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Fiber Society 2009 Fall Meeting and Technical Conference

作者： Shi, Quan Vitchuli, Narendiran Nowak, Joshua McCord, Marian Bourham, Mohamed Zhang, Xiangwu Fiber and Polymer Science Program Department of Textile Engineering Chemistry and Science North Carolina State University RaleighNC27695-8301 United States Department of Nuclear Engineering North Carolina State University RaleighNC27695-7909 United States

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Integration of computer based problem solving into engineering curricula

Integration of computer based problem solving into engineeri...

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2008 ASEE Annual Conference and Exposition

作者： Raubenheimer, Dianne Brent, Rebecca Joines, Jeff Craig, Amy North Carolina State University Department of Adult and Higher Education College of Education NCSU Education Designs Inc. Education Designs Inc. Cary NC United States College of Engineering North Carolina State University National Effective Teaching Institute Chemistry and Science Department NC State University Textile Engineering Program College of Engineering Student-Owned Computing College of Engineering Department of Industrial and Systems Engineering NC State University

The primary objectives of this engineering project are (1) to examine how to develop students' problem solving and computational skills early in their program of study and (2) to further enhance these skills by building upon critical computing concepts semester after semester. The project is a component of NC State University's quality enhancement plan, which focuses on the use of technology in enhancing student learning. The project stems from new introductory computer-based modeling courses that were created in two engineering departments, and has expanded to include other departments. We give an overview of the project, provide an example of how a problem is modeled and broken apart, present some assessment results, and discuss the emerging lessons being learned. © American Society for engineering Education, 2008.

关键词： Problem solving

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Computer-based modeling for engineers using excel and VBA

Computer-based modeling for engineers using excel and VBA

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114th Annual ASEE Conference and Exposition, 2007

作者： Joines, Jeff Roberts, Stephen Raubenheimer, Diane North Carolina State University United States Textile Engineering Chemistry And Science Department NC State University United States Textile Engineering Program United States Initiative College of Engineering United States Edward P. Fitts Department of Industrial and Systems Engineering North Carolina State University United States Institute Ofindstrial Engeeniers College of Engineering

Many engineering curriculum around the country are re-evaluating their introductory computer programming requirement. At our university, several departments have been changing from the traditional Java or C++ course to something more applicable to their discipline. This paper will address the development of a joint course across Industrial and textile engineering. Students from both departments were not using their programming knowledge in remaining courses or when they graduated. Furthermore, the introductory Java (C++) class was being taught as a service course to masses of students at one time in our university's theater. The students were not enthusiastic about the course and certainly not developing the computer modeling skills that we felt were necessary (i.e., given a problem can they develop a method for solving the problem). Therefore, we decided drop the introductory course and develop a new course in Excel and Visual Basic for Applications to better address the needs of our industry and faculty colleagues. This course was not intended to duplicate the traditional computer science method of presenting programming. Our goal was to educate students to model problems relevant to our disciplines, solve these problems using modeling tools, and then analyze these solutions through decision support (i.e., become "power users" and not programmers). This paper will address the critical development of a series of "InClassLabs" and their impact on student learning and our two curricula. Many of our homework and cases studies come from industrial sponsor data and represent real cases. The paper will discuss the fundamental issues that lead the two authors to develop this computer-intensive course. Of special interest is the classroom environment bolstered by the use of in-class teaching assistants and the use of Tablet PCs. Student evaluations are used to provide insight into the teaching strategies employed. © American Society for engineering Education, 2007.

关键词： engineering education

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Durability of a conducting shape memory polyurethane actuator

Durability of a conducting shape memory polyurethane actuato...

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17th International Conference on Adaptive Structures and Technologies, ICAST 2006

作者： Goo, N.S. Paik, I.L. Jung, Y.C. Cho, J.W. Intelligent Microsystem Program Department of Advanced Technology Fusion Konkuk University Seoul 143-701 Korea Republic of Department of Aerospace Engineering Konkuk University Seoul 143-701 Korea Republic of Department of Textile Engineering Konkuk University Seoul 143-701 Korea Republic of

ISBN: (纸本)9781605601250

This paper discusses the actuation durability of a conducting shape memory polyurethane (CSMPU) actuator. Introduced in 2004, the CSMPU actuator was manufactured by an in situ polymerization method for shape memory polyurethane with multiwalled carbon nanotubes. In order to apply the CSMPU to smart actuators and determine detailed design concepts, the durability data should be measured. Hence, the experiments in this research were designed to obtain durability data, and the maximum number of actuation cycles versus the initial elongation ratio and the actuation temperature were measured for the purpose of assessing durability. The broken surfaces of the specimens were investigated.

关键词： Durability

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OPTIMIZATION OF ELECTROSPINNING PROCESS PARAMETERS FOR TISSUE engineering SCAFFOLDS

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Biophysical Reviews and Letters 2006年第2期1卷 153-178页

作者： MING CHEN PRABIR K. PATRA STEVEN B. WARNER SANKHA BHOWMICK Biomedical Engineering and Biotechnology Program All University of Massachusetts — Dartmouth N. Dartmouth MA 02747 USA Department of Textile Sciences All University of Massachusetts — Dartmouth N. Dartmouth MA 02747 USA Department of Mechanical Engineering All University of Massachusetts — Dartmouth N. Dartmouth MA 02747 USA

The goal of the current study was to optimize important process parameters for electrospinning polycaprolactone (PCL) for growing 3T3 fibroblasts. We hypothesized that the smallest obtainable fiber diameter would provide the best cell growth kinetics and we tested this hypothesis for three different process parameters: solution concentration, voltage and collector screen distance. Beaded structures were formed when using low concentration electrospinning solutions (8 wt% to 13 wt%), in which the viscosity ranged from 16.0 c P to 340.0 c P . In this concentration range, cell growth kinetics was impeded when using a high concentration of cells (8–10 × 10 5 ). Higher PCL concentration led to an increase in the average fiber diameter from 400 nm to 1600 nm when PCL solution concentration changed from 15 wt% to 20 wt%. Although, the mean values indicated that cell growth kinetics were higher at the lower end of the concentration (15% as opposed to 20%) and this correlated with lower average fiber diameter, the results in this range were not statistically significant (p > 0.05). The average fiber diameter of scaffolds first decreased and then increased when electrospinning voltage was increased. The cell growth kinetics demonstrated that smaller average diameter PCL fiber scaffolds had higher growth kinetics than larger average diameter scaffolds with the best conditions obtained at 15 KV. By increasing the screen distance, the average fiber diameter decreased but had no significant impact on cell growth kinetics. In summary, the optimal parametric space for 3T3 fibroblast growth for our studies was electrospinning a 15 wt% PCL solution using 15 kV voltage and a 25 cm collector distance.

关键词： Electrospinning polycaprolactone tissue engineering scaffold SEM cell growth kinetics

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Development of a biodegradable nanofiber scaffold by optimization of electrospinning process parameters

Development of a biodegradable nanofiber scaffold by optimiz...

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2005 Summer Bioengineering Conference

作者： Chen, Ming Patra, Prabir Warner, Steve Bhowmick, Sankha Biomedical Engineering and Biotechnology Program University of Massachusetts Dartmouth North Dartmouth MA Textile Science Department University of Massachusetts Dartmouth North Dartmouth MA Mechanical Engineering Department University of Massachusetts Dartmouth North Dartmouth MA

ISBN: (纸本)0974249211

The goal of the current study was to develop a three dimensional scaffold for creating tissue engineered bioactive bandages. In the current study, we chose polycaprolactone (PCL) as the biomaterial and optimized the electro spinning process parameters: concentration, voltage and the distance between capillary and collection screen. Using scanning electron microscopy (SEM), we measured the fiber diameter and also studied the growth of NIH 3T3 fibroblasts into electrospun PCL scaffolds after various days post seeding. Our studies have been able to obtain uniform fibers of a minimal diameter of 650nm which also provides the best environment for cell growth.

关键词： Nanostructured materials

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Hydrolysis of biodegradable polymers by superoxide ions

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Journal of Polymer Science 2000年第18期37卷

作者： K. H. Lee C. Y. Won C. C. Chu Ivan Gitsov Fiber Science Program Department of Textile and Apparel and Biomedical Engineering Program Cornell University Ithaca NY 14853-4401 Department of Chemistry State University of New York College of Environmental Science and Forestry Syracuse NY 13210 Cornell Center for Materials Research and Department of Chemistry and Chemical Biology Cornell University Ithaca NY 14853-1301

The objective of this study was to examine the reactivity of superoxide ion as an oxygen nucleophile towards biodegradable biomaterials having an aliphatic polyester structure, such as poly( D , L -Lactide) (PDLLA). The changes in molecular weights and thermal properties of PDLLA were studied as a function of the superoxide ion concentration, hydrolysis time, and hydrolysis temperature. The superoxide ion induced fragmentation of PDLLA yielded a mixture of various species with different chain length. A combined size exclusion chromatography (SEC) method with a chemical tagging by phenyl isocyanate revealed that the structure of the oligomer species with the lowest molecular weight formed in the superoxide ion induced degradation mixture was linear. The significant reduction in T g was consistent with the significant reduction in the molecular weight of PDLLA. The linear low molecular fragments (dimers and trimers) in the reaction mixture could act as an internal plasticizers to enhance the T g reduction by increasing the free volume of chain ends. The relationship of T g with molecular weight of PDLLA followed the general theory of Fox–Flory. The mechanism of simple hydrolysis of ester by superoxide ion proposed by Forrester et al. was modified to interpret the data obtained from the synthetic biodegradable polymers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3558–3567, 1999

关键词： superoxide ion biodegradable polymers hydrolysis polylactide degradation

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Kinetics of water swelling and development of porous structure in ionic poly(acrylonitrileacrylamide-acrylic acid) hydrogels

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POLYMER 1996年第6期37卷 1019-1025页

作者： Hu, DSG Chou, KJN Program in Polymers Department of Textile Engineering National Taiwan Institute of Technology Taipei Taiwan 107 ROC

The kinetics of water uptake into the dry form of, and benzoic acid diffusion through, swollen inhomogeneous poly(acrylonitrile-acrylamide-acrylic acid) gels were investigated with gravimetry and ultra-violet visible spectroscopy, respectively. The goal is to understand the effects of ionizable moieties and water-polymer affinity on the rate of water diffusion during the formation of hydrogels from glassy polymers and on the free-volume mechanism for solute transport through the resulting swollen networks. The xerogel with intermediate acid content or minimal affinity with water has the maximum water diffusion coefficient in the initial swelling stage and the maximum deviation from Fickian transport. The molecular diffusion of benzoic acid through hydrogels was found to be controlled by the swelling, and the size of voids for solute diffusion does not remain constant over all the range of compositions. This discrepancy from the simple free-volume theory is due to a wide range of molecular interactions for gels with amide/acid moieties. In conclusion, dynamic swelling is influenced by water-polymer affinity and subsequently causes various types of steady transport in hydrogels.

关键词： dynamic swelling solute diffusion ionic hydrogels

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WATER-POLYMER INTERACTIONS AND CRITICAL PHENOMENA OF SWELLING IN INHOMOGENEOUS POLY(ACRYLONITRILE-ACRYLAMIDE-ACRYLIC ACID) GELS

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POLYMER 1994年第20期35卷 4416-4422页

作者： HU, DSG LIN, MTS Program in Polymers and Textiles Department of Textile Engineering National Taiwan Institute of Technology Taipei Taiwan 107 Republic of China

The water uptake and swelling behaviour of physically crosslinked, inhomogeneous poly(acrylonitrile-acrylamide-acrylic acid) hydrogels from 10 to 60 degrees C were determined by gravimetry/differential scanning calorimetry and volume measurement, respectively. The contents of water and its non-bound portion were found to reach a minimum value at acrylamide content around 33.5 mol%, at which the water uptake of this gel does not vary with the temperature. The non-bound water was found to decrease gradually and then increase with increasing amide concentration. The duration of the post-gelation treatment between -10 and 10 degrees C was also shown to be one of the factors affecting the extent of the water uptake in gels. The critical endpoint temperatures (T(c)s) of hydrogels, obtained from volume phase transition data upon changing the acetone concentration in aqueous solutions at various temperatures, were shown to decrease with the increasing acid or amide contents. The water uptake for gels with lower amide contents decreases with increasing temperature. However, there is an opposite trend for water uptake in gels with higher amide content, and the critical points on the plots of the amount of water uptake versus temperature appear at a temperature equal to T-c.

关键词： INHOMOGENEOUS HYDROGELS SWELLING PHASE TRANSITION

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SYNTHESIS AND DIELECTRIC CHARACTERIZATION OF POLY[ACRYLONITRILE-CO-ACRYLAMIDE-CO-(ACRYLIC ACID)] TERPOLYMER GELS

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MACROMOLECULAR CHEMISTRY AND PHYSICS 1994年第11期195卷 3629-3642页

作者： HU, DSG LIN, YS Program in Polymers and Textiles Dept. of Textile Engineering National Taiwan Institute of Technology Taipei Taiwan 107 R. O. C

The acidic hydrolysis of polyacrylonitrile, stabilization and thermal gelation in mixed solvents were sequentially carried out to yield a variety of terpolymer gels made up of 58,5 to 89,4 mol-% units of acrylonitrile, 10,2 to 39,2 mol-% acrylamide and 0,4 to 2,3 mol-% acrylic acid. The post-hydrolysis stabilization at temperature below 0-degree-C was shown to induce chemical conversion from acrylonitrile to acrylamide, that is more pronounced for a certain range of initial acrylamide contents than others as evidenced by the kinetic analysis using H-1 NMR and base titration. The dielectric relaxation measurements on swollen gels show three relaxation transitions, alpha, beta and gamma in decreasing order of temperature, over -150 to 0-degree-C. The alpha-transition, due to the segmental motion of the polymer, is the least distinct of the three. The beta- and gamma-transitions in decreasing order of temperature are associated with the cooperative motion of polar groups with water and glass transition of water, respectively, as judged from the activation energy and temperature of relaxation. The beta-relaxation was shown to be strongly influenced by the type of swelling solvent in the gel, water contents and chemical composition of the gel. Furthermore, the Cole-Cole plots in the region of the beta-relaxation were constructed to demonstrate the role of morphology in the dielectric behaviour of hydrogels.

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