• Abstract

The purpose of this paper is to investigate the influence of calendering process on polypropylene nonwoven structure and thermal resistance. The study was focused on the influence of mass per unit area, thickness, density, porosity, characteristic opening size and additional thermal bonding by calendering. Thermal resistance of polypropylene nonwoven fabric manufactured using the mechanical carding process and bonding using the needling process, where a part of the samples was additionally bonded by the thermal calendering process, were investigated. The nonwoven fabrics were tested for thermal resistance on the guarded hot plate. Statistical analyses were performed to examine the significance between the observed parameters. Correlation matrix analyses were used to reveal relationship behaviour among the variables. A change in structure of the calendered samples caused a considerably lower thermal resistance i.e. better thermal conductivity. A change of the average value of thermal resistance after calendering related to non-calendered fabric mass between 150 and 500 g/m² ranged from 53.9 to 41.0%. With increasing nonwoven fabric mass, the difference between thermal resistances of needled and needled as well as additionally bonded by calendering the nonwoven fabric was reduced.

• Abstract

In this paper, we report a bending fatigue testing apparatus which can test the bending fatigue resistance of single Kevlar 49 fiber by setting the pretension and bending angle. The cyclic tension and the (number of cyclic bending of fiber) were recorded by this apparatus. The cyclic tension curve showed that the tension changes in periods during the bending fatigue process. The cyclic tension was theoretically analyzed and found that the bending angle had significant effect on the cyclic tension. The cyclic bending number N of Kevlar 49 fiber was plotted as a function of pretension S using S-N curves, which shows that the bending angle and pretension have a significant effect on the fatigue lifetime of a fiber. The bending fatigue morphologies of Kevlar 49 fiber explained the bending failure mechanism of the Kevlar 49 fibers.

• Abstract

In recent years, more and more researchers presented their graphic representations for protein sequence. Here, we present a new 2D graphic representation of protein sequence based on four physicochemical properties of 20 amino acids. By this graphic representation we define a distance calculation formula to quantificationally calculate the similarity degree of different protein sequences. Then we apply the proposed graphical curve and new distance in the similarity/dissimilarity comparison of 10 ND5 proteins and the protein sub-cellular localization prediction about two common test datasets, ZD98 and CL317. The results show the proposed method is easy and effective.

• Abstract

Chitosan beads demonstrate good adsorption capacity in wastewater treatment. The ease with which the chitosan beads separate from the effluent and the possibilities of sorbent regeneration have made chitosan beads a more prominent form for biosorption. However, chitosan beads form gels at pHs below 5.5, which makes them unsuitable to be employed in treatment process. Bifunctional agents are introduced to increase the integrity of the beads by crosslinking chitosan. Crosslinked chitosan beads exhibit different adsorption capacities for distinct types and categories of dyestuffs. In this study, the removal of Direct Red 80 (DR80), Reactive Yellow 25 (RY25) and Acid Blue 25 (AB25) dyes by chitosan-based beads has been investigated. Variation in pH and temperature, effect of crosslinking and encapsulation of bacteria Lactobacillus casei are evaluated for their influence on the adsorption behaviour. Zeta potential and structural characterization of the synthesized chitosan beads are performed. Adsorption equilibriums are achieved in about five hours. The chitosan beads are crosslinked with glutaraldehyde to avoid their dissolution at pH 2 and the beads achieve complete removal of the three dyes within one hour. Temperature increase induces a positive effect on the adsorption of DR80, but an insignificant effect on that of RY25 and negative effect on AB25. Adsorption with the crosslinked beads at pH 5.5 and 37^°C promotes the removal of RY25 and AB25 by at least two folds more than that by non-crosslinked chitosan beads, but is found to be less effective on DR80. Significant increase of DR80 adsorption is achieved by adopting the crosslinked-bacteria-encapsulated chitosan beads while the effect on AB25 and RY25 are similar when compared to blank crosslinked beads. Langmuir and Freundlich isotherms fit the experimental data and the pseudo-second order equation agrees very well with the kinetic data.

• Abstract

In time series analysis, fitting the Moving Average (MA) model is more complicated than Autoregressive (AR) models because the error terms are not observable. This means that iterative nonlinear fitting procedures need to be used in place of linear least squares. In this paper, Time-Varying Moving Average (TVMA) models are proposed for an autocovariance nonstationary time series. Through statistical analysis, the parameter estimates of the MA models demonstrate high statistical efficiency. The Akaike Information Criterion (AIC) analyses and the simulations by the TVMA models were carried out. The suggestion about the TVMA model selection is given at the end. This research is useful for analyzing an autocovariance nonstationary time series in theoretical and practical fields.

• Abstract

Whether different affective states have specific physiological activation patterns still does not have an exact interpretation and clear validation. Skin Conductance Response (SCR) is under strict control of the autonomic nervous system, providing an efficient way to measure the emotional reactions. Since the emotional SCR signals are always short and noisy, it is of great value to study the methods suitable for short-term SCR analysis. According to the characteristic of SCR signal, we proposed a symbolic method and the symbolic information entropy, further, applied the method to analyse emotional SCR signals. Experiment results show that the symbolic information entropy of SCR is in accordance with the arousal level of emotions, and SCR is more sensitive to the variations of emotional arousal rather than to valence. Symbolic information entropy is less influenced by noise and non-stationary, providing an effective method in analyzing SCR signals or other complex physiological signals.

• Abstract

Impedance Cardiography (ICG) is a noninvasive technique for monitoring stroke volume, cardiac output and other hemodynamic parameters, which is based on sensing the change of thoracic electrical impedance caused by blood volume change in aorta during the cardiac cycle. Motion artifact and respiratory artifact can lead to baseline drift in ICG signal, particularly during or after exercise, which can cause errors when calculating hemodynamic parameters. This paper presents an LMS-based adaptive filtering algorithm to suppress the respiratory artifact of ICG signal without restricting patients' breath. Estimation of hemodynamic parameters requires error-free automatic extraction of the characteristic points. Wavelet transform is used for extracting characteristic points which include its peak point (Z), start point (B) and end point (X) of left ventricular ejection time.

• Abstract

Electrocardiography (ECG) is one of the most important physiological signals, which has been proven to contain reliable affective information. Four kinds of objective affects including happiness, sadness, angry and fear, are induced by affective fragments from movies, and ECG signals are recorded by Biopac MP 150 synchronously. In an independent experiment the affective videos are played twice, and in the second presentation the press file of affective re-evaluation is obtained, which registers the subjective experience of participants and help us intercept the reliable affective ECG. The detrended fluctuation analysis is used to quantitate the temporal correlations by the scaling exponent in affective ECG. And the result showed that ECG of happiness, sadness, angry and fear had long-range correlations. Then the scaling exponent is used by the binary classifier of Fisher as an affective feature, and the result showed that the correct recognition rate of happiness, sadness, angry and fear are 89.74%, 90.1%, 70.43%, 84.44% respectively. The whole experiment displays that the nonlinear features have a fine distinction in different emotions.

• Abstract

This paper presents a systematic analysis of the changes in thickness and the differences in the heat flux transfer for the two surfaces of selected single-side napped fabric, to explore the relationship between their heat flux and thickness during compression. The results showed that heat flow in the un-napped surface was greater than that in the napped surface when the fabric initially contacted the upper plate of a Fabric Touch Tester (p ‹ 0.05); few differences of the heat flux between the un-napped and the napped surfaces measured separately with each surface facing upwards for each fabric type were observed when the pressure exceeded 0.6 Pa (p › 0.05); the heat flux was linearly correlated with thickness for both the un-napped surface and napped surface when the pressure exceeded 0.6 Pa (correlation coefficient R² › 0.9); the gradients of the regression equation of heat flux-thickness gradually increased from the initial thickness point to the midpoint of the maximum pressure except for the first heat peak point of the un-napped surface. In conclusion, heat flux was significantly affected by the surface characteristics of the fabrics in the initial stages of compression but was then not affected by either the surface features or the fabric structures at higher levels of compression pressure. The conclusion could be useful in product development and in providing a guide for clothing wearing comfort.

• Abstract

Pd/SiO_2 organic-inorganic hybrid material was prepared by sol-gel method, in which PdCl_2 was added into methyl-modified silica sol. The Pd/SiO_2 sol particle size distribution, the hydrophobicity and phase changes of Pd/SiO_2 hybrid materials calcined at 200, 350, 500, 600 and 750 °C in air atmosphere were discussed. The Pd/SiO_2 sol system exhibits moderate dispersion and the mean particle size of Pd/SiO_2 sol is 2.70 nm. When the calcination temperature is raised to 350 °C, metallic palladium of high crystallinity is formed in the Pd/SiO_2 sample. PdO occurs in minor quantities in the Pd/SiO_2 sample calcined at 500 °C, which increases in amount in the samples calcined at 600 and 750 °C. With the increase of calcination temperature, the Si-CH_3 and Si-OH bands in Pd/SiO_2 materials are found to decrease in absorption intensity and the hydrophobicity on Pd/SiO_2 film surfaces increases. The water contact angle on the Pd/SiO_2 film surface achieves the maximum value as the calcination temperature is up to 350 °C and the particle sizes of the formed metallic Pd are about 15 ∼ 20 nm. The optimal calcination temperature for hydrophobic Pd/SiO_2 membrane materials is about 350 °C.