food, and subsequently improve livelihoods of communities inhabiting dryland ecosystems.

  13. Effect of heat treatment on the microstructure, texture and elastic anisotropy of the nickel-based superalloy CM247LC processed by selective laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz-Moreno, R., E-mail: rociomunozmoreno@gmail.com [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Divya, V.D. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Driver, S.L. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ (United Kingdom); Messé, O.M.D.M. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Illston, T.; Baker, S. [Materials Solutions, Unit 8, Great Western Business Park, McKenzie Way, Worcester WR4 9GN (United Kingdom); Carpenter, M.A. [Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ (United Kingdom); Stone, H.J. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2016-09-30

    Selective laser melting (SLM) of nickel-based superalloys is of great interest for the aerospace industry due to its capability for producing components with complex geometries. However, an improved understanding of the effect of SLM and subsequent post deposition heat treatments on the microstructure and mechanical properties is required to ensure that components with good structural integrity are produced. In this study, the microstructure, texture and elastic anisotropy of the nickel-based superalloy, CM247LC, in the as-SLM and heat-treated states have been analysed. The as-SLM microstructure showed fine elongated cells with a preferential alignment of <001> along the build direction and a significant intercellular misorientation. Heat treatments at temperatures below 1230 °C resulted in a progressive recovery of the microstructure, whilst heat treatments above this temperature gave rise to a recrystallised microstructure. The extent to which nucleation and growth of the γ′ precipitates and secondary particles were affected by increasing the heat treatment temperature was also characterised. The bulk elastic anisotropy of all samples was measured by resonant ultrasound spectroscopy (RUS) and was found to be consistent with the local textures obtained by electron backscatter diffraction (EBSD). It was observed that the initially strong elastic anisotropy exhibited by the as-SLM material was significantly reduced in the recrystallised samples, although some anisotropy was retained as a result of their elongated grain microstructures.

  14. Influence of Inherent Surface and Internal Defects on Mechanical Properties of Additively Manufactured Ti6Al4V Alloy: Comparison between Selective Laser Melting and Electron Beam Melting.

    Science.gov (United States)

    Fousová, Michaela; Vojtěch, Dalibor; Doubrava, Karel; Daniel, Matěj; Lin, Chiu-Feng

    2018-03-31

    Additive manufacture (AM) appears to be the most suitable technology to produce sophisticated, high quality, lightweight parts from Ti6Al4V alloy. However, the fatigue life of AM parts is of concern. In our study, we focused on a comparison of two techniques of additive manufacture-selective laser melting (SLM) and electron beam melting (EBM)-in terms of the mechanical properties during both static and dynamic loading. All of the samples were untreated to focus on the influence of surface condition inherent to SLM and EBM. The EBM samples were studied in the as-built state, while SLM was followed by heat treatment. The resulting similarity of microstructures led to comparable mechanical properties in tension, but, due to differences in surface roughness and specific internal defects, the fatigue strength of the EBM samples reached only half the value of the SLM samples. Higher surface roughness that is inherent to EBM contributed to multiple initiations of fatigue cracks, while only one crack initiated on the SLM surface. Also, facets that were formed by an intergranular cleavage fracture were observed in the EBM samples.

  15. Manufacturing of individual biodegradable bone substitute implants using selective laser melting technique.

    Science.gov (United States)

    Lindner, Markus; Hoeges, Simon; Meiners, Wilhelm; Wissenbach, Konrad; Smeets, Ralf; Telle, Rainer; Poprawe, Reinhart; Fischer, Horst

    2011-06-15

    The additive manufacturing technique selective laser melting (SLM) has been successfully proved to be suitable for applications in implant manufacturing. SLM is well known for metal parts and offers direct manufacturing of three-dimensional (3D) parts with high bulk density on the base of individual 3D data, including computer tomography models of anatomical structures. Furthermore, an interconnecting porous structure with defined and reproducible pore size can be integrated during the design of the 3D virtual model of the implant. The objective of this study was to develop the SLM processes for a biodegradable composite material made of β-tricalcium phosphate (β-TCP) and poly(D, L)-lactide (PDLLA). The development of a powder composite material (β-TCP/PDLLA) suitable for the SLM process was successfully performed. The microstructure of the manufactured samples exhibit a homogeneous arrangement of ceramic and polymer. The four-point bending strength was up to 23 MPa. The X-ray diffraction (XRD) analysis of the samples confirmed β-TCP as the only present crystalline phase and the gel permeations chromatography (GPC) analysis documented a degradation of the polymer caused by the laser process less than conventional manufacturing processes. We conclude that SLM presents a new possibility to manufacture individual biodegradable implants made of β-TCP/PDLLA. Copyright © 2011 Wiley Periodicals, Inc.

  16. Fine-structured aluminium products with controllable texture by selective laser melting of pre-alloyed AlSi10Mg powder

    International Nuclear Information System (INIS)

    Thijs, Lore; Kempen, Karolien; Kruth, Jean-Pierre; Van Humbeeck, Jan

    2013-01-01

    Graphical abstract: -- Abstract: This study shows that AlSi10Mg parts with an extremely fine microstructure and a controllable texture can be obtained through selective laser melting (SLM). Selective laser melting creates complex functional products by selectively melting powder particles of a powder bed layer after layer using a high-energy laser beam. The high-energy density applied to the material and the additive character of the process result in a unique material structure. To investigate this material structure, cube-shaped SLM parts were made using different scanning strategies and investigated by microscopy, X-ray diffraction and electron backscattered diffraction. The experimental results show that the high thermal gradients occurring during SLM lead to a very fine microstructure with submicron-sized cells. Consequently, the AlSi10Mg SLM products have a high hardness of 127 ± 3 Hv0.5 even without the application of a precipitation hardening treatment. Furthermore, due to the unique solidification conditions and the additive character of the process, a morphological and crystallographic texture is present in the SLM parts. Thanks to the knowledge gathered in this paper on how this texture is formed and how it depends on the process parameters, this texture can be controlled. A strong fibrous 〈1 0 0〉 texture can be altered into a weak cube texture along the building and scanning directions when a rotation of 90° of the scanning vectors within or between the layers is applied

  17. Manufacturing Feasibility and Forming Properties of Cu-4Sn in Selective Laser Melting.

    Science.gov (United States)

    Mao, Zhongfa; Zhang, David Z; Wei, Peitang; Zhang, Kaifei

    2017-03-24

    Copper alloys, combined with selective laser melting (SLM) technology, have attracted increasing attention in aerospace engineering, automobile, and medical fields. However, there are some difficulties in SLM forming owing to low laser absorption and excellent thermal conductivity. It is, therefore, necessary to explore a copper alloy in SLM. In this research, manufacturing feasibility and forming properties of Cu-4Sn in SLM were investigated through a systematic experimental approach. Single-track experiments were used to narrow down processing parameter windows. A Greco-Latin square design with orthogonal parameter arrays was employed to control forming qualities of specimens. Analysis of variance was applied to establish statistical relationships, which described the effects of different processing parameters (i.e., laser power, scanning speed, and hatch space) on relative density (RD) and Vickers hardness of specimens. It was found that Cu-4Sn specimens were successfully manufactured by SLM for the first time and both its RD and Vickers hardness were mainly determined by the laser power. The maximum value of RD exceeded 93% theoretical density and the maximum value of Vickers hardness reached 118 HV 0.3/5. The best tensile strength of 316-320 MPa is inferior to that of pressure-processed Cu-4Sn and can be improved further by reducing defects.

  18. Influence of Inherent Surface and Internal Defects on Mechanical Properties of Additively Manufactured Ti6Al4V Alloy: Comparison between Selective Laser Melting and Electron Beam Melting

    Directory of Open Access Journals (Sweden)

    Michaela Fousová

    2018-03-01

    Full Text Available Additive manufacture (AM appears to be the most suitable technology to produce sophisticated, high quality, lightweight parts from Ti6Al4V alloy. However, the fatigue life of AM parts is of concern. In our study, we focused on a comparison of two techniques of additive manufacture—selective laser melting (SLM and electron beam melting (EBM—in terms of the mechanical properties during both static and dynamic loading. All of the samples were untreated to focus on the influence of surface condition inherent to SLM and EBM. The EBM samples were studied in the as-built state, while SLM was followed by heat treatment. The resulting similarity of microstructures led to comparable mechanical properties in tension, but, due to differences in surface roughness and specific internal defects, the fatigue strength of the EBM samples reached only half the value of the SLM samples. Higher surface roughness that is inherent to EBM contributed to multiple initiations of fatigue cracks, while only one crack initiated on the SLM surface. Also, facets that were formed by an intergranular cleavage fracture were observed in the EBM samples.

  19. Development and characterization of a coronary polylactic acid stent prototype generated by selective laser melting.

    Science.gov (United States)

    Flege, Christian; Vogt, Felix; Höges, Simon; Jauer, Lucas; Borinski, Mauricio; Schulte, Vera A; Hoffmann, Rainer; Poprawe, Reinhart; Meiners, Wilhelm; Jobmann, Monika; Wissenbach, Konrad; Blindt, Rüdiger

    2013-01-01

    In-stent restenosis is still an important issue and stent thrombosis is an unresolved risk after coronary intervention. Biodegradable stents would provide initial scaffolding of the stenosed segment and disappear subsequently. The additive manufacturing technology Selective Laser Melting (SLM) enables rapid, parallel, and raw material saving generation of complex 3- dimensional structures with extensive geometric freedom and is currently in use in orthopedic or dental applications. Here, SLM process parameters were adapted for poly-L-lactid acid (PLLA) and PLLA-co-poly-ε-caprolactone (PCL) powders to generate degradable coronary stent prototypes. Biocompatibility of both polymers was evidenced by assessment of cell morphology and of metabolic and adhesive activity at direct and indirect contact with human coronary artery smooth muscle cells, umbilical vein endothelial cells, and endothelial progenitor cells. γ-sterilization was demonstrated to guarantee safety of SLM-processed parts. From PLLA and PCL, stent prototypes were successfully generated and post-processing by spray- and dip-coating proved to thoroughly smoothen stent surfaces. In conclusion, for the first time, biodegradable polymers and the SLM technique were combined for the manufacturing of customized biodegradable coronary artery stent prototypes. SLM is advocated for the development of biodegradable coronary PLLA and PCL stents, potentially optimized for future bifurcation applications.

  20. Microstructure and Properties of AlSi10Mg Powder for Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    TANG Pengjun

    2018-02-01

    Full Text Available The AlSi10Mg powder was prepared by supersonic gas atomization. After classified, the powder was fabricated into block by selective laser melting (SLM. The microstructure, phase, and evolutions of powder and block were investigated by optical microscope, scanning electron microscope and X-Ray Diffraction. The tensile properties of SLM block were tested by tensile experiments at room temperature. The results show that the size distribution of AlSi10Mg powder after classified can meet the requirements of SLM technology. The powder always is spherical and spherical-like. Meanwhile, the microstructure of powders is fine and uniform, which contain α(Al matrix and (α+Si eutectic. In addition, the melt pool boundaries of SLM block are legible. The microstructure is also uniform and densified, the relative density approaches to 99.5%. On the other hand, only α(Al and few Silicon phase are detected in this condition, due to the most alloying elements are dissolved in α(Al matrix. At room temperature, the ultimate tensile strength of SLM block reaches up to 442 MPa.

  1. Comparison of Selective Laser Melted Titanium and Magnesium Implants Coated with PCL

    Science.gov (United States)

    Matena, Julia; Petersen, Svea; Gieseke, Matthias; Teske, Michael; Beyerbach, Martin; Kampmann, Andreas; Escobar, Hugo Murua; Gellrich, Nils-Claudius; Haferkamp, Heinz; Nolte, Ingo

    2015-01-01

    Degradable implant material for bone remodeling that corresponds to the physiological stability of bone has still not been developed. Promising degradable materials with good mechanical properties are magnesium and magnesium alloys. However, excessive gas production due to corrosion can lower the biocompatibility. In the present study we used the polymer coating polycaprolactone (PCL), intended to lower the corrosion rate of magnesium. Additionally, improvement of implant geometry can increase bone remodeling. Porous structures are known to support vessel ingrowth and thus increase osseointegration. With the selective laser melting (SLM) process, defined open porous structures can be created. Recently, highly reactive magnesium has also been processed by SLM. We performed studies with a flat magnesium layer and with porous magnesium implants coated with polymers. The SLM produced magnesium was compared with the titanium alloy TiAl6V4, as titanium is already established for the SLM-process. For testing the biocompatibility, we used primary murine osteoblasts. Results showed a reduced corrosion rate and good biocompatibility of the SLM produced magnesium with PCL coating. PMID:26068455

  2. Experimental Research on Selective Laser Melting AlSi10Mg Alloys: Process, Densification and Performance

    Science.gov (United States)

    Chen, Zhen; Wei, Zhengying; Wei, Pei; Chen, Shenggui; Lu, Bingheng; Du, Jun; Li, Junfeng; Zhang, Shuzhe

    2017-12-01

    In this work, a set of experiments was designed to investigate the effect of process parameters on the relative density of the AlSi10Mg parts manufactured by SLM. The influence of laser scan speed v, laser power P and hatch space H, which were considered as the dominant parameters, on the powder melting and densification behavior was also studied experimentally. In addition, the laser energy density was introduced to evaluate the combined effect of the above dominant parameters, so as to control the SLM process integrally. As a result, a high relative density (> 97%) was obtained by SLM at an optimized laser energy density of 3.5-5.5 J/mm2. Moreover, a parameter-densification map was established to visually select the optimum process parameters for the SLM-processed AlSi10Mg parts with elevated density and required mechanical properties. The results provide an important experimental guidance for obtaining AlSi10Mg components with full density and gradient functional porosity by SLM.

  3. Fatigue Strength Prediction for Titanium Alloy TiAl6V4 Manufactured by Selective Laser Melting

    Science.gov (United States)

    Leuders, Stefan; Vollmer, Malte; Brenne, Florian; Tröster, Thomas; Niendorf, Thomas

    2015-09-01

    Selective laser melting (SLM), as a metalworking additive manufacturing technique, received considerable attention from industry and academia due to unprecedented design freedom and overall balanced material properties. However, the fatigue behavior of SLM-processed materials often suffers from local imperfections such as micron-sized pores. In order to enable robust designs of SLM components used in an industrial environment, further research regarding process-induced porosity and its impact on the fatigue behavior is required. Hence, this study aims at a transfer of fatigue prediction models, established for conventional process-routes, to the field of SLM materials. By using high-resolution computed tomography, load increase tests, and electron microscopy, it is shown that pore-based fatigue strength predictions for a titanium alloy TiAl6V4 have become feasible. However, the obtained accuracies are subjected to scatter, which is probably caused by the high defect density even present in SLM materials manufactured following optimized processing routes. Based on thorough examination of crack surfaces and crack initiation sites, respectively, implications for optimization of prediction accuracy of the models in focus are deduced.

  4. Estimation and Compensation of aberrations in Spatial Light Modulators

    International Nuclear Information System (INIS)

    Arias, Augusto; Castaneda, Roman

    2011-01-01

    The spatial light modulator (SLM) Holoeye LC-R720 is based on LCoS (Liquid Crystal on Silicon) technology. Due to the induced curvatures on the silicon plate by the production process, there are static aberrations in the wave-fronts modified by the SLM. In order to calculate the aberrated wave-front we used phase-shifting interferometry, an optimization algorithm for far field propagation, and the geometric characterization of the focal spot along the caustic. Zernike polynomials were used for expanding and comparing the wave-fronts. The aberration compensation was carried out by displaying the conjugated transmittance on the SLM. The complexity of the experimental setup and the requirements of the digital processing of each estimation method were comparatively analyzed.

  5. Photon Doppler Velocimeter to Measure Entrained Additive Manufactured Bulk Metal Powders in Hot Subsonic and Supersonic Oxygen Gas

    Science.gov (United States)

    Tylka, Jonathan

    2016-01-01

    Parts produced by additive manufacturing, particularly selective laser melting (SLM), have been shown to silt metal particulate even after undergoing stringent precision aerospace cleaning processes (Lowrey 2016). As printed parts are used in oxygen systems with increased pressures, temperatures, and gas velocity, the risk of ignition by particle impact, the most common direct ignition source of metals in oxygen, substantially increases. The White Sands Test Facility (WSTF), in collaboration with Marshall Space Flight Center (MSFC), desires to test the ignitability of SLM metals by particle impact in heated oxygen. The existing test systems rely on gas velocity calculations to infer particle velocity in both subsonic and supersonic particle impact systems. Until now, it was not possible to directly measure particle velocity. To increase the fidelity of planned SLM ignition studies, it is necessary to validate that the Photon Doppler Velocimetry(PDV) test system can accurately measure particle velocity.

  6. Thermomechanical characterization of Ni-rich NiTi fabricated by selective laser melting

    International Nuclear Information System (INIS)

    Saedi, Soheil; Turabi, Ali Sadi; Karaca, Haluk; Andani, Mohsen Taheri; Haberland, Christoph; Elahinia, Mohammad

    2016-01-01

    This study presents the shape memory behavior of as-fabricated and solution annealed Ni 50.8 Ti 49.2 alloys fabricated using the selective laser melting (SLM) technique. Results were compared to the initial ingot that was used to fabricate powders. Optical microscopy was employed to reveal the microstructure. The shape memory effect under constant compressive stress and isothermal compressive stress cycling tests were utilized to investigate the shape memory characteristics of the initial ingot and fabricated alloys. It was revealed that the SLM method and post heat treatments can be used to tailor the microstructure and shape memory response. Partial superelasticity was observed after the SLM process. Solutionizing the fabricated samples increased the strength and improved the superelasticity but slightly decreased the recoverable strain. (paper)

  7. Additive Manufacturing of NiTiHf High Temperature Shape Memory Alloy

    Science.gov (United States)

    Benafan, Othmane; Bigelow, Glen S.; Elahinia, Mohammad; Moghaddam, Narges Shayesteh; Amerinatanzi, Amirhesam; Saedi, Soheil; Toker, Guher Pelin; Karaca, Haluk

    2017-01-01

    Additive manufacturing of a NiTi-20Hf high temperature shape memory alloy (HTSMA) was investigated. A selective laser melting (SLM) process by Phenix3D Systems was used to develop components from NiTiHf powder (of approximately 25-75 m particle fractions), and the thermomechanical response was compared to the conventionally vacuum induction skull melted counterpart. Transformation temperatures of the SLM material were found to be slightly lower due to the additional oxygen pick up from the gas atomization and melting process. The shape memory response in compression was measured for stresses up to 500 MPa, and transformation strains were found to be very comparable (Up to 1.26 for the as-extruded; up to 1.52 for SLM).

  8. Polycrystalline Diamond Coating of Additively Manufactured Titanium for Biomedical Applications.

    Science.gov (United States)

    Rifai, Aaqil; Tran, Nhiem; Lau, Desmond W; Elbourne, Aaron; Zhan, Hualin; Stacey, Alastair D; Mayes, Edwin L H; Sarker, Avik; Ivanova, Elena P; Crawford, Russell J; Tran, Phong A; Gibson, Brant C; Greentree, Andrew D; Pirogova, Elena; Fox, Kate

    2018-03-14

    Additive manufacturing using selective laser melted titanium (SLM-Ti) is used to create bespoke items across many diverse fields such as medicine, defense, and aerospace. Despite great progress in orthopedic implant applications, such as for "just in time" implants, significant challenges remain with regards to material osseointegration and the susceptibility to bacterial colonization on the implant. Here, we show that polycrystalline diamond coatings on these titanium samples can enhance biological scaffold interaction improving medical implant applicability. The highly conformable coating exhibited excellent bonding to the substrate. Relative to uncoated SLM-Ti, the diamond coated samples showed enhanced mammalian cell growth, enriched apatite deposition, and reduced microbial S. aureus activity. These results open new opportunities for novel coatings on SLM-Ti devices in general and especially show promise for improved biomedical implants.

  9. A combination of selected mapping and clipping to increase energy efficiency of OFDM systems

    Science.gov (United States)

    Lee, Byung Moo; Rim, You Seung

    2017-01-01

    We propose an energy efficient combination design for OFDM systems based on selected mapping (SLM) and clipping peak-to-average power ratio (PAPR) reduction techniques, and show the related energy efficiency (EE) performance analysis. The combination of two different PAPR reduction techniques can provide a significant benefit in increasing EE, because it can take advantages of both techniques. For the combination, we choose the clipping and SLM techniques, since the former technique is quite simple and effective, and the latter technique does not cause any signal distortion. We provide the structure and the systematic operating method, and show the various analyzes to derive the EE gain based on the combined technique. Our analysis show that the combined technique increases the EE by 69% compared to no PAPR reduction, and by 19.34% compared to only using SLM technique. PMID:29023591

  10. Investigation of the microstructure and surface morphology of a Ti6Al4V plate fabricated by vacuum selective laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Yuji; Tsukamoto, Masahiro; Masuno, Shinichiro; Abe, Nobuyuki [Osaka University, Joining and Welding Research Institute, Ibaraki, Osaka (Japan); Yamashita, Yorihiro [Industrial Research Institute of Ishikawa, Kanazawa, Ishikawa (Japan); Yamashita, Kensuke; Tanigawa, Daichi [Osaka University, Graduate School of Engineering, Suita, Osaka (Japan)

    2016-04-15

    As an additive manufacturing technology, the selective laser melting (SLM) process is useful to directly form complicated shapes. The SLM process in a vacuum has been used to fabricate three-dimensional Ti6Al4V (Ti64) plates because this method can control the phase transformation. To investigate the laser melting and solidification dynamics, the formation of a Ti64 plate by SLM in a vacuum was captured by a high-speed video camera. Due to the effects of temperature and scanning speed on the phase transformation, the crystal orientation was evaluated with X-ray diffraction. A phase transformation of the crystal orientation occurred as the baseplate temperature was heated up from 50 to 150 C. (orig.)

  11. Optical image encryption scheme with multiple light paths based on compressive ghost imaging

    Science.gov (United States)

    Zhu, Jinan; Yang, Xiulun; Meng, Xiangfeng; Wang, Yurong; Yin, Yongkai; Sun, Xiaowen; Dong, Guoyan

    2018-02-01

    An optical image encryption method with multiple light paths is proposed based on compressive ghost imaging. In the encryption process, M random phase-only masks (POMs) are generated by means of logistic map algorithm, and these masks are then uploaded to the spatial light modulator (SLM). The collimated laser light is divided into several beams by beam splitters as it passes through the SLM, and the light beams illuminate the secret images, which are converted into sparse images by discrete wavelet transform beforehand. Thus, the secret images are simultaneously encrypted into intensity vectors by ghost imaging. The distances between the SLM and secret images vary and can be used as the main keys with original POM and the logistic map algorithm coefficient in the decryption process. In the proposed method, the storage space can be significantly decreased and the security of the system can be improved. The feasibility, security and robustness of the method are further analysed through computer simulations.

  12. Neural Network for Image-to-Image Control of Optical Tweezers

    Science.gov (United States)

    Decker, Arthur J.; Anderson, Robert C.; Weiland, Kenneth E.; Wrbanek, Susan Y.

    2004-01-01

    A method is discussed for using neural networks to control optical tweezers. Neural-net outputs are combined with scaling and tiling to generate 480 by 480-pixel control patterns for a spatial light modulator (SLM). The SLM can be combined in various ways with a microscope to create movable tweezers traps with controllable profiles. The neural nets are intended to respond to scattered light from carbon and silicon carbide nanotube sensors. The nanotube sensors are to be held by the traps for manipulation and calibration. Scaling and tiling allow the 100 by 100-pixel maximum resolution of the neural-net software to be applied in stages to exploit the full 480 by 480-pixel resolution of the SLM. One of these stages is intended to create sensitive null detectors for detecting variations in the scattered light from the nanotube sensors.

  13. Stable and High OSNR Compound Linear-Cavity Single-Longitudinal-Mode Erbium-Doped Silica Fiber Laser Based on an Asymmetric Four-Cavity Structure

    International Nuclear Information System (INIS)

    Feng Ting; Yan Feng-Ping; Li Qi; Peng Wan-Jing; Feng Su-Chun; Wen Xiao-Dong; Tan Si-Yu; Liu Peng

    2012-01-01

    We propose a stable and high optical signal-to-noise ratio (OSNR) compound linear-cavity single-longitudinal-mode (SLM) erbium-doped silica fiber laser. It consists of three uniform fiber Bragg gratings (FBGs) and two fiber couplers to form a simple asymmetric four-cavity structure to select the longitudinal mode. The stable SLM operation at the wavelength of 1544.053 nm with a 3 dB bandwidth of 0.014 nm and an OSNR of ∼60 dB was verified experimentally. Under laboratory conditions, a power fluctuation performance of less than 0.05 dB for 5 h and wavelength variation of less than 0.01 nm for about 150 min is demonstrated. Finally, the characteristic of laser output power as a function of pump power is investigated. The proposed system provides a simple and cost-effective approach to realize a stable SLM fiber laser

  14. Detecting mode hopping in single-longitudinal-mode fiber ring lasers based on an unbalanced fiber Michelson interferometer.

    Science.gov (United States)

    Ma, Mingxiang; Hu, Zhengliang; Xu, Pan; Wang, Wei; Hu, Yongming

    2012-10-20

    A method of detecting mode hopping for single-longitudinal-mode (SLM) fiber ring lasers has been proposed and experimentally demonstrated. The method that is based on an unbalanced Michelson interferometer (MI) utilizing phase generated carrier modulation instantly transforms mode-hopping dynamics into steep phase changes of the interferometer. Multiform mode hops in an SLM erbium-doped fiber ring laser with an 18.6 MHz mode spacing have been detected exactly in real-time domain and discussed in detail. Numerical results show that the MI-based method has a high testing sensitivity for identifying mode hopping, which will play a significant role in evaluating the output stability of SLM fiber lasers.

  15. The Influence of Selective Laser Melting Parameters on Density and Mechanical Properties of AlSi10Mg

    Directory of Open Access Journals (Sweden)

    Raus A. A.

    2016-01-01

    Full Text Available Selective Laser Melting (SLM is one of the most effective powder bed technique in the additive Manufacturing (AM which able to fabricate functional metal parts directly from 3D Computer Aided Design (CAD file data. In this paper, the influence of SLM parameters, such as laser power, scanning speed and hatching distance on the density of AlSi10Mg samples are investigated using one factor at a time (OFAT. Furthermore, the optimum results are used to fabricate samples for hardness, tensile strength, and impact toughness test. It is revealed that AlSi10Mg parts fabricated by SLM achieving the best density of 99.13% at the value of 350 watts laser power, 1650 mm/s scanning speed and hatching distance 0.13mm, whereby resulted comparable and even better mechanical properties to those of conventionally HDPC A360F and HDPC A360T6 alloys although without any comprehensive post processing methods.

  16. Fabrication of Flex Joint Utilizing Additively Manufactured Parts

    Science.gov (United States)

    Eddleman, David; Richard, Jim

    2015-01-01

    The Selective Laser Melting (SLM) manufacturing technique has been utilized in the manufacture of a flex joint typical of those found in rocket engine and main propulsion system ducting. The SLM process allowed for the combination of parts that are typically machined separately and welded together. This resulted in roughly a 65% reduction of the total number of parts, roughly 70% reduction in the total number of welds, and an estimated 60% reduction in the number of machining operations. The majority of the new design was in three SLM pieces. These pieces, as well as a few traditionally fabricated parts, were assembled into a complete unit, which has been pressure tested. The design and planned cryogenic testing of the unit will be presented.

  17. Influence of Powder Surface Contamination in the Ni-Based Superalloy Alloy718 Fabricated by Selective Laser Melting and Hot Isostatic Pressing

    Directory of Open Access Journals (Sweden)

    Yen-Ling Kuo

    2017-09-01

    Full Text Available The aim of this study was to gain a deep understanding of the microstructure-mechanical relationship between solid-state sintering and full-melting processes. The IN718 superalloy was fabricated by hot isostatic pressing (HIP and selective laser melting (SLM. Continuous precipitates were clearly localized along the prior particle boundary (PPB in the HIP materials, while SLM materials showed a microstructure free of PPB. The mechanical properties of specimens that underwent SLM + solution treatment and aging were comparable to those of conventional wrought specimens both at room temperature and 650 °C. However, a drop was observed in the ductility of HIP material at 650 °C. The brittle particles along the PPB were found to affect the HIP materials’ creep life and ductility during solid-state sintering.

  18. Investigation of the microstructure and surface morphology of a Ti6Al4V plate fabricated by vacuum selective laser melting

    International Nuclear Information System (INIS)

    Sato, Yuji; Tsukamoto, Masahiro; Masuno, Shinichiro; Abe, Nobuyuki; Yamashita, Yorihiro; Yamashita, Kensuke; Tanigawa, Daichi

    2016-01-01

    As an additive manufacturing technology, the selective laser melting (SLM) process is useful to directly form complicated shapes. The SLM process in a vacuum has been used to fabricate three-dimensional Ti6Al4V (Ti64) plates because this method can control the phase transformation. To investigate the laser melting and solidification dynamics, the formation of a Ti64 plate by SLM in a vacuum was captured by a high-speed video camera. Due to the effects of temperature and scanning speed on the phase transformation, the crystal orientation was evaluated with X-ray diffraction. A phase transformation of the crystal orientation occurred as the baseplate temperature was heated up from 50 to 150 C. (orig.)

  19. Investigation on Mechanical Properties’ Anisotropy of Rod Units in Lattice Structures Fabricated by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Jing Chenchen

    2017-01-01

    Full Text Available Lattice structure with high strength and low mass using selective laser melting (SLM has been a hot topic. However, there are some problems in the fabrication of lattice structure by SLM. Rod unit is the basic component of lattice structure and its performance affects the whole structure. It is necessary to investigate the influence of selective laser melting on rod unit’s mechanical properties. A series of rod units with different inclination angle and diameter were fabricated by SLM in this research. And the mechanical properties of these units were measured by tensile test. The results show that the rod units with different diameters and inclination angles have good mechanical properties and show no difference. It is a good news for lattice structure designing for there is no necessary to consider the mechanical properties’ anisotropy of rod units.

  20. Research on the mechanical behaviour of an airplane component made by selective laser melting technology

    Directory of Open Access Journals (Sweden)

    Păcurar Răzvan

    2017-01-01

    Full Text Available The main objective of the presented research consists in the redesign of an airplane component to decrease its weight, without affecting the mechanical behaviour of the component, at the end. Femap NX Nastran and ANSYS FEA programs were used for the shape optimization and for the estimation of the mechanical behaviour of a fixing clamp that was used to sustain the hydraulic pipes that are passing through an airplane fuselage, taking into consideration two types of raw materials – Ti6Al4V and AlSi12 powder from which this component could be manufactured by using the selective laser melting (SLM technology. Based on the obtained results, the airplane component was finally manufactured from titanium alloy using the SLM 250 HL equipment that is available at SLM Solutions GmbH company from Luebeck, in Germany.

  1. Defect, Microstructure, and Mechanical Property of Ti-6Al-4V Alloy Fabricated by High-Power Selective Laser Melting

    Science.gov (United States)

    Cao, Sheng; Chen, Zhuoer; Lim, Chao Voon Samuel; Yang, Kun; Jia, Qingbo; Jarvis, Tom; Tomus, Dacian; Wu, Xinhua

    2017-12-01

    To improve the selective laser melting (SLM) productivity, a high laser power and accordingly adjusted parameters are employed to facilitate a high build rate. Three distinct processing strategies with incremental build rate are developed for SLM Ti-6Al-4V. Various types of defects are investigated. Further studies were carried out by heat-treatment and hot isostatic pressing to evaluate the influence of microstructure and porosity on mechanical properties. The anisotropic mechanical property in horizontally and vertically build samples were observed, which was attributable to the columnar grains and spatial arrangement of defects. Regardless of anisotropy, a post-SLM heat-treatment at 800°C for 2 h produces a combined high strength and ductility.

  2. Preheat effect on titanium plate fabricated by sputter-free selective laser melting in vacuum

    Science.gov (United States)

    Sato, Yuji; Tsukamoto, Masahiro; Shobu, Takahisa; Yamashita, Yorihiro; Yamagata, Shuto; Nishi, Takaya; Higashino, Ritsuko; Ohkubo, Tomomasa; Nakano, Hitoshi; Abe, Nobuyuki

    2018-04-01

    The dynamics of titanium (Ti) melted by laser irradiation was investigated in a synchrotron radiation experiment. As an indicator of wettability, the contact angle between a selective laser melting (SLM) baseplate and the molten Ti was measured by synchrotron X-rays at 30 keV during laser irradiation. As the baseplate temperature increased, the contact angle decreased, down to 28° at a baseplate temperature of 500 °C. Based on this result, the influence of wettability of a Ti plate fabricated by SLM in a vacuum was investigated. It was revealed that the improvement of wettability by preheating suppressed sputtering generation, and a surface having a small surface roughness was fabricated by SLM in a vacuum.

  3. Formulation in vitro and in vivo evaluation of SRMS-based heterolipid-templated homolipid delivery system for diclofenac sodium.

    Science.gov (United States)

    Mumuni, Momoh; Attama, A A; Kunle, O O

    2016-01-01

    The sole objective of this work was to design successful dosage oral forms of diclofenac sodium (DiNa)-loaded solid lipid microparticles (SLM) based on solidified reverse micellar solution (SRMS). Hot homogenization technique was employed to prepare DicNa SLM using a mixture goat fat and Phospholipon® 90 G as lipid matrix and Tween®-80 as mobile surfactant. Characterization based on percentage yield, morphology, particle size, zeta potential, percentage encapsulation, pH and stability of SLMs were investigated. Anti-inflammatory, gastrointestinal tract (GIT) sparing effect and pharmacokinetics were carried out in rat model after oral administration. Results showed that the SLMs were spherical and smooth. The optimized formulation (SLM-4) had particle size of 79.40 ± 0.31 µm, polydispersity index of 0.633 ± 0.190, zeta potential of -63.20 ± 0.12 mV and encapsulation efficiency of 91.2 ± 0.1% with good stability after 8 months of storage. The DicNa SLM had sustained release effect with good anti-inflammatory activity. Higher and prolonged plasma DicNa concentration was shown by the SLM-4 compared to pure drug and a conventional sample. These studies demonstrate that DicNa-loaded SLM based on SRMS could be a promising oral formulation for enhanced bioavailability, pharmacologic activity and gastrointestinal sparing effect of the NSAID, DicNa.

  4. Fatigue of Ti6Al4V Structural Health Monitoring Systems Produced by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Maria Strantza

    2016-02-01

    Full Text Available Selective laser melting (SLM is an additive manufacturing (AM process which is used for producing metallic components. Currently, the integrity of components produced by SLM is in need of improvement due to residual stresses and unknown fracture behavior. Titanium alloys produced by AM are capable candidates for applications in aerospace and industrial fields due to their fracture resistance, fatigue behavior and corrosion resistance. On the other hand, structural health monitoring (SHM system technologies are promising and requested from the industry. SHM systems can monitor the integrity of a structure and during the last decades the research has primarily been influenced by bionic engineering. In that aspect a new philosophy for SHM has been developed: the so-called effective structural health monitoring (eSHM system. The current system uses the design freedom provided by AM. The working principle of the system is based on crack detection by means of a network of capillaries that are integrated in a structure. The main objective of this research is to evaluate the functionality of Ti6Al4V produced by the SLM process in the novel SHM system and to confirm that the eSHM system can successfully detect cracks in SLM components. In this study four-point bending fatigue tests on Ti6Al4V SLM specimens with an integrated SHM system were conducted. Fractographic analysis was performed after the final failure, while finite element simulations were used in order to determine the stress distribution in the capillary region and on the component. It was proven that the SHM system does not influence the crack initiation behavior during fatigue. The results highlight the effectiveness of the eSHM on SLM components, which can potentially be used by industrial and aerospace applications.

  5. Evaluation of mobile smartphones app as a screening tool for environmental noise monitoring.

    Science.gov (United States)

    Ibekwe, Titus S; Folorunsho, David O; Dahilo, Enoch A; Gbujie, Ibeneche O; Nwegbu, Maxwell M; Nwaorgu, Onyekwere G

    2016-01-01

    Noise is a global occupational and environmental health hazard with considerable social and physiological impact and, therefore, there is a need for regular measurements to boost monitoring and regulations of environmental noise levels in our communities. This necessitates a readily available, inexpensive, and easy to use noise measuring device. We aimed to test the sensitivity and validity of mobile "smart" phones for this purpose. This was a comparative analysis of a cross sectional study done between January 2014 and February 2015. Noise levels were measured simultaneously at different locations within Abuja Nigeria at day and night hours in real time environments. A sound level meter (SLM) (Extech407730 Digital Soundmeter, serial no.: 2310135, calibration no: 91037) and three smartphones (Samsung Galaxy note3, Nokia S, and Techno Phantom Z running on Android "Apps" Androidboy1) were used. Statistical calculations were done with Pearson correlation, T-test and Consistency within American National Standards Institute acceptable standard errors. Noise level readings for both daytime and night with the SLM and the mobile phones showed equivalent values. All noise level meters measured were <100dB. The daytime readings were nearly identical in six locations and the maximum difference in values between the SLM and Smartphone instruments was 3db, noted in two locations. Readings in dBA showed strong correlation (r = 0.9) within acceptable error limits for Type 2 SLM devices and no significant difference in the values (p = 0.12 & 0.58) for both day and night. Sensitivity of the instrument yielded 92.9%. The androidboy1 "app" performance in this study showed a good correlation and comparative high sensitivity to the Standard SLM (type 2 SLM device). However there is the need for further studies.

  6. The contaminant analysis automation robot implementation for the automated laboratory

    International Nuclear Information System (INIS)

    Younkin, J.R.; Igou, R.E.; Urenda, T.D.

    1995-01-01

    The Contaminant Analysis Automation (CAA) project defines the automated laboratory as a series of standard laboratory modules (SLM) serviced by a robotic standard support module (SSM). These SLMs are designed to allow plug-and-play integration into automated systems that perform standard analysis methods (SAM). While the SLMs are autonomous in the execution of their particular chemical processing task, the SAM concept relies on a high-level task sequence controller (TSC) to coordinate the robotic delivery of materials requisite for SLM operations, initiate an SLM operation with the chemical method dependent operating parameters, and coordinate the robotic removal of materials from the SLM when its commands and events has been established to allow ready them for transport operations as well as performing the Supervisor and Subsystems (GENISAS) software governs events from the SLMs and robot. The Intelligent System Operating Environment (ISOE) enables the inter-process communications used by GENISAS. CAA selected the Hewlett-Packard Optimized Robot for Chemical Analysis (ORCA) and its associated Windows based Methods Development Software (MDS) as the robot SSM. The MDS software is used to teach the robot each SLM position and required material port motions. To allow the TSC to command these SLM motions, a hardware and software implementation was required that allowed message passing between different operating systems. This implementation involved the use of a Virtual Memory Extended (VME) rack with a Force CPU-30 computer running VxWorks; a real-time multitasking operating system, and a Radiuses PC compatible VME computer running MDS. A GENISAS server on The Force computer accepts a transport command from the TSC, a GENISAS supervisor, over Ethernet and notifies software on the RadiSys PC of the pending command through VMEbus shared memory. The command is then delivered to the MDS robot control software using a Windows Dynamic Data Exchange conversation

  7. Adaptation and micro-structure of Co-Cr alloy maxillary complete denture base plates fabricated by selective laser melting technique.

    Science.gov (United States)

    Ye, Ye; Jiao, Ting; Zhu, Jiarui; Sun, Jian

    2018-01-24

    The purpose of the study was to evaluate the adaptation and micro-structure of Co-Cr alloy maxillary complete denture base plates fabricated by the selective laser melting (SLM) technique. Twenty pairs of edentulous casts were randomly and evenly divided into two groups, and manufacturing of the Co-Cr alloy maxillary complete denture base was conducted either by the SLM technique or by the conventional method. The base-cast sets were transversally sectioned into three sections at the distal canines, mesial of the first molars and the posterior palatal zone. The gap between the metal base and cast was measured in these three sections with a stereoscopic microscope, and the data were analysed using t tests. A total of five specimens of 5 mm diameter were fabricated with the Co-Cr alloy by SLM and the traditional casting technology. A scanning electron microscope (SEM) was used to evaluate the differences in microstructure between these specimens. There was no statistical difference between the three sections in all four groups (P > 0.05). At the region of the canines, the clearance value for the SLM Co-Cr alloy group was larger than that of the conventional method group (P  0.05). The SLM Co-Cr alloy has a denser microstructure behaviour and less casting defect than the cast Co-Cr alloy. The SLM technique showed initial feasibility for the manufacture of dental bases of complete dentures, but large sample studies are needed to prove its reliability in clinical applications. The mechanical properties and microstructure of the denture frameworks prepared by selective laser melting indicate that these dentures are appropriate for clinical use.

  8. Effects of repeated firing on the marginal accuracy of Co-Cr copings fabricated by selective laser melting.

    Science.gov (United States)

    Zeng, Li; Zhang, Yong; Liu, Zheng; Wei, Bin

    2015-02-01

    Selective laser melting (SLM) is a technique used to fabricate Co-Cr dental restorations; however, because marginal accuracy is important for the long-term success of restorations, the marginal accuracy of SLM after repeated firings must be considered. The purpose of this study was to evaluate the marginal accuracy of dental Co-Cr alloy copings fabricated by SLM and to investigate the effects of repeated firing on the marginal fit of these copings. SLM-fabricated and cast Co-Cr alloy copings (n=15) were prepared for a zirconia die. The marginal gap widths of each group were evaluated with a silicone replica technique after the first, third, fifth, and seventh firing cycle. The thickness of the reference point was measured with a stereomicroscope with ×100 magnification. Analysis of variance was used to evaluate the effect of repeated firing on the marginal accuracy of the 2 alloys. The Student t test was used to compare the marginal gap widths of the SLM-fabricated and cast Co-Cr alloy copings after repeated firing (α=.05). The marginal gap width values between the 2 groups at all firing periods were statistically significant (P.05). The SLM copings demonstrated superior marginal accuracy at all firings. Repeated firing had no significant influence on the marginal accuracy of both copings, and the marginal fit of both copings after repeated firing was within a clinically acceptable range. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  9. Improved bioactivity of selective laser melting titanium: Surface modification with micro-/nano-textured hierarchical topography and bone regeneration performance evaluation.

    Science.gov (United States)

    Xu, Jia-Yun; Chen, Xian-Shuai; Zhang, Chun-Yu; Liu, Yun; Wang, Jing; Deng, Fei-Long

    2016-11-01

    Selective laser melting (SLM) titanium requires surface modification to improve its bioactivity. The microrough surface of it can be utilized as the micro primary substrate to create a micro-/nano-textured topography for improved bone regeneration. In this study, the microrough SLM titanium substrate was optimized by sandblasting, and nano-porous features of orderly arranged nanotubes and disorderly arranged nanonet were produced by anodization (SAN) and alkali-heat treatment (SAH), respectively. The results were compared with the control group of an untreated surface (native-SLM) and a microtopography only surface treated by acid etching (SLA). The effects of the different topographies on cell functions and bone formation performance were evaluated in vitro and in vivo. It was found that micro-/nano-textured topographies of SAN and SAH showed enhanced cell behaviour relative to the microtopography of SLA with significantly higher proliferation on the 1st, 3rd, 5th and 7th day (P<0.05) and higher total protein contents on the 14th day (P<0.05). In vivo, SAN and SAH formed more successively regenerated bone, which resulted in higher bone-implant contact (BIC%) and bone-bonding force than native-SLM and SLA. In addition, the three-dimensional nanonet of SAH was expected to be more similar to native extracellular matrix (ECM) and thus led to better bone formation. The alkaline phosphatase activity of SAH was significantly higher than the other three groups at an earlier stage of the 7th day (P<0.05) and the BIC% was nearly double that of native-SLM and SLA in the 8th week. In conclusion, the addition of nano-porous features on the microrough SLM titanium surface is effective in improving the bioactivity and bone regeneration performance, in which the ECM-like nanonet with a disorderly arranged biomimetic feature is suggested to be more efficient than nanotubes. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. [Design and fabrication of the custom-made titanium condyle by selective laser melting technology].

    Science.gov (United States)

    Chen, Jianyu; Luo, Chongdai; Zhang, Chunyu; Zhang, Gong; Qiu, Weiqian; Zhang, Zhiguang

    2014-10-01

    To design and fabricate the custom-made titanium mandibular condyle by the reverse engineering technology combined with selective laser melting (SLM) technology and to explore the mechanical properties of the SLM-processed samples and the application of the custom-made condyle in the temporomandibular joint (TMJ) reconstruction. The three-dimensional model of the mandibular condyle was obtained from a series of CT databases. The custom-made condyle model was designed by the reverse engineering software. The mandibular condyle was made of titanium powder with a particle size of 20-65 µm as the basic material and the processing was carried out in an argon atmosphere by the SLM machine. The yield strength, ultimate strength, bending strength, hardness, surface morphology and roughness were tested and analyzed. The finite element analysis (FEA) was used to analyze the stress distribution. The complex geometry and the surface of the custom-made condyle can be reproduced precisely by the SLM. The mechanical results showed that the yield strength, ultimate strength, bending strength and hardness were (559±14) MPa, (659±32) MPa, (1 067±42) MPa, and (212±4)HV, respectively. The surface roughness was reduced by sandblast treatment. The custom-made titanium condyle can be fabricated by SLM technology which is time-saving and highly digitized. The mechanical properties of the SLM sample can meet the requirements of surgical implant material in the clinic. The possibility of fabricating custom-made titanium mandibular condyle combined with the FEA opens new interesting perspectives for TMJ reconstruction.

  11. Electromembrane extraction with alkylated phosphites and phosphates as supported liquid membranes

    DEFF Research Database (Denmark)

    Huang, Chuixiu; Gjelstad, Astrid; Pedersen-Bjergaard, Stig

    2017-01-01

    -nitrophenyl octyl ether) was proposed as a new and successful SLM for EME of both polar and non-polar basic drugs. An assay based on EME-HPLC/UV with a TBP/NPOE SLM was evaluated from two-fold diluted human plasma under physiological pH conditions for both polar and non-polar basic drugs. The evaluation data......A range of alkylated phosphates and phosphites were for the first time investigated as potential supported liquid membranes (SLMs) for electromembrane extraction (EME) of basic drugs from human plasma samples. Six polar basic drugs were used as model analytes for initial testing of the different...

  12. Switchable dual-wavelength single-longitudinal-mode erbium fiber laser utilizing a dual-ring scheme with a saturable absorber

    Science.gov (United States)

    Yang, Zi-Qing; Huang, Tzu-Jung; Chang, Yao-Jen; Yeh, Chien-Hung; Chow, Chi-Wai; Chen, Jing-Heng; Chen, Kun-Huang

    2018-06-01

    In this work, we propose and demonstrate a switchable dual-wavelength erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) output. Here, a dual-ring (DR) structure with an unpumped EDF of 2 m is designed to achieve SLM oscillation. Five fiber Bragg gratings (FBGs) are applied in the laser cavity serving as the reflective element to generate different dual-wavelength outputs. In the measurement, six sets of generated dual-wavelengths with various mode-spacing (Δλ) can be achieved via the five FBGs. Additionally, the stability performance of the proposed EDF DR laser is also demonstrated.

  13. Tunable orbital angular momentum mode filter based on optical geometric transformation.

    Science.gov (United States)

    Huang, Hao; Ren, Yongxiong; Xie, Guodong; Yan, Yan; Yue, Yang; Ahmed, Nisar; Lavery, Martin P J; Padgett, Miles J; Dolinar, Sam; Tur, Moshe; Willner, Alan E

    2014-03-15

    We present a tunable mode filter for spatially multiplexed laser beams carrying orbital angular momentum (OAM). The filter comprises an optical geometric transformation-based OAM mode sorter and a spatial light modulator (SLM). The programmable SLM can selectively control the passing/blocking of each input OAM beam. We experimentally demonstrate tunable filtering of one or multiple OAM modes from four multiplexed input OAM modes with vortex charge of ℓ=-9, -4, +4, and +9. The measured output power suppression ratio of the propagated modes to the blocked modes exceeds 14.5 dB.

  14. Improved Visibility of Metastatic Disease in the Liver During Intra-Arterial Therapy Using Delayed Arterial Phase Cone-Beam CT

    Energy Technology Data Exchange (ETDEWEB)

    Schernthaner, Ruediger E., E-mail: ruediger.schernthaner@meduniwien.ac.at [Medical University of Vienna, Section of Cardiovascular and Interventional Radiology, Department of Biomedical Imaging and Image-guided Therapy (Austria); Haroun, Reham R., E-mail: rehamharoun1989@gmail.com; Duran, Rafael, E-mail: rafaelduran.md@gmail.com; Lee, Howard, E-mail: mail2howielee@gmail.com; Sahu, Sonia, E-mail: sonia.p.sahu@gmail.com; Sohn, Jae Ho, E-mail: sohn87@gmail.com; Chapiro, Julius, E-mail: j.chapiro@googlemail.com; Zhao, Yan, E-mail: yanzhao211@163.com; Gorodetski, Boris, E-mail: boris.gorodetski@charite.de; Fleckenstein, Florian, E-mail: florian.fleckenstein@charite.de; Smolka, Susanne, E-mail: susanne.smolka@charite.de [Yale University School of Medicine, Department of Radiology and Biomedical Imaging (United States); Radaelli, Alessandro, E-mail: Alessandro.Radaelli@philips.com; Bom, Imramsjah Martijn van der, E-mail: martijn.van.der.bom@philips.com [Philips Healthcare, Image-Guided Therapy Systems (Netherlands); Lin, MingDe, E-mail: ming.lin@philips.com; Geschwind, Jean Francois, E-mail: jeff.geschwind@yale.edu [Yale University School of Medicine, Department of Radiology and Biomedical Imaging (United States)

    2016-10-15

    PurposeTo compare the visibility of liver metastases on dual-phase cone-beam CT (DP-CBCT) and digital subtraction angiography (DSA), with reference to preinterventional contrast-enhanced magnetic resonance imaging (CE-MRI) of the liver.MethodsThis IRB-approved, retrospective study included 28 patients with neuroendocrine (NELM), colorectal (CRCLM), or sarcoma (SLM) liver metastases who underwent DP-CBCT during intra-arterial therapy (IAT) between 01/2010 and 10/2014. DP-CBCT was acquired after a single contrast agent injection in the tumor-feeding arteries at early and delayed arterial phases (EAP and DAP). The visibility of each lesion was graded by two radiologists in consensus on a three-rank scale (complete, partial, none) on DP-CBCT and DSA images using CE-MRI as reference.Results47 NELM, 43 CRCLM, and 16 SLM were included. On DSA 85.1, 44.1, and 37.5 % of NELM, CRCLM, and SLM, were at least partially depicted, respectively. EAP-CBCT yielded significantly higher sensitivities of 88.3 and 87.5 % for CRCLM and SLM, respectively (p < 0.01), but not for NELM (89.4 %; p = 1.0). On DAP-CBCT all NELM, CRCLM, and SLM were visible (p < 0.001). Complete depiction was achieved on DSA for 59.6, 16.3, and 18.8 % of NELM, CRCLM, and SLM, respectively. The complete depiction rate on EAP-CBCT was significantly higher for CRCLM (46.5 %; p < 0.001), lower for NELM (40.4 %; p = 0.592), and similar for SLM (25 %, p = 0.399). On DAP-CBCT however, the highest rates of complete depiction were found—NELM (97.8 %; p = 0.008), CRCLM (95.3 %; p = 0.008), and SLM (100 %; p < 0.001).ConclusionDAP-CBCT substantially improved the visibility of liver metastases during IAT. Future studies need to evaluate the clinical impact.

  15. [Comparison of adaptation and microstructure of titanium upper complete denture base fabricated by selecting laser melting and electron beam melting].

    Science.gov (United States)

    Ye, Y; Xiong, Y Y; Zhu, J R; Sun, J

    2017-06-09

    Objective: To fabricate Ti alloy frameworks for a maxillary complete denture with three-dimensional printing (3DP) technique, such as selective laser melting (SLM) and electron beam melting (EBM), and to evaluate the microstructure of these frameworks and their adaptation to the die stone models. Methods: Thirty pairs of edentulous casts were divided into 3 groups randomly and equally. In each group, one of the three techniques (SLM, EBM, conventional technique) was used to fabricate Ti alloy frameworks. The base-cast sets were transversally sectioned into 3 sections at the distal of canines, mesial of first molars, and the posterior palatal zone. The gap between the metal base and cast was measured in the 3 sections. Stereoscopic microscope was used to measure the gap. Three pieces of specimens of 5 mm diameter were fabricated with Ti alloy by SLM, EBM and the traditional casting technology (as mentioned above). Scanning electron microscope (SEM) was used to evaluate the differences of microstructure among these specimens. Results: The gaps between the metal base and cast were (99.4±17.0), (98.2±26.1), and (99.6± 16.1) μm in conventional method; (99.4 ± 22.8), (83.1 ± 19.3), and (103.3 ± 13.8) μm in SLM technique; (248.3±70.3), (279.1±71.9), and (189.1±31.6) μm in EBM technique. There was no statistical difference in the value of gaps between SLM Ti alloy and conventional method Ti alloy group ( P> 0.05). There was statistical difference among EBM Ti alloy, conventional method Ti alloy and SLM Ti alloy group ( Palloy showed more uniform and compact microstructure than the cast Ti alloy and EBM Ti alloy did. Conclusions: SLM technique showed initial feasibility to manufacture the dental base of complete denture. The mechanical properties and microstructure of the denture frameworks prepared by SLM indicate that these dentures are appropriate for clinical use. EBM technique is inadequate to make a complete denture now.

  16. Trinary flip-flops using Savart plate and spatial light modulator for optical computation in multivalued logic

    Science.gov (United States)

    Ghosh, Amal K.; Basuray, Amitabha

    2008-11-01

    The memory devices in multi-valued logic are of most significance in modern research. This paper deals with the implementation of basic memory devices in multi-valued logic using Savart plate and spatial light modulator (SLM) based optoelectronic circuits. Photons are used here as the carrier to speed up the operations. Optical tree architecture (OTA) has been also utilized in the optical interconnection network. We have exploited the advantages of Savart plates, SLMs and OTA and proposed the SLM based high speed JK, D-type and T-type flip-flops in a trinary system.

  17. Parallel artificial liquid membrane extraction of new psychoactive substances in plasma and whole blood

    DEFF Research Database (Denmark)

    Vårdal, Linda; Askildsen, Hilde-Merete; Gjelstad, Astrid

    2017-01-01

    Parallel artificial liquid membrane extraction (PALME) was combined with ultra-high performance liquid chromatography-mass spectrometry (UHPLC–MS) and the potential for screening of new psychoactive substances (NPS) was investigated for the first time. PALME was performed in 96-well format...... comprising a donor plate, a supported liquid membrane (SLM), and an acceptor plate. Uncharged NPS were extracted from plasma or whole blood, across an organic SLM, and into an aqueous acceptor solution, facilitated by a pH gradient. MDAI (5,6-methylenedioxy-2-aminoindane), methylone, PFA (para...

  18. Improved bioactivity of selective laser melting titanium: Surface modification with micro-/nano-textured hierarchical topography and bone regeneration performance evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jia-yun [Department of Oral Implantology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055 (China); Chen, Xian-shuai; Zhang, Chun-yu [Guangzhou Institute of Advanced Technology, Chinese Academy of Science, Guangzhou 511458 (China); Liu, Yun; Wang, Jing [Department of Oral Implantology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055 (China); Deng, Fei-long, E-mail: drdfl@163.com [Department of Oral Implantology, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055 (China)

    2016-11-01

    Selective laser melting (SLM) titanium requires surface modification to improve its bioactivity. The microrough surface of it can be utilized as the micro primary substrate to create a micro-/nano-textured topography for improved bone regeneration. In this study, the microrough SLM titanium substrate was optimized by sandblasting, and nano-porous features of orderly arranged nanotubes and disorderly arranged nanonet were produced by anodization (SAN) and alkali-heat treatment (SAH), respectively. The results were compared with the control group of an untreated surface (native-SLM) and a microtopography only surface treated by acid etching (SLA). The effects of the different topographies on cell functions and bone formation performance were evaluated in vitro and in vivo. It was found that micro-/nano-textured topographies of SAN and SAH showed enhanced cell behaviour relative to the microtopography of SLA with significantly higher proliferation on the 1st, 3rd, 5th and 7th day (P < 0.05) and higher total protein contents on the 14th day (P < 0.05). In vivo, SAN and SAH formed more successively regenerated bone, which resulted in higher bone-implant contact (BIC%) and bone-bonding force than native-SLM and SLA. In addition, the three-dimensional nanonet of SAH was expected to be more similar to native extracellular matrix (ECM) and thus led to better bone formation. The alkaline phosphatase activity of SAH was significantly higher than the other three groups at an earlier stage of the 7th day (P < 0.05) and the BIC% was nearly double that of native-SLM and SLA in the 8th week. In conclusion, the addition of nano-porous features on the microrough SLM titanium surface is effective in improving the bioactivity and bone regeneration performance, in which the ECM-like nanonet with a disorderly arranged biomimetic feature is suggested to be more efficient than nanotubes. - Highlights: • SLM titanium is modified by adding nano-porous features to the microrough substrate

  19. Fatigue crack growth in additive manufactured products

    Directory of Open Access Journals (Sweden)

    A. Riemer

    2015-10-01

    Full Text Available Additive Manufacturing (AM is a new innovative technique that allows the direct fabrication of complex, individual, delicate and high-strength products, based on their 3D data. Selective Laser Melting (SLM is one of the AM processes that generates metallic components layer by layer using powder-bed technique. The irradiation and consequent melting of metallic powder is realised by the laser source. Employing SLM, especially complex and individual products, such as implants or aerospace parts, are well suited for economic production in small batches. The first important issue in this work was to analyse the fatigue crack growth (FCG in titanium alloy Ti-6-4 and stainless steel 316L processed by SLM. As a first step, stress intensity range decreasing tests were performed on SLM samples in their “as-built” condition. The next step was to adopt measures for optimisation of fatigue crack growth performance of SLM parts. For this purpose various heat treatments such as stress relief annealing and hot isostatic pressing (HIP were applied to the CT specimens. Finally, the strong impact of heat treatment on the residual lifetime was demonstrated by numerical fatigue crack growth simulations. For this purpose, the hip joint implant consisting of Ti-6-4 and processed by SLM was taken into account. It was found that residual stresses have a strong influence on the crack growth in Ti-6-4, while the influence of the micro-pores on the threshold values remains low. In contrast the results for 316L show that its fracturemechanical behaviour is not affected by residual stresses, whereas the microstructural features lead to modification in the da/dN-K-data. The second fundamental aim of this work was to demonstrate the possibilities of the SLM process. For that reason, the individually tailored bicycle crank was optimised regarding its weight and local stresses and finally manufactured using the SLM system. The iterative optimisation procedure was based on

  20. Power Efficiency Improvements through Peak-to-Average Power Ratio Reduction and Power Amplifier Linearization

    Directory of Open Access Journals (Sweden)

    Zhou G Tong

    2007-01-01

    Full Text Available Many modern communication signal formats, such as orthogonal frequency-division multiplexing (OFDM and code-division multiple access (CDMA, have high peak-to-average power ratios (PARs. A signal with a high PAR not only is vulnerable in the presence of nonlinear components such as power amplifiers (PAs, but also leads to low transmission power efficiency. Selected mapping (SLM and clipping are well-known PAR reduction techniques. We propose to combine SLM with threshold clipping and digital baseband predistortion to improve the overall efficiency of the transmission system. Testbed experiments demonstrate the effectiveness of the proposed approach.

  1. Aberration compensation using a spatial light modulator LCD

    International Nuclear Information System (INIS)

    Amezquita, R; Rincon, O; Torres, Y M

    2011-01-01

    The dynamic correction of aberrations introduced in optical systems have been a widely discussed topic in the past 10 years. Adaptive optics is the most important developed field where the Shack-Hartmann sensors and deformable mirrors are used for the measurement and correction of wavefronts. In this paper, an interferometric set-up which uses a Spatial Light Modulator (SLM) as an active element is proposed. Using this SLM a procedure for the compensation of all phase aberrations present in the experimental setup is shown.

  2. Converting optical scanning holograms of real objects to binary Fourier holograms using an iterative direct binary search algorithm.

    Science.gov (United States)

    Leportier, Thibault; Park, Min Chul; Kim, You Seok; Kim, Taegeun

    2015-02-09

    In this paper, we present a three-dimensional holographic imaging system. The proposed approach records a complex hologram of a real object using optical scanning holography, converts the complex form to binary data, and then reconstructs the recorded hologram using a spatial light modulator (SLM). The conversion from the recorded hologram to a binary hologram is achieved using a direct binary search algorithm. We present experimental results that verify the efficacy of our approach. To the best of our knowledge, this is the first time that a hologram of a real object has been reconstructed using a binary SLM.

  3. Two-photon polymerization of cylinder microstructures by femtosecond Bessel beams

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Liang [Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026 (China); Laser Zentrum Hannover e.V., 30419 Hannover (Germany); El-Tamer, Ayman; Hinze, Ulf; Chichkov, Boris N [Laser Zentrum Hannover e.V., 30419 Hannover (Germany); Li, Jiawen, E-mail: jwl@ustc.edu.cn; Hu, Yanlei; Huang, Wenhao; Chu, Jiaru [Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026 (China)

    2014-07-28

    In this work, we present an approach to modulate femtosecond laser beams into Bessel beams with a spatial light modulator (SLM) for two-photon polymerization applications. Bessel beams with different parameters are generated and annular optical fields are produced at the focal plane of the objective. Uniform cylinder microstructures are fabricated by a single illumination during a few seconds without stage translation. By modulating the holograms encoded on the SLM, the diameters of the fabricated annular structures can be flexibly controlled in a wide range with no need of changing the optical elements and realignment of the optical path.

  4. Improved bioactivity of selective laser melting titanium: Surface modification with micro-/nano-textured hierarchical topography and bone regeneration performance evaluation

    International Nuclear Information System (INIS)

    Xu, Jia-yun; Chen, Xian-shuai; Zhang, Chun-yu; Liu, Yun; Wang, Jing; Deng, Fei-long

    2016-01-01

    Selective laser melting (SLM) titanium requires surface modification to improve its bioactivity. The microrough surface of it can be utilized as the micro primary substrate to create a micro-/nano-textured topography for improved bone regeneration. In this study, the microrough SLM titanium substrate was optimized by sandblasting, and nano-porous features of orderly arranged nanotubes and disorderly arranged nanonet were produced by anodization (SAN) and alkali-heat treatment (SAH), respectively. The results were compared with the control group of an untreated surface (native-SLM) and a microtopography only surface treated by acid etching (SLA). The effects of the different topographies on cell functions and bone formation performance were evaluated in vitro and in vivo. It was found that micro-/nano-textured topographies of SAN and SAH showed enhanced cell behaviour relative to the microtopography of SLA with significantly higher proliferation on the 1st, 3rd, 5th and 7th day (P < 0.05) and higher total protein contents on the 14th day (P < 0.05). In vivo, SAN and SAH formed more successively regenerated bone, which resulted in higher bone-implant contact (BIC%) and bone-bonding force than native-SLM and SLA. In addition, the three-dimensional nanonet of SAH was expected to be more similar to native extracellular matrix (ECM) and thus led to better bone formation. The alkaline phosphatase activity of SAH was significantly higher than the other three groups at an earlier stage of the 7th day (P < 0.05) and the BIC% was nearly double that of native-SLM and SLA in the 8th week. In conclusion, the addition of nano-porous features on the microrough SLM titanium surface is effective in improving the bioactivity and bone regeneration performance, in which the ECM-like nanonet with a disorderly arranged biomimetic feature is suggested to be more efficient than nanotubes. - Highlights: • SLM titanium is modified by adding nano-porous features to the microrough substrate

  5. Azimuthal spectrum after parametric down-convertion with radial degrees of freedom

    CSIR Research Space (South Africa)

    Zhang, Y

    2014-08-01

    Full Text Available of the OAM spectrum, i.e. the spiral bandwidth.6–10 Hence, a large spiral bandwidth indicates that an OAM entangled quantum state contains more OAM degrees of freedom that can be used to encode quantum information. The Laguerre-Gaussian (LG) modes are OAM... counter (CC). 50/50 beam splitter Laser BBO A B SLM SLM SMF SMF CC APD APD Signal Idler Figure 1. Diagram of the experimental setup used to prepare and measure the OAM entangled photon pairs. 3.2 Modelling the experiment Due to the experimental parameters...

  6. Single-longitudinal-mode BEFL incorporating a Bragg grating written in EDF

    Science.gov (United States)

    Gao, Ya; Sun, Junqiang; Chen, Guodong; Xie, Heng

    2015-06-01

    A stable and tunable single-longitudinal-mode (SLM) Brillouin/Erbium fiber laser (BEFL) with narrow linewidth is proposed and experimentally demonstrated. A uniform Bragg grating written in a segment of unpumped Erbium-doped fiber (EDF) is incorporated as an auto-tracking filter to achieve SLM operation. A length of 5 m pumped EDF is used to provide both Brillouin and linear gain in the cavity. The linewidth is measured to be 18 kHz and the lasing peak power fluctuation and wavelength shift are monitored less than 0.027 dB and 2 pm respectively.

  7. Data demonstrating the effects of build orientation and heat treatment on fatigue behavior of selective laser melted 17–4 PH stainless steel

    Directory of Open Access Journals (Sweden)

    Aref Yadollahi

    2016-06-01

    Full Text Available Axial fully-reversed strain-controlled (R=−1 fatigue experiments were performed to obtain data demonstrating the effects of building orientation (i.e. vertical versus horizontal and heat treatment on the fatigue behavior of 17–4 PH stainless steel (SS fabricated via Selective Laser Melting (SLM (Yadollahi et al., submitted for publication [1]. This data article provides detailed experimental data including cyclic stress-strain responses, variations of peak stresses during cyclic deformation, and fractography of post-mortem specimens for SLM 17–4 PH SS.

  8. On the texture, phase and tensile properties of commercially pure Ti produced via selective laser melting assisted by static magnetic field.

    Science.gov (United States)

    Kang, Nan; Yuan, Hao; Coddet, Pierre; Ren, Zhongming; Bernage, Charles; Liao, Hanlin; Coddet, Christian

    2017-01-01

    Tensile strength and ductility of Selective Laser Melting (SLM) processed commercially pure Ti (CP-Ti) were simultaneous enhanced by preforming the melting/solidification processes under Static Magnetic Field (SMF). The effects of SMF on microstructure and tensile properties were examined. The SMF-SLMed CP-Ti sample presents a microstructure of fine acicular martensitic α'-Ti and lath-shaped α-Ti. Meanwhile, the texture structure of SLMed CP-Ti was eliminated after adding a SMF. The SMF-SLM process offers new avenues to ameliorate the microstructure and improve the mechanical properties of SLMed sample. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Peculiarities of single track formation from TI6AL4V alloy at different laser power densities by selective laser melting

    Directory of Open Access Journals (Sweden)

    Yadroitsava, I.

    2015-11-01

    Full Text Available This paper describes the geometrical characteristics of single tracks manufactured by selective laser melting (SLM at different laser powers (20-170 W and scanning speeds (0.1-2.0 m/s. Simulation of temperature distribution during processing is carried out. A conclusion about the optimal process parameters and peculiarities of selective laser melting of Ti6Al4V alloy at low and high laser powers and scanning speeds is reached. The analysis of temperature fields creates opportunities to build parts with the desired properties by using SLM.

  10. Effects of Oxygen Content on Tensile and Fatigue Performance of Ti-6Al-4 V Manufactured by Selective Laser Melting

    Science.gov (United States)

    Quintana, Oscar A.; Tong, Weidong

    2017-12-01

    We investigated the selective laser melting (SLM) process for development of Ti-6Al-4 V solid material with oxygen content corresponding to the extra low interstitial (ELI) and non-ELI conditions. The microstructure, chemistry, and tensile properties of samples in as-built and hot isostatically pressed (HIPed) condition were evaluated for both material types, while fatigue performance was evaluated by rotating bending fatigue tests on both smooth and notched SLM ELI and non-ELI Ti-6Al-4 V samples in HIPed condition.

  11. Heat treatment of Ti6Al4V produced by Selective Laser Melting: Microstructure and mechanical properties

    International Nuclear Information System (INIS)

    Vrancken, Bey; Thijs, Lore; Kruth, Jean-Pierre; Van Humbeeck, Jan

    2012-01-01

    Highlights: ► Responses of SLM-produced and wrought Ti6Al4V to heat treatment are compared. ► Temperature is found to be the controlling parameter for treatments in the α + β range. ► Ductility could be improved by a factor of 85%, from 7.27% to 13.59%. ► An optimal heat treatment for SLM produced Ti6Al4V is proposed. - Abstract: The present work shows that optimization of mechanical properties via heat treatment of parts produced by Selective Laser Melting (SLM) is profoundly different compared to conventionally processed Ti6Al4V. In order to obtain optimal mechanical properties, specific treatments are necessary due to the specific microstructure resulting from the SLM process. SLM is an additive manufacturing technique through which components are built by selectively melting powder layers with a focused laser beam. The process is characterized by short laser-powder interaction times and localized high heat input, which leads to steep thermal gradients, rapid solidification and fast cooling. In this research, the effect of several heat treatments on the microstructure and mechanical properties of Ti6Al4V processed by SLM is studied. A comparison is made with the effect of these treatments on hot forged and subsequently mill annealed Ti6Al4V with an original equiaxed microstructure. For SLM produced parts, the original martensite α′ phase is converted to a lamellar mixture of α and β for heat treating temperatures below the β-transus (995 °C), but features of the original microstructure are maintained. Treated above the β-transus, extensive grain growth occurs and large β grains are formed which transform to lamellar α + β upon cooling. Post treating at 850 °C for 2 h, followed by furnace cooling increased the ductility of SLM parts to 12.84 ± 1.36%, compared to 7.36 ± 1.32% for as-built parts.

  12. Gene transformation potential of commercial canola ( Brassica ...

    African Journals Online (AJOL)

    of efficient transformation methods in commercial varieties. In this research transformation potential of 8 commercial cultivars; Licord, SLM046, RGS003, Zarfam, Okapi, Sarigol, Modena and Opera adapted to different regions of Iran was studied using cotyledon and hypocotyl explants. Agrobacterium tumifaciens strain AGL0 ...

  13. Controlled acceleration of superimposed Bessel beams

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2013-06-01

    Full Text Available spatial light modulator (SLM) to create superimposed, non-canonical, higher-order Bessel beams and a CCD camera to investigate the propagation of the resulting field. It is already known that the intensity profile of the resulting field experiences...

  14. Investigation of NOx Reduction by Low Temperature Oxidation Using Ozone Produced by Dielectric Barrier Discharge

    DEFF Research Database (Denmark)

    Stamate, Eugen; Irimiea, Cornelia; Salewski, Mirko

    2013-01-01

    NOx reduction by low temperature oxidation using ozone produced by a dielectric barrier discharge generator is investigated for different process parameters in a 6m long reactor in serpentine arrangement using synthetic dry flue gas with NOx levels below 500 ppm, flows up to 50 slm and temperatures...

  15. Biological Components of Colour Preference in Infancy

    Science.gov (United States)

    Franklin, Anna; Bevis, Laura; Ling, Yazhu; Hurlbert, Anya

    2010-01-01

    Adult colour preference has been summarized quantitatively in terms of weights on the two fundamental neural processes that underlie early colour encoding: the S-(L+M) ("blue-yellow") and L-M ("red-green") cone-opponent contrast channels ( Ling, Hurlbert & Robinson, 2006; Hurlbert & Ling, 2007). Here, we investigate whether colour preference in…

  16. Simulation of flux during electro-membrane extraction based on the Nernst-Planck equation.

    Science.gov (United States)

    Gjelstad, Astrid; Rasmussen, Knut Einar; Pedersen-Bjergaard, Stig

    2007-12-07

    The present work has for the first time described and verified a theoretical model of the analytical extraction process electro-membrane extraction (EME), where target analytes are extracted from an aqueous sample, through a thin layer of 2-nitrophenyl octylether immobilized as a supported liquid membrane (SLM) in the pores in the wall of a porous hollow fibre, and into an acceptor solution present inside the lumen of the hollow fibre by the application of an electrical potential difference. The mathematical model was based on the Nernst-Planck equation, and described the flux over the SLM. The model demonstrated that the magnitude of the electrical potential difference, the ion balance of the system, and the absolute temperature influenced the flux of analyte across the SLM. These conclusions were verified by experimental data with five basic drugs. The flux was strongly dependent of the potential difference over the SLM, and increased potential difference resulted in an increase in the flux. The ion balance, defined as the sum of ions in the donor solution divided by the sum of ions in the acceptor solution, was shown to influence the flux, and high ionic concentration in the acceptor solution relative to the sample solution was advantageous for high flux. Different temperatures also led to changes in the flux in the EME system.

  17. Design of single-longitudinal-mode laser oscillator for edge Thomson scattering system in ITER

    International Nuclear Information System (INIS)

    Hatae, Takaki; Kusama, Yoshinori; Kubomura, Hiroyuki; Matsuoka, Shin-ichi

    2006-06-01

    A high output energy (5J) and high repetition rate (100 Hz) laser system is required for the edge Thomson scattering system in ITER. A YAG laser (Nd:YAG laser) is a first candidate for the laser system satisfying the requirements. It is important to develop a high beam quality and single longitudinal mode (SLM) laser oscillator in order to realize this high power laser system. In this design work, following activities relating to the SLM laser oscillator have been carried out: design of the laser head and the resonator, estimation of the output power for the SLM laser oscillator, consideration of the feedback control scheme and consideration of interface for amplification system to achieve required performance (5J, 100 Hz). It is expected that the designed laser diode (LD) pumped SLM laser oscillator realizes: 100 Hz of repetition rate, 10 mJ of output energy, 10 ns of pulse width, single longitudinal mode, TEM 00 of transversal mode, divergence less than 4 times of the diffraction limit, energy stability within 5%. (author)

  18. 3D shape measurement using deterministic phase retrieval and a partially developed speckle field

    DEFF Research Database (Denmark)

    Almoro, Percival F.; Waller, Laura; Agour, Mostafa

    2012-01-01

    Fourier domain. The local variations of the recorded speckle patterns and the defocus distance approximate the axial intensity derivative which, in turn, is required to recover the wavefront phase via the transport of intensity equation (TIE). The SLM setup reduces the speckle recording time and the TIE...

  19. community participatory sustainable land management byelaw

    African Journals Online (AJOL)

    ACSS

    2014-02-11

    Feb 11, 2014 ... Public SWC investments were largely based Focus on low cost SLM practices on food for work or cash ... land and environmental protection, livestock production and marketing agency, .... Government policy prohibit free grazing, but SWC structures destroyed, trees trampled and .... Nutrient flows and.

  20. Applying Theories of Deviance to Academic Cheating.

    Science.gov (United States)

    Michaels, James W.; Miethe, Terance D.

    1989-01-01

    Reports on a study that extends social psychological theories of deviance to explain academic cheating. Uses self-report data from college students to examine the theories of deterrence, rational choice, social bond, and social learning formulations of cheating. Supports the claim that cheating is a serious problem in higher education. (SLM)

  1. Hot-Fire Test of Liquid Oxygen/Hydrogen Space Launch Mission Injector Applicable to Exploration Upper Stage

    Science.gov (United States)

    Barnett, Greg; Turpin, Jason; Nettles, Mindy

    2015-01-01

    This task is to hot-fire test an existing Space Launch Mission (SLM) injector that is applicable for all expander cycle engines being considered for the exploration upper stage. The work leverages investment made in FY 2013 that was used to additively manufacture three injectors (fig. 1) all by different vendors..

  2. Microhardness and microstructure evolution of TiB2 reinforced Inconel 625/TiB2 composite produced by selective laser melting

    Science.gov (United States)

    Zhang, Baicheng; Bi, Guijun; Nai, Sharon; Sun, Chen-nan; Wei, Jun

    2016-06-01

    In this study, micron-size TiB2 particles were utilized to reinforce Inconel 625 produced by selective laser melting. Exceptional microhardness 600-700 HV0.3 of the composite was obtained. In further investigation, the microstructure and mechanical properties of Inconel 625/TiB2 composite can be significantly influenced by addition of TiB2 particles during SLM. It was found that the long directional columnar grains observed from SLM-processed Inconel 625 were totally changed to fine dendritic matrix due to the addition of TiB2 particles. Moreover, with laser energy density (LED) of 1200 J/m, a Ti, Mo rich interface around TiB2 particles with fine thickness can be observed by FESEM and EDS. The microstructure evolution can be determined by different laser energy density (LED): under 1200 J/m, γ phase in dendrite grains; under 600 J/m, γ phase in combination of dendritic and acicular grains; under 400 J/m, γ phase acicular grains. Under optimized LED 1200 J/m, the dynamic nanohardness (8.62 GPa) and elastic modulus (167 GPa) of SLM-processed Inconel 625/TiB2 composite are higher compared with those of SLM-processed Inconel 625 (3.97 GPa and 135 GPa, respectively).

  3. Protective effect of rutin in comparison to silymarin against induced hepatotoxicity in rats

    Directory of Open Access Journals (Sweden)

    M. Kasi Reddy

    2017-01-01

    Full Text Available Aim: The aim of this study is to evaluate the hepatoprotective effect of rutin (RTN in comparison to silymarin (SLM against acetaminophen (APAP-induced hepatotoxicity in rats. Materials and Methods: Male Wistar albino rats (n=24 of 3 months age were equally divided into four groups. Group 1 served as normal control. Hepatotoxicity was induced in the remaining three groups with administration of 500 mg/kg po APAP from day 1-3. Groups 2, 3, and 4 were subsequently administered orally with distilled water, 25 mg/kg of SLM, and 20 mg/kg of RTN, respectively, for 11 days. The mean body weights and biomarkers of hepatotoxicity were estimated on day 0, 4 (confirmation of toxicity, and 15 (at the end of treatment. Hematological parameters were evaluated on day 4 and 15. Antioxidant profile and adenosine triphosphatases (ATPases were assessed at the end of the experiment. Liver tissues were subjected to histopathology and transmission electron microscopy after the sacrifice on day 15. Results: Antioxidant profile, ATPases, and hematological and sero-biochemical parameters were significantly altered, and histopathological changes were noticed in the liver of toxic control group. These changes were reversed in groups 3 and 4 that were administered with SLM and RTN, respectively. Conclusion: The results of the present investigation enunciated that SLM has potent hepatoprotective activity though the RTN was found superior in restoring the pathological alterations in paracetamol-induced hepatotoxicity in Wistar albino rats.

  4. Generating and measuring non-diffracting vector Bessel beams

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2014-03-01

    Full Text Available We demonstrate how to create non-diffracting vector Bessel beams by implementing a spatial light modulator (SLM) to generate scalar Bessel beams which are then converted into vector fields by the use of an azimuthally-varying birefringent plate...

  5. Encoding mutually unbiased bases in orbital angular momentum for quantum key distribution

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2013-07-01

    Full Text Available We encode mutually unbiased bases (MUBs) using the higher-dimensional orbital angular momentum (OAM) degree of freedom associated with optical fields. We illustrate how these states are encoded with the use of a spatial light modulator (SLM). We...

  6. Transmitting more than 10 bit with a single photon

    NARCIS (Netherlands)

    Tentrup, T.B.H.; Hummel, T.; Wolterink, T.A.W.; Uppu, R.; Mosk, Allard; Pinkse, P.W.H.

    2017-01-01

    Encoding information in the position of single photons has no known limits, given infinite resources. Using a heralded single-photon source and a spatial light modulator (SLM), we steer single photons to specific positions in a virtual grid on a large-area spatially resolving photon-counting

  7. Optimal Fisher Discriminant Ratio for an Arbitrary Spatial Light Modulator

    Science.gov (United States)

    Juday, Richard D.

    1999-01-01

    Optimizing the Fisher ratio is well established in statistical pattern recognition as a means of discriminating between classes. I show how to optimize that ratio for optical correlation intensity by choice of filter on an arbitrary spatial light modulator (SLM). I include the case of additive noise of known power spectral density.

  8. Study of flow stress and spall strength of additively manufactured Ti-6-4 alloy

    Science.gov (United States)

    Cohen, Amitay; Paris, Vitaly; Yosef-Hai, Arnon; Gudinetsky, Eli; Tiferet, Eitan

    2017-06-01

    The use of additive manufacturing (AM) by Electron Beam Melting (EBM) or Selective Laser Melting (SLM) has extensively grown in the past few years. A major goal in AM is to manufacture materials with mechanical properties at least as good as traditionally manufactured materials. In this work we present results of planar impact tests and Split Hopkinson Pressure Bar tests (SHPB) on Ti-6-4 manufactured by EBM and SLM processes. Results of planar impact tests on SLM samples display slightly higher spall strength compared to EBM while the stress at Hugoniot elastic limit (HEL) is practically the same. Stress strain curves based on SHPB measurements at two different strain rates present similar plastic flow stresses for SLM and EBM processed Ti-6-4 alloy, while the flow stress is about 20% higher than reported for commercial reference material. The strain to failure of both materials shows considerable strain rate sensitivity. The results of post-mortem analysis of spall fracture will also be presented.

  9. Effects of turmeric (Curcuma longa) and vitamin E on histopathological lesions induced in bursa of Fabricius of broiler chicks by salinomycin.

    Science.gov (United States)

    Sayrafi, Reza; Mirzakhani, Navideh; Mobaseri, Reza

    2017-01-01

    The aim of this study was to evaluate the protective effects of the turmeric in comparison to vitamin E on bursal damages induced by salinomycin in broiler chickens. In this study, forty one day-old broiler chicks were randomly divided into four treatment groups: 1- basal diet as control, 2- basal diet plus salinomycin, 3- basal diet plus salinomycin (SLM) and vitamin E (Vit. E) and 4- basal diet plus salinomycin and turmeric powder. The chicks were treated for two weeks. At the end of the experiment, the bursal tissues were removed and fixed in 10% formalin solution. Tissue sections were stained with hematoxylin and eosin stain for histopathological studies. Light microscopic observations showed that, SLM diminished cortex thickness of bursal tissue, enhanced its medulla zone and caused severe lymphocytic necrosis. In addition, SLM led to fibrosis of interstitium along with sever edema of medulla zone in the bursal tissue of the chicken. Administration of Vit. E and TP significantly inhibited the SLM-induced derangements and comparing the Vit. E and TP showed no significant differences. The results of this study indicated that the turmeric may protect bursa of Fabricius against toxicity induced by salinomycin in chicks.

  10. Physics and technology of tunable pulsed single longitudinal mode ...

    Indian Academy of Sciences (India)

    precious materials. In particular, single-longitudinal mode dye lasers are useful ... to the longitudinal mode spacing of 10 GHz. Grating of 3300 .... the band of wavelength covering 3 pm and SLM operation was shown in the band of 0.5 pm.

  11. A framework for the economic valuation of land use change

    NARCIS (Netherlands)

    Hein, L.G.; Groot, de R.S.

    2007-01-01

    There is a broad recognition that sustainable land management (SLM) is crucial for ensuring an adequate, long-term supply of food, raw materials and other services provided by the natural environment to the human society. This paper presents a methodological framework for analyzing the benefits of

  12. IN718 Additive Manufacturing Properties and Influences

    Science.gov (United States)

    Lambert, Dennis M.

    2015-01-01

    The results of tensile, fracture, and fatigue testing of IN718 coupons produced using the selective laser melting (SLM) additive manufacturing technique are presented. The data have been "sanitized" to remove the numerical values, although certain references to material standards are provided. This document provides some knowledge of the effect of variation of controlled build parameters used in the SLM process, a snapshot of the capabilities of SLM in industry at present, and shares some of the lessons learned along the way. For the build parameter characterization, the parameters were varied over a range that was centered about the machine manufacturer's recommended value, and in each case they were varied individually, although some co-variance of those parameters would be expected. Tensile, fracture, and high-cycle fatigue properties equivalent to wrought IN718 are achievable with SLM-produced IN718. Build and post-build processes need to be determined and then controlled to established limits to accomplish this. It is recommended that a multi-variable evaluation, e.g., design-of experiment (DOE), of the build parameters be performed to better evaluate the co-variance of the parameters.

  13. Comparison of Maraging Steel Micro- and Nanostructure Produced Conventionally and by Laser Additive Manufacturing

    Directory of Open Access Journals (Sweden)

    Eric A. Jägle

    2016-12-01

    Full Text Available Maraging steels are used to produce tools by Additive Manufacturing (AM methods such as Laser Metal Deposition (LMD and Selective Laser Melting (SLM. Although it is well established that dense parts can be produced by AM, the influence of the AM process on the microstructure—in particular the content of retained and reversed austenite as well as the nanostructure, especially the precipitate density and chemistry, are not yet explored. Here, we study these features using microhardness measurements, Optical Microscopy, Electron Backscatter Diffraction (EBSD, Energy Dispersive Spectroscopy (EDS, and Atom Probe Tomography (APT in the as-produced state and during ageing heat treatment. We find that due to microsegregation, retained austenite exists in the as-LMD- and as-SLM-produced states but not in the conventionally-produced material. The hardness in the as-LMD-produced state is higher than in the conventionally and SLM-produced materials, however, not in the uppermost layers. By APT, it is confirmed that this is due to early stages of precipitation induced by the cyclic re-heating upon further deposition—i.e., the intrinsic heat treatment associated with LMD. In the peak-aged state, which is reached after a similar time in all materials, the hardness of SLM- and LMD-produced material is slightly lower than in conventionally-produced material due to the presence of retained austenite and reversed austenite formed during ageing.

  14. High-temperature solution nitriding and low-temperature surface nitriding of 3D printed stainless steel

    DEFF Research Database (Denmark)

    Valente, Emilie H.; Christiansen, Thomas L.; Somers, Marcel A. J.

    structure and the fusion-boundaries present in the as-printed SLM 316L stainless steel are removed by austenitisation and HTSN treatment. The treatments result in a homogenization of the printed microstructure and a lower bulk hardness compared to the as printed state. Due to the continued presence...

  15. 40 CFR Appendix A to Part 425 - Potassium Ferricyanide Titration Method

    Science.gov (United States)

    2010-07-01

    ...) EFFLUENT GUIDELINES AND STANDARDS LEATHER TANNING AND FINISHING POINT SOURCE CATEGORY Pt. 425, App. A... method is based on method SLM 4/2 described in “Official Method of Analysis,” Society of Leather Trades..., “Ann. chim, anal,”, 1945, 27, 153; Booth; “J. Soc. Leather Trades' Chemists,” 1956, 40, 238). Apparatus...

  16. A Lightweight Structure Redesign Method Based on Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Li Tang

    2016-11-01

    Full Text Available The purpose of this paper is to present a new design method of lightweight parts fabricated by selective laser melting (SLM based on the “Skin-Frame” and to explore the influence of fabrication defects on SLM parts with different sizes. Some standard lattice parts were designed according to the Chinese GB/T 1452-2005 standard and manufactured by SLM. Then these samples were tested in an MTS Insight 30 compression testing machine to study the trends of the yield process with different structure sizes. A set of standard cylinder samples were also designed according to the Chinese GB/T 228-2010 standard. These samples, which were made of iron-nickel alloy (IN718, were also processed by SLM, and then tested in the universal material testing machine INSTRON 1346 to obtain their tensile strength. Furthermore, a lightweight redesigned method was researched. Then some common parts such as a stopper and connecting plate were redesigned using this method. These redesigned parts were fabricated and some application tests have already been performed. The compression testing results show that when the minimum structure size is larger than 1.5 mm, the mechanical characteristics will hardly be affected by process defects. The cylinder parts were fractured by the universal material testing machine at about 1069.6 MPa. These redesigned parts worked well in application tests, with both the weight and fabrication time of these parts reduced more than 20%.

  17. Modulation of the pupil function of microscope objective lens for multifocal multi-photon microscopy using a spatial light modulator

    Science.gov (United States)

    Matsumoto, Naoya; Okazaki, Shigetoshi; Takamoto, Hisayoshi; Inoue, Takashi; Terakawa, Susumu

    2014-02-01

    We propose a method for high precision modulation of the pupil function of a microscope objective lens to improve the performance of multifocal multi-photon microscopy (MMM). To modulate the pupil function, we adopt a spatial light modulator (SLM) and place it at the conjugate position of the objective lens. The SLM can generate an arbitrary number of spots to excite the multiple fluorescence spots (MFS) at the desired positions and intensities by applying an appropriate computer-generated hologram (CGH). This flexibility allows us to control the MFS according to the photobleaching level of a fluorescent protein and phototoxicity of a specimen. However, when a large number of excitation spots are generated, the intensity distribution of the MFS is significantly different from the one originally designed due to misalignment of the optical setup and characteristics of the SLM. As a result, the image of a specimen obtained using laser scanning for the MFS has block noise segments because the SLM could not generate a uniform MFS. To improve the intensity distribution of the MFS, we adaptively redesigned the CGH based on the observed MFS. We experimentally demonstrate an improvement in the uniformity of a 10 × 10 MFS grid using a dye solution. The simplicity of the proposed method will allow it to be applied for calibration of MMM before observing living tissue. After the MMM calibration, we performed laser scanning with two-photon excitation to observe a real specimen without detecting block noise segments.

  18. 78 FR 56263 - HydroGen Corp., QueryObject Systems Corp., Security Intelligence Technologies, Inc., Skins, Inc...

    Science.gov (United States)

    2013-09-12

    ... SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] HydroGen Corp., QueryObject Systems Corp., Security Intelligence Technologies, Inc., Skins, Inc., SLM Holdings, Inc., Spring Creek Healthcare Systems... securities of Security Intelligence Technologies, Inc. because it has not filed any periodic reports since...

  19. Local electrophoresis deposition assisted by laser trapping coupled with a spatial light modulator for three-dimensional microfabrication

    Science.gov (United States)

    Matsuura, Toshiki; Takai, Takanari; Iwata, Futoshi

    2017-10-01

    We describe a novel three-dimensional fabrication technique using local electrophoresis deposition assisted by laser trapping coupled with a spatial light modulator (SLM). In a solution containing nanometer-scale colloidal Au particles, multiple laser spots formed on a conductive substrate by the SLM gathered the nanoparticles together, and then the nanoparticles were electrophoretically deposited onto the substrate by an applied electrical field. However, undesirable sub-spots often appeared due to optical interference from the multiple laser spots, which deteriorated the accuracy of the deposition. To avoid the appearance of undesirable sub-spots, we proposed a method using quasi-multiple spots, which we realized by switching the position of a single spot briefly using the SLM. The method allowed us to deposit multiple dots on the substrate without undesirable sub-dot deposition. By moving the substrate downward during deposition, multiple micro-pillar structures could be fabricated. As a fabrication property, the dependence of the pillar diameter on laser intensity was investigated by changing the number of laser spots. The smallest diameter of the four pillars fabricated in this study was 920 nm at the laser intensity of 2.5 mW. To demonstrate the effectiveness of the method, multiple spiral structures were fabricated. Quadruple spirals of 46 µm in height were successfully fabricated with a growth rate of 0.21 µm/s using 2200 frames of the CGH patterns displayed in the SLM at a frame rate of 10 fps.

  20. Physical properties and microstructure study of stainless steel 316L alloy fabricated by selective laser melting

    Science.gov (United States)

    Islam, Nurul Kamariah Md Saiful; Harun, Wan Sharuzi Wan; Ghani, Saiful Anwar Che; Omar, Mohd Asnawi; Ramli, Mohd Hazlen; Ismail, Muhammad Hussain

    2017-12-01

    Selective Laser Melting (SLM) demonstrates the 21st century's manufacturing infrastructure in which powdered raw material is melted by a high energy focused laser, and built up layer-by-layer until it forms three-dimensional metal parts. SLM process involves a variation of process parameters which affects the final material properties. 316L stainless steel compacts through the manipulation of building orientation and powder layer thickness parameters were manufactured by SLM. The effect of the manipulated parameters on the relative density and dimensional accuracy of the 316L stainless steel compacts, which were in the as-build condition, were experimented and analysed. The relationship between the microstructures and the physical properties of fabricated 316L stainless steel compacts was investigated in this study. The results revealed that 90° building orientation has higher relative density and dimensional accuracy than 0° building orientation. Building orientation was found to give more significant effect in terms of dimensional accuracy, and relative density of SLM compacts compare to build layer thickness. Nevertheless, the existence of large number and sizes of pores greatly influences the low performances of the density.

  1. Layered surface structure of gas-atomized high Nb-containing TiAl powder and its impact on laser energy absorption for selective laser melting

    Science.gov (United States)

    Zhou, Y. H.; Lin, S. F.; Hou, Y. H.; Wang, D. W.; Zhou, P.; Han, P. L.; Li, Y. L.; Yan, M.

    2018-05-01

    Ti45Al8Nb alloy (in at.%) is designed to be an important high-temperature material. However, its fabrication through laser-based additive manufacturing is difficult to achieve. We present here that a good understanding of the surface structure of raw material (i.e. Ti45Al8Nb powder) is important for optimizing its process by selective laser melting (SLM). Detailed X-ray photoelectron spectroscopy (XPS) depth profiling and transmission electron microscopy (TEM) analyses were conducted to determine the surface structure of Ti45Al8Nb powder. An envelope structure (∼54.0 nm in thickness) was revealed for the powder, consisting of TiO2 + Nb2O5 (as the outer surface layer)/Al2O3 + Nb2O5 (as the intermediate layer)/Al2O3 (as the inner surface layer)/Ti45Al8Nb (as the matrix). During SLM, this layered surface structure interacted with the incident laser beam and improved the laser absorptivity of Ti45Al8Nb powder by ∼32.21%. SLM experiments demonstrate that the relative density of the as-printed parts can be realized to a high degree (∼98.70%), which confirms good laser energy absorption. Such layered surface structure with appropriate phase constitution is essential for promoting SLM of the Ti45Al8Nb alloy.

  2. A Comparison of the Spatial Linear Model to Nearest Neighbor (k-NN) Methods for Forestry Applications

    Science.gov (United States)

    Jay M. Ver Hoef; Hailemariam Temesgen; Sergio Gómez

    2013-01-01

    Forest surveys provide critical information for many diverse interests. Data are often collected from samples, and from these samples, maps of resources and estimates of aerial totals or averages are required. In this paper, two approaches for mapping and estimating totals; the spatial linear model (SLM) and k-NN (k-Nearest Neighbor) are compared, theoretically,...

  3. Stable single longitudinal mode erbium-doped silica fiber laser based on an asymmetric linear three-cavity structure

    International Nuclear Information System (INIS)

    Feng Ting; Yan Feng-Ping; Li Qi; Peng Wan-Jing; Feng Su-Chun; Tan Si-Yu; Wen Xiao-Dong

    2013-01-01

    We present a stable linear-cavity single longitudinal mode (SLM) erbium-doped silica fiber laser. It consists of four fiber Bragg gratings (FBGs) directly written in a section of photosensitive erbium-doped fiber (EDF) to form an asymmetric three-cavity structure. The stable SLM operation at a wavelength of 1545.112 nm with a 3-dB bandwidth of 0.012 nm and an optical signal-to-noise ratio (OSNR) of about 60 dB is verified experimentally. Under laboratory conditions, the performance of a power fluctuation of less than 0.05 dB observed from the power meter for 6 h and a wavelength variation of less than 0.01 nm obtained from the optical spectrum analyzer (OSA) for about 1.5 h are demonstrated. The gain fiber length is no longer limited to only several centimeters for SLM operation because of the excellent mode-selecting ability of the asymmetric three-cavity structure. The proposed scheme provides a simple and cost-effective approach to realizing a stable SLM fiber laser. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  4. Electromembrane extraction

    DEFF Research Database (Denmark)

    Huang, Chuixiu; Chen, Zhiliang; Gjelstad, Astrid

    2017-01-01

    Electromembrane extraction (EME) was inspired by solid-phase microextraction and developed from hollow fiber liquid-phase microextraction in 2006 by applying an electric field over the supported liquid membrane (SLM). EME provides rapid extraction, efficient sample clean-up and selectivity based...

  5. A Hybrid Approach to Composite Damage and Failure Analysis Combining Synergistic Damage Mechanics and Peridynamics

    Science.gov (United States)

    2016-12-31

    micormechanics; Cavitational induced cracking; Peridynamics; Porous media 16. SECURITY CLASSIFICATION OF: 17. LIMITATION 18. NUMBER OF ABSTRACT OF PAGES a...shown, each with a different range of the radial and orientation variations. Realization Without Voids lOI!m dia voids Sl!m dia voids 2.51!m dia

  6. Reconstruction of laser beam wavefronts based on mode analysis

    CSIR Research Space (South Africa)

    Schulze, C

    2013-07-01

    Full Text Available . Experimental setup for measuring the far field of differ- ently aberrated Gaussian beams. He–Ne, helium–neon laser; L 1–3 , lenses; M, mirror; SLM 1 , spatial light modulator; CCD, camera. Fig. 8. Theoretical and measured far fields FFth and FFm of a...

  7. Liquid-phase microextraction in a microfluidic-chip

    DEFF Research Database (Denmark)

    Payán, María D. Ramos; Jensen, Henrik; Petersen, Nickolaj J.

    2012-01-01

    , methadone, haloperidol, loperamide, and pethidine were selected as model analytes, and they were extracted from alkaline sample solution, through the SLM, and into 10mM HCl or 100mM HCOOH functioning as acceptor phase. Subsequently, the acceptor phase was either analyzed off-line by capillary...

  8. Browse Title Index - African Journals Online

    African Journals Online (AJOL)

    Items 351 - 400 of 506 ... JLM Gonçalves, MCP Wichert, JL Gava, AV Masetto, JC Arthur Junior, MIP Serrano, SLM Mello. Vol 192 (2001), Solar-assisted drying of timber at industrial scale: management paper, Abstract. M Bux, K Bauer, W Mühlbauer, T Conrad. Vol 70, No 1 (2008), Solid-wood production from temperate ...

  9. Southern Forests: a Journal of Forest Science - Vol 69, No 2 (2007)

    African Journals Online (AJOL)

    Soil fertility and growth of Eucalyptus grandis in Brazil under different residue management practices · EMAIL FULL TEXT EMAIL FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. JLM Gonçalves, MCP Wichert, JL Gava, AV Masetto, JC Arthur Junior, MIP Serrano, SLM Mello, 95-102 ...

  10. Generating superpositions of higher–order Bessel beams [Journal article

    CSIR Research Space (South Africa)

    Vasilyeu, R

    2009-12-01

    Full Text Available The authors report the first experimental generation of the superposition of higher-order Bessel beams, by means of a spatial light modulator (SLM) and a ring slit aperture. They present illuminating a ring slit aperture with light which has...

  11. Speckless head-up display on two spatial light modulators

    Science.gov (United States)

    Siemion, Andrzej; Ducin, Izabela; Kakarenko, Karol; Makowski, Michał; Siemion, Agnieszka; Suszek, Jarosław; Sypek, Maciej; Wojnowski, Dariusz; Jaroszewicz, Zbigniew; Kołodziejczyk, Andrzej

    2010-12-01

    There is a continuous demand for the computer generated holograms to give an almost perfect reconstruction with a reasonable cost of manufacturing. One method of improving the image quality is to illuminate a Fourier hologram with a quasi-random, but well known, light field phase distribution. It can be achieved with a lithographically produced phase mask. Up to date, the implementation of the lithographic technique is relatively complex and time and money consuming, which is why we have decided to use two Spatial Light Modulators (SLM). For the correctly adjusted light polarization a SLM acts as a pure phase modulator with 256 adjustable phase levels between 0 and 2π. The two modulators give us an opportunity to use the whole surface of the device and to reduce the size of the experimental system. The optical system with one SLM can also be used but it requires dividing the active surface into halves (one for the Fourier hologram and the second for the quasi-random diffuser), which implies a more complicated optical setup. A larger surface allows to display three Fourier holograms, each for one primary colour: red, green and blue. This allows to reconstruct almost noiseless colourful dynamic images. In this work we present the results of numerical simulations of image reconstructions with the use of two SLM displays.

  12. Process monitoring of additive manufacturing by using optical tomography

    Energy Technology Data Exchange (ETDEWEB)

    Zenzinger, Guenter, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Bamberg, Joachim, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Ladewig, Alexander, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Hess, Thomas, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Henkel, Benjamin, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de; Satzger, Wilhelm, E-mail: guenter.zenzinger@mtu.de, E-mail: alexander.ladewig@mtu.de [MTU Aero Engines AG, Dachauerstrasse 665, 80995 Munich (Germany)

    2015-03-31

    Parts fabricated by means of additive manufacturing are usually of complex shape and owing to the fabrication procedure by using selective laser melting (SLM), potential defects and inaccuracies are often very small in lateral size. Therefore, an adequate quality inspection of such parts is rather challenging, while non-destructive-techniques (NDT) are difficult to realize, but considerable efforts are necessary in order to ensure the quality of SLM-parts especially used for aerospace components. Thus, MTU Aero Engines is currently focusing on the development of an Online Process Control system which monitors and documents the complete welding process during the SLM fabrication procedure. A high-resolution camera system is used to obtain images, from which tomographic data for a 3dim analysis of SLM-parts are processed. From the analysis, structural irregularities and structural disorder resulting from any possible erroneous melting process become visible and may be allocated anywhere within the 3dim structure. Results of our optical tomography (OT) method as obtained on real defects are presented.

  13. Determination of Strain Rate Sensitivity of Micro-struts Manufactured Using the Selective Laser Melting Method

    Science.gov (United States)

    Gümrük, Recep; Mines, R. A. W.; Karadeniz, Sami

    2018-03-01

    Micro-lattice structures manufactured using the selective laser melting (SLM) process provides the opportunity to realize optimal cellular materials for impact energy absorption. In this paper, strain rate-dependent material properties are measured for stainless steel 316L SLM micro-lattice struts in the strain rate range of 10-3 to 6000 s-1. At high strain rates, a novel version of the split Hopkinson Bar has been developed. Strain rate-dependent materials data have been used in Cowper-Symonds material model, and the scope and limit of this model in the context of SLM struts have been discussed. Strain rate material data and the Cowper-Symonds model have been applied to the finite element analysis of a micro-lattice block subjected to drop weight impact loading. The model output has been compared to experimental results, and it has been shown that the increase in crush stress due to impact loading is mainly the result of strain rate material behavior. Hence, a systematic methodology has been developed to investigate the impact energy absorption of a micro-lattice structure manufactured using additive layer manufacture (SLM). This methodology can be extended to other micro-lattice materials and configurations, and to other impact conditions.

  14. Comparison of Maraging Steel Micro- and Nanostructure Produced Conventionally and by Laser Additive Manufacturing.

    Science.gov (United States)

    Jägle, Eric A; Sheng, Zhendong; Kürnsteiner, Philipp; Ocylok, Sörn; Weisheit, Andreas; Raabe, Dierk

    2016-12-24

    Maraging steels are used to produce tools by Additive Manufacturing (AM) methods such as Laser Metal Deposition (LMD) and Selective Laser Melting (SLM). Although it is well established that dense parts can be produced by AM, the influence of the AM process on the microstructure-in particular the content of retained and reversed austenite as well as the nanostructure, especially the precipitate density and chemistry, are not yet explored. Here, we study these features using microhardness measurements, Optical Microscopy, Electron Backscatter Diffraction (EBSD), Energy Dispersive Spectroscopy (EDS), and Atom Probe Tomography (APT) in the as-produced state and during ageing heat treatment. We find that due to microsegregation, retained austenite exists in the as-LMD- and as-SLM-produced states but not in the conventionally-produced material. The hardness in the as-LMD-produced state is higher than in the conventionally and SLM-produced materials, however, not in the uppermost layers. By APT, it is confirmed that this is due to early stages of precipitation induced by the cyclic re-heating upon further deposition-i.e., the intrinsic heat treatment associated with LMD. In the peak-aged state, which is reached after a similar time in all materials, the hardness of SLM- and LMD-produced material is slightly lower than in conventionally-produced material due to the presence of retained austenite and reversed austenite formed during ageing.

  15. Notes on Conservation Laws, Equations of Motion of Matter, and Particle Fields in Lorentzian and Teleparallel de Sitter Space-Time Structures

    Directory of Open Access Journals (Sweden)

    Waldyr A. Rodrigues

    2016-01-01

    Full Text Available We discuss the physics of interacting fields and particles living in a de Sitter Lorentzian manifold (dSLM, a submanifold of a 5-dimensional pseudo-Euclidean (5dPE equipped with a metric tensor inherited from the metric of the 5dPE space. The dSLM is naturally oriented and time oriented and is the arena used to study the energy-momentum conservation law and equations of motion for physical systems living there. Two distinct de Sitter space-time structures MdSL and MdSTP are introduced given dSLM, the first equipped with the Levi-Civita connection of its metric field and the second with a metric compatible parallel connection. Both connections are used only as mathematical devices. Thus, for example, MdSL is not supposed to be the model of any gravitational field in the General Relativity Theory (GRT. Misconceptions appearing in the literature concerning the motion of free particles in dSLM are clarified. Komar currents are introduced within Clifford bundle formalism permitting the presentation of Einstein equation as a Maxwell like equation and proving that in GRT there are infinitely many conserved currents. We prove that in GRT even when the appropriate Killing vector fields exist it is not possible to define a conserved energy-momentum covector as in special relativistic theories.

  16. Sherlock Holmes as a Social Scientist.

    Science.gov (United States)

    Ward, Veronica; Orbell, John

    1988-01-01

    Presents a way of teaching the scientific method through studying the adventures of Sherlock Holmes. Asserting that Sherlock Holmes used the scientific method to solve cases, the authors construct Holmes' method through excerpts from novels featuring his adventures. Discusses basic assumptions, paradigms, theory building, and testing. (SLM)

  17. Spatial modeling on the upperstream of the Citarum watershed: An application of geoinformatics

    Science.gov (United States)

    Ningrum, Windy Setia; Widyaningsih, Yekti; Indra, Tito Latif

    2017-03-01

    The Citarum watershed is the longest and the largest watershed in West Java, Indonesia, located at 106°51'36''-107°51' E and 7°19'-6°24'S across 10 districts, and serves as the water supply for over 15 million people. In this area, the water criticality index is concerned to reach the balance between water supply and water demand, so that in the dry season, the watershed is still able to meet the water needs of the society along the Citarum river. The objective of this research is to evaluate the water criticality index of Citarum watershed area using spatial model to overcome the spatial dependencies in the data. The result of Lagrange multiplier diagnostics for spatial dependence results are LM-err = 34.6 (p-value = 4.1e-09) and LM-lag = 8.05 (p-value = 0.005), then modeling using Spatial Lag Model (SLM) and Spatial Error Model (SEM) were conducted. The likelihood ratio test show that both of SLM dan SEM model is better than OLS model in modeling water criticality index in Citarum watershed. The AIC value of SLM and SEM model are 78.9 and 51.4, then the SEM model is better than SLM model in predicting water criticality index in Citarum watershed.

  18. Affects of binary and continuous phase modulations on the structure of Bessel beams

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2010-09-01

    Full Text Available The authors implement a novel technique to operate a phase-only spatial light modulator (SLM) in amplitude mode, allowing them to reproduce Durnin’s ring slit on a liquid crystal display (LCD). The affects of binary and continuous phase modulations...

  19. Community participatory sustainable land management byelaw ...

    African Journals Online (AJOL)

    Widespread adoption of sustainable land management (SLM) innovations by land users is considered key in addressing the rampant land degradation in the high rainfall and densely populated highlands of eastern and southern Africa. However, absence of enabling policy environments hamperes massive adoption of SLM ...

  20. Holographic Resonant Laser Printing of Metasurfaces Using Plasmonic Template

    DEFF Research Database (Denmark)

    Carstensen, Marcus S.; Zhu, Xiaolong; Iyore, Oseze Esther

    2018-01-01

    Laser printing with a spatial light modulator (SLM) has several advantages over conventional raster-writing and dot-matrix display (DMD) writing: multiple pixel exposure, high power endurance and existing software for computer generated holograms (CGH). We present a technique for the design...

  1. Residual damage in different ground logging methods alongside skid trails and winching strips

    Czech Academy of Sciences Publication Activity Database

    Aysan Badraghi, Naghimeg; Erler, J.; Hosseini, S. A. O.

    2015-01-01

    Roč. 61, č. 12 (2015), s. 526-534 ISSN 1212-4834 Institutional support: RVO:67179843 Keywords : Long-length method (LLM) * Short-length method (SLM) * Skidding and winching operations * Tree-length method (TLM) Subject RIV: EF - Botanics

  2. Exhaustive extraction of peptides by electromembrane extraction

    DEFF Research Database (Denmark)

    Huang, Chuixiu; Gjelstad, Astrid; Pedersen-Bjergaard, Stig

    2015-01-01

    trifluoroacetate, and leu-enkephalin were extracted from 600 μL of 25 mM phosphate buffer (pH 3.5), through a supported liquid membrane (SLM) containing di-(2-ethylhexyl)-phosphate (DEHP) dissolved in an organic solvent, and into 600 μL of an acidified aqueous acceptor solution using a thin flat membrane-based EME...

  3. Ti-6Al-4V Additively Manufactured by Selective Laser Melting with Superior Mechanical Properties

    Science.gov (United States)

    Xu, W.; Sun, S.; Elambasseril, J.; Liu, Q.; Brandt, M.; Qian, M.

    2015-03-01

    The Achilles' heel of additively manufactured Ti-6Al-4V by selective laser melting (SLM) is its inferior mechanical properties compared with its wrought (forged) counterparts. Acicular α' martensite resulted from rapid cooling by SLM is primarily responsible for high strength but inadequate tensile ductility achieved in the as-fabricated state. This study presents a solution to eliminating the adverse effect of the nonequilibrium α' martensite. This is achieved by enabling in situ martensite decomposition into a novel ultrafine (200-300 nm) lamellar ( α + β) microstructure via the selection of an array of processing variables including the layer thickness, energy density, and focal offset distance. The resulting tensile elongation reached 11.4% while the yield strength was kept above 1100 MPa. These properties compare favorably with those of mill-annealed Ti-6Al-4V consisting of globular α and β. The fatigue life of SLM-fabricated Ti-6Al-4V with an ultrafine lamellar ( α + β) structure has approached that of the mill-annealed counterparts and is much superior to that of SLM-fabricated Ti-6Al-4V with α' martensite.

  4. Sequence Classification: 889813 [

    Lifescience Database Archive (English)

    Full Text Available mplicated in myoclonus epilepsy associated with ragged red fibers (MERRF); Slm3p || http://www.ncbi.nlm.nih.gov/protein/6320172 ... ...2-thiouridylase, responsible for 2-thiolation of the wobble base of mitochondrial tRNAs; human ortholog is i

  5. Evaluation of single tracks of 17-4PH steel manufactured at different power densities and scanning speeds by selective laser melting

    CSIR Research Space (South Africa)

    Moller, Hein

    2016-11-01

    Full Text Available In Selective Laser Melting, the initial units produced are single tracks that overlap to create a single layer; from the sequence of layers, a 3D object is manufactured. The properties of the parts produced by SLM depend heavily on the properties...

  6. Pramana – Journal of Physics | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Based on the inverse transformation, an appropriate pre-processing scheme for electrically addressed input gray-scale images, particularly important in several optical processing and imaging applications, is suggested. Further, the necessity to compensate the SLM image nonlinearities in a volume holographic data ...

  7. Putting light in a spin

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2012-08-01

    Full Text Available rotation rates for some example superposition fields, which are shown to be in good agreement with that predicted theoretically. Introducing a second SLM and a Fourier transforming lens, we demonstrate a simple approach to perform an azimuthal decomposition...

  8. Comparison of Microstructure and Mechanical Properties of Scalmalloy® Produced by Selective Laser Melting and Laser Metal Deposition.

    Science.gov (United States)

    Awd, Mustafa; Tenkamp, Jochen; Hirtler, Markus; Siddique, Shafaqat; Bambach, Markus; Walther, Frank

    2017-12-23

    The second-generation aluminum-magnesium-scandium (Al-Mg-Sc) alloy, which is often referred to as Scalmalloy ® , has been developed as a high-strength aluminum alloy for selective laser melting (SLM). The high-cooling rates of melt pools during SLM establishes the thermodynamic conditions for a fine-grained crack-free aluminum structure saturated with fine precipitates of the ceramic phase Al₃-Sc. The precipitation allows tensile and fatigue strength of Scalmalloy ® to exceed those of AlSi10Mg by ~70%. Knowledge about properties of other additive manufacturing processes with slower cooling rates is currently not available. In this study, two batches of Scalmalloy ® processed by SLM and laser metal deposition (LMD) are compared regarding microstructure-induced properties. Microstructural strengthening mechanisms behind enhanced strength and ductility are investigated by scanning electron microscopy (SEM). Fatigue damage mechanisms in low-cycle (LCF) to high-cycle fatigue (HCF) are a subject of study in a combined strategy of experimental and statistical modeling for calculation of Woehler curves in the respective regimes. Modeling efforts are supported by non-destructive defect characterization in an X-ray computed tomography (µ-CT) platform. The investigations show that Scalmalloy ® specimens produced by LMD are prone to extensive porosity, contrary to SLM specimens, which is translated to ~30% lower fatigue strength.

  9. [Comparative study of microleakage by using different finished lines in selective laser melting metal crowns].

    Science.gov (United States)

    Peng, Yan; Zhong, Qun; Wu, Xue-Ying; Weng, Jia-Wei

    2016-12-01

    To evaluate microleakage of SLM Co -Cr alloy metal crown with two types finished line (chamfer and shoulder), compared with conventional fabrication of Co -Cr alloy metal crowns. Thirty healthy non-carious human molars were selected and randomly assigned to 3 groups, 10 in each. Teeth in group A and C received a chamfer finish line preparation, whereas teeth in group C received a shoulder finish line. Conventional Co -Cr alloy metal crowns were fabricated for group A when SLM metal crowns were made for group B and group C. Glass ionomer was applied for bonding. After 5000 thermocycles ranging from 5degrees centigrade to 55degrees centigrade,all the specimens were evaluated by dye penetration and then microleakage was examined under light microscope. The data were analyzed statistically with SPSS 20.0 software package. Microleakage in group A was significantly higher than the other two groups, group B and group C showed no significant difference in microleakage while microleakage in group B was higher than that in group C. Microleakage of SLM metal crowns was significantly less than that of conventional Co-Cr alloy metal crowns; chamfer finish line designs was recommended for SLM metal crowns in consideration of reducing microleakage and protecting tooth.

  10. Exploiting Process-Related Advantages of Selective Laser Melting for the Production of High-Manganese Steel.

    Science.gov (United States)

    Haase, Christian; Bültmann, Jan; Hof, Jan; Ziegler, Stephan; Bremen, Sebastian; Hinke, Christian; Schwedt, Alexander; Prahl, Ulrich; Bleck, Wolfgang

    2017-01-11

    Metal additive manufacturing has strongly gained scientific and industrial importance during the last decades due to the geometrical flexibility and increased reliability of parts, as well as reduced equipment costs. Within the field of metal additive manufacturing methods, selective laser melting (SLM) is an eligible technique for the production of fully dense bulk material with complex geometry. In the current study, we addressed the application of SLM for processing a high-manganese TRansformation-/TWinning-Induced Plasticity (TRIP/TWIP) steel. The solidification behavior was analyzed by careful characterization of the as-built microstructure and element distribution using optical and scanning electron microscopy (SEM). In addition, the deformation behavior was studied using uniaxial tensile testing and SEM. Comparison with conventionally produced TRIP/TWIP steel revealed that elemental segregation, which is normally very pronounced in high-manganese steels and requires energy-intensive post processing, is reduced due to the high cooling rates during SLM. Also, the very fast cooling promoted ε- and α'-martensite formation prior to deformation. The superior strength and pronounced anisotropy of the SLM-produced material was correlated with the microstructure based on the process-specific characteristics.

  11. Bone ingrowth potential of electron beam and selective laser melting produced trabecular-like implant surfaces with and without a biomimetic coating

    NARCIS (Netherlands)

    Biemond, J.E.; Hannink, G.; Verdonschot, Nicolaas Jacobus Joseph; Buma, P.

    2013-01-01

    The bone ingrowth potential of trabecular-like implant surfaces produced by either selective laser melting (SLM) or electron beam melting (EBM), with or without a biomimetic calciumphosphate coating, was examined in goats. For histological analysis and histomorphometry of bone ingrowth depth and

  12. Microstructures and mechanical properties of Co-29Cr-6Mo alloy fabricated by selective laser melting process for dental applications.

    Science.gov (United States)

    Takaichi, Atsushi; Suyalatu; Nakamoto, Takayuki; Joko, Natsuka; Nomura, Naoyuki; Tsutsumi, Yusuke; Migita, Satoshi; Doi, Hisashi; Kurosu, Shingo; Chiba, Akihiko; Wakabayashi, Noriyuki; Igarashi, Yoshimasa; Hanawa, Takao

    2013-05-01

    The selective laser melting (SLM) process was applied to a Co-29Cr-6Mo alloy, and its microstructure, mechanical properties, and metal elution were investigated to determine whether the fabrication process is suitable for dental applications. The microstructure was evaluated using scanning electron microscopy with energy-dispersed X-ray spectroscopy (SEM-EDS), X-ray diffractometry (XRD), and electron back-scattered diffraction pattern analysis. The mechanical properties were evaluated using a tensile test. Dense builds were obtained when the input energy of the laser scan was higher than 400 J mm⁻³, whereas porous builds were formed when the input energy was lower than 150 J mm⁻³. The microstructure obtained was unique with fine cellular dendrites in the elongated grains parallel to the building direction. The γ phase was dominant in the build and its preferential orientation was confirmed along the building direction, which was clearly observed for the builds fabricated at lower input energy. Although the mechanical anisotropy was confirmed in the SLM builds due to the unique microstructure, the yield strength, UTS, and elongation were higher than those of the as-cast alloy and satisfied the type 5 criteria in ISO22764. Metal elution from the SLM build was smaller than that of the as-cast alloy, and thus, the SLM process for the Co-29Cr-6Mo alloy is a promising candidate for fabricating dental devices. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Comparison of the bond strength of ceramics to Co-Cr alloys made by casting and selective laser melting.

    Science.gov (United States)

    Lawaf, Shirin; Nasermostofi, Shahbaz; Afradeh, Mahtasadat; Azizi, Arash

    2017-02-01

    Considering the importance of metal-ceramic bond, the present study aimed to compare the bond strength of ceramics to cobalt-chrome (Co-Cr) alloys made by casting and selective laser melting (SLM). In this in-vitro experimental study, two sample groups were prepared, with one group comprising of 10 Co-Cr metal frameworks fabricated by SLM method and the other of 10 Co-Cr metal frameworks fabricated by lost wax cast method with the dimensions of 0.5 × 3 × 25 mm (following ISO standard 9693). Porcelain with the thickness of 1.1 mm was applied on a 3 × 8-mm central rectangular area of each sample. Afterwards, bond strengths of the samples were assessed with a Universal Testing Machine. Statistical analysis was performed with Kolmogorov-Smirnov test and T-test. Bond strength in the conventionally cast group equaled 74.94 ± 16.06 MPa, while in SLM group, it equaled 69.02 ± 5.77 MPa. The difference was not statistically significant ( P ≤ .05). The results indicated that the bond strengths between ceramic and Co-Cr alloys made by casting and SLM methods were not statistically different.

  14. Single track and single layer formation in selective laser melting of niobium solid solution alloy

    Directory of Open Access Journals (Sweden)

    Yueling GUO

    2018-04-01

    Full Text Available Selective laser melting (SLM was employed to fabricate Nb-37Ti-13Cr-2Al-1Si (at% alloy, using pre-alloyed powders prepared by plasma rotating electrode processing (PREP. A series of single tracks and single layers under different processing parameters was manufactured to evaluate the processing feasibility by SLM, including laser power, scanning speed, and hatch distance. Results showed that continuous single tracks could be fabricated using proper laser powers and scanning velocities. Both the width of a single track and its penetration depth into a substrate increased with an increase of the linear laser beam energy density (LED, i.e., an increase of the laser power and a decrease of the scanning speed. Nb, Ti, Si, Cr, and Al elements distributed heterogeneously over the melt pool in the form of swirl-like patterns. An excess of the hatch distance was not able to interconnect neighboring tracks. Under improper processing parameters, a balling phenomenon occurred, but could be eliminated with an increased LED. This work testified the SLM-processing feasibility of Nb-based alloy and promoted the application of SLM to the manufacture of niobium-based alloys. Keywords: Additive manufacturing, Melt pool, Niobium alloy, Powder metallurgy, Selective laser melting

  15. Single scan vector prediction in selective laser melting

    NARCIS (Netherlands)

    Wits, Wessel Willems; Bruins, R.; Terpstra, L.; Huls, R.A.; Geijselaers, Hubertus J.M.

    2015-01-01

    In selective laser melting (SLM) products are built by melting layers of metal powder successively. Optimal process parameters are usually obtained by scanning single vectors and subsequently determining which settings lead to a good compromise between product density and build speed. This paper

  16. [A preliminary study on the forming quality of titanium alloy removable partial denture frameworks fabricated by selective laser melting].

    Science.gov (United States)

    Liu, Y F; Yu, H; Wang, W N; Gao, B

    2017-06-09

    Objective: To evaluate the processing accuracy, internal quality and suitability of the titanium alloy frameworks of removable partial denture (RPD) fabricated by selective laser melting (SLM) technique, and to provide reference for clinical application. Methods: The plaster model of one clinical patient was used as the working model, and was scanned and reconstructed into a digital working model. A RPD framework was designed on it. Then, eight corresponding RPD frameworks were fabricated using SLM technique. Three-dimensional (3D) optical scanner was used to scan and obtain the 3D data of the frameworks and the data was compared with the original computer aided design (CAD) model to evaluate their processing precision. The traditional casting pure titanium frameworks was used as the control group, and the internal quality was analyzed by X-ray examination. Finally, the fitness of the frameworks was examined on the plaster model. Results: The overall average deviation of the titanium alloy RPD framework fabricated by SLM technology was (0.089±0.076) mm, the root mean square error was 0.103 mm. No visible pores, cracks and other internal defects was detected in the frameworks. The framework fits on the plaster model completely, and its tissue surface fitted on the plaster model well. There was no obvious movement. Conclusions: The titanium alloy RPD framework fabricated by SLM technology is of good quality.

  17. Highly porous, low elastic modulus 316L stainless steel scaffold prepared by selective laser melting.

    Science.gov (United States)

    Čapek, Jaroslav; Machová, Markéta; Fousová, Michaela; Kubásek, Jiří; Vojtěch, Dalibor; Fojt, Jaroslav; Jablonská, Eva; Lipov, Jan; Ruml, Tomáš

    2016-12-01

    Recently, porous metallic materials have been extensively studied as candidates for use in the fabrication of scaffolds and augmentations to repair trabecular bone defects, e.g. in surroundings of joint replacements. Fabricating these complex structures by using common approaches (e.g., casting and machining) is very challenging. Therefore, rapid prototyping techniques, such as selective laser melting (SLM), have been investigated for these applications. In this study, we characterized a highly porous (87 vol.%) 316L stainless steel scaffold prepared by SLM. 316L steel was chosen because it presents a biomaterial still widely used for fabrication of joint replacements and, from the practical point of view, use of the same material for fabrication of an augmentation and a joint replacement is beneficial for corrosion prevention. The results are compared to the reported properties of two representative nonporous 316L stainless steels prepared either by SLM or casting and subsequent hot forging. The microstructural and mechanical properties and the surface chemical composition and interaction with the cells were investigated. The studied material exhibited mechanical properties that were similar to those of trabecular bone (compressive modulus of elasticity ~0.15GPa, compressive yield strength ~3MPa) and cytocompatibility after one day that was similar to that of wrought 316L stainless steel, which is a commonly used biomaterial. Based on the obtained results, SLM is a suitable method for the fabrication of porous 316L stainless steel scaffolds with highly porous structures. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Influence of Annealing on Mechanical Properties of Al-20Si Processed by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Pan Ma

    2014-01-01

    Full Text Available The microstructure and mechanical properties of Al-20Si produced by selective laser melting (SLM are investigated for different heat treatment conditions. As a result of the high cooling rate during processing, the as-built SLM material displays a microstructure consisting of a supersaturated Al(Si solid solution along with heavily refined eutectic Si and Si particles. The Si particles become coarser, and the eutectic Si gradually changes its morphology from fibrous to plate-like shape with increasing annealing temperature. The microstructural variations occurring during heat treatment significantly affect the mechanical behavior of the samples. The yield and ultimate strengths decrease from 374 and 506 MPa for the as-built SLM material to 162 and 252 MPa for the sample annealed at 673 K, whereas the ductility increases from 1.6 to 8.7%. This offers the possibility to tune microstructure and corresponding properties of the Al-20Si SLM parts to meet specific requirements.

  19. Exploiting Process-Related Advantages of Selective Laser Melting for the Production of High-Manganese Steel

    Directory of Open Access Journals (Sweden)

    Christian Haase

    2017-01-01

    Full Text Available Metal additive manufacturing has strongly gained scientific and industrial importance during the last decades due to the geometrical flexibility and increased reliability of parts, as well as reduced equipment costs. Within the field of metal additive manufacturing methods, selective laser melting (SLM is an eligible technique for the production of fully dense bulk material with complex geometry. In the current study, we addressed the application of SLM for processing a high-manganese TRansformation-/TWinning-Induced Plasticity (TRIP/TWIP steel. The solidification behavior was analyzed by careful characterization of the as-built microstructure and element distribution using optical and scanning electron microscopy (SEM. In addition, the deformation behavior was studied using uniaxial tensile testing and SEM. Comparison with conventionally produced TRIP/TWIP steel revealed that elemental segregation, which is normally very pronounced in high-manganese steels and requires energy-intensive post processing, is reduced due to the high cooling rates during SLM. Also, the very fast cooling promoted ε- and α’-martensite formation prior to deformation. The superior strength and pronounced anisotropy of the SLM-produced material was correlated with the microstructure based on the process-specific characteristics.

  20. Testing of Selective Laser Melting Turbomachinery Applicable to Exploration Upper Stage

    Science.gov (United States)

    Calvert, Marty; Turpin, Jason; Nettles, Mindy

    2015-01-01

    This task is to design, fabricate, and spin test to failure a Ti6-4 hydrogen turbopump impeller that was built using the selective laser melting (SLM) fabrication process (fig. 1). The impeller is sized around upper stage engine requirements. In addition to the spin burst test, material testing will be performed on coupons that are built with the impeller.

  1. IN718 Additive Manufacturing Properties and Influences

    Science.gov (United States)

    Lambert, Dennis M.

    2015-01-01

    The results of tensile, fracture, and fatigue testing of IN718 coupons produced using the selective laser melting (SLM) additive manufacturing technique are presented. The data has been "generalized" to remove the numerical values, although certain references to material standards are provided. This document provides some knowledge of the effect of variation of controlled build parameters used in the SLM process, a snapshot of the capabilities of SLM in industry at present, and shares some of the lessons learned along the way. For the build parameter characterization, the parameters were varied over a range about the machine manufacturer's recommended value, and in each case they were varied individually, although some co-variance of those parameters would be expected. SLM-produced IN718, tensile, fracture, and high-cycle fatigue properties equivalent to wrought IN718 are achievable. Build and post-build processes need to be determined and then controlled to established limits to accomplish this. It is recommended that a multi-variable evaluation, e.g., design-of-experiment (DOE), of the build parameters be performed to better evaluate the co-variance of the parameters.

  2. Strong morphological and crystallographic texture and resulting yield strength anisotropy in selective laser melted tantalum

    International Nuclear Information System (INIS)

    Thijs, Lore; Montero Sistiaga, Maria Luz; Wauthle, Ruben; Xie, Qingge; Kruth, Jean-Pierre; Van Humbeeck, Jan

    2013-01-01

    Selective laser melting (SLM) makes use of a high energy density laser beam to melt successive layers of metallic powders in order to create functional parts. The energy density of the laser is high enough to melt refractory metals like Ta and produce mechanically sound parts. Furthermore, the localized heat input causes a strong directional cooling and solidification. Epitaxial growth due to partial remelting of the previous layer, competitive growth mechanism and a specific global direction of heat flow during SLM of Ta result in the formation of long columnar grains with a 〈1 1 1〉 preferential crystal orientation along the building direction. The microstructure was visualized using both optical and scanning electron microscopy equipped with electron backscattered diffraction and the global crystallographic texture was measured using X-ray diffraction. The thermal profile around the melt pool was modeled using a pragmatic model for SLM. Furthermore, rotation of the scanning direction between different layers was seen to promote the competitive growth. As a result, the texture strength increased to as large as 4.7 for rotating the scanning direction 90° every layer. By comparison of the yield strength measured by compression tests in different orientations and the averaged Taylor factor calculated using the viscoplastic self-consistent model, it was found that both the morphological and crystallographic texture observed in SLM Ta contribute to yield strength anisotropy

  3. Simulating spontaneous parametric down-conversion using classical light: Conference paper

    CSIR Research Space (South Africa)

    Zhang, Y

    2014-08-01

    Full Text Available We present a simple way of simulating Spontaneous parametric down-conversion (SPDC) by modulating a classical laser beam with two spatial light modulators (SLM) through a back projection setup. This system has the advantage of having very high...

  4. Curriculum Resources.

    Science.gov (United States)

    Thompson, Norma H.

    1988-01-01

    Discusses an article which presents a concise discussion of secular humanism. Reviews additional materials on censorship from the perspective of the new religious right, the fundamentalists, and public policy and the law. The sources provide background to enhance teaching about secular humanism and textbook censorship. (SLM)

  5. Relevance of soil and terrain information in studies of major global issues

    NARCIS (Netherlands)

    Bindraban, P.S.; Batjes, N.H.; Leenaars, J.G.B.; Bai, Z.G.

    2010-01-01

    The Carbon Benefits Project (CBP) is working to produce a standardized system for Global Environmental Facility (GEF) and other sustainable land management (SLM) projects to measure, monitor and model carbon stock changes and greenhouse gas (GHG) emissions. The project builds on existing C-inventory

  6. Osteostatin-coated porous titanium can improve early bone regeneration of cortical bone defects in rats

    NARCIS (Netherlands)

    Van Der Stok, Johan; Lozano, Daniel; Chai, Yoke Chin; Amin Yavari, Saber; Bastidas Coral, Angela P.; Verhaar, Jan A N; Gómez-Barrena, Enrique; Schrooten, Jan; Jahr, Holger; Zadpoor, Amir A.; Esbrit, Pedro; Weinans, Harrie

    2015-01-01

    A promising bone graft substitute is porous titanium. Porous titanium, produced by selective laser melting (SLM), can be made as a completely open porous and load-bearing scaffold that facilitates bone regeneration through osteoconduction. In this study, the bone regenerative capacity of porous

  7. Mesoporous bioactive glass functionalized 3D Ti-6Al-4V scaffolds with improved surface bioactivity

    NARCIS (Netherlands)

    Ye, Xiaotong; Leeflang, M.A.; Wu, Chengtie; Chang, Jiang; Zhou, J.; Huan, Z.

    2017-01-01

    Porous Ti-6Al-4V scaffolds fabricated by means of selective laser melting (SLM),
    having controllable geometrical features and preferable mechanical properties, have been developed as a class of biomaterials that hold promising potential for bone repair. However, the inherent bio-inertness of the

  8. Using Children's Literature to Teach about the American Revolution.

    Science.gov (United States)

    Drake, Janet J.; Drake, Frederick D.

    1990-01-01

    Reports on an ethnographic study in which the teacher of a combined third and fourth grade class reads historical literature from the U.S. Revolutionary period to students daily for nine weeks. Finds that study of historical content through literature is appropriate at these grade levels. Reports student enthusiasm for this activity. (SLM)

  9. Evaluation of metal-ceramic bond characteristics of three dental Co-Cr alloys prepared with different fabrication techniques.

    Science.gov (United States)

    Wang, Hongmei; Feng, Qing; Li, Ning; Xu, Sheng

    2016-12-01

    Limited information is available regarding the metal-ceramic bond strength of dental Co-Cr alloys fabricated by casting (CAST), computer numerical control (CNC) milling, and selective laser melting (SLM). The purpose of this in vitro study was to evaluate the metal-ceramic bond characteristics of 3 dental Co-Cr alloys fabricated by casting, computer numerical control milling, and selective laser melting techniques using the 3-point bend test (International Organization for Standardization [ISO] standard 9693). Forty-five specimens (25×3×0.5 mm) made of dental Co-Cr alloys were prepared by CAST, CNC milling, and SLM techniques. The morphology of the oxidation surface of metal specimens was evaluated by scanning electron microscopy (SEM). After porcelain application, the interfacial characterization was evaluated by SEM equipped with energy-dispersive spectrometry (EDS) analysis, and the metal-ceramic bond strength was assessed with the 3-point bend test. Failure type and elemental composition on the debonding interface were assessed by SEM/EDS. The bond strength was statistically analyzed by 1-way ANOVA and Tukey honest significant difference test (α=.05). The oxidation surfaces of the CAST, CNC, and SLM groups were different. They were porous in the CAST group but compact and irregular in the CNC and SLM groups. The metal-ceramic interfaces of the SLM and CNC groups showed excellent combination compared with those of the CAST group. The bond strength was 37.7 ±6.5 MPa for CAST, 43.3 ±9.2 MPa for CNC, and 46.8 ±5.1 MPa for the SLM group. Statistically significant differences were found among the 3 groups tested (P=.028). The debonding surfaces of all specimens exhibited cohesive failure mode. The oxidation surface morphologies and thicknesses of dental Co-Cr alloys are dependent on the different fabrication techniques used. The bond strength of all 3 groups exceed the minimum acceptable value of 25 MPa recommended by ISO 9693; hence, dental Co-Cr alloy

  10. Serbian music criticism in the first half of the twentieth century: Its canon, its method and its educational role

    Directory of Open Access Journals (Sweden)

    Vasić Aleksandar

    2008-01-01

    Full Text Available Serbian music criticism became a subject of professional music critics at the beginning of the twentieth century, after being developed by music amateurs throughout the whole previous century. The Serbian Literary Magazine (1901- 1914, 1920-1941, the forum of the Serbian modernist writers in the early 1900s, had a crucial role in shaping the Serbian music criticism and essayistics of the modern era. The Serbian elite musicians wrote for the SLM and therefore it reflects the most important issues of the early twentieth century Serbian music. The SLM undertook the mission of educating its readers. The music culture of the Serbian public was only recently developed. The public needed an introduction into the most important features of the European music, as well as developing its own taste in music. This paper deals with two aspects of the music criticism in the SLM, in view of its educational role: the problem of virtuosity and the method used by music critics in this magazine. The aesthetic canon of the SLM was marked by decisively negative attitude towards the virtuosity. Mainly concerned by educating the Serbian music public in the spirit of the highest music achievements in Europe, the music writers of the SLM criticized both domestic and foreign performers who favoured virtuosity over the 'essence' of music. Therefore, Niccolò Paganini, Franz Liszt, and even Peter Tchaikowsky with his Violin concerto became the subject of the magazine's criticism. However their attitude towards the interpreters with both musicality and virtuoso technique was always positive. That was evident in the writings on Jan Kubelík. This educational mission also had its effect on the structure of critique writings in the SLM. In their wish to inform the Serbian public on the European music (which they did very professionally, the critics gave much more information on biographies, bibliographies and style of the European composers, than they valued the interpretation

  11. Evaluation of mechanical properties and microstructural characterization of consolidated Cobalt-Chromium-Molybdenum obtained by selective laser melting and precision casting; Avaliação de propriedades mecânicas e caracterização microestrutural de consolidados de Cobalto-Cromo-Molibdênio obtidos por fusão seletiva a laser e fundição de precisão

    Energy Technology Data Exchange (ETDEWEB)

    Mergulhão, Marcello Vertamatti

    2017-07-01

    The objective of this work was to study the mechanical properties and microstructural characterization of specimens of the Co-Cr-Mo alloy obtained by additive manufacturing -selective laser melting (SLM) and precision casting aiming at the manufacture of dental prostheses. The following steps were carried out on Co-Cr-Mo gas-atomized powders: 1) investigation of the physical, chemical and thermal properties of atomized powders in different grain sizes (denominated: D1 <15 μm, D2 20-50 μm and D3 > 75 μm); 2) the consolidation of standard specimens via consolidation techniques; 3) characterization of consolidated by analysis of: cytotoxicity, porosity, X ray diffraction and dilatometry; 4) mechanical characterization of tensile, 3 point bending, hardness (macro and micro Vickers) tests and microstructural characterization (optical and scanning electron microscopy). In general, the results observed were: the grain size D2 (20-50 μm) is the one that best fits in the analysis of packaging, for the consolidation by SLM; the biocompatibility of the samples obtained a positive result for both processing techniques; the mechanical evaluation of the specimens shows that the SLM technique provides superior mechanical properties (yield stress, rupture stress, maximum stress, elongation and hardness), compared to those obtained by the precision casting technique; the microstructure obtained by the SLM process results in an ultrafine grains with high chemical homogeneity, differentiated by the gross dendritic microstructure in the casting process. In this way, the development of the present study evidenced superior quality in manufacturing customized dental components (copings) by SLM technique compared to precision casting. (author)

  12. Additive manufacturing technologies of porous metal implants

    Directory of Open Access Journals (Sweden)

    Yang Quanzhan

    2014-06-01

    Full Text Available Biomedical metal materials with good corrosion resistance and mechanical properties are widely used in orthopedic surgery and dental implant materials, but they can easily cause stress shielding due to the significant difference in elastic modulus between the implant and human bones. The elastic modulus of porous metals is lower than that of dense metals. Therefore, it is possible to adjust the pore parameters to make the elastic modulus of porous metals match or be comparable with that of the bone tissue. At the same time, the open porous metals with pores connected to each other could provide the structural condition for bone ingrowth, which is helpful in strengthening the biological combination of bone tissue with the implants. Therefore, the preparation technologies of porous metal implants and related research have been drawing more and more attention due to the excellent features of porous metals. Selective laser melting (SLM and electron beam melting technology (EBM are important research fields of additive manufacturing. They have the advantages of directly forming arbitrarily complex shaped metal parts which are suitable for the preparation of porous metal implants with complex shape and fine structure. As new manufacturing technologies, the applications of SLM and EBM for porous metal implants have just begun. This paper aims to understand the technology status of SLM and EBM, the research progress of porous metal implants preparation by using SLM and EBM, and the biological compatibility of the materials, individual design and manufacturing requirements. The existing problems and future research directions for porous metal implants prepared by SLM and EBM methods are discussed in the last paragraph.

  13. The positive effect of hot isostatic pressing on improving the anisotropies of bending and impact properties in selective laser melted Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Wu, Ming-Wei; Lai, Pang-Hsin

    2016-01-01

    Selective laser melting (SLM) is a versatile additive manufacturing process for fabricating solid or porous metallic materials with complicated three-dimensional shapes. SLM Ti alloys, particularly Ti-6Al-4V, and other alloys have been manufactured and analyzed in numerous studies. However, the high anisotropy of the microstructures and inconsistent mechanical properties of SLM materials have been extensively reported, and these disadvantages could prohibit its widespread use. To clarify how to alleviate the anisotropic behaviors of SLM materials, the main objective of this study was to evaluate the influences of hot isostatic pressing (HIP) on the microstructure, densification, bending strength, impact toughness, and fracture behavior of the as-built Ti-6Al-4V alloy. The results showed that the vertical and horizontal building directions obviously affect the bending and impact properties of as-built alloys. The transverse rupture strength (TRS) and impact energy of the horizontally-built alloy were respectively found to be 48% and 100% higher than those of the vertically-built one. In the vertically-built alloy, disc-shaped building defects, identified by X-ray computed tomography (CT) and microscopy, obviously reduce the effective load-bearing cross-section and deteriorate the bending and impact performances. After HIP at 1000 °C/150 MPa, the α′-martensite structure in the as-built alloy is transformed into an α+β lamellar one, and the disc-shaped building defects are evidently eliminated. As a result, the impact energies of as-built vertical and horizontal specimens are improved by 28 J (560%) and 19 J (190%), respectively, and the TRS of the as-built vertical alloy is raised by 550 MPa (37%). Consequently, the discrepancies in TRS and impact energy between the HIPed vertical and horizontal specimens are merely 3% and 14%, respectively, and the anisotropic behaviors of the SLM Ti-6Al-4V alloy are thus substantially lessened.

  14. Evaluation of mechanical properties and microstructural characterization of consolidated Cobalt-Chromium-Molybdenum obtained by selective laser melting and precision casting

    International Nuclear Information System (INIS)

    Mergulhão, Marcello Vertamatti

    2017-01-01

    The objective of this work was to study the mechanical properties and microstructural characterization of specimens of the Co-Cr-Mo alloy obtained by additive manufacturing -selective laser melting (SLM) and precision casting aiming at the manufacture of dental prostheses. The following steps were carried out on Co-Cr-Mo gas-atomized powders: 1) investigation of the physical, chemical and thermal properties of atomized powders in different grain sizes (denominated: D1 <15 μm, D2 20-50 μm and D3 > 75 μm); 2) the consolidation of standard specimens via consolidation techniques; 3) characterization of consolidated by analysis of: cytotoxicity, porosity, X ray diffraction and dilatometry; 4) mechanical characterization of tensile, 3 point bending, hardness (macro and micro Vickers) tests and microstructural characterization (optical and scanning electron microscopy). In general, the results observed were: the grain size D2 (20-50 μm) is the one that best fits in the analysis of packaging, for the consolidation by SLM; the biocompatibility of the samples obtained a positive result for both processing techniques; the mechanical evaluation of the specimens shows that the SLM technique provides superior mechanical properties (yield stress, rupture stress, maximum stress, elongation and hardness), compared to those obtained by the precision casting technique; the microstructure obtained by the SLM process results in an ultrafine grains with high chemical homogeneity, differentiated by the gross dendritic microstructure in the casting process. In this way, the development of the present study evidenced superior quality in manufacturing customized dental components (copings) by SLM technique compared to precision casting. (author)

  15. The positive effect of hot isostatic pressing on improving the anisotropies of bending and impact properties in selective laser melted Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ming-Wei, E-mail: mwwu@ntut.edu.tw; Lai, Pang-Hsin

    2016-03-21

    Selective laser melting (SLM) is a versatile additive manufacturing process for fabricating solid or porous metallic materials with complicated three-dimensional shapes. SLM Ti alloys, particularly Ti-6Al-4V, and other alloys have been manufactured and analyzed in numerous studies. However, the high anisotropy of the microstructures and inconsistent mechanical properties of SLM materials have been extensively reported, and these disadvantages could prohibit its widespread use. To clarify how to alleviate the anisotropic behaviors of SLM materials, the main objective of this study was to evaluate the influences of hot isostatic pressing (HIP) on the microstructure, densification, bending strength, impact toughness, and fracture behavior of the as-built Ti-6Al-4V alloy. The results showed that the vertical and horizontal building directions obviously affect the bending and impact properties of as-built alloys. The transverse rupture strength (TRS) and impact energy of the horizontally-built alloy were respectively found to be 48% and 100% higher than those of the vertically-built one. In the vertically-built alloy, disc-shaped building defects, identified by X-ray computed tomography (CT) and microscopy, obviously reduce the effective load-bearing cross-section and deteriorate the bending and impact performances. After HIP at 1000 °C/150 MPa, the α′-martensite structure in the as-built alloy is transformed into an α+β lamellar one, and the disc-shaped building defects are evidently eliminated. As a result, the impact energies of as-built vertical and horizontal specimens are improved by 28 J (560%) and 19 J (190%), respectively, and the TRS of the as-built vertical alloy is raised by 550 MPa (37%). Consequently, the discrepancies in TRS and impact energy between the HIPed vertical and horizontal specimens are merely 3% and 14%, respectively, and the anisotropic behaviors of the SLM Ti-6Al-4V alloy are thus substantially lessened.

  16. Effect of pore size on bone ingrowth into porous titanium implants fabricated by additive manufacturing: An in vivo experiment.

    Science.gov (United States)

    Taniguchi, Naoya; Fujibayashi, Shunsuke; Takemoto, Mitsuru; Sasaki, Kiyoyuki; Otsuki, Bungo; Nakamura, Takashi; Matsushita, Tomiharu; Kokubo, Tadashi; Matsuda, Shuichi

    2016-02-01

    Selective laser melting (SLM) is an additive manufacturing technique with the ability to produce metallic scaffolds with accurately controlled pore size, porosity, and interconnectivity for orthopedic applications. However, the optimal pore structure of porous titanium manufactured by SLM remains unclear. In this study, we evaluated the effect of pore size with constant porosity on in vivo bone ingrowth in rabbits into porous titanium implants manufactured by SLM. Three porous titanium implants (with an intended porosity of 65% and pore sizes of 300, 600, and 900μm, designated the P300, P600, and P900 implants, respectively) were manufactured by SLM. A diamond lattice was adapted as the basic structure. Their porous structures were evaluated and verified using microfocus X-ray computed tomography. Their bone-implant fixation ability was evaluated by their implantation as porous-surfaced titanium plates into the cortical bone of the rabbit tibia. Bone ingrowth was evaluated by their implantation as cylindrical porous titanium implants into the cancellous bone of the rabbit femur for 2, 4, and 8weeks. The average pore sizes of the P300, P600, and P900 implants were 309, 632, and 956μm, respectively. The P600 implant demonstrated a significantly higher fixation ability at 2weeks than the other implants. After 4weeks, all models had sufficiently high fixation ability in a detaching test. Bone ingrowth into the P300 implant was lower than into the other implants at 4weeks. Because of its appropriate mechanical strength, high fixation ability, and rapid bone ingrowth, our results indicate that the pore structure of the P600 implant is a suitable porous structure for orthopedic implants manufactured by SLM. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. The development of a colour liquid crystal display spatial light modulator and applications in polychromatic optical data processing

    Science.gov (United States)

    Aiken, John Charles

    The development of a colour Spatial Light Modulator (SLM) and its application to optical information processing is described. Whilst monochrome technology has been established for many years, this is not the case for colour where commercial systems are unavailable. A main aspect of this study is therefore, how the use of colour can add an additional dimension to optical information processing. A well established route to monochrome system development has been the use of (black and white) liquid crystal televisions (LCTV) as SLM, providing useful performance at a low-cost. This study is based on the unique use of a colour display removed from a LCTV and operated as a colour SLM. A significant development has been the replacement of the original TV electronics operating the display with enhanced drive electronics specially developed for this application. Through a computer interface colour images from a drawing package or video camera can now be readily displayed on the LCD as input to an optical system. A detailed evaluation of the colour LCD optical properties, indicates that the new drive electronics have considerably improved the operation of the display for use as a colour SLM. Applications are described employing the use of colour in Fourier plane filtering, image correlation and speckle metrology. The SLM (and optical system) developed demonstrates, how the addition of colour has greatly enhanced its capabilities to implement principles of optical data processing, conventionally performed monochromatically. The hybrid combination employed, combining colour optical data processing with electronic techniques has resulted in a capable development system. Further development of the system using current colour LCDs and the move towards a portable system, is considered in the study conclusion.

  18. Linking trajectories of land change, land degradation processes and ecosystem services.

    Science.gov (United States)

    Smiraglia, D; Ceccarelli, T; Bajocco, S; Salvati, L; Perini, L

    2016-05-01

    Land Degradation (LD) is a complex phenomenon resulting in a progressive reduction in the capacity of providing ecosystem services (ES). Landscape transformations promoting an unsustainable use of land often reveal latent processes of LD. An evaluation carried out in respect to the different ecosystem services is nowadays regarded as the most appropriate approach for assessing the effects of LD. The aim of this study is to develop an evaluation framework for identifying the linkages between land changes, LD processes and ES and suggesting Sustainable Land Management (SLM) options suited to reverse (or mitigate) LD impact. A SWOT analysis was carried out with the aim to identify internal and external factors that are favorable (or unfavorable) to achieve the proposed SLM actions. The study areas are the Fortore valley and the Valpadana, in Italy. The main trajectory identified for the Fortore valley is related to land abandonment due to population aging and the progressive emigration started in the 1950s. The most relevant LD processes are soil erosion and geomorphological instability, affecting regulating services such as natural hazard and erosion control. SLM options should consider interventions to contrast geomorphological instability, the promotion of climate smart agriculture and of typical products, and an efficient water resources management. The main trajectories identified for Valpadana are related to urban expansion and farmland abandonment and, as a consequence, land take due to anthropogenic pressure and woodland expansion as the main LD process. The reduction of food production was identified as the most relevant provisioning service affected. SLM should envisage best practices finalized to water saving and soil consumption reduction: efficient irrigation solutions, climate smart agriculture and zero sealing practices. This study highlights the diagnostic value of the suggested approach where LD processes are elicited from land change trajectories

  19. Sequential Logic Model Deciphers Dynamic Transcriptional Control of Gene Expressions

    Science.gov (United States)

    Yeo, Zhen Xuan; Wong, Sum Thai; Arjunan, Satya Nanda Vel; Piras, Vincent; Tomita, Masaru; Selvarajoo, Kumar; Giuliani, Alessandro; Tsuchiya, Masa

    2007-01-01

    Background Cellular signaling involves a sequence of events from ligand binding to membrane receptors through transcription factors activation and the induction of mRNA expression. The transcriptional-regulatory system plays a pivotal role in the control of gene expression. A novel computational approach to the study of gene regulation circuits is presented here. Methodology Based on the concept of finite state machine, which provides a discrete view of gene regulation, a novel sequential logic model (SLM) is developed to decipher control mechanisms of dynamic transcriptional regulation of gene expressions. The SLM technique is also used to systematically analyze the dynamic function of transcriptional inputs, the dependency and cooperativity, such as synergy effect, among the binding sites with respect to when, how much and how fast the gene of interest is expressed. Principal Findings SLM is verified by a set of well studied expression data on endo16 of Strongylocentrotus purpuratus (sea urchin) during the embryonic midgut development. A dynamic regulatory mechanism for endo16 expression controlled by three binding sites, UI, R and Otx is identified and demonstrated to be consistent with experimental findings. Furthermore, we show that during transition from specification to differentiation in wild type endo16 expression profile, SLM reveals three binary activities are not sufficient to explain the transcriptional regulation of endo16 expression and additional activities of binding sites are required. Further analyses suggest detailed mechanism of R switch activity where indirect dependency occurs in between UI activity and R switch during specification to differentiation stage. Conclusions/Significance The sequential logic formalism allows for a simplification of regulation network dynamics going from a continuous to a discrete representation of gene activation in time. In effect our SLM is non-parametric and model-independent, yet providing rich biological

  20. Sequential logic model deciphers dynamic transcriptional control of gene expressions.

    Directory of Open Access Journals (Sweden)

    Zhen Xuan Yeo

    Full Text Available BACKGROUND: Cellular signaling involves a sequence of events from ligand binding to membrane receptors through transcription factors activation and the induction of mRNA expression. The transcriptional-regulatory system plays a pivotal role in the control of gene expression. A novel computational approach to the study of gene regulation circuits is presented here. METHODOLOGY: Based on the concept of finite state machine, which provides a discrete view of gene regulation, a novel sequential logic model (SLM is developed to decipher control mechanisms of dynamic transcriptional regulation of gene expressions. The SLM technique is also used to systematically analyze the dynamic function of transcriptional inputs, the dependency and cooperativity, such as synergy effect, among the binding sites with respect to when, how much and how fast the gene of interest is expressed. PRINCIPAL FINDINGS: SLM is verified by a set of well studied expression data on endo16 of Strongylocentrotus purpuratus (sea urchin during the embryonic midgut development. A dynamic regulatory mechanism for endo16 expression controlled by three binding sites, UI, R and Otx is identified and demonstrated to be consistent with experimental findings. Furthermore, we show that during transition from specification to differentiation in wild type endo16 expression profile, SLM reveals three binary activities are not sufficient to explain the transcriptional regulation of endo16 expression and additional activities of binding sites are required. Further analyses suggest detailed mechanism of R switch activity where indirect dependency occurs in between UI activity and R switch during specification to differentiation stage. CONCLUSIONS/SIGNIFICANCE: The sequential logic formalism allows for a simplification of regulation network dynamics going from a continuous to a discrete representation of gene activation in time. In effect our SLM is non-parametric and model-independent, yet

  1. Improving the fatigue performance of porous metallic biomaterials produced by Selective Laser Melting.

    Science.gov (United States)

    Van Hooreweder, Brecht; Apers, Yanni; Lietaert, Karel; Kruth, Jean-Pierre

    2017-01-01

    This paper provides new insights into the fatigue properties of porous metallic biomaterials produced by additive manufacturing. Cylindrical porous samples with diamond unit cells were produced from Ti6Al4V powder using Selective Laser Melting (SLM). After measuring all morphological and quasi-static properties, compression-compression fatigue tests were performed to determine fatigue strength and to identify important fatigue influencing factors. In a next step, post-SLM treatments were used to improve the fatigue life of these biomaterials by changing the microstructure and by reducing stress concentrators and surface roughness. In particular, the influence of stress relieving, hot isostatic pressing and chemical etching was studied. Analytical and numerical techniques were developed to calculate the maximum local tensile stress in the struts as function of the strut diameter and load. With this method, the variability in the relative density between all samples was taken into account. The local stress in the struts was then used to quantify the exact influence of the applied post-SLM treatments on the fatigue life. A significant improvement of the fatigue life was achieved. Also, the post-SLM treatments, procedures and calculation methods can be applied to different types of porous metallic structures and hence this paper provides useful tools for improving fatigue performance of metallic biomaterials. Additive Manufacturing (AM) techniques such as Selective Laser Melting (SLM) are increasingly being used for producing customized porous metallic biomaterials. These biomaterials are regularly used for biomedical implants and hence a long lifetime is required. In this paper, a set of post-built surface and heat treatments is presented that can be used to significantly improve the fatigue life of porous SLM-Ti6Al4V samples. In addition, a novel and efficient analytical local stress method was developed to accurately quantify the influence of the post

  2. Serbian Literary Magazine and avant-garde music

    Directory of Open Access Journals (Sweden)

    Vasić Aleksandar N.

    2005-01-01

    Full Text Available One of the most excellent periodicals in the history of Serbian literature Serbian Literary Magazine (1901-1914, 1920-1941, also played an exceptionally important part in the history of Serbian music criticism and essay literature. During the period of 35 years, SLM had released nearly 800 articles about music. Majority of that number belongs to the music criticism, but there are also studies and essays about music ethno musicological treatises, polemics, obituary notices, as well as many ample and diverse notes. SLM was published during the time when Serbian society, culture and art were influenced by strong challenges of Europeanization and modernization. Therefore, one of the most complicated questions that music writers of this magazine were confronted with was the question of avant-garde music evaluation. Relation of critics and essay writers to the avant-garde was ambiguous. On one side, SLM's authors accepted modern art in principle, but, on the other side, they questioned that acceptance when facing even a bit radical music composition. This ambivalence as a whole marked the work of Dr Miloje Milojević, the leading music writer of SLM. It is not the same with other critics and essayists Kosta Manojlović was more tolerant, and Dragutin Čolić and Stanislav Vinaver were true protectors of the most avant-garde aspirations in music. First of all SLM was a literary magazine. In the light of that fact it has to be pointed out that very early, way back in 1912, critics wrote about Arnold Schoenberg, and that until the end of existence of this magazine the readers were regularly informed about all important avant-garde styles and composers of European, Serbian and Yugoslav music. The fact that Schoenberg Stravinsky, Honegger or Josip Slavenski mostly were not accepted by critics and essayists, expresses the basic aesthetic position of this magazine. Namely, SLM remained loyal to the moderate wing of modern music, music that had not rejected

  3. Earth's evolving subcontinental lithospheric mantle: inferences from LIP continental flood basalt geochemistry

    Science.gov (United States)

    Greenough, John D.; McDivitt, Jordan A.

    2018-04-01

    Archean and Proterozoic subcontinental lithospheric mantle (SLM) is compared using 83 similarly incompatible element ratios (SIER; minimally affected by % melting or differentiation, e.g., Rb/Ba, Nb/Pb, Ti/Y) for >3700 basalts from ten continental flood basalt (CFB) provinces representing nine large igneous provinces (LIPs). Nine transition metals (TM; Fe, Mn, Sc, V, Cr, Co, Ni, Cu, Zn) in 102 primitive basalts (Mg# = 0.69-0.72) from nine provinces yield additional SLM information. An iterative evaluation of SIER values indicates that, regardless of age, CFB transecting Archean lithosphere are enriched in Rb, K, Pb, Th and heavy REE(?); whereas P, Ti, Nb, Ta and light REE(?) are higher in Proterozoic-and-younger SLM sources. This suggests efficient transfer of alkali metals and Pb to the continental lithosphere perhaps in association with melting of subducted ocean floor to form Archean tonalite-trondhjemite-granodiorite terranes. Titanium, Nb and Ta were not efficiently transferred, perhaps due to the stabilization of oxide phases (e.g., rutile or ilmenite) in down-going Archean slabs. CFB transecting Archean lithosphere have EM1-like SIER that are more extreme than seen in oceanic island basalts (OIB) suggesting an Archean SLM origin for OIB-enriched mantle 1 (EM1). In contrast, OIB high U/Pb (HIMU) sources have more extreme SIER than seen in CFB provinces. HIMU may represent subduction-processed ocean floor recycled directly to the convecting mantle, but to avoid convective homogenization and produce its unique Pb isotopic signature may require long-term isolation and incubation in SLM. Based on all TM, CFB transecting Proterozoic lithosphere are distinct from those cutting Archean lithosphere. There is a tendency for lower Sc, Cr, Ni and Cu, and higher Zn, in the sources for Archean-cutting CFB and EM1 OIB, than Proterozoic-cutting CFB and HIMU OIB. All CFB have SiO2 (pressure proxy)-Nb/Y (% melting proxy) relationships supporting low pressure, high % melting

  4. Continued Advancement of Supported Liquid Membranes for Carbon Dioxide Control in Extravehicular Activity Applications

    Science.gov (United States)

    Wickham, David T.; Gleason, Kevin J.; Engel, Jeffrey R.; Cowley, Scott W.; Chullen, Cinda

    2015-01-01

    The Development of a new, robust, portable life support system (PLSS) is currently a high NASA priority in order to support longer and safer extravehicular activity (EVA) missions that will be necessary as space travel extends to near-Earth asteroids and eventually Mars. One of the critical PLSS functions is maintaining the carbon dioxide (CO2) concentration in the suit at acceptable levels. The Metal Oxide (MetOx) canister has a finite CO2 adsorption capacity and therefore in order to extend mission times, the unit would have to be larger and heavier, which is undesirable; therefore new CO2 control technologies must be developed. While recent work has centered on the use of alternating sorbent beds that can be regenerated during the EVA, this strategy increases the system complexity and power consumption. A simpler approach is to use a membrane that vents CO2 to space but retains oxygen(O2). A membrane has many advantages over current technology: it is a continuous system with no theoretical capacity limit, it requires no consumables, and it requires no hardware for switching beds between absorption and regeneration. Conventional gas separation membranes do not have adequate selectivity for use in the PLSS, but the required performance could be obtained with a supported liquid membrane (SLM), which consists of a microporous film filled with a liquid that selectively reacts with CO2 over oxygen (O2). In a recently completed Phase II Small Business Innovative Research project, Reaction Systems developed a new reactive liquid that has effectively zero vapor pressure, making it an ideal candidate for use in an SLM. Results obtained with the SLM in a flat sheet configuration with representative pressures of CO2, O2, and water (H2O) have shown that the CO2 permeation rate and CO2/O2 selectivity requirements have been met. In addition, the SLM vents moisture to space very effectively. The SLM has also been prepared and tested in a hollow fiber form, which will be

  5. Additive Manufacturing of High-Performance 316L Stainless Steel Nanocomposites via Selective Laser Melting

    Science.gov (United States)

    AlMangour, Bandar Abdulaziz

    Austenitic 316L stainless steel alloy is an attractive industrial material combining outstanding corrosion resistance, ductility, and biocompatibility, with promising structural applications and biomedical uses. However, 316L has low strength and wear resistance, limiting its high-performance applicability. Adding secondary hard nanoscale reinforcements to steel matrices, thereby forming steel-matrix nanocomposites (SMCs), can overcome these problems, improving the performance and thereby the applicability of 316L. However, SMC parts with complex-geometry cannot be easily achieved limiting its application. This can be avoided through additive manufacturing (AM) by generating layer-by-layer deposition using computer-aided design data. Expanding the range of AM-applicable materials is necessary to fulfill industrial demand. This dissertation presents the characteristics of new AM-processed high-performance 316L-matrix nanocomposites with nanoscale TiC or TiB2 reinforcements, addressing specific aspects of material design, process control and optimization, and physical metallurgy theory. The nanocomposites were prepared by high-energy ball-milling and consolidated by AM selective laser melting (SLM). Continuous and refined ring-like network structures were obtained with homogenously distributed reinforcements. Additional grain refinement occurred with reinforcement addition, attributed to nanoparticles acting as nuclei for heterogeneous nucleation. The influence of reinforcement content was first investigated; mechanical and tribological behaviors improved with increased reinforcement contents. The compressive yield strengths of composites with TiB2 or TiC reinforcements were approximately five or two times those of 316L respectively. Hot isostatic pressing post-treatment effectively eliminated major cracks and pores in SLM-fabricated components. The effects of the SLM processing parameters on the microstructure and mechanical performance were also investigated. Laser

  6. Complexation-mediated electromembrane extraction of highly polar basic drugs – a fundamental study with catecholamines in urine as model system

    DEFF Research Database (Denmark)

    Fernández, Elena; Vårdal, Linda; Vidal, Lorena

    2017-01-01

    Complexation-mediated electromembrane extraction (EME) of highly polar basic drugs (log P ... as complexation reagent, and selectively formed boronate esters by reversible covalent binding with the model analytes at the sample/SLM interface. This enhanced the mass transfer of the highly polar model analytes across the SLM, and EME of basic drugs with log P in the range -1 to -2 was shown for the first...... chromatography coupled to tandem mass spectrometry and evaluated for quantification of epinephrine and dopamine. Standard addition calibration was applied to a pooled human urine sample. Calibration curves using standards between 25 and 125 μg L-1 gave a high level of linearity with a correlation coefficient...

  7. A multi-modal stereo microscope based on a spatial light modulator.

    Science.gov (United States)

    Lee, M P; Gibson, G M; Bowman, R; Bernet, S; Ritsch-Marte, M; Phillips, D B; Padgett, M J

    2013-07-15

    Spatial Light Modulators (SLMs) can emulate the classic microscopy techniques, including differential interference (DIC) contrast and (spiral) phase contrast. Their programmability entails the benefit of flexibility or the option to multiplex images, for single-shot quantitative imaging or for simultaneous multi-plane imaging (depth-of-field multiplexing). We report the development of a microscope sharing many of the previously demonstrated capabilities, within a holographic implementation of a stereo microscope. Furthermore, we use the SLM to combine stereo microscopy with a refocusing filter and with a darkfield filter. The instrument is built around a custom inverted microscope and equipped with an SLM which gives various imaging modes laterally displaced on the same camera chip. In addition, there is a wide angle camera for visualisation of a larger region of the sample.

  8. Strength analysis and modeling of cellular lattice structures manufactured using selective laser melting for tooling applications

    DEFF Research Database (Denmark)

    Mahshid, Rasoul; Hansen, Hans Nørgaard; Loft Højbjerre, Klaus

    2016-01-01

    Additive manufacturing is rapidly developing and gaining popularity for direct metal fabrication systems like selective laser melting (SLM). The technology has shown significant improvement for high-quality fabrication of lightweight design-efficient structures such as conformal cooling channels...... in injection molding tools and lattice structures. This research examines the effect of cellular lattice structures on the strength of workpieces additively manufactured from ultra high-strength steel powder. Two commercial SLM machines are used to fabricate cellular samples based on four architectures— solid......, hollow, lattice structure and rotated lattice structure. Compression test is applied to the specimens while they are deformed. The analytical approach includes finite element (FE), geometrical and mathematical models for prediction of collapse strength. The results from the the models are verified...

  9. Using pico-LCoS SLMs for high speed cell sorting

    DEFF Research Database (Denmark)

    Bañas, Andrew Rafael; Aabo, Thomas; Palima, Darwin

    2012-01-01

    We propose the use of consumer pico projectors as cost effective spatial light modulators in cell sorting applications. The matched filtering Generalized Phase Contrast (mGPC) beam shaping method is used to produce high intensity optical spots for trapping and catapulting cells. A pico projector......’s liquid crystal on silicon (LCoS) chip was used as a binary phase spatial light modulator (SLM) wherein correlation target patterns are addressed. Experiments using the binary LCoS phase SLM with a fabricated Pyrex matched filter demonstrate the generation of intense optical spots that can potentially...... be used for cell sorting. Numerical studies also show mGPC’s robustness to phase aberrations in the LCoS device, and its ability to outperform a top hat beam with the same power....

  10. Modeling of the thermal physical process and study on the reliability of linear energy density for selective laser melting

    Science.gov (United States)

    Xiang, Zhaowei; Yin, Ming; Dong, Guanhua; Mei, Xiaoqin; Yin, Guofu

    2018-06-01

    A finite element model considering volume shrinkage with powder-to-dense process of powder layer in selective laser melting (SLM) is established. Comparison between models that consider and do not consider volume shrinkage or powder-to-dense process is carried out. Further, parametric analysis of laser power and scan speed is conducted and the reliability of linear energy density as a design parameter is investigated. The results show that the established model is an effective method and has better accuracy allowing for the temperature distribution, and the length and depth of molten pool. The maximum temperature is more sensitive to laser power than scan speed. The maximum heating rate and cooling rate increase with increasing scan speed at constant laser power and increase with increasing laser power at constant scan speed as well. The simulation results and experimental result reveal that linear energy density is not always reliable using as a design parameter in the SLM.

  11. Application of the fractional Fourier transform to the design of LCOS based optical interconnects and fiber switches.

    Science.gov (United States)

    Robertson, Brian; Zhang, Zichen; Yang, Haining; Redmond, Maura M; Collings, Neil; Liu, Jinsong; Lin, Ruisheng; Jeziorska-Chapman, Anna M; Moore, John R; Crossland, William A; Chu, D P

    2012-04-20

    It is shown that reflective liquid crystal on silicon (LCOS) spatial light modulator (SLM) based interconnects or fiber switches that use defocus to reduce crosstalk can be evaluated and optimized using a fractional Fourier transform if certain optical symmetry conditions are met. Theoretically the maximum allowable linear hologram phase error compared to a Fourier switch is increased by a factor of six before the target crosstalk for telecom applications of -40 dB is exceeded. A Gerchberg-Saxton algorithm incorporating a fractional Fourier transform modified for use with a reflective LCOS SLM is used to optimize multi-casting holograms in a prototype telecom switch. Experiments are in close agreement to predicted performance.

  12. Efficient illumination of spatial light modulators for optical trapping and manipulation

    DEFF Research Database (Denmark)

    Bañas, Andrew Rafael; Kopylov, Oleksii; Raaby, Peter

    Energy efficiency is always desirable. This is particularly true with lasers that find many applications in research and industry. Combined with spatial light modulators (SLMs) lasers are used for optical trapping and manipulation, sorting, microscopy or biological stimulation1. Besides efficiency....... We have also shown dynamic SLM-generated patterns for materials processing and biological research. To efficiently illuminate an SLM, we used a compact pen-sized GPC-LS in place of an iris. For the same input power, hologram reconstructions are ~3x brighter or alternatively ~3x more focal spots can...... be addressed. This allows better response or increased parallel addressing for e.g. optical manipulation and sorting. Simple yet effective, a GPC-LS could save substantial power in applications that truncate lasers to a specific shape....

  13. A low-voltage high-speed terahertz spatial light modulator using active metamaterial

    Directory of Open Access Journals (Sweden)

    Saroj Rout

    2016-11-01

    Full Text Available An all solid-state metamaterial based terahertz (THz spatial light modulator (SLM is presented which uses high mobility 2DEG to manipulate the metamaterial resonant frequency (0.45 THz leading to terahertz wave modulation. The 2DEG is created by embedding pseudomorphic high-electron mobility transistors in the capacitive gap of each electrical-LC resonator, allowing the charge density to be controlled with very low voltage (1 V and modulating speeds up to 10 MHz while consuming sub-milliwatt power. We have demonstrated our SLM as a 2 × 2 pixel array operating around 0.45 THz by raster scanning a 6 × 6 image of an occluded metal object behind a thick polystyrene screen using a single-pixel THz imaging setup.

  14. Computational Simulation of Thermal and Spattering Phenomena and Microstructure in Selective Laser Melting of Inconel 625

    Science.gov (United States)

    Özel, Tuğrul; Arısoy, Yiğit M.; Criales, Luis E.

    Computational modelling of Laser Powder Bed Fusion (L-PBF) processes such as Selective laser Melting (SLM) can reveal information that is hard to obtain or unobtainable by in-situ experimental measurements. A 3D thermal field that is not visible by the thermal camera can be obtained by solving the 3D heat transfer problem. Furthermore, microstructural modelling can be used to predict the quality and mechanical properties of the product. In this paper, a nonlinear 3D Finite Element Method based computational code is developed to simulate the SLM process with different process parameters such as laser power and scan velocity. The code is further improved by utilizing an in-situ thermal camera recording to predict spattering which is in turn included as a stochastic heat loss. Then, thermal gradients extracted from the simulations applied to predict growth directions in the resulting microstructure.

  15. CoCr F75 scaffolds produced by additive manufacturing: Influence of chemical etching on powder removal and mechanical performance.

    Science.gov (United States)

    Hooreweder, Brecht Van; Lietaert, Karel; Neirinck, Bram; Lippiatt, Nicholas; Wevers, Martine

    2017-06-01

    Additive manufacturing techniques such as Selective Laser Melting (SLM) allow carefully controlled production of complex porous structures such as scaffolds. These advanced structures can offer many interesting advantages over conventionally produced products in terms of biological response and patient specific design. The surface finish of AM parts is often poor because of the layer wise nature of the process and adhering particles. Loosening of these particles after implantation should be avoided, as this could put the patient's health at risk. In this study the use of hydrochloric acid and hydrogen peroxide mixtures for surface treatment of cobalt-chromium F75 scaffolds produced by SLM is investigated. A 27% HCl and 8% H 2 O 2 etchant proved effective in removing adhering particles while retaining the quasi-static and fatigue performance of the scaffolds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Optical implementation of multifocal programmable lens with single and multiple axes

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Lenny A; Millan, Maria S; Perez-Cabre, Elisabet, E-mail: lenny.alexandra.romero@upc.edu [Optics and Optometry Dep. Technical University of Catalonia Violinista Vellsola 37, 08222 Terrassa (Spain)

    2011-01-01

    In this work we analyse the generation of a diffractive optical element (DOE) consisting of a multifocal Fresnel lens by means of an LCoS (liquid cristal on silicon) spatial light modulator (SLM). The multifocal lens is composed of a set of lenses of different focal length that share a common optical axis (coaxial combination) or have different axes in parallel (multi-axis combination). For both configurations, we present several ways to combine the phase distributions for three lenses with different focal lengths (f1, f2, f3), into a single-phase distribution addressed to the SLM. Numerical simulations were carried out along with the experimental analysis to corroborate the results.

  17. Numerical simulation of complex part manufactured by selective laser melting process

    Science.gov (United States)

    Van Belle, Laurent

    2017-10-01

    Selective Laser Melting (SLM) process belonging to the family of the Additive Manufacturing (AM) technologies, enable to build parts layer by layer, from metallic powder and a CAD model. Physical phenomena that occur in the process have the same issues as conventional welding. Thermal gradients generate significant residual stresses and distortions in the parts. Moreover, the large and complex parts to manufacturing, accentuate the undesirable effects. Therefore, it is essential for manufacturers to offer a better understanding of the process and to ensure production reliability of parts with high added value. This paper focuses on the simulation of manufacturing turbine by SLM process in order to calculate residual stresses and distortions. Numerical results will be presented.

  18. High-efficiency and flexible generation of vector vortex optical fields by a reflective phase-only spatial light modulator.

    Science.gov (United States)

    Cai, Meng-Qiang; Wang, Zhou-Xiang; Liang, Juan; Wang, Yan-Kun; Gao, Xu-Zhen; Li, Yongnan; Tu, Chenghou; Wang, Hui-Tian

    2017-08-01

    The scheme for generating vector optical fields should have not only high efficiency but also flexibility for satisfying the requirements of various applications. However, in general, high efficiency and flexibility are not compatible. Here we present and experimentally demonstrate a solution to directly, flexibly, and efficiently generate vector vortex optical fields (VVOFs) with a reflective phase-only liquid crystal spatial light modulator (LC-SLM) based on optical birefringence of liquid crystal molecules. To generate the VVOFs, this approach needs in principle only a half-wave plate, an LC-SLM, and a quarter-wave plate. This approach has some advantages, including a simple experimental setup, good flexibility, and high efficiency, making the approach very promising in some applications when higher power is need. This approach has a generation efficiency of 44.0%, which is much higher than the 1.1% of the common path interferometric approach.

  19. Compact and high-resolution optical orbital angular momentum sorter

    Directory of Open Access Journals (Sweden)

    Chenhao Wan

    2017-03-01

    Full Text Available A compact and high-resolution optical orbital angular momentum (OAM sorter is proposed and demonstrated. The sorter comprises a quadratic fan-out mapper and a dual-phase corrector positioned in the pupil plane and the Fourier plane, respectively. The optical system is greatly simplified compared to previous demonstrations of OAM sorting, and the performance in resolution and efficiency is maintained. A folded configuration is set up using a single reflective spatial light modulator (SLM to demonstrate the validity of the scheme. The two phase elements are implemented on the left and right halves of the SLM and connected by a right-angle prism. Experimental results demonstrate the high resolution of the compact OAM sorter, and the current limit in efficiency can be overcome by replacing with transmissive SLMs and removing the beam splitters. This novel scheme paves the way for the miniaturization and integration of high-resolution OAM sorters.

  20. Local density measurement of additive manufactured copper parts by instrumented indentation

    Science.gov (United States)

    Santo, Loredana; Quadrini, Fabrizio; Bellisario, Denise; Tedde, Giovanni Matteo; Zarcone, Mariano; Di Domenico, Gildo; D'Angelo, Pierpaolo; Corona, Diego

    2018-05-01

    Instrumented flat indentation has been used to evaluate local density of additive manufactured (AM) copper samples with different relative density. Indentations were made by using tungsten carbide (WC) flat pins with 1 mm diameter. Pure copper powders were used in a selective laser melting (SLM) machine to produce samples to test. By changing process parameters, samples density was changed from the relative density of 63% to 71%. Indentation tests were performed on the xy surface of the AM samples. In order to make a correlation between indentation test results and sample density, the indentation pressure at fixed displacement was selected. Results show that instrumented indentation is a valid technique to measure density distribution along the geometry of an SLM part. In fact, a linear trend between indentation pressure and sample density was found for the selected density range.

  1. Microstructure and Mechanical Properties of Ti-6Al-4V Fabricated by Selective Laser Melting of Powder Produced by Granulation-Sintering-Deoxygenation Method

    Science.gov (United States)

    Sun, Pei; Fang, Z. Zak; Zhang, Ying; Xia, Yang

    2017-12-01

    Commercial spherical Ti powders for additive manufacturing applications are produced today by melt-atomization methods at relatively high costs. A meltless production method, called granulation-sintering-deoxygenation (GSD), was developed recently to produce spherical Ti alloy powder at a significantly reduced cost. In this new process, fine hydrogenated Ti particles are agglomerated to form spherical granules, which are then sintered to dense spherical particles. After sintering, the solid fully dense spherical Ti alloy particles are deoxygenated using novel low-temperature deoxygenation processes with either Mg or Ca. This technical communication presents results of 3D printing using GSD powder and the selective laser melting (SLM) technique. The results showed that tensile properties of parts fabricated from spherical GSD Ti-6Al-4V powder by SLM are comparable with typical mill-annealed Ti-6Al-4V. The characteristics of 3D printed Ti-6Al-4V from GSD powder are also compared with that of commercial materials.

  2. Modeling of structural and thermodynamics properties of sigma-phase for the Fe-Cr system

    Directory of Open Access Journals (Sweden)

    Udovskya A.

    2012-01-01

    Full Text Available The three- sub-lattice model (3SLM for description of atom’s distribution of two components with different coordination numbers (12, 14 and 15, into s-phase structure depended on composition and temperature is depictured in this paper. Energetic parameters of 3SLM were calculated by fitting procedure fixed to results obtained by ab-initio calculations conducted for paramagnetic states of differently ordered complexes stayed at the sigma-phase’s crystal structure for Fe-Cr system at 0 K. Respective algorithm and computer program have allowed to calculate an atom distribution of components upon the sub-lattices of s-phase at 300 - 1100 K. There is satisfactory agreement between calculated results and the experimental data obtained by neutron and structural research methods. Obtained results demonstrate satisfactory agreement between calculated and experimental data of BCC solutions and sigma - phase of the Fe-Cr system stayed at an equilibrium state.

  3. Optical Implementation Of The Hopfield Model Using A Spatial Light Modulator Discussion Of Properties And Performance

    Science.gov (United States)

    Torzynski, Marc

    1989-01-01

    In this paper we propose an optical design for implementation of neuronic Hopfield network. We describe the algorithm and its potential possibilities as associative (or content addressable) memory. We then describe the optical set (using a magneto-optic spatial light modulator) and explaning its operating mode: the binary transparency of the SLM does not allow a direct and accurate experimental realisation of the theoretical algorithm. However, there is a particular setup that can implemented it powerfully but with a reduction of the effective number of neurons. The operating speed is then evaluated from the characteristics of the SLM "Sight-Mod" manufactured by SEMETEX corp.: the maximun operating frequency seems limited by the speed of the optical valve.

  4. Microstructure and mechanical properties of a novel β titanium metallic composite by selective laser melting

    International Nuclear Information System (INIS)

    Vrancken, B.; Thijs, L.; Kruth, J.-P.; Van Humbeeck, J.

    2014-01-01

    Selective laser melting (SLM) is an additive manufacturing process in which functional, complex parts are produced by selectively melting consecutive layers of powder with a laser beam. This flexibility enables the exploration of a wide spectrum of possibilities in creating novel alloys or even metal–metal composites with unique microstructures. In this research, Ti6Al4V-ELI powder was mixed with 10 wt.% Mo powder. In contrast to the fully α′ microstructure of Ti6Al4V after SLM, the novel microstructure consists of a β titanium matrix with randomly dispersed pure Mo particles, as observed by light optical microscopy, scanning electron microscopy and X-ray diffraction. Most importantly, the solidification mechanism changes from planar to cellular mode. Microstructures after heat treatment indicate that the β phase is metastable and locate the β transus at ∼900 °C, and tensile properties are equal to or better than conventional β titanium alloys

  5. Building leadership among laboratory-based and clinical and translational researchers: the University of California, San Francisco experience.

    Science.gov (United States)

    Wides, Cynthia; Mertz, Elizabeth; Lindstaedt, Bill; Brown, Jeanette

    2014-02-01

    In 2005 the University of California, San Francisco (UCSF) implemented the Scientific Leadership and Management (SLM) course, a 2-day leadership training program to assist laboratory-based postdoctoral scholars in their transition to independent researchers managing their own research programs. In 2011, the course was expanded to clinical and translational junior faculty and fellows. The course enrollment was increased from approximate 100 to 123 participants at the same time. Based on course evaluations, the number and percent of women participants appears to have increased over time from 40% (n = 33) in 2007 to 53% (n = 58) in 2011. Course evaluations also indicated that participants found the course to be relevant and valuable in their transition to academic leadership. This paper describes the background, structure, and content of the SLM and reports on participant evaluations of the course offerings from 2007 through 2011. © 2014 Wiley Periodicals, Inc.

  6. Partitioning of actinides from high level waste of PUREX origin using octylphenyl-N,N'-diisobutylcarbamoylmethyl phosphine oxide (CMPO)-based supported liquid membrane

    International Nuclear Information System (INIS)

    Ramanujam, A.; Dhami, P.S.; Gopalakrishnan, V.; Dudwadkar, N.L.; Chitnis, R.R.; Mathur, J.N.

    1999-01-01

    The present studies deal with the application of the supported liquid membrane (SLM) technique for partitioning of actinides from high level waste of PUREX origin. The process uses a solution of octylphenyl-N,N'-diisobutylcarbamoylmethyl phosphine oxide (CMPO) in n-dodecane as a carrier with a polytetrafluoroethylene support and a mixture of citric acid, formic acid, and hydrazine hydrate as the receiving phase. The studies involve the investigation of such parameters as carrier concentration in SLM, acidity of the feed, and the feed composition. The studies indicated good transport of actinides like neptunium, americium, and plutonium across the membrane from nitric acid medium. A high concentration of uranium in the feed retards the transport of americium, suggesting the need for prior removal of uranium from the waste. The separation of actinides from uranium-lean simulated samples as well as actual high level waste has been found to be feasible using the above technique

  7. Optical particle trapping and dynamic manipulation using spatial light modulation

    DEFF Research Database (Denmark)

    Eriksen, René Lynge

    suitable for optical trapping. A phaseonly spatial light modulator (SLM) is used for the phase encoding of the laser beam. The SLM is controlled directly from a standard computer where phase information is represented as gray-scale image information. Experimentally, both linear and angular movements......This thesis deals with the spatial phase-control of light and its application for optical trapping and manipulation of micron-scale objects. Utilizing the radiation pressure, light exerts on dielectric micron-scale particles, functionality of optical tweezers can be obtained. Multiple intensity...... compression factors of two, which is not achievable with binary phase encoding, have been successfully demonstrated. In addition, the GPC method has been miniaturized and implemented in a planar optical platform and shown to work acceptably, with relatively high visibility. Furthermore, the GPC method has...

  8. Scanless multitarget-matching multiphoton excitation fluorescence microscopy

    Directory of Open Access Journals (Sweden)

    Junpeng Qiu

    2018-03-01

    Full Text Available Using the combination of a reflective blazed grating and a reflective phase-only diffractive spatial light modulator (SLM, scanless multitarget-matching multiphoton excitation fluorescence microscopy (SMTM-MPM was achieved. The SLM shaped an incoming mode-locked, near-infrared Ti:sapphire laser beam into an excitation pattern with addressable shapes and sizes that matched the samples of interest in the field of view. Temporal and spatial focusing were simultaneously realized by combining an objective lens and a blazed grating. The fluorescence signal from illuminated areas was recorded by a two-dimensional sCMOS camera. Compared with a conventional temporal focusing multiphoton microscope, our microscope achieved effective use of the laser power and decreased photodamage with higher axial resolution.

  9. High-fidelity phase and amplitude control of phase-only computer generated holograms using conjugate gradient minimisation.

    Science.gov (United States)

    Bowman, D; Harte, T L; Chardonnet, V; De Groot, C; Denny, S J; Le Goc, G; Anderson, M; Ireland, P; Cassettari, D; Bruce, G D

    2017-05-15

    We demonstrate simultaneous control of both the phase and amplitude of light using a conjugate gradient minimisation-based hologram calculation technique and a single phase-only spatial light modulator (SLM). A cost function, which incorporates the inner product of the light field with a chosen target field within a defined measure region, is efficiently minimised to create high fidelity patterns in the Fourier plane of the SLM. A fidelity of F = 0.999997 is achieved for a pattern resembling an LG10 mode with a calculated light-usage efficiency of 41.5%. Possible applications of our method in optical trapping and ultracold atoms are presented and we show uncorrected experimental realisation of our patterns with F = 0.97 and 7.8% light efficiency.

  10. Efficient and accurate laser shaping with liquid crystal spatial light modulators

    Energy Technology Data Exchange (ETDEWEB)

    Maxson, Jared M.; Bartnik, Adam C.; Bazarov, Ivan V. [Cornell Laboratory for Accelerator-Based Sciences and Education, Cornell University, Ithaca, New York 14853 (United States)

    2014-10-27

    A phase-only spatial light modulator (SLM) is capable of precise transverse laser shaping by either functioning as a variable phase grating or by serving as a variable mask via polarization rotation. As a phase grating, the highest accuracy algorithms, based on computer generated holograms (CGHs), have been shown to yield extended laser shapes with <10% rms error, but conversely little is known about the experimental efficiency of the method in general. In this work, we compare the experimental tradeoff between error and efficiency for both the best known CGH method and polarization rotation-based intensity masking when generating hard-edged flat top beams. We find that the masking method performs comparably with CGHs, both having rms error < 10% with efficiency > 15%. Informed by best practices for high efficiency from a SLM phase grating, we introduce an adaptive refractive algorithm which has high efficiency (92%) but also higher error (16%), for nearly cylindrically symmetric cases.

  11. Binary zone-plate array for a parallel joint transform correlator applied to face recognition.

    Science.gov (United States)

    Kodate, K; Hashimoto, A; Thapliya, R

    1999-05-10

    Taking advantage of small aberrations, high efficiency, and compactness, we developed a new, to our knowledge, design procedure for a binary zone-plate array (BZPA) and applied it to a parallel joint transform correlator for the recognition of the human face. Pairs of reference and unknown images of faces are displayed on a liquid-crystal spatial light modulator (SLM), Fourier transformed by the BZPA, intensity recorded on an optically addressable SLM, and inversely Fourier transformed to obtain correlation signals. Consideration of the bandwidth allows the relations among the channel number, the numerical aperture of the zone plates, and the pattern size to be determined. Experimentally a five-channel parallel correlator was implemented and tested successfully with a 100-person database. The design and the fabrication of a 20-channel BZPA for phonetic character recognition are also included.

  12. Sound level measurements using smartphone "apps": Useful or inaccurate?

    Directory of Open Access Journals (Sweden)

    Daniel R Nast

    2014-01-01

    Full Text Available Many recreational activities are accompanied by loud concurrent sounds and decisions regarding the hearing hazards associated with these activities depend on accurate sound measurements. Sound level meters (SLMs are designed for this purpose, but these are technical instruments that are not typically available in recreational settings and require training to use properly. Mobile technology has made such sound level measurements more feasible for even inexperienced users. Here, we assessed the accuracy of sound level measurements made using five mobile phone applications or "apps" on an Apple iPhone 4S, one of the most widely used mobile phones. Accuracy was assessed by comparing application-based measurements to measurements made using a calibrated SLM. Whereas most apps erred by reporting higher sound levels, one application measured levels within 5 dB of a calibrated SLM across all frequencies tested.

  13. Preparation of n-type Bi{sub 2}Te{sub 3} thermoelectric materials by non-contact dispenser printing combined with selective laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Keping; Yan, Yonggao; Zhang, Jian; Mao, Yu; Xie, Hongyao; Zhang, Qingjie; Tang, Xinfeng [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, Hubei (China); Yang, Jihui [Department of Materials Science and Engineering, University of Washington, Seattle, WA (United States); Uher, Ctirad [Department of Physics, University of Michigan, Ann Arbor, MI (United States)

    2017-06-15

    The manufacturing cost has been a bottle neck for broader applications of thermoelectric (TE) modules. We have developed a rapid, facile, and low cost method that combines non-contact dispenser printing with selective laser melting (SLM) and we demonstrate it on n-type Bi{sub 2}Te{sub 3}-based materials. Using this approach, single phase n-type Bi{sub 2}Te{sub 2.7}Se{sub 0.3} thin layers with the Seebeck coefficient of -152 μV K{sup -1} at 300 K have been prepared. Assembling such thin layers on top of each other, the performance of thus prepared bulk sample is comparable to Bi{sub 2}Te{sub 3}-based materials fabricated by the conventional techniques. Dispenser printing combined with SLM is a promising manufacturing process for TE materials. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Densification behavior of gas and water atomized 316L stainless steel powder during selective laser melting

    Science.gov (United States)

    Li, Ruidi; Shi, Yusheng; Wang, Zhigang; Wang, Li; Liu, Jinhui; Jiang, Wei

    2010-04-01

    The densification during selective laser melting (SLM) process is an important factor determining the final application of SLM-part. In the present work, the densifications under different processing conditions were investigated and the densification mechanisms were elucidated. It was found that the higher laser power, lower scan speed, narrower hatch spacing and thinner layer thickness could enable a much smoother melting surface and consequently a higher densification. The gas atomized powder possessed better densification than water atomized powder, due to the lower oxygen content and higher packing density of gas atomized powder. A large number of regular-shaped pores can be generated at a wider hatch spacing, even if the scanning track is continuous and wetted very well. The densification mechanisms were addressed and the methods for building dense metal parts were also proposed as follows: inhibiting the balling phenomenon, increasing the overlap ratio of scanning tracks and reducing the micro-cracks.

  15. Effects of NH3 Flow Rate During AlGaN Barrier Layer Growth on the Material Properties of AlGaN/GaN HEMT Heterostructure

    Science.gov (United States)

    Lumbantoruan, Franky J.; Wong, Yuen-Yee; Huang, Wei-Ching; Yu, Hung-Wei; Chang, Edward-Yi

    2017-10-01

    NH3 flow rate during AlGaN barrier layer growth not only affects the growth efficiency and surface morphology as a result of parasitic reactions but also influences the concentration of carbon impurity in the AlGaN barrier. Carbon, which decomposes from metal precursors, plays a role in electron compensation for AlGaN/GaN HEMT. No 2-dimensional electron gas (2-DEG) was detected in the AlGaN/GaN structure if grown with 0.5 slm of NH3 due to the presence of higher carbon impurity (2.6 × 1019 cm-2). When the NH3 flow rate increased to 6.0 slm, the carbon impurity reduced to 2.10 × 1018 atom cm-3 and the 2 DEG electron density recovered to 9.57 × 1012 cm-2.

  16. Tunable single-polarization single-longitudinal-mode erbium-doped fiber ring laser employing a CMFBG filter and saturable absorber

    Science.gov (United States)

    Feng, Suchun; Lu, Shaohua; Peng, Wanjing; Li, Qi; Feng, Ting; Jian, Shuisheng

    2013-04-01

    A tunable single-polarization single-longitudinal-mode (SLM) erbium-doped fiber ring laser is proposed and demonstrated. For the first time as we know, a chirped moiré fiber Bragg grating (CMFBG) filter with ultra-narrow transmission band and a uniform fiber Bragg grating (UFBG) are used to select the laser longitudinal mode. The stable SLM operation of the fiber laser is guaranteed by the combination of the CMFBG filter and 3 m unpumped erbium-doped fiber acting as a saturable absorber. The single polarization operation of the fiber laser is obtained by using an inline broadband polarizer. A tuning range of about 0.7 nm with about 0.1 nm step is achieved by stretching the uniform FBG.

  17. Effect of Build Angle on Surface Properties of Nickel Superalloys Processed by Selective Laser Melting

    Science.gov (United States)

    Covarrubias, Ernesto E.; Eshraghi, Mohsen

    2018-03-01

    Aerospace, automotive, and medical industries use selective laser melting (SLM) to produce complex parts through solidifying successive layers of powder. This additive manufacturing technique has many advantages, but one of the biggest challenges facing this process is the resulting surface quality of the as-built parts. The purpose of this research was to study the surface properties of Inconel 718 alloys fabricated by SLM. The effect of build angle on the surface properties of as-built parts was investigated. Two sets of sample geometries including cube and rectangular artifacts were considered in the study. It was found that, for angles between 15° and 75°, theoretical calculations based on the "stair-step" effect were consistent with the experimental results. Downskin surfaces showed higher average roughness values compared to the upskin surfaces. No significant difference was found between the average roughness values measured from cube and rectangular test artifacts.

  18. The ability of S.aureus to form biofilm on the Ti-6Al-7Nb scaffolds produced by Selective Laser Melting and subjected to the different types of surface modifications.

    Science.gov (United States)

    Szymczyk, Patrycja; Junka, Adam; Ziółkowski, Grzegorz; Smutnicka, Danuta; Bartoszewicz, Marzenna; Chlebus, Edward

    2013-01-01

    The Gram-positive coccus, Staphylococcus aureus, is the leading etiologic agent of limb and life-threatening biofilm-related infections in the patients following the orthopaedic implantations. The aim of the present paper is to estimate the ability of S. aureus to form biofilm on titanium alloy (Ti-6Al-7Nb) scaffolds produced by Selective Laser Melting (SLM) and subjected to the different types of surface modifications, including ultrasonic cleaning and chemical polishing. The results obtained indicate significantly the decreased ability of S.aureus to form biofilm on the surface of scaffolds subjected to the chemical polishing in comparison to the scaffolds cleaned ultrasonically. The data provided can be useful for future applications of the SLM technology in production of Ti-6Al-7Nb medical implants.

  19. The study of the laser parameters and environment variables effect on mechanical properties of high compact parts elaborated by selective laser melting 316L powder

    International Nuclear Information System (INIS)

    Zhang, Baicheng; Dembinski, Lucas; Coddet, Christian

    2013-01-01

    In this work, a systematic analysis of the main parameters for the selective laser melting (SLM) of a commercial stainless steel 316L powder was conducted to improve the mechanical properties and dimensional accuracy of the fabricated parts. First, the effects of the processing parameters, such as the laser beam scanning velocity, laser power, substrate condition and thickness of the powder layer, on the formation of single tracks for achieving a continuous melting and densification of the material were analysed. Then, the influence of the environmental conditions (gas nature) and of the preheating temperature on the density and dimensional accuracy of the parts was considered. The microstructural features of the SLM SS 316L parts were carefully observed to elucidate the melting-solidification mechanism and the thermal history, which are the basis of the manufacturing process. Finally, the mechanical properties of the corresponding material were also determined

  20. Basic research on lattice structures focused on the reliance of the cross sectional area and additional coatings

    Directory of Open Access Journals (Sweden)

    Kessler Julia

    2017-01-01

    Full Text Available This scientific survey is about periodic lattice structures which are made by Selective Laser Melting (SLM. Selective laser melting is based on Additive Manufacturing. The increased use and increasing demand of lattice structures in different fields of applications forms the necessity of a closer look on complex structures. Lattice structures can be found in different fields of applications for example in lightweight applications, filters and heat exchangers. Because of the expanding of application areas and thus arising requirements, the quality improvement is indispensable. Additive manufacturing and especially the SLM process enable the manufacturing of highly complex shapes and structures. Further it allows the integration of lightweight structures within to be manufactured applications. These high performance structures and applications need specific boundary and process conditions [1-3]. The main aim of this survey is an extraction of important parameters concerning the shape of lattices. A first focus will be on mechanical properties and the therefore necessary tensile tests.

  1. Design of conformal cooling for plastic injection moulding by heat transfer simulation

    Directory of Open Access Journals (Sweden)

    Sabrina Marques

    2015-12-01

    Full Text Available The cooling channels of a mold for plastic injection have to be as close as possible to the part geometry in order to ensure fast and homogeneous cooling. However, conventional methods to manufacture cooling channels (drilling can only produce linear holes. Selective laser melting (SLM is an additive manufacturing technique capable to manufacture complex cooling channels (known as conformal cooling. Nevertheless, because of the high costs of SLM the benefits of conformal collings are still not clear. The current work investigates two designs of conformal coolings: i parallel circuit; ii serial circuit. Both coolings are evaluated against to traditional cooling circuits (linear channels by CAE simulation to produce parts of polypropylene. The results show that if the conformal cooling is not properly designed it cannot provide reasonable results. The deformation of the product can be reduced significantly after injection but the cycle time reduced not more than 6%.

  2. Coaxial monitoring of temperature field in selective pulsed laser melting

    Science.gov (United States)

    Liu, Che; Chen, Zhongyun; Cao, Hongzhong; Zhou, Jianhong

    2017-10-01

    Selective Laser Melting is a rapid manufacturing technology which produces complex parts layer by layer. The presence of thermal stress and thermal strain in the forming process often leads to defects in the formed parts. In order to detect fabricate errors and avoid failure which caused by thermal gradient in time. An infrared thermal imager and a high speed CCD camera were applied to build a coaxial optical system for real-time monitoring the temperature distribution and changing trend of laser affected zone in SLM forming process. Molten tracks were fabricated by SLM under different laser parameters such as frequency, pulse width. And the relationship between the laser parameters and the temperature distribution were all obtained and analyzed.

  3. Remote metrology by comparative digital holography

    International Nuclear Information System (INIS)

    Baumbach, Torsten; Osten, Wolfgang; Kopylow, Christoph von; Jueptner, Werner

    2006-01-01

    A method for the remote comparison of objects with regard to their shape or response to a load is presented. The method allows interferometric sensitivity for comparing objects with different microstructure. In contrast to the well-known incoherent techniques based on inverse fringe projection this new approach uses the coherent optical wave field of the master object as a mask for the illumination of the sample object. The coherent mask is created by digital holography to allow instant access to the complete optical information of the master object at any place desired. The mask is reconstructed by a spatial light modulator (SLM). The optical reconstruction of digital holograms with SLM technology allows modification of reconstructed wavefronts with respect to improvement of image quality, the skilled introduction of additional information about the object (augmented reality), and the alignment of the master and test object

  4. Scanning laser techniques for dynamic thermo-magnetic recording onto stationary media

    Energy Technology Data Exchange (ETDEWEB)

    Clegg, Warwick; Jenkins, David; Helian, Na; Windmill, James; Windmill, Robert; Atkinson, Ron; Hendren, Bill; Wright, C. David

    2002-09-01

    Scanning laser microscopes (SLMs) have been used to characterise the magnetic properties of materials for some time (J. Magn. Magn. Mater. 95(1) (1991); IEEE Trans. Magn. 31(6 Pt. 1) (1995)). An SLM has been designed to facilitate a number of operating modes: both for writing and reading magneto-optical data. The current SLM is capable of thermo-magnetically recording bits onto magneto-optical thin films. Unlike previous SLMs, the current instrument has been designed to write bits both statically and dynamically onto stationary media. It will be used to write to magneto-optic (MO) disk material thermo-magnetically prior to imaging. Images may be derived from the longitudinal and polar magneto-optic Kerr effects, which are wavelength dependent, using the appropriate laser wavelength. In this paper the two configurations for dynamic recording are described.

  5. Scanning laser techniques for dynamic thermo-magnetic recording onto stationary media

    International Nuclear Information System (INIS)

    Clegg, Warwick; Jenkins, David; Helian, Na; Windmill, James; Windmill, Robert; Atkinson, Ron; Hendren, Bill; Wright, C. David

    2002-01-01

    Scanning laser microscopes (SLMs) have been used to characterise the magnetic properties of materials for some time (J. Magn. Magn. Mater. 95(1) (1991); IEEE Trans. Magn. 31(6 Pt. 1) (1995)). An SLM has been designed to facilitate a number of operating modes: both for writing and reading magneto-optical data. The current SLM is capable of thermo-magnetically recording bits onto magneto-optical thin films. Unlike previous SLMs, the current instrument has been designed to write bits both statically and dynamically onto stationary media. It will be used to write to magneto-optic (MO) disk material thermo-magnetically prior to imaging. Images may be derived from the longitudinal and polar magneto-optic Kerr effects, which are wavelength dependent, using the appropriate laser wavelength. In this paper the two configurations for dynamic recording are described

  6. Flicker in a twisted nematic spatial light modulator

    Science.gov (United States)

    Calderón-Hermosillo, Yuliana; García-Márquez, Jorge; Espinosa-Luna, Rafael; Ochoa, Noé Alcalá; López, Víctor; Aguilar, Alberto; Noé-Arias, Enrique; Alayli, Yasser

    2013-06-01

    Liquid Crystal on Silicon (LCoS) Spatial Light Modulators (SLM) are widely used for their capability to control beams howbeit fluctuations in phase and amplitude. It is then necessary to understand the negative effects of these fluctuations, also known as flicker, and the means to mitigate them. The flicker is observed either as high frequency variations of polarization, attenuation or high phase fluctuations on the wave front modulated by the LCoS device. Here, we compare the flicker behavior in a twisted nematic (TN) LCoS-SLM for different polarization schemes and temperatures. The quantitative evaluation shows that flicker is effectively reduced only by chilling the LCoS panel to temperatures just below 0 °C but, the LCoS modulation capability is also affected.

  7. [Research progress in CoCr metal-ceramic alloy fabricated by selective laser melting].

    Science.gov (United States)

    Yan, X; Lin, H

    2018-02-09

    Cobalt-chromium alloys have been applied to dental porcelain fused to metal (PFM) restorations over the past decades owing to their excellent corrosion resistance, good biocompatibility and low price. The production of CoCr metal-ceramic restorations has always been based on traditional lost-wax casting techniques. However, in recent years, selective laser melting (SLM) is becoming more and more highly valued by dental laboratories and dental practitioners due to its individuation, precision and efficiency. This paper mainly reviews the recent researches on the production process of copings, microstructure, mechanical property, metal-ceramic bond strength, fit of copings, corrosion resistance and biocompatibility of SLM CoCr metal-ceramic alloy.

  8. Salt effects in electromembrane extraction

    DEFF Research Database (Denmark)

    Seip, Knut Fredrik; Jensen, Henrik; Kieu, Thanh Elisabeth

    2014-01-01

    Electromembrane extraction (EME) was performed on samples containing substantial amounts of NaCl to investigate how the presence of salts affected the recovery, repeatability, and membrane current in the extraction system. A group of 17 non-polar basic drugs with various physical chemical...... this loss and the physical chemical properties of these substances was seen. The recovery loss was hypothesized to be caused by ion pairing in the SLM, and a mathematical model for the extraction recovery in the presence of salts was made according to the experimental observations. Some variations...... to the EME system reduced this recovery loss, such as changing the SLM solvent from NPOE to 6-undecanone, or by using a different EME setup with more favorable volume ratios. This was in line with the ion pairing hypothesis and the mathematical model. This thorough investigation of how salts affect EME...

  9. All-digital wavefront sensing for structured light beams

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2014-01-01

    Full Text Available the topology of neutral pairs of closely positioned phase singularities in speckle fields [21]. Apart from implementing Stokes polarimetry to investigate phase singularities, it can be used to study polarization singularities in coherent beams [22... together with digital holograms en- coded on a spatial light modulator (SLM). Since these holograms are dynamic, we can demon- strate for the first time Stokes polarimetry in real-time on propagating beams. We illustrate the robustness of our technique...

  10. Wavefront sensing with all-digital Stokes measurements

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2014-09-25

    Full Text Available to wavefront sensing [8] based on Stokes polarimetry which makes use of the amplitude and phase relationship between orthogonal states of polarization. With our approach a field of interest is generated by encoding an appropriate hologram on a spatial light... modulator (SLM). Since SLMs are diffraction-inefficient, we can exploit the amplitude relationship between the orthogonal polarization states allowing the execution of Stokes polarimetry of the co-linear superposition of the reference beam and the beam...

  11. Variability in leaf optical properties among 26 species from a broad range of habitats

    International Nuclear Information System (INIS)

    Knapp, A.K.; Carter, G.A.

    1998-01-01

    Leaves from 26 species with growth forms from annual herbs to trees were collected from open, intermediate, and shaded understory habitats in Mississippi and Kansas, USA. Leaf optical properties including reflectance, transmittance, and absorptance in visible and near infrared (NIR) wavelengths were measured along with leaf thickness and specific leaf mass (SLM). These leaf properties and internal light scattering have been reported to vary with light availability in studies that have focused on a limited number of species. Our objective was to determine whether these patterns in leaf optics and light availability were consistent when a greater number of species were evaluated. Leaf thickness and SLM varied by tenfold among species sampled, but within-habitat variance was high. Although there was a strong trend toward thicker leaves in open habitats, only SLM was significantly greater in open vs. understory habitats. In contrast, leaf optical properties were strikingly similar among habitats. Reflectance and reflectance/transmittance in the NIR were used to estimate internal light scattering and there were strong relationships (r2 0.65) between these optical properties and leaf thickness. We concluded that leaf thickness, which did not vary consistently among habitats, was the best predictor of NIR reflectance and internal light scattering. However, because carbon allocation to leaves was lower in understory species (low SLM) yet gross optical properties were similar among all habitats, the energy investment by shade leaves required to achieve optical equivalence with sun leaves was lower. Differences in leaf longevity and growth form within a habitat may help explain the lack of consistent patterns in leaf optics as the number of species sampled increases

  12. Functionalisation of Ti6Al4V components fabricated using selective laser melting with a bioactive compound

    Energy Technology Data Exchange (ETDEWEB)

    Vaithilingam, Jayasheelan [Additive Manufacturing and 3D Printing Research Group, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Kilsby, Samuel [Department of Chemistry, Loughborough University, Loughborough LE11 3TU (United Kingdom); Goodridge, Ruth D., E-mail: Ruth.Goodridge@nottingham.ac.uk [Additive Manufacturing and 3D Printing Research Group, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom); Christie, Steven D.R. [Department of Chemistry, Loughborough University, Loughborough LE11 3TU (United Kingdom); Edmondson, Steve [School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Hague, Richard J.M. [Additive Manufacturing and 3D Printing Research Group, School of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2015-01-01

    Surface modification of an implant with a biomolecule is used to improve its biocompatibility and to reduce post-implant complications. In this study, a novel approach has been used to functionalise phosphonic acid monolayers with a drug. Ti6Al4V components fabricated using selective laser melting (SLM) were functionalised with Paracetamol (a pharmaceutically relevant biomolecule) using phosphonic acid based self-assembled monolayers (SAMs). The attachment, stability of the monolayers on the SLM fabricated surface and functionalisation of SAMs with Paracetamol were studied using X-ray photoelectron spectroscopy (XPS) and surface wettability measurements. The obtained results confirmed that SAMs were stable on the Ti6Al4V surface for over four weeks and then began to desorb from the surface. The reaction used to functionalise the phosphonic acid monolayers with Paracetamol was noted to be successful. Thus, the proposed method has the potential to immobilise drugs/proteins to SAM coated surfaces and improve their biocompatibility and reduce post-implant complications. - Graphical abstract: A significant change in the contact angle confirming the immobilisation of Paracetamol. (a) Before self-assembled monolayer (SAM) attachment, (b) after SAM attachment and (c) after the immobilisation of Paracetamol to the SAMs. - Highlights: • Ti6Al4V parts were fabricated using selective laser melting (SLM). • Monolayers used to modify the SLM surface were stable for over 28 days (in-vitro). • Surface roughness did not have a significant impact on the monolayer stability. • Paracetamol was successfully immobilised to the adsorbed monolayers. • Caution required before selecting Paracetamol as a model drug.

  13. Developing a self-learning training program for RIS computer skills.

    Science.gov (United States)

    Stike, R; Olivi, P

    2000-01-01

    The demonstration of competency by healthcare professionals remains a priority for hospital administrators, as well as for the Joint Commission on Accreditation of Healthcare Organizations (JCAHO). Unfortunately, staff members who have to complete competency exercises often describe the process as a burden. Ineffective training processes may be the culprit. Our teaching hospital developed a training program for the radiology information system (RIS) computer system used by an imaging department of more than 200 staff members. The emphasis of our training program was on the design phase and the contribution of subject-matter experts (SMEs) to the content and testing of training materials, which included a computer-assisted, self-learning manual (SLM) and a pocket guide. The first step in the design process was to identify subject matter experts (SMEs) within the imaging department. Seven SMEs were shadowed by the IT educator. The role of the SME was to demonstrate current practices with RIS, to state principles involved and to serve as a reference for questions during training development. The steps that followed planning and design were: training delivery, evaluation and ongoing training. These steps were implemented in a series of workshops, which included soliciting feedback about the training program. Feedback was used to revise the SLM. The RIS SLM training project was a huge success for everyone involved. The average score for the core-skills test was higher than 90 percent. Seventy-five percent of the current staff was trained in the first phase, including radiology students. Our yearly cost savings using SLM workshops instead of on-the-job training will be about $35,000. We attribute the success of this project to a detailed timeline, SME contributions, the pilot testing phase, and the positive attitude of the imaging staff.

  14. Permeabilitas Membran Transpor Campuran Unsur Tanah Jarang (La, Nd, Gd, Lu Menggunakan Carrier (TBP : D2EHPA Melalui Supported Liquid Membrane

    Directory of Open Access Journals (Sweden)

    Djabal Nur Basir

    2015-01-01

    Full Text Available Methods that have been developed currently for the separation and purification of rare earth elements, REE’s are solvent extraction by through immobilization of an extracting agent in a porous polymeric membrane. This methods beside could increase the transport selectivity, also the amount of carrier was very few. This technique is known as supported liquid membrane, SLM. Research toward transport and separation of REE’s through SLM have been still relatively limited merely to single feed-binary mixture, and one type of carrier. The transport   membrane permeability was obtained in a mixture of REE’s (La,Nd,Gd,Lu using the carrier TBP : D2EHPA by SLM. In this SLM technique, supporting membrane PTFE (polytetrafluoroethylene was soaked in a mixture of TBP carrier (tributilfosfat as a neutral ligand and D2EHPA (acid-2- etilheksilfosfat as anionic ligand with a particular concentration ratio in the solvent kerosene as membrane phase. HCl as receiver phase and solution mixture of REE’s as feed phase. Determination of the REE’s total concentration was carried out by UV-Vis spectrophotometry with NAS (sodium alizarin sulfonate as the colouring agent at pH 4,75 and the solution absorbance was determinated at 534 nm as maximum wavelength. Transport patterns of REE’s on the variation of the concentration of total mixed carrier composition, pH, and concentration  of the receiver phase were done for 300 minutes. The optimum conditions of transport mixture of REE’s (La, Nd, Gd, Lu were feed phase pH 3,0; carrier TBP: D2EHPA (0,3:0,7 M; and receiver phase HCl 3,0 M. In this condition, the transport membrane permeability in mixture of REE’s was 0,1077 cm.menit-1 with the percent of transport was 95,24%.

  15. Variation for yield, water-use efficiency, and canopy morphology among nine alfalfa germplasms

    International Nuclear Information System (INIS)

    Ray, I.M.; Townsend, M.S.; Henning, J.A.

    1998-01-01

    Alfalfa (Medicago sativa L.) production under irrigated and rainfed conditions may benefit from improvements in water-use efficiency (WUE), the amount of forage and root biomass produced per unit of water transpired. If benefits from improved WUE are to be realized, correlations between important agronomic traits and key physiological traits associated with WUE must be determined. This study characterized variation for dry matter yield, forage maturity, leaf-to-stem ratio (LSR), carbon isotope discrimination (delta), canopy temperature, ash content, and specific leaf mass (SLM) in alfalfa. Associations between traits were also determined. Nine alfalfa germplasms representing eight of the nine historical genetic diversity groups, and a very fall-dormant (VFD) population, were established in seeded, irrigated plots for 2 yr near Las Cruces, NM. Significant variation (P less than or equal to 0.10) was detected for all traits and was greatest for delta and maturity, intermediate for yield, canopy temperature, ash content, and LSR, and least for SLM. The African, Peruvian, and Indian germplasms exhibited a higher delta than either the Turkistan, VFD, M. varia Martyn., or Ladak germplasms. Carbon isotope discrimination was positively correlated with forage yield (r = 0.64; P less than or equal to 0.10; n = 9) and forage maturity (r = 0.66; P less than or equal to 0.05; n = 9). No association was detected between delta and either canopy temperature, ash content, SLM, or LSR. The results indicate that differences in stomatal conductance or photosynthetic capacity exist among the nine populations, and that germplasms with low delta tended to have slower growth and development rates under irrigated conditions. Neither canopy temperature, ash content, nor SLM provided suitable alternate measurements of delta among the nine alfalfa germplasms

  16. NASA Advances Technologies for Additive Manufacturing of GRCop-84 Copper Alloy

    Science.gov (United States)

    Gradl, Paul; Protz, Chris

    2017-01-01

    The Low Cost Upper Stage Propulsion project has successfully developed and matured Selective Laser Melting (SLM) Fabrication of the NASA developed GRCop-84 copper alloy. Several parts have been printed in house and at a commercial vendor, and these parts have been successfully machined and have undergone further fabrication steps to allow hot-fire testing. Hot-fire testing has demonstrated parts manufactured with this technique can survive and perform well in the relevant environments for liquid rocket propulsion systems.

  17. Parity generator and parity checker in the modified trinary number system using savart plate and spatial light modulator

    Science.gov (United States)

    Ghosh, Amal K.

    2010-09-01

    The parity generators and the checkers are the most important circuits in communication systems. With the development of multi-valued logic (MVL), the proposed system with parity generators and checkers is the most required using the recently developed optoelectronic technology in the modified trinary number (MTN) system. This system also meets up the tremendous needs of speeds by exploiting the savart plates and spatial light modulators (SLM) in the optical tree architecture (OTA).

  18. Individual titanium zygomatic implant

    Science.gov (United States)

    Nekhoroshev, M. V.; Ryabov, K. N.; Avdeev, E. V.

    2018-03-01

    Custom individual implants for the reconstruction of craniofacial defects have gained importance due to better qualitative characteristics over their generic counterparts – plates, which should be bent according to patient needs. The Additive Manufacturing of individual implants allows reducing cost and improving quality of implants. In this paper, the authors describe design of zygomatic implant models based on computed tomography (CT) data. The fabrication of the implants will be carried out with 3D printing by selective laser melting machine SLM 280HL.

  19. Mesoporous Bioactive Glass Functionalized 3D Ti-6Al-4V Scaffolds with Improved Surface Bioactivity.

    Science.gov (United States)

    Ye, Xiaotong; Leeflang, Sander; Wu, Chengtie; Chang, Jiang; Zhou, Jie; Huan, Zhiguang

    2017-10-27

    Porous Ti-6Al-4V scaffolds fabricated by means of selective laser melting (SLM), having controllable geometrical features and preferable mechanical properties, have been developed as a class of biomaterials that hold promising potential for bone repair. However, the inherent bio-inertness of the Ti-6Al-4V alloy as the matrix of the scaffolds results in a lack in the ability to stimulate bone ingrowth and regeneration. The aim of the present study was to develop a bioactive coating on the struts of SLM Ti-6Al-4V scaffolds in order to add the desired surface osteogenesis ability. Mesoporous bioactive glasses (MBGs) coating was applied on the strut surfaces of the SLM Ti-6Al-4V scaffolds through spin coating, followed by a heat treatment. It was found that the coating could maintain the characteristic mesoporous structure and chemical composition of MBG, and establish good interfacial adhesion to the Ti-6Al-4V substrate. The compressive strength and pore interconnectivity of the scaffolds were not affected by the coating. Moreover, the results obtained from in vitro cell culture experiments demonstrated that the attachment, proliferation, and differentiation of human bone marrow stromal cells (hBMSCs) on the MBG-coated Ti-6Al-4V scaffolds were improved as compared with those on the conventional bioactive glass (BG)-coated Ti-6Al-4V scaffolds and bare-metal Ti-6Al-4V scaffolds. Our results demonstrated that the MBG coating by using the spinning coating method could be an effective approach to achieving enhanced surface biofunctionalization for SLM Ti-6Al-4V scaffolds.

  20. The interaction effect of body mass index and age on fat-free mass, waist-to-hip ratio, and soft lean mass

    Directory of Open Access Journals (Sweden)

    Alireza Shahab Jahanlou

    2017-01-01

    Full Text Available Background: Research has shown that body mass index (BMI does not take into consideration the gender and ethnicity. The primary purpose of this study was to examine the interaction effect of the BMI and age on fat-free mass (FFM, waist-to-hip ratio (WHR, and soft lean mass (SLM. The secondary purpose was to evaluate the practical significance of the findings by examining effect sizes. Materials and Methods: The study was comparative in nature and employed a factorial design. Due to nonexperimental nature of the investigation, no causal inferences were drawn. The nonprobability sample consisted of 19,356 adults. Analysis of the data included factorial analysis of variance, analysis of simple effects, calculation of mean difference effect sizes, and data transformation. The Statistical Package for the Social Sciences version 22 was employed for the purpose of data manipulation and analysis. Results: The BMI by age interaction effects on FFM, F (10, 19,338 = 28.26, P < 0.01, on WHR, F (10, 19,338 = 18.46, P < 0.01, and on SLM, F (10, 19,338 = 14.65, P < 0.01, was statistically significant and ordinal in nature. Analysis of the effect sizes, ranging from 0.30 to 1.20, showed that the BMI and age influenced the WHR but their interaction effects on FFM and SLM, ranging from 0.04 to 0.36 and 0.03 to 0.33, respectively, were mainly negligible. Conclusion: Based on the examination of the statistical and practical significance of the results, it is concluded that the BMI and age together can influence the WHR but their interaction effect on the FFM and SLM is questionable.

  1. Development testing of the chemical analysis automation polychlorinated biphenyl standard analysis method during surface soils sampling at the David Witherspoon 1630 site

    International Nuclear Information System (INIS)

    Hunt, M.A.; Klatt, L.N.; Thompson, D.H.

    1998-02-01

    The Chemical Analysis Automation (CAA) project is developing standardized, software-driven, site-deployable robotic laboratory systems with the objective of lowering the per-sample analysis cost, decreasing sample turnaround time, and minimizing human exposure to hazardous and radioactive materials associated with DOE remediation projects. The first integrated system developed by the CAA project is designed to determine polychlorinated biphenyls (PCB) content in soil matrices. A demonstration and development testing of this system was conducted in conjuction with surface soil characterization activities at the David Witherspoon 1630 Site in Knoxville, Tennessee. The PCB system consists of five hardware standard laboratory modules (SLMs), one software SLM, the task sequence controller (TSC), and the human-computer interface (HCI). Four of the hardware SLMs included a four-channel Soxhlet extractor, a high-volume concentrator, a column cleanup, and a gas chromatograph. These SLMs performed the sample preparation and measurement steps within the total analysis protocol. The fifth hardware module was a robot that transports samples between the SLMs and the required consumable supplies to the SLMs. The software SLM is an automated data interpretation module that receives raw data from the gas chromatograph SLM and analyzes the data to yield the analyte information. The TSC is a software system that provides the scheduling, management of system resources, and the coordination of all SLM activities. The HCI is a graphical user interface that presents the automated laboratory to the analyst in terms of the analytical procedures and methods. Human control of the automated laboratory is accomplished via the HCI. Sample information required for processing by the automated laboratory is entered through the HCI. Information related to the sample and the system status is presented to the analyst via graphical icons

  2. Tilt-effect of holograms and images displayed on a spatial light modulator.

    Science.gov (United States)

    Harm, Walter; Roider, Clemens; Bernet, Stefan; Ritsch-Marte, Monika

    2015-11-16

    We show that a liquid crystal spatial light modulator (LCOS-SLM) can be used to display amplitude images, or phase holograms, which change in a pre-determined way when the display is tilted, i.e. observed under different angles. This is similar to the tilt-effect (also called "latent image effect") known from various security elements ("kinegrams") on credit cards or bank notes. The effect is achieved without any specialized optical components, simply by using the large phase shifting capability of a "thick" SLM, which extends over several multiples of 2π, in combination with the angular dependence of the phase shift. For hologram projection one can use the fact that the phase of a monochromatic wave is only defined modulo 2π. Thus one can design a phase pattern extending over several multiples of 2π, which transforms at different readout angles into different 2π-wrapped phase structures, due to the angular dependence of the modulo 2π operation. These different beams then project different holograms at the respective readout angles. In amplitude modulation mode (with inserted polarizer) the intensity of each SLM pixel oscillates over several periods when tuning its control voltage. Since the oscillation period depends on the readout angle, it is possible to find a certain control voltage which produces two (or more) selectable gray levels at a corresponding number of pre-determined readout angles. This is done with all SLM pixels individually, thus constructing different images for the selected angles. We experimentally demonstrate the reconstruction of multiple (Fourier- and Fresnel-) holograms, and of different amplitude images, by readout of static diffractive patterns in a variable angular range between 0° and 60°.

  3. Functionalisation of Ti6Al4V components fabricated using selective laser melting with a bioactive compound

    International Nuclear Information System (INIS)

    Vaithilingam, Jayasheelan; Kilsby, Samuel; Goodridge, Ruth D.; Christie, Steven D.R.; Edmondson, Steve; Hague, Richard J.M.

    2015-01-01

    Surface modification of an implant with a biomolecule is used to improve its biocompatibility and to reduce post-implant complications. In this study, a novel approach has been used to functionalise phosphonic acid monolayers with a drug. Ti6Al4V components fabricated using selective laser melting (SLM) were functionalised with Paracetamol (a pharmaceutically relevant biomolecule) using phosphonic acid based self-assembled monolayers (SAMs). The attachment, stability of the monolayers on the SLM fabricated surface and functionalisation of SAMs with Paracetamol were studied using X-ray photoelectron spectroscopy (XPS) and surface wettability measurements. The obtained results confirmed that SAMs were stable on the Ti6Al4V surface for over four weeks and then began to desorb from the surface. The reaction used to functionalise the phosphonic acid monolayers with Paracetamol was noted to be successful. Thus, the proposed method has the potential to immobilise drugs/proteins to SAM coated surfaces and improve their biocompatibility and reduce post-implant complications. - Graphical abstract: A significant change in the contact angle confirming the immobilisation of Paracetamol. (a) Before self-assembled monolayer (SAM) attachment, (b) after SAM attachment and (c) after the immobilisation of Paracetamol to the SAMs. - Highlights: • Ti6Al4V parts were fabricated using selective laser melting (SLM). • Monolayers used to modify the SLM surface were stable for over 28 days (in-vitro). • Surface roughness did not have a significant impact on the monolayer stability. • Paracetamol was successfully immobilised to the adsorbed monolayers. • Caution required before selecting Paracetamol as a model drug

  4. Spectroscopic measurement of the electric field in a helium plasma jet

    NARCIS (Netherlands)

    Hofmans, M.; Sobota, A.

    2017-01-01

    The electric field in a plasma jet is measured spectroscopically utilizing the Stark-effect. A cold atmospheric pressure helium plasma jet is used, which operates at a μs-pulsed applied voltage of 6 kV, a frequency of 5 kHz and with a helium flow of 1.5 slm. Due to the electric field in the jet, the

  5. Enhanced Interferometry with Programmable Spatial Light Modulator

    Science.gov (United States)

    2010-06-07

    Interferometry, Spatial Light Modulator, Surface Accuracy, Optics, Mirror, Zernike , Freeform Optics, Null Testing, Hartman, Wavefront 16. SECURITY...S L M P ix e l- c a m Tilted Flat Mirror L a s e r PV. ± 3.4 λ -Tilt by the flat mirror, ~7 waves ~ 14 fringes Interferogram 3D view (Various...Interferogram ( 3D view) x- profile y- profile (Various waveplates and telescopes not shown) SLM can compensate tilted wavefronts with an accuracy of

  6. Design and additive manufacture for flow chemistry.

    Science.gov (United States)

    Capel, Andrew J; Edmondson, Steve; Christie, Steven D R; Goodridge, Ruth D; Bibb, Richard J; Thurstans, Matthew

    2013-12-07

    We review the use of additive manufacturing (AM) as a novel manufacturing technique for the production of milli-scale reactor systems. Five well-developed additive manufacturing techniques: stereolithography (SL), multi-jet modelling (MJM), selective laser melting (SLM), laser sintering (LS) and fused deposition modelling (FDM) were used to manufacture a number of miniaturised reactors which were tested using a range of organic and inorganic reactions.

  7. Swiftly moving focus points and forming shapes through the scattering media

    Science.gov (United States)

    Tran, Vinh; Sahoo, Sujit Kumar; Tang, Dongliang; Dang, Cuong

    2018-02-01

    Propagation of light through scattering media such as ground glass or biological tissue limits the quality and intensity of focusing point. Wave front shaping technique which uses spatial light modulator (SLM) devices to reshape the field profile of incoming light, is considered as one of the most effective and convenient methods. Advanced biomedical or manufacturing applications require drawing various contours or shapes quickly and precisely. However, creating each shape behind the scattering medium needs different phase profiles, which are time consuming to optimize or measure. Here, we demonstrate a technique to draw various shapes or contours behind the scattering medium by swiftly moving the focus point without any mechanical movements. Our technique relies on the existence of speckle correlation property in scattering media, also known as optical memory effect. In our procedure, we first modulate the phase-only SLM to create the focus point on the other side of scattering medium. Then, we digitally shift the preoptimized phase profile on the SLM and ramp it to tilt the beam accordingly. Now, the incoming beam with identical phase profile shines on the same scattering region at a tilted angle to regenerate the focus point at the desired position due to memory effect. Moreover, with linear combination of different field patterns, we can generate a single phase profile on SLM to produce two, three or more focus points simultaneously on the other side of a turbid medium. Our method could provide a useful tool for prominent applications such as opto-genetic excitation, minimally invasive laser surgery and other related fields.

  8. Towards a semantic learning model fostering learning object reusability

    OpenAIRE

    Fernandes , Emmanuel; Madhour , Hend; Wentland Forte , Maia; Miniaoui , Sami

    2005-01-01

    We try in this paper to propose a domain model for both author's and learner's needs concerning learning objects reuse. First of all, we present four key criteria for an efficient authoring tool: adaptive level of granularity, flexibility, integration and interoperability. Secondly, we introduce and describe our six-level Semantic Learning Model (SLM) designed to facilitate multi-level reuse of learning materials and search by defining a multi-layer model for metadata. Finally, after mapping ...

  9. In vitro biocompatibility of CoCrMo dental alloys fabricated by selective laser melting.

    Science.gov (United States)

    Hedberg, Yolanda S; Qian, Bin; Shen, Zhijian; Virtanen, Sannakaisa; Wallinder, Inger Odnevall

    2014-05-01

    Selective laser melting (SLM) is increasingly used for the fabrication of customized dental components made of metal alloys such as CoCrMo. The main aim of the present study is to elucidate the influence of the non-equilibrium microstructure obtained by SLM on corrosion susceptibility and extent of metal release (measure of biocompatibility). A multi-analytical approach has been employed by combining microscopic and bulk compositional tools with electrochemical techniques and chemical analyses of metals in biologically relevant fluids for three differently SLM fabricated CoCrMo alloys and one cast CoCrMo alloy used for comparison. Rapid cooling and strong temperature gradients during laser melting resulted in the formation of a fine cellular structure with cell boundaries enriched in Mo (Co depleted), and suppression of carbide precipitation and formation of a martensitic ɛ (hcp) phase at the surface. These features were shown to decrease the corrosion and metal release susceptibility of the SLM alloys compared with the cast alloy. Unique textures formed in the pattern of the melting pools of the three different laser melted CoCrMo alloys predominantly explain observed small, though significant, differences. The susceptibility for corrosion and metal release increased with an increased number (area) of laser melt pool boundaries. This study shows that integrative and interdisciplinary studies of microstructural characteristics, corrosion, and metal release are essential to assess and consider during the design and fabrication of CoCrMo dental components of optimal biocompatibility. The reason is that the extent of metal release from CoCrMo is dependent on fabrication procedures. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Defects-tolerant Co-Cr-Mo dental alloys prepared by selective laser melting.

    Science.gov (United States)

    Qian, B; Saeidi, K; Kvetková, L; Lofaj, F; Xiao, C; Shen, Z

    2015-12-01

    CrCoMo alloy specimens were successfully fabricated using selective laser melting (SLM). The aim of this study was to carefully investigate microstructure of the SLM specimens in order to understand the influence of their structural features inter-grown on different length scales ranging from nano- to macro-levels on their mechanical properties. Two different sets of processing parameters developed for building the inner part (core) and the surface (skin) of dental prostheses were tested. Microstructures were characterized by SEM, EBSD and XRD analysis. The elemental distribution was assessed by EDS line profile analysis under TEM. The mechanical properties of the specimens were measured. The microstructures of both specimens were characterized showing formation of grains comprised of columnar sub-grains with Mo-enrichment at the sub-grain boundaries. Clusters of columnar sub-grains grew coherently along one common crystallographic direction forming much larger single crystal grains which are intercrossing in different directions forming an overall dendrite-like microstructure. Three types of microstructural defects were occasionally observed; small voids (10 μm). Despite the presence of these defects, the yield and the ultimate tensile strength (UTS) were 870 and 430MPa and 1300MPa and 1160MPa, respectively, for the skin and core specimens which are higher than casted dental alloy. Although the formation of microstructural defects is hard to be avoided during the SLM process, the SLM CoCrMo alloys can achieve improved mechanical properties than their casted counterparts, implying they are "defect-tolerant". Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  11. Continuous functionally graded porous titanium scaffolds manufactured by selective laser melting for bone implants.

    Science.gov (United States)

    Han, Changjun; Li, Yan; Wang, Qian; Wen, Shifeng; Wei, Qingsong; Yan, Chunze; Hao, Liang; Liu, Jie; Shi, Yusheng

    2018-04-01

    A significant requirement for a bone implant is to replicate the functional gradient across the bone to mimic the localization change in stiffness. In this work, continuous functionally graded porous scaffolds (FGPSs) based on the Schwartz diamond unit cell with a wide range of graded volume fraction were manufactured by selective laser melting (SLM). The micro-topology, strut dimension characterization and effect of graded volume fraction on the mechanical properties of SLM-processed FGPSs were systematically investigated. The micro-topology observations indicate that diamond FGPSs with a wide range of graded volume fraction from 7.97% to 19.99% were fabricated without any defects, showing a good geometric reproduction of the original designs. The dimensional characterization demonstrates the capability of SLM in manufacturing titanium diamond FGPSs with the strut size of 483-905µm. The elastic modulus and yield strength of the titanium diamond FGPSs can be tailored in the range of 0.28-0.59GPa and 3.79-17.75MPa respectively by adjusting the graded volume fraction, which are comparable to those of the cancellous bone. The mathematical relationship between the graded porosity and compression properties of a FGPS was revealed. Furthermore, two equations based on the Gibson and Ashby model have been established to predict the modulus and yield strength of SLM-processed diamond FGPSs. Compared to homogeneous diamond porous scaffolds, FGPSs provide a wide range of mutative pore size and porosity, which are potential to be tailored to optimize the pore space for bone tissue growth. The findings provide a basis of new methodologies to design and manufacture superior graded scaffolds for bone implant applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Fatigue strength of Co-Cr-Mo alloy clasps prepared by selective laser melting.

    Science.gov (United States)

    Kajima, Yuka; Takaichi, Atsushi; Nakamoto, Takayuki; Kimura, Takahiro; Yogo, Yoshiaki; Ashida, Maki; Doi, Hisashi; Nomura, Naoyuki; Takahashi, Hidekazu; Hanawa, Takao; Wakabayashi, Noriyuki

    2016-06-01

    We aimed to investigate the fatigue strength of Co-Cr-Mo clasps for removable partial dentures prepared by selective laser melting (SLM). The Co-Cr-Mo alloy specimens for tensile tests (dumbbell specimens) and fatigue tests (clasp specimens) were prepared by SLM with varying angles between the building and longitudinal directions (i.e., 0° (TL0, FL0), 45° (TL45, FL45), and 90° (TL90, FL90)). The clasp specimens were subjected to cyclic deformations of 0.25mm and 0.50mm for 10(6) cycles. The SLM specimens showed no obvious mechanical anisotropy in tensile tests and exhibited significantly higher yield strength and ultimate tensile strength than the cast specimens under all conditions. In contrast, a high degree of anisotropy in fatigue performance associated with the build orientation was found. For specimens under the 0.50mm deflection, FL90 exhibited significantly longer fatigue life (205,418 cycles) than the cast specimens (112,770 cycles). In contrast, the fatigue lives of FL0 (28,484 cycles) and FL45 (43,465 cycles) were significantly shorter. The surface roughnesses of FL0 and FL45 were considerably higher than those of the cast specimens, whereas there were no significant differences between FL90 and the cast specimens. Electron backscatter diffraction (EBSD) analysis indicated the grains of FL0 showed preferential close to orientation of the γ phase along the normal direction to the fracture surface. In contrast, the FL45 and FL90 grains showed no significant preferential orientation. Fatigue strength may therefore be affected by a number of factors, including surface roughness and crystal orientation. The SLM process is a promising candidate for preparing tough removable partial denture frameworks, as long as the appropriate build direction is adopted. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Fatigue behavior of thin-walled grade 2 titanium samples processed by selective laser melting. Application to life prediction of porous titanium implants.

    Science.gov (United States)

    Lipinski, P; Barbas, A; Bonnet, A-S

    2013-12-01

    Because of its biocompatibility and high mechanical properties, the commercially pure grade 2 titanium (CPG2Ti) is largely used for fabrication of patient specific implants or hard tissue substitutes with complex shape. To avoid the stress-shielding and help their colonization by bone, prostheses with a controlled porosity are designed. The selective laser melting (SLM) is well adapted to manufacture such geometrically complicated structures constituted by struts with rough surfaces and relatively small diameters. Few studies were dedicated to characterize the fatigue properties of SLM processed samples and bulk parts. They followed conventional or standard protocols. The fatigue behavior of standard samples is very different from the one of porous raw structures. In this study, the SLM made "as built" (AB) and "heat treated" (HT) tubular samples were tested in fatigue. Wöhler curves were determined in both cases. The obtained endurance limits were equal to σD(AB)=74.5MPa and σD(HT)=65.7MPa, respectively. The heat treatment worsened the endurance limit by relaxation of negative residual stresses measured on the external surface of the samples. Modified Goodman diagram was established for raw specimens. Porous samples, based on the pattern developed by Barbas et al. (2012), were manufactured by SLM. Fatigue tests and finite element simulations performed on these samples enabled the determination of a simple rule of fatigue assessment. The method based on the stress gradient appeared as the best approach to take into account the notch influence on the fatigue life of CPG2Ti structures with a controlled porosity. The direction dependent apparent fatigue strength was found. A criterion based on the effective, or global, nominal stress was proposed taking into account the anisotropy of the porous structures. Thanks to this criterion, the usual calculation methods can be used to design bone substitutes, without a precise modelling of their internal fine porosity.

  14. Investigation of Performance and Residual Stress Generation of AlSi10Mg Processed by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Lianfeng Wang

    2018-01-01

    Full Text Available During the selective laser melting (SLM process, the scanned layers are subjected to rapid thermal cycles. By working on the mechanical properties, residual stress, and microstructure, the high-temperature gradients can have significant effect on the proper functioning and the structural integrity of built parts. This work presents a comprehensive study on the scanning path type and preheating temperature for AlSi10Mg alloy during SLM. According to the results, SLM AlSi10Mg parts fabricated in chessboard scanning strategy have higher mechanical properties or at least comparable to the parts fabricated in uniformity scanning strategy. In the SLM processing, the residual stress in different parts of the specimen varies with temperature gradient, and the residual stress at the edge of the specimen is obviously larger than that at the center. Under the chessboard scanning and preheating temperature 160°C, the residual stress in each direction of the specimens reaches the minimum. Under different forming processes, the morphology of the microstructure is obviously different. With the increase of preheating temperature, the molten pool in the side surface is obviously elongated and highly unevenly distributed. From the coupling relationship between the residual stress and microstructure, it can be found that the microstructure of top surface is affected by residual stresses σx and σy. But the side surface is mainly governed by residual stress σy; moreover, the greater the residual stress, the more obvious the grain tilt. In the XY and XZ surfaces, the scanning strategy has little influence on the tilt angle of the grain. But, the tilt angle and morphology of the microstructure are obviously affected by the preheating temperature. The results show that the residual stresses can effectively change the properties of the materials under the combined influence of scanning strategy and preheating temperature.

  15. Establishing Information Security Systems via Optical Imaging

    Science.gov (United States)

    2015-08-11

    SLM, spatial light modulator; BSC, non - polarizing beam splitter cube; CCD, charge-coupled device. In computational ghost imaging, a series of...Laser Object Computer Fig. 5. A schematic setup for the proposed method using holography: BSC, Beam splitter cube; CCD, Charge-coupled device. The...interference between reference and object beams . (a) (e) (d) (c) (b) Distribution Code A: Approved for public release, distribution is unlimited

  16. Mesoporous Bioactive Glass Functionalized 3D Ti-6Al-4V Scaffolds with Improved Surface Bioactivity

    Directory of Open Access Journals (Sweden)

    Xiaotong Ye

    2017-10-01

    Full Text Available Porous Ti-6Al-4V scaffolds fabricated by means of selective laser melting (SLM, having controllable geometrical features and preferable mechanical properties, have been developed as a class of biomaterials that hold promising potential for bone repair. However, the inherent bio-inertness of the Ti-6Al-4V alloy as the matrix of the scaffolds results in a lack in the ability to stimulate bone ingrowth and regeneration. The aim of the present study was to develop a bioactive coating on the struts of SLM Ti-6Al-4V scaffolds in order to add the desired surface osteogenesis ability. Mesoporous bioactive glasses (MBGs coating was applied on the strut surfaces of the SLM Ti-6Al-4V scaffolds through spin coating, followed by a heat treatment. It was found that the coating could maintain the characteristic mesoporous structure and chemical composition of MBG, and establish good interfacial adhesion to the Ti-6Al-4V substrate. The compressive strength and pore interconnectivity of the scaffolds were not affected by the coating. Moreover, the results obtained from in vitro cell culture experiments demonstrated that the attachment, proliferation, and differentiation of human bone marrow stromal cells (hBMSCs on the MBG-coated Ti-6Al-4V scaffolds were improved as compared with those on the conventional bioactive glass (BG-coated Ti-6Al-4V scaffolds and bare-metal Ti-6Al-4V scaffolds. Our results demonstrated that the MBG coating by using the spinning coating method could be an effective approach to achieving enhanced surface biofunctionalization for SLM Ti-6Al-4V scaffolds.

  17. High precision wavefront control in point spread function engineering for single emitter localization

    Science.gov (United States)

    Siemons, M.; Hulleman, C. N.; Thorsen, R. Ø.; Smith, C. S.; Stallinga, S.

    2018-04-01

    Point Spread Function (PSF) engineering is used in single emitter localization to measure the emitter position in 3D and possibly other parameters such as the emission color or dipole orientation as well. Advanced PSF models such as spline fits to experimental PSFs or the vectorial PSF model can be used in the corresponding localization algorithms in order to model the intricate spot shape and deformations correctly. The complexity of the optical architecture and fit model makes PSF engineering approaches particularly sensitive to optical aberrations. Here, we present a calibration and alignment protocol for fluorescence microscopes equipped with a spatial light modulator (SLM) with the goal of establishing a wavefront error well below the diffraction limit for optimum application of complex engineered PSFs. We achieve high-precision wavefront control, to a level below 20 m$\\lambda$ wavefront aberration over a 30 minute time window after the calibration procedure, using a separate light path for calibrating the pixel-to-pixel variations of the SLM, and alignment of the SLM with respect to the optical axis and Fourier plane within 3 $\\mu$m ($x/y$) and 100 $\\mu$m ($z$) error. Aberrations are retrieved from a fit of the vectorial PSF model to a bead $z$-stack and compensated with a residual wavefront error comparable to the error of the SLM calibration step. This well-calibrated and corrected setup makes it possible to create complex `3D+$\\lambda$' PSFs that fit very well to the vectorial PSF model. Proof-of-principle bead experiments show precisions below 10~nm in $x$, $y$, and $\\lambda$, and below 20~nm in $z$ over an axial range of 1 $\\mu$m with 2000 signal photons and 12 background photons.

  18. Determination of strain fields in porous shape memory alloys using micro-computed tomography

    Science.gov (United States)

    Bormann, Therese; Friess, Sebastian; de Wild, Michael; Schumacher, Ralf; Schulz, Georg; Müller, Bert

    2010-09-01

    Shape memory alloys (SMAs) belong to 'intelligent' materials since the metal alloy can change its macroscopic shape as the result of the temperature-induced, reversible martensite-austenite phase transition. SMAs are often applied for medical applications such as stents, hinge-less instruments, artificial muscles, and dental braces. Rapid prototyping techniques, including selective laser melting (SLM), allow fabricating complex porous SMA microstructures. In the present study, the macroscopic shape changes of the SMA test structures fabricated by SLM have been investigated by means of micro computed tomography (μCT). For this purpose, the SMA structures are placed into the heating stage of the μCT system SkyScan 1172™ (SkyScan, Kontich, Belgium) to acquire three-dimensional datasets above and below the transition temperature, i.e. at room temperature and at about 80°C, respectively. The two datasets were registered on the basis of an affine registration algorithm with nine independent parameters - three for the translation, three for the rotation and three for the scaling in orthogonal directions. Essentially, the scaling parameters characterize the macroscopic deformation of the SMA structure of interest. Furthermore, applying the non-rigid registration algorithm, the three-dimensional strain field of the SMA structure on the micrometer scale comes to light. The strain fields obtained will serve for the optimization of the SLM-process and, more important, of the design of the complex shaped SMA structures for tissue engineering and medical implants.

  19. Proposal for automated transformations on single-photon multipath qudits

    Science.gov (United States)

    Baldijão, R. D.; Borges, G. F.; Marques, B.; Solís-Prosser, M. A.; Neves, L.; Pádua, S.

    2017-09-01

    We propose a method for implementing automated state transformations on single-photon multipath qudits encoded in a one-dimensional transverse spatial domain. It relies on transferring the encoding from this domain to the orthogonal one by applying a spatial phase modulation with diffraction gratings, merging all the initial propagation paths by using a stable interferometric network, and filtering out the unwanted diffraction orders. The automation feature is attained by utilizing a programmable phase-only spatial light modulator (SLM) where properly designed diffraction gratings displayed on its screen will implement the desired transformations, including, among others, projections, permutations, and random operations. We discuss the losses in the process which is, in general, inherently nonunitary. Some examples of transformations are presented and, considering a realistic scenario, we analyze how they will be affected by the pixelated structure of the SLM screen. The method proposed here enables one to implement much more general transformations on multipath qudits than is possible with a SLM alone operating in the diagonal basis of which-path states. Therefore, it will extend the range of applicability for this encoding in high-dimensional quantum information and computing protocols as well as fundamental studies in quantum theory.

  20. An improved multi-exposure approach for high quality holographic femtosecond laser patterning

    International Nuclear Information System (INIS)

    Zhang, Chenchu; Hu, Yanlei; Li, Jiawen; Lao, Zhaoxin; Ni, Jincheng; Chu, Jiaru; Huang, Wenhao; Wu, Dong

    2014-01-01

    High efficiency two photon polymerization through single exposure via spatial light modulator (SLM) has been used to decrease the fabrication time and rapidly realize various micro/nanostructures, but the surface quality remains a big problem due to the speckle noise of optical intensity distribution at the defocused plane. Here, a multi-exposure approach which used tens of computer generate holograms successively loaded on SLM is presented to significantly improve the optical uniformity without losing efficiency. By applying multi-exposure, we found that the uniformity at the defocused plane was increased from ∼0.02 to ∼0.6 according to our simulation. The fabricated two series of letters “HELLO” and “USTC” under single-and multi-exposure in our experiment also verified that the surface quality was greatly improved. Moreover, by this method, several kinds of beam splitters with high quality, e.g., 2 × 2, 5 × 5 Daman, and complex nonseperate 5 × 5, gratings were fabricated with both of high quality and short time (<1 min, 95% time-saving). This multi-exposure SLM-two-photon polymerization method showed the promising prospect in rapidly fabricating and integrating various binary optical devices and their systems

  1. Additively Manufactured Low Cost Upper Stage Combustion Chamber

    Science.gov (United States)

    Protz, Christopher; Cooper, Ken; Ellis, David; Fikes, John; Jones, Zachary; Kim, Tony; Medina, Cory; Taminger, Karen; Willingham, Derek

    2016-01-01

    Over the past two years NASA's Low Cost Upper Stage Propulsion (LCUSP) project has developed Additive Manufacturing (AM) technologies and design tools aimed at reducing the costs and manufacturing time of regeneratively cooled rocket engine components. High pressure/high temperature combustion chambers and nozzles must be regeneratively cooled to survive their operating environment, causing their design fabrication to be costly and time consuming due to the number of individual steps and different processes required. Under LCUSP, AM technologies in Sintered Laser Melting (SLM) GRCop-84 and Electron Beam Freeform Fabrication (EBF3) Inconel 625 have been significantly advanced, allowing the team to successfully fabricate a 25k-class regenerative chamber. Estimates of the costs and schedule of future builds indicate cost reductions and significant schedule reductions will be enabled by this technology. Characterization of the microstructural and mechanical properties of the SLM-produced GRCop-84, EBF3 Inconel 625 and the interface layer between the two has been performed and indicates the properties will meet the design requirements. The LCUSP chamber is to be tested with a previously demonstrated SLM injector in order to advance the Technology Readiness Level (TRL) and demonstrate the capability of the application of these processes. NASA is advancing these technologies to reduce cost and schedule for future engine applications and commercial needs.

  2. Microstructure and Magnetic Properties of Magnetic Material Fabricated by Selective Laser Melting

    Science.gov (United States)

    Jhong, Kai Jyun; Huang, Wei-Chin; Lee, Wen Hsi

    Selective Laser Melting (SLM) is a powder-based additive manufacturing which is capable of producing parts layer-by-layer from a 3D CAD model. The aim of this study is to adopt the selective laser melting technique to magnetic material fabrication. [1]For the SLM process to be practical in industrial use, highly specific mechanical properties of the final product must be achieved. The integrity of the manufactured components depend strongly on each single laser-melted track and every single layer, as well as the strength of the connections between them. In this study, effects of the processing parameters, such as the space distance of surface morphology is analyzed. Our hypothesis is that when a magnetic product is made by the selective laser melting techniques instead of traditional techniques, the finished component will have more precise and effective properties. This study analyzed the magnitudes of magnetic properties in comparison with different parameters in the SLM process and compiled a completed product to investigate the efficiency in contrast with products made with existing manufacturing processes.

  3. Inconel 939 processed by selective laser melting: Effect of microstructure and temperature on the mechanical properties under static and cyclic loading

    Energy Technology Data Exchange (ETDEWEB)

    Kanagarajah, P., E-mail: p.kanagarajah@uni-paderborn.de [Lehrstuhl für Werkstoffkunde (Materials Science), University of Paderborn, Pohlweg 47-49, 33098 Paderborn (Germany); Brenne, F. [Lehrstuhl für Werkstoffkunde (Materials Science), University of Paderborn, Pohlweg 47-49, 33098 Paderborn (Germany); Direct Manufacturing Research Center (DMRC), Mersinweg 3, 33098 Paderborn (Germany); Niendorf, T. [Lehrstuhl für Werkstoffkunde (Materials Science), University of Paderborn, Pohlweg 47-49, 33098 Paderborn (Germany); Maier, H.J. [Direct Manufacturing Research Center (DMRC), Mersinweg 3, 33098 Paderborn (Germany); Institut für Werkstoffkunde, Leibniz Universität Hannover, An der Universität 2, 30823 Garbsen (Germany)

    2013-12-20

    Nickel-based superalloys, such as Inconel 939, are a long-established construction material for high-temperature applications and profound knowledge of the mechanical properties for this alloy produced by conventional techniques exists. However, many applications demand for highly complex geometries, e.g. in order to optimize the cooling capability of thermally loaded parts. Thus, additive manufacturing (AM) techniques have recently attracted substantial interest as they provide for an increased freedom of design. However, the microstructural features after AM processing are different from those after conventional processing. Thus, further research is vital for understanding the microstructure-processing relationship and its impact on the resulting mechanical properties. The aim of the present study was to investigate Inconel 939 processed by selective laser melting (SLM) and to reveal the differences to the conventional cast alloy. Thorough examinations were conducted using electron backscatter diffraction, transmission electron microscopy, optical microscopy and mechanical testing. It is demonstrated that the microstructure of the SLM-material is highly influenced by the heat flux during layer-wise manufacturing and consequently anisotropic microstructural features prevail. An epitaxial grain growth accounts for strong bonding between the single layers resulting in good mechanical properties already in the as-built condition. A heat treatment following SLM leads to microstructural features different to those obtained after the same heat treatment of the cast alloy. Still, the mechanical performance of the latter is met underlining the potential of this technique for producing complex parts for high temperature applications.

  4. In-situ formation of Ni4Ti3 precipitate and its effect on pseudoelasticity in selective laser melting additive manufactured NiTi-based composites

    Science.gov (United States)

    Gu, Dongdong; Ma, Chenglong

    2018-05-01

    Selective laser melting (SLM) additive manufacturing technology was applied to synthesize NiTi-based composites via using ball-milled Ti, Ni, and TiC mixed powder. By transmission electron microscope (TEM) characterization, it indicated that the B2 (NiTi) matrix was obtained during SLM processing. In spite of more Ti content (the Ti/Ni ratio >1), a mass of Ni-rich intermetallic compounds containing Ni4Ti3 with nanostructure features and eutectic Ni3Ti around in-situ Ti6C3.75 dendrites were precipitated. Influence of the applied laser volume energy density (VED) on the morphology and content of Ni4Ti3 precipitate was investigated. Besides, nanoindentation test of the matrix was performed in order to assess pseudoelastic recovery behavior of SLM processed NiTi-based composites. At a relatively high VED of 533 J/mm3, the maximum pseudoelastic recovery was obtained due to the lowest content of Ni4Ti3 precipitates. Furthermore, the precipitation mechanism of in-situ Ni4Ti3 was present based on the redistribution of titanium element and thermodynamics analysis, and then the relationship of Ni4Ti3 precipitate, VED and pseudoelastic recovery behavior was also revealed.

  5. Melting and solidification behavior of Cu/Al and Ti/Al bimetallic core/shell nanoparticles during additive manufacturing by molecular dynamics simulation

    Science.gov (United States)

    Rahmani, Farzin; Jeon, Jungmin; Jiang, Shan; Nouranian, Sasan

    2018-05-01

    Molecular dynamics (MD) simulations were performed to investigate the role of core volume fraction and number of fusing nanoparticles (NPs) on the melting and solidification of Cu/Al and Ti/Al bimetallic core/shell NPs during a superfast heating and slow cooling process, roughly mimicking the conditions of selective laser melting (SLM). One recent trend in the SLM process is the rapid prototyping of nanoscopically heterogeneous alloys, wherein the precious core metal maintains its particulate nature in the final manufactured part. With this potential application in focus, the current work reveals the fundamental role of the interface in the two-stage melting of the core/shell alloy NPs. For a two-NP system, the melting zone gets broader as the core volume fraction increases. This effect is more pronounced for the Ti/Al system than the Cu/Al system because of a larger difference between the melting temperatures of the shell and core metals in the former than the latter. In a larger six-NP system (more nanoscopically heterogeneous), the melting and solidification temperatures of the shell Al roughly coincide, irrespective of the heating or cooling rate, implying that in the SLM process, the part manufacturing time can be reduced due to solidification taking place at higher temperatures. The nanostructure evolution during the cooling of six-NP systems is further investigated. [Figure not available: see fulltext.

  6. Characterization Of Improved Binary Phase-Only Filters In A Real-Time Coherent Optical Correlation System

    Science.gov (United States)

    Flannery, D.; Keller, P.; Cartwright, S.; Loomis, J.

    1987-06-01

    Attractive correlation system performance potential is possible using magneto-optic spatial light modulators (SLM) to implement binary phase-only reference filters at high rates, provided the correlation performance of such reduced-information-content filters is adequate for the application. In the case studied here, the desired filter impulse response is a rectangular shape, which cannot be achieved with the usual binary phase-only filter formulation. The correlation application problem is described and techniques for synthesizing improved filter impulse response are considered. A compromise solution involves the cascading of a fixed amplitude-only weighting mask with the binary phase-only SLM. Based on simulations presented, this approach provides improved impulse responses and good correlation performance, while retaining the critical feature of real-time variations of the size, shape, and orientation of the rectangle by electronic programming of the phase pattern in the SLM. Simulations indicate that, for at least one very challenging input scene clutter situation, these filters provide higher correlation signal-to-noise than does "ideal" correlation, i.e. using a perfect rectangle filter response.

  7. Influence of Scanning Strategies on Processing of Aluminum Alloy EN AW 2618 Using Selective Laser Melting

    Science.gov (United States)

    Palousek, David; Pantelejev, Libor; Hoeller, Christian; Pichler, Rudolf; Tesicky, Lukas; Kaiser, Jozef

    2018-01-01

    This paper deals with various selective laser melting (SLM) processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 × 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material. PMID:29443912

  8. Thermal dynamic behavior during selective laser melting of K418 superalloy: numerical simulation and experimental verification

    Science.gov (United States)

    Chen, Zhen; Xiang, Yu; Wei, Zhengying; Wei, Pei; Lu, Bingheng; Zhang, Lijuan; Du, Jun

    2018-04-01

    During selective laser melting (SLM) of K418 powder, the influence of the process parameters, such as laser power P and scanning speed v, on the dynamic thermal behavior and morphology of the melted tracks was investigated numerically. A 3D finite difference method was established to predict the dynamic thermal behavior and flow mechanism of K418 powder irradiated by a Gaussian laser beam. A three-dimensional randomly packed powder bed composed of spherical particles was established by discrete element method. The powder particle information including particle size distribution and packing density were taken into account. The volume shrinkage and temperature-dependent thermophysical parameters such as thermal conductivity, specific heat, and other physical properties were also considered. The volume of fluid method was applied to reconstruct the free surface of the molten pool during SLM. The geometrical features, continuity boundaries, and irregularities of the molten pool were proved to be largely determined by the laser energy density. The numerical results are in good agreement with the experiments, which prove to be reasonable and effective. The results provide us some in-depth insight into the complex physical behavior during SLM and guide the optimization of process parameters.

  9. Double liquid membrane system for the removal of actinides and lanthanides from acidic nuclear wastes

    International Nuclear Information System (INIS)

    Chiarizia, R.; Danesi, P.R.

    1985-01-01

    Supported liquid membranes (SLM), consisting of an organic solution of n-octyl-(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and tributyl-phosphate (TBP) in decalin are able to perform selective separation and concentration of actinide and lanthanide ions from aqueous nitrate feed solutions and synthetic nuclear wastes. In the membrane process a possible strip solution is a mixture of formic acid and hydroxylammonium formate (HAF). The effectiveness of this strip solution is reduced and eventually nullified by the simultaneous transfer through the SLM of nitric acid which accumulates in the strip solution. A possible way to overcome this drawback is to make use of a second SLM consisting of a primary amine which is able to extract only HNO 3 from the strip solution. In this work the results obtained by experimentally studying the membrane system: synthetic nuclear waste/CMPO-TBP membrane/HCOOH-HAF strip solution/primary amine membrane/NaOH solution, are reported. They show that the use of a second liquid membrane is effective in controlling the HNO 3 concentration in the strip solution, thus allowing the actinide and lanthanide ions removal from the feed solution to proceed to completion. 15 refs., 10 figs., 1 tab

  10. Application of supported liquid membranes for removal of uranium from groundwater

    International Nuclear Information System (INIS)

    Chiarizia, R.; Horwitz, E.P.; Rickert, P.G.; Hodgson, K.M.

    1989-01-01

    The separation of uranium from Hanford site groundwater as studied by hollow-fiber supported liquid membranes, SLM. The carrier bis(2,4,4-trimethylpentyl)phosphinic acid, H[DTMPep], contained in the commercial extractant Cyanex trademark 272 was used as a membrane carrier, because of its selectivity for U over calcium and magnesium. The water soluble complexing agent, 1-hydroxyethane-1,1-diphosphonic acid, HEDPA, was used as stripping agent. Polypropylene hollow-fibers and n-dodecane were used as polymeric support and diluent, respectively. Laboratory scale hollow-fiber modules were employed in a recycling mode, using as feed synthetic groundwater at pH 2, to confirm the capability of the proposed SLM system to separate and concentrate U(VI) in the strip solution. Information was obtained on the U(VI) concentration factor and on the long-term performance of the SLMs. Encouraging results were obtained both with a conventional module and with a module containing a carrier solution reservoir. Industrial scale modules were used at Hanford to test the SLM separation of U(VI) from real contaminated groundwater. The uranium concentration was reduced from approximately 3500 ppB to about 1 ppB in a few hours. 9 refs., 8 figs., 4 tabs

  11. Fundamental Aspects of Selective Melting Additive Manufacturing Processes

    Energy Technology Data Exchange (ETDEWEB)

    van Swol, Frank B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Miller, James E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-12-01

    Certain details of the additive manufacturing process known as selective laser melting (SLM) affect the performance of the final metal part. To unleash the full potential of SLM it is crucial that the process engineer in the field receives guidance about how to select values for a multitude of process variables employed in the building process. These include, for example, the type of powder (e.g., size distribution, shape, type of alloy), orientation of the build axis, the beam scan rate, the beam power density, the scan pattern and scan rate. The science-based selection of these settings con- stitutes an intrinsically challenging multi-physics problem involving heating and melting a metal alloy, reactive, dynamic wetting followed by re-solidification. In addition, inherent to the process is its considerable variability that stems from the powder packing. Each time a limited number of powder particles are placed, the stacking is intrinsically different from the previous, possessing a different geometry, and having a different set of contact areas with the surrounding particles. As a result, even if all other process parameters (scan rate, etc) are exactly the same, the shape and contact geometry and area of the final melt pool will be unique to that particular configuration. This report identifies the most important issues facing SLM, discusses the fundamental physics associated with it and points out how modeling can support the additive manufacturing efforts.

  12. Compressed sensing approach for wrist vein biometrics.

    Science.gov (United States)

    Lantsov, Aleksey; Ryabko, Maxim; Shchekin, Aleksey

    2018-04-01

    The work describes features of the compressed sensing (CS) approach utilized for development of a wearable system for wrist vein recognition with single-pixel detection; we consider this system useful for biometrics authentication purposes. The CS approach implies use of a spatial light modulation (SLM) which, in our case, can be performed differently-with a liquid crystal display or diffusely scattering medium. We show that compressed sensing combined with above-mentioned means of SLM allows us to avoid using an optical system-a limiting factor for wearable devices. The trade-off between the 2 different SLM approaches regarding issues of practical implementation of CS approach for wrist vein recognition purposes is discussed. A possible solution of a misalignment problem-a typical issue for imaging systems based upon 2D arrays of photodiodes-is also proposed. Proposed design of the wearable device for wrist vein recognition is based upon single-pixel detection. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Additive manufacturing of reflective optics: evaluating finishing methods

    Science.gov (United States)

    Leuteritz, G.; Lachmayer, R.

    2018-02-01

    Individually shaped light distributions become more and more important in lighting technologies and thus the importance of additively manufactured reflectors increases significantly. The vast field of applications ranges from automotive lighting to medical imaging and bolsters the statement. However, the surfaces of additively manufactured reflectors suffer from insufficient optical properties even when manufactured using optimized process parameters for the Selective Laser Melting (SLM) process. Therefore post-process treatments of reflectors are necessary in order to further enhance their optical quality. This work concentrates on the effectiveness of post-process procedures for reflective optics. Based on already optimized aluminum reflectors, which are manufactured with a SLM machine, the parts are differently machined after the SLM process. Selected finishing methods like laser polishing, sputtering or sand blasting are applied and their effects quantified and compared. The post-process procedures are investigated on their impact on surface roughness and reflectance as well as geometrical precision. For each finishing method a demonstrator will be created and compared to a fully milled sample and among themselves. Ultimately, guidelines are developed in order to figure out the optimal treatment of additively manufactured reflectors regarding their optical and geometrical properties. Simulations of the light distributions will be validated with the developed demonstrators.

  14. Integrated test plan for the field demonstration of the supported liquid membrane unit

    International Nuclear Information System (INIS)

    Dunks, K.L.; Hodgson, K.M.

    1995-06-01

    This Integrated Test Plan describes the operation and testing of a hybrid reverse osmosis (RO)/coupled transport (CT) groundwater remediation test unit, also referred to as the Environmental Restoration Technology Demonstrations at the Hanford Site. The SLM will be used to remove uranium, technetium-99, and nitrate from a selected groundwater source at the Hanford Site. The overall purpose of this test is to determine the efficiency of the RO/CT membranes operating in a hybrid unit, the ease of operating and maintaining the SLM, and the amount of secondary waste generated as a result of processing. The goal of the SLM is to develop a RO/CT process that will be applicable for removing contaminants from almost any contaminated water. This includes the effluents generated as part of the day-to-day operation of most any US Department of Energy (DOE) site. The removal of contaminants from the groundwaters before they reach the Columbia River or offsite extraction wells will reduce the risk that the population will be exposed to these compounds and will reduce the cost of subsequent groundwater cleanup

  15. Effect of Laser Power and Scan Speed on Melt Pool Characteristics of Commercially Pure Titanium (CP-Ti)

    Science.gov (United States)

    Kusuma, Chandrakanth; Ahmed, Sazzad H.; Mian, Ahsan; Srinivasan, Raghavan

    2017-07-01

    Selective laser melting (SLM) is an additive manufacturing technique that creates complex parts by selectively melting metal powder layer-by-layer using a laser. In SLM, the process parameters decide the quality of the fabricated component. In this study, single beads of commercially pure titanium (CP-Ti) were melted on a substrate of the same material using an in-house built SLM machine. Multiple combinations of laser power and scan speed were used for single bead fabrication, while the laser beam diameter and powder layer thickness were kept constant. This experimental study investigated the influence of laser power, scan speed, and laser energy density on the melt pool formation, surface morphology, geometry (width and height), and hardness of solidified beads. In addition, the observed unfavorable effect such as inconsistency in melt pool width formation is discussed. The results show that the quality, geometry, and hardness of solidified melt pool are significantly affected by laser power, scanning speed, and laser energy density.

  16. Metallic powder-bed based 3D printing of cellular scaffolds for orthopaedic implants: A state-of-the-art review on manufacturing, topological design, mechanical properties and biocompatibility.

    Science.gov (United States)

    Tan, X P; Tan, Y J; Chow, C S L; Tor, S B; Yeong, W Y

    2017-07-01

    Metallic cellular scaffold is one of the best choices for orthopaedic implants as a replacement of human body parts, which could improve life quality and increase longevity for the people needed. Unlike conventional methods of making cellular scaffolds, three-dimensional (3D) printing or additive manufacturing opens up new possibilities to fabricate those customisable intricate designs with highly interconnected pores. In the past decade, metallic powder-bed based 3D printing methods emerged and the techniques are becoming increasingly mature recently, where selective laser melting (SLM) and selective electron beam melting (SEBM) are the two representatives. Due to the advantages of good dimensional accuracy, high build resolution, clean build environment, saving materials, high customisability, etc., SLM and SEBM show huge potential in direct customisable manufacturing of metallic cellular scaffolds for orthopaedic implants. Ti-6Al-4V to date is still considered to be the optimal materials for producing orthopaedic implants due to its best combination of biocompatibility, corrosion resistance and mechanical properties. This paper presents a state-of-the-art overview mainly on manufacturing, topological design, mechanical properties and biocompatibility of cellular Ti-6Al-4V scaffolds via SLM and SEBM methods. Current manufacturing limitations, topological shortcomings, uncertainty of biocompatible test were sufficiently discussed herein. Future perspectives and recommendations were given at the end. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Speed and the coherence of superimposed chromatic gratings.

    Science.gov (United States)

    Bosten, J M; Smith, L; Mollon, J D

    2016-05-01

    On the basis of measurements of the perceived coherence of superimposed drifting gratings, Krauskopf and Farell (1990) proposed that motion is analysed independently in different chromatic channels. They found that two gratings appeared to slip if each modulated one of the two 'cardinal' color mechanisms S/(L+M) and L/(L+M). If the gratings were defined along intermediate color directions, observers reported a plaid, moving coherently. We hypothesised that slippage might occur in chromatic gratings if the motion signal from the S/(L+M) channel is weak and equivalent to a lower speed. We asked observers to judge coherence in two conditions. In one, S/(L+M) and L/(L+M) gratings were physically the same speed. In the other, the two gratings had perceptually matched speeds. We found that the relative incoherence of cardinal gratings is the same whether gratings are physically or perceptually matched in speed. Thus our hypothesis was firmly contradicted. In a control condition, observers were asked to judge the coherence of stationary gratings. Interestingly, the difference in judged coherence between cardinal and intermediate gratings remained as strong as it was when the gratings moved. Our results suggest a possible alternative interpretation of Krauskopf and Farell's result: the processes of object segregation may precede the analysis of the motion of chromatic gratings, and the same grouping signals may prompt object segregation in the stationary and moving cases. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. A hybrid system for beam steering and wavefront control

    Science.gov (United States)

    Nikulin, Vladimir V.

    2004-06-01

    Performance of long-range mobile laser systems operating within Earth's atmosphere is generally limited by several factors. Movement of the communicating platforms, such as aircraft, terrain vehicles, etc., complemented by mechanical vibrations, is the main cause of pointing errors. In addition, atmospheric turbulence causes changes of the refractive index along the propagation path that lead to phase distortions (aberrations), thus creating random redistribution of optical energy in the spatial domain. The combined effect of these factors leads to an increased bit-error probability under adverse operation conditions. While traditional approaches provide separate treatment of these problems, suggesting the development of high-bandwidth beam steering systems to perform tracking and jitter rejection, and wavefront control for the mitigation of atmospheric effects, the two tasks could be integrated. In this paper we present a hybrid laser beam steering/wavefront control system comprising an electrically addressed spatial light modulator (SLM) installed on the Omni-Wrist sensor mount platform. The function of the Omni-Wrist is to provide coarse steering over a wide range of pointing angles, while the purpose of the SLM is twofold: it performs wavefront correction and fine steering. The control law for the Omni-Wrist is synthesized using the decentralized approach that provides independent access to the azimuth and declination channels, while the algorithm for calculating the required phase profile for the SLM is optimization-based. This paper presents the control algorithms, the approach to coordinating the operation of the both systems and the simulation results.

  19. Fusion of adaptive beam steering and optimization-based wavefront control for laser communications in atmosphere

    Science.gov (United States)

    Nikulin, Vladimir V.

    2005-10-01

    The performance of mobile laser communication systems operating within Earth's atmosphere is generally limited by the pointing errors due to movement of the platforms and mechanical vibrations. In addition, atmospheric turbulence causes changes of the refractive index along the propagation path, creating random redistribution of the optical energy in the spatial domain. Under adverse conditions these effects lead to increased bit error rate. While traditional approaches provide separate treatment of these problems, suggesting high-bandwidth beam steering systems for tracking and wavefront control for the mitigation of atmospheric effects, the two tasks can be integrated. This paper presents a hybrid laser beam-steering-wavefront-control system comprising an electrically addressed spatial light modulator (SLM) installed on the Omni-Wrist sensor mount. The function of the Omni-Wrist is to provide coarse steering over a wide range of pointing angles, while that of the SLM is twofold: wavefront correction and fine steering. The control law for the Omni-Wrist is synthesized using a decentralized approach that provides independent access to the azimuth and declination channels; calculation of the required phase profile for the SLM is optimization-based. This paper presents the control algorithms, the approach to coordinating the operation of the two systems, and the results.

  20. Fabrication and characterization of selective laser melting printed Ti–6Al–4V alloys subjected to heat treatment for customized implants design

    Directory of Open Access Journals (Sweden)

    Mengke Wang

    2016-12-01

    Full Text Available Selective laser melting (SLM is a promising technique capable of rapidly fabricating customized implants having desired macro- and micro-structures by using computer-aided design models. However, the SLM-based products often have non-equilibrium microstructures and partial surface defects because of the steep thermal gradients and high solidification rates that occur during the laser melting. To meet clinical requirements, a heat treatment was used to tailor the physiochemical properties, homogenize the metallic microstructures, and eliminate surface defects, expecting to improve the cytocompatibility in vitro. Compared with the as-printed Ti–6Al–4V substrate, the heat-treated substrate had a more hydrophilic, rougher and more homogeneous surface, which should promote the early cell attachment, proliferation and osseointegration. More importantly, a crystalline rutile TiO2 layer formed during the heat treatment, which should greatly promote the biocompatibility and corrosion resistance of the implant. Compared to the untreated surfaces, the adhesion and proliferation of human bone mesenchymal stem cells (hBMSCs on heat-treated substrates were significantly enhanced, implying an excellent cytocompatibility after annealing. Therefore, these findings provide an alternative to biofunctionalized SLM-based Ti–6Al–4V implants with optimized physiochemical properties and biocompatibility for orthopedic and dental applications.

  1. Comparison between basal and apical dendritic spines in estrogen-induced rapid spinogenesis of CA1 principal neurons in the adult hippocampus

    International Nuclear Information System (INIS)

    Murakami, Gen; Tsurugizawa, Tomokazu; Hatanaka, Yusuke; Komatsuzaki, Yoshimasa; Tanabe, Nobuaki; Mukai, Hideo; Hojo, Yasushi; Kominami, Shiro; Yamazaki, Takeshi; Kimoto, Tetsuya; Kawato, Suguru

    2006-01-01

    Modulation of hippocampal synaptic plasticity by estrogen has been attracting much attention. Here, we demonstrated the rapid effect of 17β-estradiol on the density and morphology of spines in the stratum oriens (s.o., basal side) and in the stratum lacunosum-moleculare (s.l.m., apical side) by imaging Lucifer Yellow-injected CA1 neurons in adult male rat hippocampal slices, because spines in s.o. and s.l.m. have been poorly understood as compared with spines in the stratum radiatum. The application of 1 nM estradiol-induced a rapid increase in the density of spines of pyramidal neurons within 2 h. This increase by estradiol was blocked by Erk MAP kinase inhibitor and estrogen receptor inhibitor in both regions. Effect of blockade by agonists of AMPA receptors and NMDA receptors was different between s.o. and s.l.m. In both regions, ERα agonist PPT induced the same enhancing effect of spinogenesis as that induced by estradiol

  2. An improved multi-exposure approach for high quality holographic femtosecond laser patterning

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chenchu; Hu, Yanlei, E-mail: huyl@ustc.edu.cn, E-mail: jwl@ustc.edu.cn; Li, Jiawen, E-mail: huyl@ustc.edu.cn, E-mail: jwl@ustc.edu.cn; Lao, Zhaoxin; Ni, Jincheng; Chu, Jiaru; Huang, Wenhao; Wu, Dong [Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026 (China)

    2014-12-01

    High efficiency two photon polymerization through single exposure via spatial light modulator (SLM) has been used to decrease the fabrication time and rapidly realize various micro/nanostructures, but the surface quality remains a big problem due to the speckle noise of optical intensity distribution at the defocused plane. Here, a multi-exposure approach which used tens of computer generate holograms successively loaded on SLM is presented to significantly improve the optical uniformity without losing efficiency. By applying multi-exposure, we found that the uniformity at the defocused plane was increased from ∼0.02 to ∼0.6 according to our simulation. The fabricated two series of letters “HELLO” and “USTC” under single-and multi-exposure in our experiment also verified that the surface quality was greatly improved. Moreover, by this method, several kinds of beam splitters with high quality, e.g., 2 × 2, 5 × 5 Daman, and complex nonseperate 5 × 5, gratings were fabricated with both of high quality and short time (<1 min, 95% time-saving). This multi-exposure SLM-two-photon polymerization method showed the promising prospect in rapidly fabricating and integrating various binary optical devices and their systems.

  3. Metallurgy of high-silicon steel parts produced using Selective Laser Melting

    International Nuclear Information System (INIS)

    Garibaldi, Michele; Ashcroft, Ian; Simonelli, Marco; Hague, Richard

    2016-01-01

    The metallurgy of high-silicon steel (6.9%wt.Si) processed using Selective Laser Melting (SLM) is presented for the first time in this study. High-silicon steel has great potential as a soft magnetic alloy, but its employment has been limited due to its poor workability. The effect of SLM-processing on the metallurgy of the alloy is investigated in this work using microscopy, X-Ray Diffraction (XRD) and Electron Backscatter Diffraction (EBSD). XRD analysis suggests that the SLM high-silicon steel is a single ferritic phase (solid solution), with no sign of phase ordering. This is expected to have beneficial effects on the material properties, since ordering has been shown to make silicon steels more brittle and electrically conductive. For near-fully dense samples, columnar grains with a high aspect ratio and oriented along the build direction are found. Most importantly, a <001> fibre-texture along the build direction can be changed into a cube-texture when the qualitative shape of the melt-pool is altered (from shallow to deep) by increasing the energy input of the scanning laser. This feature could potentially open the path to the manufacture of three-dimensional grain-oriented high-silicon steels for electromechanical applications.

  4. Induction of osteogenic differentiation of adipose derived stem cells by microstructured nitinol actuator-mediated mechanical stress.

    Directory of Open Access Journals (Sweden)

    Sarah Strauß

    Full Text Available The development of large tissue engineered bone remains a challenge in vitro, therefore the use of hybrid-implants might offer a bridge between tissue engineering and dense metal or ceramic implants. Especially the combination of the pseudoelastic implant material Nitinol (NiTi with adipose derived stem cells (ASCs opens new opportunities, as ASCs are able to differentiate osteogenically and therefore enhance osseointegration of implants. Due to limited knowledge about the effects of NiTi-structures manufactured by selective laser melting (SLM on ASCs the study started with an evaluation of cytocompatibility followed by the investigation of the use of SLM-generated 3-dimensional NiTi-structures preseeded with ASCs as osteoimplant model. In this study we could demonstrate for the first time that osteogenic differentiation of ASCs can be induced by implant-mediated mechanical stimulation without support of osteogenic cell culture media. By use of an innovative implant design and synthesis via SLM-technique we achieved high rates of vital cells, proper osteogenic differentiation and mechanically loadable NiTi-scaffolds could be achieved.

  5. Application of Spatial Regression Models to Income Poverty Ratios in Middle Delta Contiguous Counties in Egypt

    Directory of Open Access Journals (Sweden)

    Sohair F Higazi

    2013-02-01

    Full Text Available Regression analysis depends on several assumptions that have to be satisfied. A major assumption that is never satisfied when variables are from contiguous observations is the independence of error terms. Spatial analysis treated the violation of that assumption by two derived models that put contiguity of observations into consideration. Data used are from Egypt's 2006 latest census, for 93 counties in middle delta seven adjacent Governorates. The dependent variable used is the percent of individuals classified as poor (those who make less than 1$ daily. Predictors are some demographic indicators. Explanatory Spatial Data Analysis (ESDA is performed to examine the existence of spatial clustering and spatial autocorrelation between neighboring counties. The ESDA revealed spatial clusters and spatial correlation between locations. Three statistical models are applied to the data, the Ordinary Least Square regression model (OLS, the Spatial Error Model (SEM and the Spatial Lag Model (SLM.The Likelihood Ratio test and some information criterions are used to compare SLM and SEM to OLS. The SEM model proved to be better than the SLM model. Recommendations are drawn regarding the two spatial models used.

  6. Computational hologram synthesis and representation on spatial light modulators for real-time 3D holographic imaging

    International Nuclear Information System (INIS)

    Reichelt, Stephan; Leister, Norbert

    2013-01-01

    In dynamic computer-generated holography that utilizes spatial light modulators, both hologram synthesis and hologram representation are essential in terms of fast computation and high reconstruction quality. For hologram synthesis, i.e. the computation step, Fresnel transform based or point-source based raytracing methods can be applied. In the encoding step, the complex wave-field has to be optimally represented by the SLM with its given modulation capability. For proper hologram reconstruction that implies a simultaneous and independent amplitude and phase modulation of the input wave-field by the SLM. In this paper, we discuss full complex hologram representation methods on SLMs by considering inherent SLM parameter such as modulation type and bit depth on their reconstruction performance such as diffraction efficiency and SNR. We review the three implementation schemes of Burckhardt amplitude-only representation, phase-only macro-pixel representation, and two-phase interference representation. Besides the optical performance we address their hardware complexity and required computational load. Finally, we experimentally demonstrate holographic reconstructions of different representation schemes as obtained by functional prototypes utilizing SeeReal's viewing-window holographic display technology. The proposed hardware implementations enable a fast encoding of complex-valued hologram data and thus will pave the way for commercial real-time holographic 3D imaging in the near future.

  7. Pilot study of methods and equipment for in-home noise level measurements.

    Science.gov (United States)

    Neitzel, Richard L; Heikkinen, Maire S A; Williams, Christopher C; Viet, Susan Marie; Dellarco, Michael

    2015-01-15

    Knowledge of the auditory and non-auditory effects of noise has increased dramatically over the past decade, but indoor noise exposure measurement methods have not advanced appreciably, despite the introduction of applicable new technologies. This study evaluated various conventional and smart devices for exposure assessment in the National Children's Study. Three devices were tested: a sound level meter (SLM), a dosimeter, and a smart device with a noise measurement application installed. Instrument performance was evaluated in a series of semi-controlled tests in office environments over 96-hour periods, followed by measurements made continuously in two rooms (a child's bedroom and a most used room) in nine participating homes over a 7-day period with subsequent computation of a range of noise metrics. The SLMs and dosimeters yielded similar A-weighted average noise levels. Levels measured by the smart devices often differed substantially (showing both positive and negative bias, depending on the metric) from those measured via SLM and dosimeter, and demonstrated attenuation in some frequency bands in spectral analysis compared to SLM results. Virtually all measurements exceeded the Environmental Protection Agency's 45 dBA day-night limit for indoor residential exposures. The measurement protocol developed here can be employed in homes, demonstrates the possibility of measuring long-term noise exposures in homes with technologies beyond traditional SLMs, and highlights potential pitfalls associated with measurements made by smart devices.

  8. [Effect of fluoride concentration on the corrosion behavior of cobalt-chromium alloy fabricated by two different technology processes].

    Science.gov (United States)

    Qiuxia, Yang; Ying, Yang; Han, Xu; Di, Wu; Ke, Guo

    2016-02-01

    This study aims to determine the effect of fluoride concentration on the corrosion behavior of cobalt-chromium alloy fabricated by two different technology processes in a simulated oral environment. A total of 15 specimens were employed with selective laser melting (SLM) and another 15 for traditional casting (Cast) in cobalt-chromium alloy powders and blocks with the same material composition. The corrosion behavior of the specimens was studied by potentiodynamic polarization test under different oral environments with varying solubilities of fluorine (0, 0.05%, and 0.20% for each) in acid artificial saliva (pH = 5.0). The specimens were soaked in fluorine for 24 h, and the surface microstructure was observed under a field emission scanning electron microscope after immersing the specimens in the test solution at constant temperature. The corrosion potential (Ecorr) value of the cobalt-chromium alloy cast decreased with increasing fluoride concentration in acidic artificial saliva. The Ecorr, Icorr, and Rp values of the cobalt-chromium alloy fabricated by two different technology processes changed significantly when the fluoride concentration was 0.20% (P technology processes exhibited a statistically significant difference. The Icorr value of the cobalt-chromium alloy cast was higher than that in the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20% (P technology processes. The corrosion resistance of the cobalt-chromium alloy cast was worse than that of the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20%.

  9. Interleaved segment correction achieves higher improvement factors in using genetic algorithm to optimize light focusing through scattering media

    Science.gov (United States)

    Li, Runze; Peng, Tong; Liang, Yansheng; Yang, Yanlong; Yao, Baoli; Yu, Xianghua; Min, Junwei; Lei, Ming; Yan, Shaohui; Zhang, Chunmin; Ye, Tong

    2017-10-01

    Focusing and imaging through scattering media has been proved possible with high resolution wavefront shaping. A completely scrambled scattering field can be corrected by applying a correction phase mask on a phase only spatial light modulator (SLM) and thereby the focusing quality can be improved. The correction phase is often found by global searching algorithms, among which Genetic Algorithm (GA) stands out for its parallel optimization process and high performance in noisy environment. However, the convergence of GA slows down gradually with the progression of optimization, causing the improvement factor of optimization to reach a plateau eventually. In this report, we propose an interleaved segment correction (ISC) method that can significantly boost the improvement factor with the same number of iterations comparing with the conventional all segment correction method. In the ISC method, all the phase segments are divided into a number of interleaved groups; GA optimization procedures are performed individually and sequentially among each group of segments. The final correction phase mask is formed by applying correction phases of all interleaved groups together on the SLM. The ISC method has been proved significantly useful in practice because of its ability to achieve better improvement factors when noise is present in the system. We have also demonstrated that the imaging quality is improved as better correction phases are found and applied on the SLM. Additionally, the ISC method lowers the demand of dynamic ranges of detection devices. The proposed method holds potential in applications, such as high-resolution imaging in deep tissue.

  10. A narrow linewidth tunable single longitudinal mode Ga-EDF fiber laser

    Science.gov (United States)

    Mohamed Halip, N. H.; Abu Bakar, M. H.; Latif, A. A.; Muhd-Yasin, S. Z.; Zulkifli, M. I.; Mat-Sharif, K. A.; Omar, N. Y. M.; Mansoor, A.; Abdul-Rashid, H. A.; Mahdi, M. A.

    2018-05-01

    A tunable ring cavity single longitudinal mode (SLM) fiber laser incorporating Gallium-Erbium co-doped fiber (Ga-EDF) gain medium and several mode filtration techniques is demonstrated. With Ga-EDF, high emission power was accorded in short fiber length, allowing shorter overall cavity length and wider free spectral range. Tunable bandpass filter, sub-ring structure, and cascaded dissimilar fiber taper were utilized to filter multi-longitudinal modes. Each of the filter mechanism was tested individually within the laser cavity to assess its performance. Once the performance of each filter was obtained, all of them were deployed into the laser system. Ultimately, the 1561.47 nm SLM laser achieved a narrow linewidth laser, optical signal-to-noise ratio, and power fluctuation of 1.19 kHz, 61.52 dB and 0.16 dB, respectively. This work validates the feasibility of Ga-EDF to attain a stable SLM output in simple laser configuration.

  11. Fabrication and heat treatment of high strength Al-Cu-Mg alloy processed using selective laser melting

    Science.gov (United States)

    Zhang, Hu; Zhu, Haihong; Nie, Xiaojia; Qi, Ting; Hu, Zhiheng; Zeng, Xiaoyan

    2016-04-01

    The proposed paper illustrates the fabrication and heat treatment of high strength Al-Cu-Mg alloy produced by selective laser melting (SLM) process. Al-Cu-Mg alloy is one of the heat treatable aluminum alloys regarded as difficult to fusion weld. SLM is an additive manufacturing technique through which components are built by selectively melting powder layers with a focused laser beam. The process is characterized by short laser-powder interaction times and localized high heat input, which leads to steep thermal gradients, rapid solidification and fast cooling. In this research, 3D Al-Cu-Mg parts with relative high density of 99.8% are produced by SLM from gas atomized powders. Room temperature tensile tests reveal a remarkable mechanical behavior: the samples show yield and tensile strengths of about 276 MPa and 402 MPa, respectively, along with fracture strain of 6%. The effect of solution treatment on microstructure and related tensile properties is examined and the results demonstrate that the mechanical behavior of the SLMed Al-Cu-Mg samples can be greatly enhanced through proper heat treatment. After T4 solution treatment at 540°C, under the effect of precipitation strengthening, the tensile strength and the yield strength increase to 532 MPa and 338 MPa, respectively, and the elongation increases to 13%.

  12. Leaf phenology and its associated traits in the wintergreen species Aristotelia chilensis (Mol. Stuntz (Elaeocarpaceae Fenología foliar y sus caracteres asociados en la especie invierno-verde Aristotelia chilensis (Mol. Stuntz (Elaeocarpaceae

    Directory of Open Access Journals (Sweden)

    MARÍA ANGÉLICA DAMASCOS

    2001-12-01

    Full Text Available The post-summer leaf demography of the wintergreen species Aristotelia chilensis growing near San Carlos de Bariloche, Argentina, is described. Its specific leaf mass (SLM, g m-2 is compared to that of the deciduous and evergreen species of the Andean-Patagonian forests and to that of other communities abroad. The pattern of leaf emergence is intermediate, with leaf flush in spring (basal cohort, BC, followed by successive unfolding of the remaining leaves (distal cohort, DC during summer. The senescence of the BC occurs mainly in autumn, with a loss of 11-31 % of its SLM. The DC falls synchronously in mid-spring and the SLM loss in winter is 10-13 %. The SLM of A. chilensis (103.6 ± 6.2 g m-2 is intermediate when compared to the general mean values of deciduous (73.7 ± 15.9 g m-2 and evergreen species (154.8 ± 45.8 g m-2. The SLM of deciduous and evergreen species of three different forests near San Carlos de Bariloche varied significantly at the end of the growing season while that of A. chilensis showed more constant values. The periodicity of leaf production and senescence in A. chilensis allows the maintenance of one leaf cohort throughout the year, covering the carbon demand for flowering and leaf production in spring. This differentiates the deciduous from the wintergreen species, despite their similar mean leaf life span values, while the evergreen species have a longer leaf turnover. Considering the conditions for growth in each studied forest, the leaf life span was not the only factor determining the SLM value. This variable would also depend on multiple stresses that may act during the ontogenesis and evolution of the leaves in each phenological groupSe describe la demografía foliar después del verano de la especie invierno-verde Aristotelia chilensis, creciendo cerca de la ciudad de San Carlos de Bariloche, Argentina. Se compara su peso específico foliar (SLM, g m-2 con los valores de especies deciduas y siempreverdes de los

  13. Mechanical Properties of Optimized Diamond Lattice Structure for Bone Scaffolds Fabricated via Selective Laser Melting

    Science.gov (United States)

    Zhang, David Z.; Zhang, Peng; Zhao, Miao; Jafar, Salman

    2018-01-01

    Developments in selective laser melting (SLM) have enabled the fabrication of periodic cellular lattice structures characterized by suitable properties matching the bone tissue well and by fluid permeability from interconnected structures. These multifunctional performances are significantly affected by cell topology and constitutive properties of applied materials. In this respect, a diamond unit cell was designed in particular volume fractions corresponding to the host bone tissue and optimized with a smooth surface at nodes leading to fewer stress concentrations. There were 33 porous titanium samples with different volume fractions, from 1.28 to 18.6%, manufactured using SLM. All of them were performed under compressive load to determine the deformation and failure mechanisms, accompanied by an in-situ approach using digital image correlation (DIC) to reveal stress–strain evolution. The results showed that lattice structures manufactured by SLM exhibited comparable properties to those of trabecular bone, avoiding the effects of stress-shielding and increasing longevity of implants. The curvature of optimized surface can play a role in regulating the relationship between density and mechanical properties. Owing to the release of stress concentration from optimized surface, the failure mechanism of porous titanium has been changed from the pattern of bottom-up collapse by layer (or cell row) to that of the diagonal (45°) shear band, resulting in the significant enhancement of the structural strength. PMID:29510492

  14. Influence of Load Modes on Voltage Stability of Receiving Network at DC/AC System

    Directory of Open Access Journals (Sweden)

    Mao Chizu

    2016-01-01

    Full Text Available This paper analyses influence of load modes on DC/AC system. Because of widespread use of HVDC, DC/AC system become more complex than before and the present modes used in dispatch and planning departments are not fit in simulation anymore. So it is necessary to find load modes accurately reflecting characteristics of the system. For the sake of the voltage stability, commutation failure, etc. the practical example of the receiving network in a large DC/AC system in China is simulated with BPA, and the influence of Classical Load Mode (CLM and Synthesis load model (SLM on simulation results is studies. Furthermore, some important parameters of SLM are varied respectively among an interval to analyse how they affect the system. According to this practical examples, the result is closely related to load modes and their parameters, and SLM is more conservative but more reasonable than the present modes. The consequences indicate that at critical states, micro variation in parameters may give rise to change in simulation results radically. Thus, correct mode and parameters are important to enhance simulation accuracy of DC/AC system and researches on how they affect the system make senses.

  15. An investigation of the effects of experimental parameters on the closed-loop control of photoionization/dissociation processes in acetophenone

    Science.gov (United States)

    Graham, Paul; Menkir, Getahun; Levis, Robert J.

    2003-06-01

    The photodissociation channels of acetophenone (C 6H 5)CO(CH 3), can be controlled by the use of tailored strong-field laser pulses together with a feedback loop incorporating an adaptive algorithm. This optimal control strategy is used to selectively cleave either the OCCH 3 or OCC 6H 5 bonds, monitored by detecting either mass 105 or 77, respectively. Varying the pulse chirp and duration prior to optimization is shown to affect the dynamic range of control. We show that it is possible to decrease the search space by limiting the retardance range of the spatial light modulator (SLM), or by decreasing the number of frequency elements manipulated by the SLM, and still achieve a certain degree of control over acetophenone dissociation. Performing consecutive experiments with identical experimental parameters and search criteria reveals that the learning algorithm may find solutions that have the same degree of control (various local solutions), with either similar SLM retardances or markedly different retardances. Comparison of the dynamic range of control between single-parameter optimizations (pulse energy and duration) with the tailored electric field profiles generated by the adaptive algorithm reveals an enhancement in the control of reaction product distributions in the latter scheme.

  16. Investigation into Effects of Scanning Speed on in Vitro Biocompatibility of Selective Laser Melted 316L Stainless Steel Parts

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    Shang Yitong

    2017-01-01

    Full Text Available In recent years, selective laser melting (SLM has gained an important place in fabrication due to their strong individualization which cannot be manufactured using conventional processes such as casting or forging. By proper control of the SLM processing parameters, characteristics of the alloy can be optimized. In the present work, 316L stainless steel (SS, as a widely used biomedical material, is investigated in terms of the effects of scanning speed on in vitro biocompatibility during SLM process. Cytotoxicity assay is adopted to assess the in vitro biocompatibility. The results show the scanning speed strongly affects the in vitro biocompatibility of 316L SS parts and with prolongs of incubation time, the cytotoxicity increase and the in vitro biocompatibility gets worse. The optimal parameters are determined as follows: scanning speed of 900 mm/s, laser power of 195 W, hatch spacing of 0.09 mm and layer thickness of 0.02 mm. The processing parameters lead to the change of surface morphology and microstructures of samples, which can affect the amount of toxic ions release, such as Cr, Mo and Co, that can increase risks to patient health and reduce the biocompatibility.

  17. Influence of Scanning Strategies on Processing of Aluminum Alloy EN AW 2618 Using Selective Laser Melting.

    Science.gov (United States)

    Koutny, Daniel; Palousek, David; Pantelejev, Libor; Hoeller, Christian; Pichler, Rudolf; Tesicky, Lukas; Kaiser, Jozef

    2018-02-14

    This paper deals with various selective laser melting (SLM) processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 × 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material.

  18. Surface Roughness of a 3D-Printed Ni-Cr Alloy Produced by Selective Laser Melting: Effect of Process Parameters.

    Science.gov (United States)

    Hong, Min-Ho; Son, Jun Sik; Kwon, Tae-Yub

    2018-03-01

    The selective laser melting (SLM) process parameters, which directly determine the melting behavior of the metallic powders, greatly affect the nanostructure and surface roughness of the resulting 3D object. This study investigated the effect of various laser process parameters (laser power, scan rate, and scan line spacing) on the surface roughness of a nickel-chromium (Ni-Cr) alloy that was three-dimensionally (3D) constructed using SLM. Single-line formation tests were used to determine the optimal laser power of 200 W and scan rate of 98.8 mm/s, which resulted in beads with an optimal profile. In the subsequent multi-layer formation tests, the 3D object with the smoothest surface (Ra = 1.3 μm) was fabricated at a scan line spacing of 60 μm (overlap ratio = 73%). Narrow scan line spacing (and thus large overlap ratios) was preferred over wide scan line spacing to reduce the surface roughness of the 3D body. The findings of this study suggest that the laser power, scan rate, and scan line spacing are the key factors that control the surface quality of Ni-Cr alloys produced by SLM.

  19. Microstructures and Mechanical Properties of Co-Cr Dental Alloys Fabricated by Three CAD/CAM-Based Processing Techniques

    Directory of Open Access Journals (Sweden)

    Hae Ri Kim

    2016-07-01

    Full Text Available The microstructures and mechanical properties of cobalt-chromium (Co-Cr alloys produced by three CAD/CAM-based processing techniques were investigated in comparison with those produced by the traditional casting technique. Four groups of disc- (microstructures or dumbbell- (mechanical properties specimens made of Co-Cr alloys were prepared using casting (CS, milling (ML, selective laser melting (SLM, and milling/post-sintering (ML/PS. For each technique, the corresponding commercial alloy material was used. The microstructures of the specimens were evaluated via X-ray diffractometry, optical and scanning electron microscopy with energy-dispersive X-ray spectroscopy, and electron backscattered diffraction pattern analysis. The mechanical properties were evaluated using a tensile test according to ISO 22674 (n = 6. The microstructure of the alloys was strongly influenced by the manufacturing processes. Overall, the SLM group showed superior mechanical properties, the ML/PS group being nearly comparable. The mechanical properties of the ML group were inferior to those of the CS group. The microstructures and mechanical properties of Co-Cr alloys were greatly dependent on the manufacturing technique as well as the chemical composition. The SLM and ML/PS techniques may be considered promising alternatives to the Co-Cr alloy casting process.

  20. Meso-scale defect evaluation of selective laser melting using spatially resolved acoustic spectroscopy.

    Science.gov (United States)

    Hirsch, M; Catchpole-Smith, S; Patel, R; Marrow, P; Li, Wenqi; Tuck, C; Sharples, S D; Clare, A T

    2017-09-01

    Developments in additive manufacturing technology are serving to expand the potential applications. Critical developments are required in the supporting areas of measurement and in process inspection to achieve this. CM247LC is a nickel superalloy that is of interest for use in aerospace and civil power plants. However, it is difficult to process via selective laser melting (SLM) as it suffers from cracking during rapid cooling and solidification. This limits the viability of CM247LC parts created using SLM. To quantify part integrity, spatially resolved acoustic spectroscopy (SRAS) has been identified as a viable non-destructive evaluation technique. In this study, a combination of optical microscopy and SRAS was used to identify and classify the surface defects present in SLM-produced parts. By analysing the datasets and scan trajectories, it is possible to correlate morphological information with process parameters. Image processing was used to quantify porosity and cracking for bulk density measurement. Analysis of surface acoustic wave data showed that an error in manufacture in the form of an overscan occurred. Comparing areas affected by overscan with a bulk material, a change in defect density from 1.17% in the bulk material to 5.32% in the overscan regions was observed, highlighting the need to reduce overscan areas in manufacture.