Mechanistic modelling of pilling. Part II: Individual-fibre computational model

A one-dimensional computational model of pilling of a fibre assembly has been created. The model follows a set of individual fibres, as free ends and loops appear as fuzz and arc progressively withdrawn from the body of the assembly, and entangle to form pills, which eventually break off or are pulled out. The time dependence of the computation is given by ticks, which correspond to cycles of a wear and laundering process. The movement of the fibres is treated as a reptation process. A set of standard values is used as inputs to the computation. Predictions arc given of the change with a number Of cycles of mass of fuzz, mass of pills, and mass removed from the assembly. Changes in the standard values allow sensitivity studies to be carried out.

Mechanistic modelling of pilling. Part I: Detailing of mechanisms

Mechanistic models of pilling are discussed in general terms, and a framework for pilling simulations is thereby created. A fundamental flaw in earlier models of pilling is revealed. A more comprehensive model of fibre diffusion and withdrawal from the fabric is proposed, and this is solved in general terms to find the rate of fuzz growth. Fuzz wear-off and entanglement into pills are discussed. Fibre fatigue is introduced, and it is demonstrated that this potentially increases the rate of withdrawal of anchor fibres.

Fibre slippage in cyclically perturbed fibrous assemblies

The dynamics of fibre slippage within general non-bonded fibrous assemblies is studied in the situation where the assembly is subjected to general small cyclic loads. Two models are proposed. The first is applicable when the general cyclic loading is complemented by an occasional tugging force on one end of a fibre, which causes it to gradually withdraw from the assembly, such as might occur during the pilling of a textile. The second considers the situation in which the cyclic perturbations act around a constant background load applied to the assembly. The dynamics is reminiscent of self-organized critical behaviour. This model is applied to predict the progressive elongation of a single yarn during weaving.

Fibre Bragg gratings in polymer optical fibre for applications in sensing

This thesis presents the potential sensing applications of fibre Bragg gratings in polymer optical fibres. Fibre Bragg gratings are fabricated in different kinds of polymer optical fibres, including Poly methyl methacrylate (PMMA) and TOPAS cyclic olefin copolymer based microstructured polymer optical fibres and PMMA based step-index photosensitive polymer optical fibre, using the 325nm continuous wave ultraviolet laser and phase mask technique. The thermal response of fabricated microstructured polymer optical fibre Bragg gratings has been characterized. The PMMA based single mode microstructured polymer optical fibre Bragg gratings exhibit negative non-linear Bragg wavelength shift with temperature, including a quasi-linear region. The thermal sensitivity of such Bragg gratings in the linear region is up to -97pm/°C. A permanent shift in the grating wavelength at room temperature is observed when such gratings are heated above a threshold temperature which can be extended by annealing the fibre before grating inscription. The largest positive Bragg wavelength shift with temperature in transmission is observed in TOPAS based few moded microstructured polymer optical fibre Bragg gratings and the measured temperature sensitivity is 250±0.5pm/°C. Gluing method is developed to maintain stable optical coupling between PMMA based single mode step index polymer optical fibre Bragg gratings and single mode step index silica optical fibre. Being benefit from this success, polymer optical fibre Bragg gratings are able to be characterised for their temperature, humidity and strain sensitivity, which are -48.2±1pm/°C, 38.3±0.5pm per %RH and 1.33±0.04 pm/µ??respectively. These sensitivities have been utilised to achieve several applications. The strain sensitivity of step index polymer optical fibre Bragg grating devices has been exploited in the potential application of the strain condition monitoring of heavy textiles and when being attached to textile specimens with certain type of adhesives. These polymer fibre Bragg grating devices show better strain transfer and lower structure reinforcement than silica optical fibre Bragg grating devices. The humidity sensitivity of step index polymer optical fibre Bragg grating devices is applied to detecting water in jet fuel and is proved to be able to measure water content of less than 20 ppm in Jet fuel. A simultaneous temperature and humidity sensor is also made by attaching a polymer fibre Bragg grating to a silica optical fibre Bragg grating and it shows better humidity measurement accuracy than that of electronic competitors.

Isolation, characterisation and application of novel microbial protein cross-linking enzymes

Microbial transglutaminase is favoured for use in industry over the mammalian isoform, and hence has been utilized, to great effect, as an applied biocatalyst in many industrial areas including the food and textiles industries. There are currently only a limited number of microbial TGase sources known. A number of organisms have been screened for transglutaminase activity using biochemical assays directed towards TGase catalyzed reactions (amine incorporation and peptide cross-linking assay). Of those organisms screened, TGase was identified in a number of isolates including members of the Bacillus and Streptomyces families. In addition, a protein capable of performing a TGase-like reaction was identified in the organism Pseudomonas putida that was deemed immunologically distinct from previously described TGase isoforms, though further work would be required to purify the protein responsible. The genuses Streptoverticillium and Streptomyces are known to be closely related. A number of micro-organisms relating to Streptomyces mobaraensis (formerly Streptoverticillium mobaraensis) have been identified as harboring a TGase enzyme. The exact biological role of Streptomyces TGase is not well understood, though from work undertaken here it would appear to be involved in cell wall growth. Comparison of the purified Streptomyces TGase proteins showed them to exhibit marginally different characteristics in relation to enzymatic activity and pH dependency upon comparison with Streptomyces mobaraensis TGase. In addition, TGase was identified in the organism Saccharomonospora viridis that was found to be genetically identical to that from S. mobaraensis raising questions about the enzymes dissemination in nature. TGase from S. baldaccii was found to be most diverse with respect to enzymatic characteristics whilst still retaining comparable E(y-glutamyl) lysine bond formation to S. mobaraensis TGase. As such S. baldaccii TGase was cloned into an expression vector enabling mass production of the enzyme thereby providing a viable alternative to S. mobaraensis TGase for many industrial processes.

Modeling foreign exchange rate pass-through using the exponential GARCH

In this chapter, the authors use an EGARCH-ECM to estimate the pass-through effects of Foreign Exchange (FX) rate changes and changes in producers' prices for 20 U.K. export sectors. The long-run adjustments of export prices to FX rate changes and changes in producers' prices are within the range of -1.02% (for the Textiles sector) and -17.22% (for the Meat sector). The contemporaneous Pricing-To-Market (PTM) coefficients are within the range of -72.84% (for the Fuels sector) and -8.05% (for the Textiles sector). Short-run FX rate pass-through is not complete even after several months. Rolling EGARCH-ECMs show that the short and long-run effects of changes in FX rate and producers' prices vary substantially, as do asymmetry and volatility estimates before equilibrium is achieved.

Does institutional quality affect firm performance? Insights from a semiparametric approach

Using a novel modeling approach, and cross-country firm level data for the textiles industry, we examine the impact of institutional quality on firm performance. Our methodology allows us to estimate the marginal impact of institutional quality on productivity of each firm. Our results bring into question conventional wisdom about the desirable characteristics of market institutions, which is based on empirical evidence about the impact of institutional quality on the average firm. We demonstrate, for example, that once both the direct impact of a change in institutional quality on total factor productivity and the indirect impact through changes in efficiency of use of factor inputs are taken into account, an increase in labor market rigidity may have a positive impact on firm output, at least for some firms. We also demonstrate that there are significant intra-country variations in the marginal impact of institutional quality, such that the characteristics of “winners” and “losers” will have to be taken into account before policy is introduced to change institutional quality in any direction.

Does human capital endowment of FDI recipient countries really matter? Evidence from cross-country firm level data

The stylized literature on foreign direct investment suggests that developing countries should invest in the human capital of their labour force in order to attract foreign direct investment. However, if educational quality in developing country is uncertain such that formal education is a noisy signal of human capital, it might be rational for multinational enterprises to focus more on job-specific training than on formal education of the labour force. Using cross-country data from the textiles and garments industry, we demonstrate that training indeed has greater impact on firm efficiency in developing countries than formal education of the work force.

Policy, economic federalism, and product market entry:the Indian experience

Productivity growth has long been associated with, among other things, contestability of markets which, in turn, is dependent on the ease with which potential competitors to the incumbent firms can enter the product market. There is a growing consensus that in emerging markets regulatory and institutional factors may have a greater influence on a firm's ability to enter a product market than strategic positions adopted by the incumbent firms. We examine this proposition in the context of India where the industrial policies of the 1980s and the 1990s are widely believed to be pro-incumbent and pro-competition, respectively, thereby providing the setting for a natural experiment with 1991 as the watershed year. In our analysis, we also take into consideration the possibility that the greater economic federalism associated with the reforms of the 1990s may have affected the distribution of industrial units across states after 1991. Our paper, which uses the experiences of the textiles and electrical machinery sectors during the two decades as the basis for the analysis, finds broad support for both these hypotheses.

Entry, reforms complementarity and performance:a tale of two Indian manufacturing sectors

In this paper, we use plant-level data from two Indian industries, namely, electrical machinery and textiles, to examine the empirical relationship between structural reforms like abandonment of entry restrictions to the product market, competition and firm-level productivity and efficiency. These industries have faced different sets of policies since Independence but both were restricted in the adoption of technology and in the development of optimal scales of production. They also belonged to the first set of industries that benefited from the liberalization process started in the 1980s. Our results suggest that both the industries have improved their efficiency and scales of operation by the turn of the century. However, the process of adjustment seems to have been worked out more fully for electrical machinery. We also find evidence of spatial fragmentation of the market as late as 2000–2001. Gains in labour productivity were much more evident in states that either have a strong history of industrial activity or those that have experienced significant improvements in business environment since 1991.

Pricing-to-market using EGARCH-error correction model

In this paper, the authors use an exponential generalized autoregressive conditional heteroscedastic (EGARCH) error-correction model (ECM), that is, EGARCH-ECM, to estimate the pass-through effects of foreign exchange (FX) rates and producers’ prices for 20 U.K. export sectors. The long-run adjustment of export prices to FX rates and producers’ prices is within the range of -1.02% (for the Textiles sector) and -17.22% (for the Meat sector). The contemporaneous pricing-to-market (PTM) coefficient is within the range of -72.84% (for the Fuels sector) and -8.05% (for the Textiles sector). Short-run FX rate pass-through is not complete even after several months. Rolling EGARCH-ECMs show that the short and long-run effects of FX rate and producers’ prices fluctuate substantially as are asymmetry and volatility estimates before equilibrium is achieved.

Does human capital endowment of foreign direct investment recipient countries really matter? evidence from cross-country firm level data

The stylized literature on foreign direct investment (FDI) suggests that developing countries should invest in the human capital of their labor force in order to attract FDI. However, if educational quality in developing country is uncertain such that formal education is a noisy signal of human capital, it might be rational for multinational enterprises to focus more on job-specific training than on formal education of the labor force. Using cross-country data from the textiles and garments industry, we demonstrate that training indeed has a greater impact on firm efficiency in developing countries than formal education of the workforce. © 2013 John Wiley & Sons Ltd.

The impact of the changing weaving industry on the culture and socioeconomic development of Maya women in Guatemala

Growing demand for handwoven Maya textiles from Guatemala parallels recent international fascination with Maya civilization. This thesis surveys the effects of increases in demands for artisan textiles in Guatemala, and explores the reactions of women involved in Aj Quen, a weavers' association. The hypothesis is that the well-being of Maya women depends on their participation in the association. This is tested by using indicators of the weavers' attitudes defined as their "well-being" regarding (1) health, (2) education levels, (3) child care practices, and (4) economic stability. Interviews were conducted with 127 Maya women. Data were documented, providing a crucial missing link in the current literature of "women in Guatemala." The results of this study yield baseline data demonstrating that health and child care practices are not directly related to women's participation in the association. Their education levels increased as a direct result of working with the association, as did economic stability, although less consistently.

The impact of the changing weaving industry on the culture and socioeconomic development of maya women in Guatemala

Growing demand for handwoven Maya textiles from Guatemala parallels recent international fascination with Maya civilization. This thesis surveys the effects of increases in demands for artisan textiles in Guatemala, and explores the reactions of women involved in Aj Quen, a weavers' association. The hypothesis is that the well-being of Maya women depends on their participation in the association. This is tested by using indicators of the weavers' attitudes defined as their "well-being" regarding 1) health, 2) education levels, 3) child care practices, and 4) economic stability. Interviews were conducted with 127 Maya women. Data were documented, providing a crucial missing link in the current literature of "women in Guatemala." The results of this study yield baseline data demonstrating that health and child care practices are not directly related to women's participation in the association. Their education levels increased as a direct result of working with the association, as did economic stability, although less consistently.