• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1239
  • 393
  • 263
  • 199
  • 119
  • 118
  • 78
  • 76
  • 61
  • 15
  • 15
  • 14
  • 14
  • 12
  • 12
  • Tagged with
  • 2943
  • 701
  • 422
  • 301
  • 273
  • 250
  • 230
  • 214
  • 188
  • 185
  • 175
  • 169
  • 166
  • 163
  • 162
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Stress Relaxation of Tufted Carpets and Carpet Components

Phillips, Kristie Jo 28 October 2002 (has links)
Dimensional stability of tufted carpets has been a continuing problem in the industry for years. When a tufted carpet is installed by the stretch method, it experiences stress relaxation over time which can cause the carpet to buckle, wrinkle and become loose with the only option being a costly re-stretching of the carpet. Since woven carpets seldom require re-stretching, the carpet buckling problem seems to be linked primarily to the tufted construction. This research seeks to analyze the various components of the tufted carpet composite structure and identify the role each component plays in the phenomenon of stress relaxation. Since a carpet is always stretched in both dimensions simultaneously during installation, understanding its biaxial stress decay is important. To this end, a biaxial loading system has been used to test various samples of the primary backing alone (before tufting), primary backing after tufting (with tufts), the secondary backing alone, and the finished carpet after attaching the backings with various binder weights per area. The four variables under consideration include: primary and secondary backing constructions, tufting density, and latex weight, with the secondary backing and latex weight expected to have the greatest effects on stress decay. In order to collect the most information, the biaxial test system was connected to a computer-based data acquisition system to continuously monitor stress levels and generate stress relaxation curves over a 20-hour testing period. A viscoelastic model that included representations of each component in the carpet structure was used to analyze and understand the influence of the components on the stress relaxation of carpets.
202

Strategic Shifts in Textile Production 1994-2006

Ji, Yan Ms. 08 November 2006 (has links)
In order to better understand the changes and trends in the increasingly competitive dynamics of global textile complex, this research focuses on analyzing the rate of change in country of production origin for fiber, yarn, fabric and end-use products in the past decade. By using the model of textile product complex as framework, the data presented in this research paper were firstly collected from various data sources, such as the Fiber Economics Bureau, ITMF, ICAC, Textiles Intelligence, CIRFS, and WTO as well. The data were then validated to ensure its integrity, which represented a significant stage in the process. Finally, the data were analyzed and conclusions were drawn based on the obvious trends in the data. This research offers a practical interpretation of the direction and magnitude of changes in worldwide textile and apparel production. Meanwhile, it provides an outline of the relationships between textile trade and production, as well as the relationships between production and employment. In addition, the findings from this study will show the direction for global sourcing of textile and apparel products.
203

COMBINATION OF HYDROENTANGLEMENT AND FOAM BONDING TECHNOLOGIES FORWOOD PULP AND POLYESTER FIBERS IN WET LAY NONWOVEN FABRICS

Gahide, Severine 23 February 1999 (has links)
<p>This project searches for synergism between two binder technologies, specifically 1) low levels ofhydroentanglement energy which avoid excessive fiber loss but do not give adequate fabric strength, abrasionresistance or strain recovery, and 2) low levels of binder which do not degrade fabric aesthetics. The mainsteps were to 1) determine the fiber loss while hydroentangling, by testing three fabric weights and severalspecific energy levels for a 50% wood pulp and 50% polyester, and then 2) combine both technologies, fortwo fiber blends, at three levels of specific energy and four levels of binder add on. We found that: 1. Thecarrier screen mesh size, during hydroentanglement, was a critical factor for making the desired fabrics. 2.The fiber loss during hydroentanglement increases linearly with increasing specific energy, in the rangestudied. 3. The fabric basis weight has a very weak influence on the fiber loss during hydroentanglement. 4.Fabrics hydroentangled from one side only or on both sides lose the same amount of fibers. 5. The physicalproperties -strength, load at 5% strain, abrasion resistance- are greatly improved with an add-on of binder,while different levels of hydroentanglement energy input were found to be less significant. 6. Thehydroentangled and foam bonded fabrics are softer than those which were foam bonded only. 7. Theaddition of foam bonding up to 5% did not affect the softness of the hydroentangled fabrics. 8. The hydrogenbonding effect is shown to be significant at these levels of hydroentanglement and binder add-on. 9. Thefabric bending rigidity can be correlated with the Young's modulus of the bonded fabric for a 60% woodpulp fabric. 10. The abrasion resistance behavior is very different depending on the side tested: foam free orfoamed. <P>
204

A Pattern Language Describing Apparel Design Creativity

Pechoux, Beatrice Le 12 April 2000 (has links)
<p>The apparel design process involves gathering and analyzing information on fashion trends, markets, past line sales and editing ideas for successful combinations of fabric, style and price. These ideas are the result of creativity. Creativity is most often modeled as a problem solving process involving complex chaotic systems. In the fields of architecture and software design, pattern languages have been developed to help understand the various fundamental components and dynamics of complex systems by using a series of related generic problem-solving patterns empirically proven to be successful in a specified context of forces. Patterns record existing knowledge to make it rapidly and easily accessible and communicated between different users. The research objective of this dissertation was to develop a pattern language describing the initial creative phase of the apparel design process. First, an archetype of the initial creative process in apparel design was constructed based on the literature reviewed to integrate the intervening marketing and design components, and suggest a set of links between these components and the various stages of the process. Second, patterns describing these links and the archetype were developed to form a pattern language representing the dynamics of the archetypal model, i.e. the articulation and interdependencies of all its components and stages. Design professionals reviewed the pattern language. Students used it to develop product concepts and storyboards, which were evaluated by a panel of judges. Feedback from these participants indicates the pattern language offers a "design manual" that can be used by all team members to improve design efficiency and effectiveness, i.e. higher success rates of new products in a timely manner. Combining information technology and the pattern language could make an even greater contribution to apparel design, both at an operational level and a strategic planning level. This research provides a working example of a pattern language and shows the benefits to be attained. Also, the dissertation includes a guide on constructing pattern languages in the hope of reaching the ultimate goal of encouraging industry and academic apparel design experts to contribute to the necessary ongoing developments of the pattern language. <P>
205

U.S. Trends in Short Staple Spinning

Dodd, Erin Linnea 16 November 2000 (has links)
<p>The purpose of this research has been to examine possible factors which effect yarn production and prices in the U.S.The research approach first involved gathering the data from different sources about yarn production and prices. Second, data was gathered about the different factors which could have an effect on these. These factors included enduse demand, cotton consumption, the effect of spinning systems, labor cost and demand, machinery hours and shipments, and the level of imports and exports. Third, the data was compared and conclusions were made based solely on the obvious trends in the data. Fourth, current situations in the textile market were examined in order to conclude if any have had an effect on yarn production and price. The main issues which are facing the textile industry and were included in this analysis were NAFTA, CBI, Asia and the WTO. The effect that these have had and will have on the spinning industry was examined in detail. Fifth, a statistical analysis was conducted. The analysis included the use of a correlation matrix for both yarn production levels and yarn prices in order to see which factors statistically had the strongest impact on these. Overall, this research offers a view into the inside of the U.S. spinning industry, including the dynamics which effect final yarn production levels and yarn prices, as well as situations which will have an impact on the future of the spinning industry.<P>
206

Model Based Conceptual Communication Design in Coordination Systems

Kuehnen, Stefan Alexander 06 April 2001 (has links)
<p>KUEHNEN, STEFAN ALEXANDER. Model Based Conceptual Communication Design in Coordination Systems (under the Direction of Dr. Padmini Srinivasan-Hands and Dr. Samuel C. Winchester)The purpose of this research has been to investigate the feasibility of developing a model-based method for conceptual communication design in coordination systems. Business process modeling methodologies are surveyed and the methodology of choice, Actionworkflow?, is presented. As the basis for method development Language/Action and Speech Act theories, underlying the Actionworkflow? methodology, are examined for potential concepts aiding the development of the method. Their history and surrounding philosophies are presented. Critique of the Actionworkflow? methodology is presented and discussed.The major focus of the research is the development of the model-based method to conceptually design communications in coordination systems. Its development, structure and components are presented and explained. The method is illustrated with a simple, everyday-life, application example. Applications of the method to examine web-based e-commerce sites are presented. It has been determined that the application for these environments is insightful. The examples discussed are ebay, an auction provider, e-trade, an on-line broker, and priceline.com, a purchasing service applying a unique process for the purchase of services and goods. Consequently the application of the method to establish the feasibility of designing coordination support systems for textile new product development is provided. Coordination model development and design of communications are discussed in parallel. Application results show that the method can successfully be used for conceptually designing coordination support systems, although practical issues have to be further investigated.Finally underlying assumptions are displayed and discussed, model validation provided, performance evaluation, as to the goals set forth for the research undertaken, and recommendations for future research provided. <P>
207

Exploration of Micromachines to Textiles: Monitoring Warp Tension and Breaks during the Formation of Woven Fabrics

Gahide, Severine Francoise 13 June 2001 (has links)
<p>MicroElectroMechanical Systems, or MEMS, is an emerging high technology that has proven to be very successful in several industries such as medical, automotive and ink jet industries. The technology philosophy is to integrate sensors, actuators and electronics onto a silicon substrate (polysilicon batch) to form as small as a square millimeter micromachine at low manufacturing cost. Such advantages prompted investigating the potential applications of MEMS in textiles.Initially, we identified possible applications of MEMS technology in spinning, weaving, knitting, fiber formation, nonwovens, testing and evaluation, and dyeing and finishing. Based on a perceived real need and large potential market for a successful device, it was decided to concentrate efforts into the development of a MEMS based detection device to monitor warp tension and end breaks in weaving. Thus replacing the abrasive and passive traditional drop wire with gentle and active device that has the potential to expand the markets for weavers. A macro prototype device (sensors, software and hardware) to monitor warp tension and break was designed and built. Descriptions of the device components along with weaving specifics are given. To demonstrate the benefits of the device, several experiments were conducted. The experiments along with their results are reported. The experiments include: Simultaneously monitor tension of eight individual warp ends in real time  Identify complex weave patterns through matching tension fingerprint with weave floats and intersections Detect yarn tension trends while weaving Quantify variations of warp tension across beam width Identify variations of warp tension at the warp sheet edges Monitor the behavior of the warp let-off mechanism Detect broken warp yarns Assess warp yarn damage caused by using drop wiresBased on the results of these experiments, it can be concluded that monitoring individual warp yarn tension could provide a useful mean for woven fabric producers as well as weaving machine manufacturers. From these findings, the micromachine, an array of piezoresistive sensors, was designed and built.<P>
208

Creation of Casual Index Based on Habit Stocks and General Social Behaviors

Lee, Eun-Kyung 11 July 2001 (has links)
<p>LEE, EUN-KYUNG. Creation of Casual Index Based on Habit Stocks and General Social Behaviors. (Under the direction of Dr. Moon W. Suh and Dr. William Oxenham.)A fashion preference indicator called "Casual Index" was created to signify and measure the degree of casualness at any given time point by using various statistical and econometrics models. The indices were created based on two approaches; one for theoretically constructed and the other for practical application. The theory-based Casual Index is a composite index formulated from two sub-indices that were derived from the general social behaviors and apparel demand patterns of contemporary Americans. The consumption-based Casual Index is also a composite index aimed at practical application, derived from consumption data on certain apparel items. In addition, the Total Casual Index was created by combining the consumption-based Casual Indices of men and women based on unit volumes of apparel consumption. In deriving the various casual indices, the General Social Survey data from National Opinion Research Center (University of Chicago) and the Current Industrial Report MQ23A of U.S. Bureau of Census from 1972 through 1998 were applied. For the first time, the behavioral patterns of the society and the habit formation by consumers were combined in creating and successfully validating theoretically formulated Casual Index. The statistical methods applied were proven to be highly effective. The consumption-based Casual Index was shown to be most useful for practical applications as well as for forecasting for the future casual trends. Although somewhat subjective in the formulation, the newly created Total Casual Index is expected to enhance its utility in the absence of complex data and mathematical models. The casual indices derived for both men and women suggest that the casual trends have shifted dynamically during the last three decades. Based on the Total Casual Index, the 1998 figure (75.7) is shown to be higher than that of 1972 (63.7). <P>
209

The Effect of Anisotropy on In-Plane liquid Distribution in Nonwoven Fabrics

Konopka, Amy Elizabeth 25 September 2001 (has links)
<p>AbstractKonopka, Amy Elizabeth. The Effect of Anisotropy on In-Plane liquid Distribution in Nonwoven Fabrics. (Under the direction of Behnam Pourdeyhimi)Anisotropy has been shown to be an influencing factor of many nonwoven structural properties such as the bending rigidity and the tensile strength. The effect on liquid distribution (a very important property in many nonwoven applications), however, has not been determined. In this study the effect on anisotropy on a material's in-plane liquid distribution is examined. By using the new NCRC GATS device, which enables the in-plane liquid distribution and the recording of the spread to occur simultaneously, it was determined that the liquid distribution was indeed influenced by the structural anisotropy. Also determined was the effect of the testing method on the wicking rate of the material. A comparison between conventional test methods and a newly developed test method, which utilizes the NCRC GATS and a hollowed plate, were made. It was determined from the results that the new method is the only method that measures the intrinsic wicking of the material.<P>
210

Abrasion Characteristics of Ring-Spun and Open-End Yarns

Jones, Jeremy 20 November 2001 (has links)
<p> Jones, Jeremy. Abrasion Characteristics of Ring-Spun and Open-End Yarns. (Under the direction of Dr. Pam Banks-Lee and Dr. William Oxenham.) In the early 1980s, widespread claims in the knitting industry suggesting that the use of open-end yarns significantly increased the wear of mechanical components, especially knitting needles. Since then, many studies have attempted to explain this phenomenon and have yielded widely varying results. A study was conducted to compare the yarn properties of open-end yarn to ring-spun yarn. Identical yarns of varying parameters including yarn type, yarn count, and twist multiple were produced from the same raw cotton stock to eliminate variability in raw material. These yarns were tested for abrasiveness on a Lawson-Hemphill CTT (Continuous Tension Transport) tester. The device passes the yarn over a wire and records the length of yarn required to sever the wire. For this study the CTT was encoded to abrade a fixed length of yarn over the wire. The wire was then observed with both a Hitcahi ESEM (Environmental Scanning Electron Microscope) and a digital imaging microscope. The resultant images were examined for attrition and the abrasion values were evaluated using statistical analysis. It was confirmed that an increase in yarn count corresponded to a decrease in abrasion. Twist multiple had a noticeable effect on abrasion although the trends between yarn types, and yarn counts were inconsistent. Open-end yarn abrasion values were only slightly greater than their ring-spun counterparts, contradicting the claims of the knitting industry.<P>

Page generated in 0.048 seconds