Akio Sakaguchi

Image Analysis of Woven Fabric Surface Irregularity

Applying image analysis to fabric quality evaluation is suggested as a substitute for human inspection of fabric surfaces. A fabric image is captured on an image scanner, and from it, the coefficient of variation and power spectra of yarn interval are calculated as indices of irregularity in the yarn arrangement. However, neither shows a significant relationship with the results of human evaluations. As another approach to the irregularity of fabric surfaces, the power spectral peak width of the intensity data is computed. The peak width, containing surface irregularity information, shows it is related to fabric quality. The study also shows that the peak width changes with the back beam height.

Twisting Mechanisms of Open-End Rotor Spun Hybrid Yarns:

We have developed a mechanical hybrid yam spinning system that produces different kinds of yam on a modified open-end rotor spinning frame. In order to understand the characteristics of hybrid yam and produce novel yarns, it is necessary to investigate yarn formation and the twisting mechanism in the spinning rotor during yam production. Our results reveal that the rotor revolution generally results in combining the filament yam and the staple fiber strand. The fiber twist angle of the strand in a hybrid yarn is smaller than that of a rotor spun single yam with the same spinning conditions. Although a fed filament yam has a false twist inserted by increasing the filament over-feed, the filament yarn in the hybrid yarn has a smaller level of fiber twist angle in the same direction as the twist of the staple fiber strand due to untwisting of the false twist.

Measuring Cloth Fell Fluctuation on a Weaving Machine

In this paper, we use an oblique scanning method with an image scanner to capture the fabric surface image on the running air-jet loom and to develop a new approach to measure the fluctuation of the cloth fell point during weaving. Based on our theoretical analysis of the cloth structure formation process, we also propose a fluctuation index of woven fabric in the cloth fell as an evaluation parameter for stable beating-up motion during weaving.

Woven Fabric Quality Evaluation Using Image Analysis

As a factor important to fabric quality, reed marks are studied by theoretical and experimental methods. In order to analyze their appearance, the power spectrum of a fabrics image is simulated in terms of that fabrics geometry. These power spectra offer peaks of wavelength coincident with the reed spacing. Further, they are used as an indicator to explain reed marks in terms of packed warps. At this same wavelength in experimental power spectra, there is also a peak that exhibits dependence on fabric quality. This peak adequately describes the appearance of the reed marks and thus can be used as a quality indicator for a woven fabric.

Novel Observation Technique for Contact Condition of Fabric

An observation technique is developed to provide a fundamental understanding of the surface contact condition between the human body and clothes. As a substitute for the body, transparent silicone rubber is used. The contact condition between the rubber and fabric is observed through the rubber using photomicrography. The method visualizes contact condition changes for different contact pressures and fabric structures. Using the relationship between the contact condition and the pressure, it is useful to estimate the two-dimensional distribution of contact pressure, which is important in clothing comfort.

Influence on Calculated Blood Pressure of Measurement Posture for the Development of Wearable Vital Sign Sensors

We studied a wearable blood pressure sensor using a fiber Bragg grating (FBG) sensor, which is a highly accurate strain sensor. This sensor is installed at the pulsation point of the human body to measure the pulse wave signal. A calibration curve is built that calculates the blood pressure by multivariate analysis using the pulse wave signal and a reference blood pressure measurement. However, if the measurement height of the FBG sensor is different from the reference measurement height, an error is included in the reference blood pressure. We verified the accuracy of the blood pressure calculation with respect to the measurement height difference and the posture of the subject. As the difference between the measurement height of the FBG sensor and the reference blood pressure measurement increased, the accuracy of the blood pressure calculation decreased. When the measurement height was identical and only posture was changed, good accuracy was achieved. In addition, when calibration curves were built using data measured in multiple postures, the blood pressure of each posture could be calculated from a single calibration curve. This will allow miniaturization of the necessary electronics of the sensor system, which is important for a wearable sensor.

Single hook model of fiber figures in card webs

In card webs, many fibers are not straight and generally have hooks or bends. In this study, a one-dimensional fiber figure model is discussed. Using correlation coefficients, a simple classification method for fiber figures is proposed. This method enables us to classify fiber figures into five categories: straight, leading- and trailing-hooked, and leading- and trailing-bent figures. This method is then applied to experimental data. The results indicate that the absolute values of the correlation coefficients of the vector quantities between the measured fiber figures and one of our models are greater than 0.8 in many cases. Thus, our proposed method is viable for the classification of fiber figures in card webs.

Mechanical performance of wool fabrics grafted with methacrylamide and 2-hydroxyethyl methacrylate by the Kawabata Evaluation System for Fabric method

Wool fabrics were graft copolymerized with methacrylamide (MAAm) and 2-hydroxyethyl methacrylate (HEMA) in aqueous media, using a chemical redox system as an initiator. After grafting, the mechanical properties related to the hand evaluation, such as tensile, shearing, bending, compression and surface properties of wool fabrics, were evaluated by means of the Kawabata Evaluation System for Fabric. The surface morphology was examined by scanning electron microscopy. The results revealed that the surface morphology and low-stress mechanical properties of wool fabrics were remarkably changed after grafting with HEMA. The weight gain of the wool fabrics grafted with HEMA increased rapidly in the initial grafting stage and reached saturation level at 17 wt% after 20 minutes. Small deposits of oligomers were visible on wool surfaces and typical scale patterns were changed after grafting wool fabric with HEMA. The slope of the shearing hysteresis curves in the weft and warp directions for wool fabrics grafted with HEMA was increased compared with the control and wool fabrics grafted with MAAm. These results imply that the changes in tensile, shearing, bending and compression behavior of grafted wool fabrics are due to the reduction of the free internal volumes of the fabrics, leading to a tightening of its texture.

Effects of Pin Drafting on Irregularities of Sliver Made from Fine Denier Fibers

To improve the quality of spun yarn made from fine denier fibers, the technique of pin drafting is examined and discussed. Slivers made from four levels of fiber fineness are drafted with an experimental pin drafting system by changing the draft ratio. Deviations between indices of irregularities I corresponding to output and input slivers are calculated to evaluate the performance of the drafting process. Deviations of the gill sliver decrease with decreasing fiber denier. This phenomenon can be explained by the larger number of fibers contacting the pins of the gill fallers and the greater interfiber cohesive force with decreasing fiber denier. Irregularities of sliver from fine denier fibers are effectively negated by an appropriate pin drafting system.

Application of a truncated distribution for tsumugi yarn width

Hand-spun, silk yarn made from floss silk is referred to as tsumugi yarn. It gives a unique appearance on the products, also called tsumugi, which are considered to be an important type of fabric for their aesthetics. The essential factor of this visual effect is originated by the thickness variation of tsumugi yarn; however, the detail of the variation is unknown. In this paper, as a fundamental study of tsumugi yarn, its width distribution is discussed. To model the width distribution, the Polya–Eggenberger distribution is introduced. Moreover some modifications are applied for the distribution to describe the yarns situation. That is to say, it is impossible to be thinner than a level of thickness for the yarn to maintain a shape of a thread; on the other hand, tsumugi yarn is not limited to only containing thicker parts. Additionally, it is unavoidable to involve errors and fluctuations in the actual data. Hence, the distribution is truncated and convoluted. By using an image scanner, the width of tsumugi yarn is measured. With the measured data, the parameters of the width distribution are estimated using the maximum likelihood method. The results show that the width distribution of tsumugi yarn is asymmetric and well summarized by the distribution.