3,442 research outputs found

    Combinatorial synthesis and high-throughput photopotential and photocurrent screening of mixed-metal oxides for photoelectrochemical water splitting

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    A high-throughput method has been developed using a commercial piezoelectric inkjet printer for synthesis and characterization of mixed-metal oxide photoelectrode materials for water splitting. The printer was used to deposit metal nitrate solutions onto a conductive glass substrate. The deposited metal nitrate solutions were then pyrolyzed to yield mixed-metal oxides that contained up to eight distinct metals. The stoichiometry of the metal oxides was controlled quantitatively, allowing for the creation of vast libraries of novel materials. Automated methods were developed to measure the open-circuit potentials (Eoc), short-circuit photocurrent densities (Jsc), and current density vs. applied potential (J–E) behavior under visible light irradiation. The high-throughput measurement of Eoc is particularly significant because open-circuit potential measurements allow the interfacial energetics to be probed regardless of whether the band edges of the materials of concern are above, close to, or below the values needed to sustain water electrolysis under standard conditions. The Eoc measurements allow high-throughput compilation of a suite of data that can be associated with the composition of the various materials in the library, to thereby aid in the development of additional screens and to form a basis for development of theoretical guidance in the prediction of additional potentially promising photoelectrode compositions

    The development of the toner density sensor for closed-loop feedback laser printer calibration

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    A new infrared (IR) sensor was developed for application in closed-loop feedback printer calibration as it relates to monochrome (black toner only) laser printers. The toner density IR sensor (TDS) was introduced in the early 1980’s; however, due to cost and limitation of technologies at the time, implementation was not accomplished until within the past decade. Existing IR sensor designs do not discuss/address: • EMI (electromagnetic interference) effects on the sensor due to EP (electrophotography) components • Design considerations for environmental conditions • Sensor response time as it affects printer process speed The toner density sensor (TDS) implemented in the Lexmark E series printer reduces these problems and eliminates the use of the current traditional “open-loop” (meaning feedback are parameters not directly affecting print darkness such as page count, toner level, etc.) calibration process where print darkness is adjusted using previously calculated and stored EP process parameters. The historical process does not have the ability to capture cartridge component variation and environmental changes which affect print darkness variation. The TDS captures real time data which is used to calculate EP process parameters for the adjustment of print darkness; as a result, greatly reducing variations uncontrolled by historical printer calibration. Specifically, the first and primary purpose of this research is to reduce print darkness variation using the TDS. The second goal is to mitigate the TDS EMI implementation issue for reliable data accuracy

    Appearance-based image splitting for HDR display systems

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    High dynamic range displays that incorporate two optically-coupled image planes have recently been developed. This dual image plane design requires that a given HDR input image be split into two complementary standard dynamic range components that drive the coupled systems, therefore there existing image splitting issue. In this research, two types of HDR display systems (hardcopy and softcopy HDR display) are constructed to facilitate the study of HDR image splitting algorithm for building HDR displays. A new HDR image splitting algorithm which incorporates iCAM06 image appearance model is proposed, seeking to create displayed HDR images that can provide better image quality. The new algorithm has potential to improve image details perception, colorfulness and better gamut utilization. Finally, the performance of the new iCAM06-based HDR image splitting algorithm is evaluated and compared with widely spread luminance square root algorithm through psychophysical studies

    Spectrally stable ink variability in a multi-primary printer

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    It was shown previously that a multi-ink printer can reproduce spectral reflectances within a specified tolerance range using many distinct ink combinations. An algorithm was developed to systematically analyze a printer to determine the amount of multi-ink variability throughout its spectral gamut. The advantage of this algorithm is that any spectral difference metric can be used as the objective function. Based on the results of the analysis for one spectral difference metric, six-dimensional density map displays were constructed to illustrate the amount of spectral redundancy throughout the ink space. One CMYKGO ink-jet printer was analyzed using spectral reflectance factor RMS as the spectral difference metric and selecting 0.02 RMS as the tolerance limit. For these parameters, the degree of spectral matching freedom for the printer reduced to five inks because the chromatic inks were able to reproduce spectra within the 0.02 tolerance limit throughout the printer\u27s gamut. Experiments were designed to exploit spectrally stable multi-ink variability within the analyzed printer. The first experiment used spectral redundancy to visually evaluate spectral difference metrics. Using the developed database of spectrally similar samples allows any spectral difference metric to be compared to a visual response. The second experiment demonstrated the impact of spectral redundancy on spectral color management. Typical color image processing techniques use profiles consisting of sparse multi-dimensional lookup tables that interpolate between adjacent nodes to prepare an image for rendering. It was shown that colorimetric error resulted when interpolating between lookup table nodes that were inconsistent in digital count space although spectrally similar. Finally, the analysis was used to enable spectral watermarking of images. To illustrate the significance of this watermarking technique, information was embedded into three images with varying levels of complexity. Prints were made verifying that information could be hidden while preserving the visual and spectral integrity of the original image

    The Journal of Undergraduate Research: Volume 13

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    This is the complete issue of the South Dakota State University Journal of Undergraduate Research, Volume 13

    Developing a spectral and colorimetric database of artist paint materials

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    As the project of the author\u27s Master\u27s thesis, the development of a spectral and colorimetric database of artist paint materials for acrylic paints was started. The goal of this research project was to: - provide the academic resource of colorant spectral characteristics - give scientifc explanations on various paint-particular phenomena (paint mixing, gloss effects and color gamut expansion by varnishing) These tasks were planned to satisfy possible interests on paint research from not only conservators in museums but also color educators in schools and color reproduction engineers in imaging companies

    Spectral modeling of a six-color inkjet printer

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    After customizing an Epson Stylus Photo 1200 by adding a continuous-feed ink system and a cyan, magenta, yellow, black, orange and green ink set, a series of research tasks were carried out to build a full spectral model of the printers output. First, various forward printer models were tested using the fifteen two color combinations of the printer. Yule- Nielsen-spectral-Neugebauer (YNSN) was selected as the forward model and its accuracy tested throughout the colorant space. It was found to be highly accurate, performing as well as a more complex local, cellular version. Next, the performance of nonlinear optimization-routine algorithms were evaluated for their ability to efficiently invert the YNSN model. A quasi-Newton based algorithm designed by Davidon, Fletcher and Powell (DFP) was found to give the best performance when combined with starting values produced from the non-negative least squares fit of single-constant Kubelka- Munk. The accuracy of the inverse model was tested and different optimization objective functions were evaluated. A multistage objective function based on minimizing spectral RMS error and then colorimetric error was found to give highly accurate matches with low metameric potential. Finally, the relationship between the number of printing inks and the ability to eliminate metamerism was explored

    In-situ Thermal and Deformation Characterization of Additive Manufacturing Processes

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    Additive manufacturing (AM) is a rapidly growing industry with numerous applications in the aerospace industry such as aircraft parts and emergency tools on the International Space Station. Defects in additively manufactured structures, however, can waste a lot of time and money. Being able to monitor the manufacturing process for defects is one of the first steps which can be taken to mitigate these losses. This study focuses on the use of thermography in conjunction with deep learning to identify flaws during 3D printing of composite structures made using Onyx, a mixture of chopped carbon fiber and nylon, composite prints. In addition, polymeric structures using polylactic acid (PLA) were analyzed using thermography and digital image correlation (DIC) to understand the interactions between the thermal variations and resulting deformation. The inclusion of a zero-bias deep neural network (ZBDNN) to classify given images can also show real-time monitoring of defects in composite prints as a realizable goal. The ZBDNN was trained to classify thermal images of undamaged prints based on which layer of the print they occurred on and to set aside any of these images containing defects. The addition of a non-bias layer in the deep neural network ensures the classifications of these images remain consistent and accurate, with a learning accuracy of over 90%. The algorithm was also used to analyze grayscale images from multiple angles of the prints and compared these images to thermal images as another means of detecting defects in each print. The use of these multiple data sources may be used as the basis for an early-warning detection system for real-time analysis

    N-colour separation methods for accurate reproduction of spot colours

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    In packaging, spot colours are used to print key information like brand logos and elements for which the colour accuracy is critical. The present study investigates methods to aid the accurate reproduction of these spot colours with the n-colour printing process. Typical n-colour printing systems consist of supplementary inks in addition to the usual CMYK inks. Adding these inks to the traditional CMYK set increases the attainable colour gamut, but the added complexity creates several challenges in generating suitable colour separations for rendering colour images. In this project, the n-colour separation is achieved by the use of additional sectors for intermediate inks. Each sector contains four inks with the achromatic ink (black) common to all sectors. This allows the extension of the principles of the CMYK printing process to these additional sectors. The methods developed in this study can be generalised to any number of inks. The project explores various aspects of the n-colour printing process including the forward characterisation methods, gamut prediction of the n-colour process and the inverse characterisation to calculate the n-colour separation for target spot colours. The scope of the study covers different printing technologies including lithographic offset, flexographic, thermal sublimation and inkjet printing. A new method is proposed to characterise the printing devices. This method, the spot colour overprint (SCOP) model, was evaluated for the n-colour printing process with different printing technologies. In addition, a set of real-world spot colours were converted to n-colour separations and printed with the 7-colour printing process to evaluate against the original spot colours. The results show that the proposed methods can be effectively used to replace the spot coloured inks with the n-colour printing process. This can save significant material, time and costs in the packaging industry
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