The Experts below are selected from a list of 7311 Experts worldwide ranked by ideXlab platform
Pierangiola Bracco - One of the best experts on this subject based on the ideXlab platform.
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Effects of microtoming on oxidation of ultra high molecular weight polyethylene (UHMWPE)
Polymer Degradation and Stability, 2001Co-Authors: K. Jacobson, Luigi Costa, Pierangiola Bracco, N. Augustsson, Bengt StenbergAbstract:It has been found that the rate of oxidation, as measured by the growth of the carbonyl band of oven aged microtomed UHMWPE films, is dependent on the Velocity at which the films are microtomed. The same observation was made when real time chemiluminescence measurements were performed in air at 120°C. The lower the Cutting Velocity, the faster the oxidation. By using NO derivatisation of unaged films, it was discovered that the hydroperoxide contents were also higher the lower the Cutting Velocity was. The knife used was quite blunt and left scratch marks on the films. When a sharper knife was used, no clear correlation could be found between the Cutting conditions and the rate of oxidation. The films cut with the sharp knife did, however, also contain hydroperoxides. The most probable explanation of the observation that additional hydroperoxides were formed during Cutting with the blunt knife is oxidation induced by the cobalt present in the tungsten carbide knife. It was found that the oxidation of the films was accelerated by just placing the knife on top of them during oven ageing.
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Effects of microtomy on the material properties of Ultra High Molecular Weight Polyethylene
Polymer Testing, 2001Co-Authors: Luigi Costa, K. Jacobson, Valentina Giovanna Brunella, Pierangiola BraccoAbstract:In order to study the properties of retrieved orthopaedic prosthetic implants, microtomy is often used to produce pieces suitable for examination. However, the cut made with the microtome can change the characteristics of the material to be studied and thus give an incorrect picture of some of its actual properties. This paper is based on a thorough investigation of the effects of different Cutting depth, Cutting Velocity and Cutting angle on the orientation and crystallinity of ultra high molecular weight polyethylene. It was found that the orientation decreases with greater Cutting depth and Cutting Velocity and increases slightly with a greater Cutting angle. The degree of crystallinity as measured by FTIR and calculated from the first DSC heating was found to increase with greater Cutting depth. The crystallinity calculated from the second heating, however, always gave an average value of 50.5±0.5%. Cutting angle and Cutting Velocity did not influence the crystallinity. Two different knives were used in the investigation. One was old and left scratch marks on the film while the other had recently been sharpened. The main difference between the two knives, apart from the scratch marks, was that the films cut with the old knife had a lower degree of crystallinity than the ones cut with the new knife when measured immediately after Cutting. The crystallinity did, however, increase during ageing in ambient atmosphere, and after about 2 months it was the same as for the samples cut with the new knife.
Harald Rohm - One of the best experts on this subject based on the ideXlab platform.
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High-speed Cutting of foods: Cutting behavior and initial Cutting forces
Journal of Food Engineering, 2018Co-Authors: Stefan Schuldt, Yvonne Schneider, Harald RohmAbstract:Abstract The viscoelastic properties of foods determine deformation, fracture and friction during industrial Cutting applications and substantially affect the Cutting behavior, especially at high Cutting Velocity. Using a custom-built high-speed test station the Cutting behavior of representative foods (either based on a protein network, plant tissues and sugar based confectionary) and food models on elastomer basis was investigated at a Cutting Velocity ranging from 10−4 m/s up to 10 m/s. On the basis of Cutting force data and dynamic mechanical analysis performed between 1 rad/s and 100 rad/s, the Cutting behavior of the systems was investigated. In general, the Cutting force profiles depended on Cutting Velocity and could be related to deformation characteristics that were measured in dynamic mechanical analysis (except for plant tissue whose inherent composite structures seem to contribute to brittle behavior at each Cutting Velocity). Sugar based confectionary showed a strong rate dependence with brittle fracture and splintering in the high-speed region. For all systems except plant tissues a Velocity dependent deformation Cutting parameter, derived from the initial Cutting forces, coincides with the power law frequency dependence of the complex modulus. This relation was used to build a model approach with which the pre-crack Cutting forces at high-speed Cutting Velocity can be predicted with commercially available standard testing machines.
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Ultrasonic Cutting of cheese : Composition affects Cutting work reduction and energy demand
International Dairy Journal, 2009Co-Authors: G. Arnold, Susann Zahn, L. Leiteritz, Harald RohmAbstract:Abstract Eight cheese varieties with different moisture (357–488 g kg −1 ), fat (183–335 g kg −1 ) and protein content (202–292 g kg −1 ) were subjected to ultrasonic Cutting using a 40 kHz guillotine sonotrode. Cutting force curves were evaluated with respect to ultrasound-induced Cutting work reduction and energy demand of the sonotrode. With Cutting Velocity and ultrasonic amplitude set to 2500 mm min −1 and 12 μm, respectively, composition had a significant effect on the response of the cheeses. Whereas Cutting work reduction was mainly determined by fat-in-dry matter, the energy demanded by the sonotrode to maintain vibration was inversely interrelated to the ratio of moisture to solids-non-fat. Three selected cheeses were subjected to Cutting experiments with systematically varied Cutting Velocity and amplitude. The results indicate that the cheeses respond differently to the Cutting parameters, and that their careful adjustment is helpful for a target-orientated design of the process.
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Ultrasonic Cutting of foods: Effects of excitation magnitude and Cutting Velocity on the reduction of Cutting work
Innovative Food Science and Emerging Technologies, 2006Co-Authors: Susann Zahn, Yvonne Schneider, Harald RohmAbstract:Abstract The effects of vertical Cutting Velocity and the magnitude of ultrasonic excitation on the reduction of the work necessary to separate various food materials were investigated. Generally, Cutting work increased with increasing Cutting Velocity but, at each particular Cutting Velocity, decreased with increasing magnitude of the ultrasonic excitation of the Cutting tool. Interactions between Cutting Velocity and the maximum vibration speed at the Cutting edge, which is determined by both excitation amplitude and excitation frequency, are significant. Depending on the food under action, the relative amount of Cutting work reduction is either affected by the maximum vibration speed or, additionally, by vertical Cutting Velocity. No distinct effects of the excitation frequency (20 or 40 kHz) were observed. Industrial relevance Ultrasonic Cutting is used in the food industry, especially for the separation of products consisting of layers with different rheological properties to achieve minimally damaged cut surfaces. The results of the study may be useful for selecting operational variables (Cutting Velocity, excitation amplitude) during Cutting to achieve a controlled reduction of the Cutting work.
Luigi Costa - One of the best experts on this subject based on the ideXlab platform.
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Effects of microtoming on oxidation of ultra high molecular weight polyethylene (UHMWPE)
Polymer Degradation and Stability, 2001Co-Authors: K. Jacobson, Luigi Costa, Pierangiola Bracco, N. Augustsson, Bengt StenbergAbstract:It has been found that the rate of oxidation, as measured by the growth of the carbonyl band of oven aged microtomed UHMWPE films, is dependent on the Velocity at which the films are microtomed. The same observation was made when real time chemiluminescence measurements were performed in air at 120°C. The lower the Cutting Velocity, the faster the oxidation. By using NO derivatisation of unaged films, it was discovered that the hydroperoxide contents were also higher the lower the Cutting Velocity was. The knife used was quite blunt and left scratch marks on the films. When a sharper knife was used, no clear correlation could be found between the Cutting conditions and the rate of oxidation. The films cut with the sharp knife did, however, also contain hydroperoxides. The most probable explanation of the observation that additional hydroperoxides were formed during Cutting with the blunt knife is oxidation induced by the cobalt present in the tungsten carbide knife. It was found that the oxidation of the films was accelerated by just placing the knife on top of them during oven ageing.
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Effects of microtomy on the material properties of Ultra High Molecular Weight Polyethylene
Polymer Testing, 2001Co-Authors: Luigi Costa, K. Jacobson, Valentina Giovanna Brunella, Pierangiola BraccoAbstract:In order to study the properties of retrieved orthopaedic prosthetic implants, microtomy is often used to produce pieces suitable for examination. However, the cut made with the microtome can change the characteristics of the material to be studied and thus give an incorrect picture of some of its actual properties. This paper is based on a thorough investigation of the effects of different Cutting depth, Cutting Velocity and Cutting angle on the orientation and crystallinity of ultra high molecular weight polyethylene. It was found that the orientation decreases with greater Cutting depth and Cutting Velocity and increases slightly with a greater Cutting angle. The degree of crystallinity as measured by FTIR and calculated from the first DSC heating was found to increase with greater Cutting depth. The crystallinity calculated from the second heating, however, always gave an average value of 50.5±0.5%. Cutting angle and Cutting Velocity did not influence the crystallinity. Two different knives were used in the investigation. One was old and left scratch marks on the film while the other had recently been sharpened. The main difference between the two knives, apart from the scratch marks, was that the films cut with the old knife had a lower degree of crystallinity than the ones cut with the new knife when measured immediately after Cutting. The crystallinity did, however, increase during ageing in ambient atmosphere, and after about 2 months it was the same as for the samples cut with the new knife.
K. Jacobson - One of the best experts on this subject based on the ideXlab platform.
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Effects of microtoming on oxidation of ultra high molecular weight polyethylene (UHMWPE)
Polymer Degradation and Stability, 2001Co-Authors: K. Jacobson, Luigi Costa, Pierangiola Bracco, N. Augustsson, Bengt StenbergAbstract:It has been found that the rate of oxidation, as measured by the growth of the carbonyl band of oven aged microtomed UHMWPE films, is dependent on the Velocity at which the films are microtomed. The same observation was made when real time chemiluminescence measurements were performed in air at 120°C. The lower the Cutting Velocity, the faster the oxidation. By using NO derivatisation of unaged films, it was discovered that the hydroperoxide contents were also higher the lower the Cutting Velocity was. The knife used was quite blunt and left scratch marks on the films. When a sharper knife was used, no clear correlation could be found between the Cutting conditions and the rate of oxidation. The films cut with the sharp knife did, however, also contain hydroperoxides. The most probable explanation of the observation that additional hydroperoxides were formed during Cutting with the blunt knife is oxidation induced by the cobalt present in the tungsten carbide knife. It was found that the oxidation of the films was accelerated by just placing the knife on top of them during oven ageing.
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Effects of microtomy on the material properties of Ultra High Molecular Weight Polyethylene
Polymer Testing, 2001Co-Authors: Luigi Costa, K. Jacobson, Valentina Giovanna Brunella, Pierangiola BraccoAbstract:In order to study the properties of retrieved orthopaedic prosthetic implants, microtomy is often used to produce pieces suitable for examination. However, the cut made with the microtome can change the characteristics of the material to be studied and thus give an incorrect picture of some of its actual properties. This paper is based on a thorough investigation of the effects of different Cutting depth, Cutting Velocity and Cutting angle on the orientation and crystallinity of ultra high molecular weight polyethylene. It was found that the orientation decreases with greater Cutting depth and Cutting Velocity and increases slightly with a greater Cutting angle. The degree of crystallinity as measured by FTIR and calculated from the first DSC heating was found to increase with greater Cutting depth. The crystallinity calculated from the second heating, however, always gave an average value of 50.5±0.5%. Cutting angle and Cutting Velocity did not influence the crystallinity. Two different knives were used in the investigation. One was old and left scratch marks on the film while the other had recently been sharpened. The main difference between the two knives, apart from the scratch marks, was that the films cut with the old knife had a lower degree of crystallinity than the ones cut with the new knife when measured immediately after Cutting. The crystallinity did, however, increase during ageing in ambient atmosphere, and after about 2 months it was the same as for the samples cut with the new knife.
Chihhung Tsai - One of the best experts on this subject based on the ideXlab platform.
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optimization of wire electrical discharge machining for pure tungsten using a neural network integrated simulated annealing approach
Expert Systems With Applications, 2010Co-Authors: Hsienching Chen, Jenchang Lin, Yungkuang Yang, Chihhung TsaiAbstract:This study analyzed variation of Cutting Velocity and workpiece surface finish depending on wire electrical discharge machining (WEDM) process parameters during manufacture of pure tungsten profiles. A method integrating back-propagation neural network (BPNN) and simulated annealing algorithm (SAA) is proposed to determine an optimal parameter setting of the WEDM process. The specimens are prepared under different WEDM process conditions based on a Taguchi orthogonal array table. The results of 18 experimental runs were utilized to train the BPNN predicting the Cutting Velocity, roughness average (Ra), and roughness maximum (Rt) properties at various WEDM process conditions and then the SAA approaches was applied to search for an optimal setting. In addition, the analysis of variance (ANOVA) was implemented to identify significant factors for the WEDM process and the proposed algorithm was also compared with respect to the confirmation experiments. The results of proposed algorithm and confirmation experiments are show that the BPNN/SAA method is effective tool for the optimization of WEDM process parameters.
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optimization of wire electrical discharge machining for pure tungsten using a neural network integrated simulated annealing approach
Expert Systems With Applications, 2010Co-Authors: Hsienching Chen, Yungkuang Yang, Chihhung TsaiAbstract:This study analyzed variation of Cutting Velocity and workpiece surface finish depending on wire electrical discharge machining (WEDM) process parameters during manufacture of pure tungsten profiles. A method integrating back-propagation neural network (BPNN) and simulated annealing algorithm (SAA) is proposed to determine an optimal parameter setting of the WEDM process. The specimens are prepared under different WEDM process conditions based on a Taguchi orthogonal array table. The results of 18 experimental runs were utilized to train the BPNN predicting the Cutting Velocity, roughness average (Ra), and roughness maximum (Rt) properties at various WEDM process conditions and then the SAA approaches was applied to search for an optimal setting. In addition, the analysis of variance (ANOVA) was implemented to identify significant factors for the WEDM process and the proposed algorithm was also compared with respect to the confirmation experiments. The results of proposed algorithm and confirmation experiments are show that the BPNN/SAA method is effective tool for the optimization of WEDM process parameters.
