Ahmet Çay

Prediction of the air permeability of woven fabrics using neural networks

Purpose – The target of the current work is the creation of a model for the prediction of the air permeability of the woven fabrics and the water content of the fabrics after the vacuum drying.Design/methodology/approach – There have been produced 30 different woven fabrics under certain weft and warp densities. The values of the air permeability and water content after the vacuum drying have been measured using standard laboratory techniques. The structural parameters of the fabrics and the measured values have been correlated using techniques like multiple linear regression and Artificial Neural Networks (ANN). The ANN and especially the generalized regression ANN permit the prediction of the air permeability of the fabrics and consequently of the water content after vacuum drying. The performance of the related models has been evaluated by comparing the predicted values with the respective experimental ones.Findings – The predicted values from the nonlinear models approach satisfactorily the experiment...

Effects of β-cyclodextrin on selected properties of electrospun thermoplastic polyurethane nanofibres.

Cyclodextrins are one of the most promising materials for the development of products with advanced properties due to inclusion complex formation ability with a wide variety of substances. More specifically, incorporation of cyclodextrins into electrospun nanofibrous materials is considered as potential candidates for functional textile applications. This study examines the electrospinning of thermoplastic polyurethane (TPU) nanofibres including β-cyclodextrin and investigates the effects of β-cyclodextrin (β-CD) on resultant fibre properties. TPU/CD nanofibres were characterized by scanning electron microscopy, FTIR, TGA and DSC analysis. Additionally phenolphthalein absorption tests were applied. It was observed that the incorporation of β-CD increased the mean fibre diameter and heterogeneity of nanofibrous membranes. The effects of β-CD on the thermal properties of TPU membranes were shown. It was proven that β-CD within TPU nanostructure could be able to form inclusion complexes. TPU/CD nanofibres are believed to have good potentials for functional textile applications.

Exergetic Analysis of Textile Convective Drying with Stenters by Subsystem Models: Part 1—Exergetic Modeling and Evaluation

This study, which consists of two parts, deals with the exergy analyses and assessments of the direct gas–heated (DGHS) and hot oil–heated (HOHS) stenters. In the first part, a new model for the exergetic analysis of the convective drying of textiles at stenters was presented and the variations of exergetic parameters for each chamber of the stenter were examined. It was emphasized that the exergy efficiency of the last chambers decreased drastically due to the lower evaporation rate of the falling rate period of drying. Additionally, the subsystems of the chambers were analyzed. For this purpose, the detailed control volume models were conducted for the stenters. It was determined that the combustion chamber and mixing unit of the DGHS and the hot oil boiler of the HOHS led to higher exergy destruction rates. Furthermore, total exergy destruction and loss rates of the HOHS were higher compared to those with the DGHS. The exergy efficiency values of each chamber of the DGHS were calculated to be 10.9, 14.9, 15.3, 12.2, 9.8, and 5.3%, respectively.

Relation between fabric porosity and vacuum extraction efficiency: Energy issues

Abstract Vacuum extraction is a technique that removes the unbound water from the fabrics by the help of air flow through the fabrics at high velocities. Air flow through textile fabrics is mainly affected by the fabric structure such as tightness, porosity and air permeability. This paper outlines the effects of the fabric structure on the vacuum drying efficiency. Thirty woven fabrics with different porosities were dried by vacuum extraction method, and it was found that the lower the porosity or the lower the air permeability, the higher the water removal effects and energy requirement.

A study on the exergetic analysis of continuous textile dryers

This study deals with the exergetic analyses of the continuous textile dryers consisting of a stenter and a conveyor belt dryer. The exergy destructions in each of the components of the overall system are determined for average values of experimentally measured parameters. Exergy efficiencies of the system components are calculated to assess their performance. The effects of varying exhaust air humidity ratio and dead state temperature are also investigated. The total exergy efficiency values for the stenter and conveyor belt dryer are found to be 13.7% and 14.3% for the exhaust air humidity ratio of 0.1 kgair/kgwater, respectively.

Artificial Neural Networks and Their Applications in the Engineering of Fabrics

Historically the main use of the textile fabrics has been limited mainly to clothing and domestic applications. The technical uses were of minor importance. However in the last decades the use of the textile structures has started to spread over other sectors like construction, medicine, vehicles, aeronautics, etc. The increased interest in technical applications have improved the fabric design and engineeringprocedures, given that the final products must be characterized by certain mechanical, electrical etc. properties. The performance of the fabrics should be predictable right from the design phase. The design of a fabric is focusing on the materials selection as well as on the definition of its structural parameters, so that the requirements of the end use be fulfilled. These changes in the application field of the textile structures caused a move from the esthetic design to the total technical design, where the fabric appearance and the particular properties affecting its final performance are taken in account. However, the textile structures are highly complex. A textile fabric consists of yarns; yarns in turn consist of fibres. Thus the mechanical performance of the fabrics is characterized by the structural geometrical complexity and non-linearity, as well as from the non-linearities of the materials themselves. This double non-linear bahaviour of the textile fabrics increases the difficulty in the fabric design and engineering processes. The complex structure and the difficulties introduced by the raw materials do not allow the use of precise analytical models for the technical design of the fabrics. Fabric engineering activities are increasingly based on computational models that aim at the prediction of the properties and the performance of the fabrics under consideration. Various computational tools have been used in order to represent the fabrics in a computational environment and to predict their final properties. Among others, Finite Element Method (FEM) analysis has supported mainly the prediction of the behaviour of the complex textile structures under mechanical loads. In the case of classification problems Artificial Neural Networks (ANNs) have proved a very efficient tool for the fast and precise solution. ANNs have found an increasing application in the textile field in the classification as well as in the

Exergetic Analysis of Textile Convective Drying with Stenters by Subsystem Models: Part 2—Parametric Study on Exergy Analysis

In this study, the effects of exhaust air humidity ratio, the residual moisture content of fabric outlet, and the temperature of the drying air on the exergy destruction and efficiency of stenters were investigated. The exergy efficiencies of the direct gas heated stenter (DGHS) and hot oil heated stenter (HOHS) were calculated to be varying from 8.5 to 17.5% and from 6.8 to 14.0%, depending on the exhaust air humidity ratio, respectively. The increase in the drying air temperature led to an increase in the exergy efficiency, especially in the constant rate and second rate period of the drying. On the other hand, the application of the gradual temperature method caused the highest total exergy efficiency due to the highest drying rates in the first chambers where considerably high air temperatures were set. Overdrying resulted in the higher irreversibility due to the increase in the fuel consumption in the falling rate period of drying. Thus, the exergy efficiency decreased drastically.

Crosslinking of poly(vinyl alcohol) nanofibres with polycarboxylic acids: biocompatibility with human skin keratinocyte cells

AbstractIn this study, poly(vinyl alcohol) nanofibres were produced and evaluated for wound dressing applications. However, the solubility of the poly(vinyl alcohol) matrix in the aqueous medium generally limits its applications. To overcome this problem, 1,2,3,4 butanetetracarboxylic acid (BTCA) and citric acid (CA) were used as crosslinking agents. Successful bead-free nanofibres were produced, and they both preserved their fibrous structure after water treatment. The mean fibre diameters of polycarboxylic acid crosslinked nanofibres were lower compared to pure PVA nanofibres. Although the morphology of BTCA and CA crosslinked nanofibres was similar, the swelling degree of PVA/CA was found to be higher. Furthermore, toxicity and keratinocyte cell proliferation performance of produced PVA/BTCA and PVA/CA nanofibres indicated that these nanofibrous materials could be used in wound dressing applications.

Pamuklu Süprem Kumaşlarda Hava Geçirgenliğinin Basınç Farkına Bağlı Olarak Tahminlenmesi

Hava gecirgenligi, giyim konfor ozellikleri arasinda onemli bir yere sahiptir. Hem isi transferinin daha kolay yapilmasini hem de nefes alabilirlik ozelligi ile kisinin daha konforlu hissetmesini saglayan bu ozellik, bircok parametreden etkilenen kompleks bir niteliktir. Bu calisma kapsaminda hava gecirgenligi kumas ozellikleri ile birlikte basinc farki da dikkate alinarak ongorulmustur. Varyans analizi sonuclari, elde edilen modelin anlamli oldugunu ortaya koymus ve hava gecirgenliginin yuksek guvenilirlikte tahminlenebildigini gostermistir. Calismada ayrica, basinc farkinin hava gecirgenligi ozelligine etkisi detayli olarak incelenerek ve kumaslarin basinc artisina bagli davranislari analiz edilmistir. Sonuclar, uygulanan basinc farki artisi ile hava gecirgenligi degerlerinin arttigini ve kumas sikligina bagli olarak bu artistaki egilimin degistigini ortaya koymustur. Bu durum, hava gecirgenligi ve gozeneklilik arasindaki iliskiye bagli olarak irdelenmistir. Seyrek kumaslarda, ozellikle yuksek basinc farklarindaki hava akimlarinda, kumas yapisinin deforme oldugu ortaya konmustur.

Termofiksaj İşlemleri için Ramöz Atık Havasından Isı Geri Kazanım Sisteminin Enerji ve Ekserji Analizi

Enerji geri kazanim uygulamalari, dogal kaynaklarin verimli kullanilmasi adina surdurulebilir uretimin temel kosullarindan birisidir. Tekstil terbiye isletmelerinde uygulanan surecler sonucunda oldukca fazla miktarda atik enerji ortaya cikmaktadir. Bu atik enerjinin geri kazanilmasi hem ekonomik hem de cevresel fayda saglamaktadir. Bu calisma kapsaminda tekstil terbiye isletmelerinde kullanilan ramozlerin atik havasindan isi geri kazanimi analiz edilmistir. Incelenen isletme olcekli isi geri kazanim sisteminde kuru termofiksaj havasi ile isletme suyu isitilmaktadir. Sistemin termodinamik modeli enerji ve ekserji analizleri ile sunulmustur. Sistemde isitilan suyun sicakligini etkileyen en onemli parametrenin su debisi oldugu gorulmustur. Dusuk su debilerinde 70-75 °C’de sicak su elde etmek mumkundur. Su debisi azaldikca sistemde ortaya cikan ekserji tahribi azalmakta, ekserji verimi artmaktadir. Isi geri kazanim sisteminin ekserji verimi su debisine bagli olarak %10 ile %30 araliginda degismektedir.