Cotton fabric surface modification for improved UV radiation protection using sol–gel process

In this study, lightweight 100% cotton fabric was successfully modified by the sol–gel process to impart high ultraviolet radiation (UVR) scattering property to the fabric surface. Active ingredients were tetraethyl orthotitanate [Ti(OCH₂CH₃)₄] and tetraethyl orthosilicate [Si(OCH₂CH₃)₄]. The cotton fabric was padded with the nanosol solution, dried at 60°C, and cured at 150°C. Scanning electron microscopy showed continuous and uniform film on the fiber surface. Excellent UVR scattering was obtained with all treated fabrics. Increasing titania content in the nanosol solution leads to increased UVR protection. This is attributed to the increase of the refractive index of the film formed on the fabric surface. Excellent durability of the treatment was obtained, which indicates a good adhesion between the coating and the fabric surface. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 111–117, 2007.     

Adsorptive removal of anionic and non‐ionic surfactants from aqueous phase using Posidonia oceanica (L.) marine biomass

BACKGROUND: In this study, the capability of low‐cost, renewable and abundant marine biomass Posidonia oceanica (L.) for adsorptive removal of anionic and non‐ionic surfactants from aqueous solutions have been carried out in batch mode. Several experimental key parameters were investigated including exposure time, pH, temperature and initial surfactant concentration. RESULTS: It was found that the highest surfactant adsorption capacities reached at 30 °C were determined as 2.77 mg g^?1 for anionic NaDBS and as 1.81 mg g^?1 for non‐ionic TX‐100, both at pH 2. The biosorption process was revealed as a thermo‐dependent phenomenon. Equilibrium data were well described by the Langmuir isotherm model, suggesting therefore a homogeneous sorption surface with active sites of similar affinities. The thermodynamic constants of the adsorption process (i.e. ΔG°, ΔH° and ΔS°) were respectively evaluated as ? 8.28 kJ mol^?1, 48.07 kJ mol^?1 and ? 42.38 J mol^?1 K^?1 for NaDBS and ? 9.67 kJ mol^?1, 95.13 kJ mol^?1 and ? 174.09 J mol^?1 K^?1 for TX‐100. CONCLUSION: Based on this research, valorization of highly available Posidonia oceanica biomass, as biological adsorbent to remove anionic and non‐ionic surfactants, seems to be a promising technique, since the sorption systems studied were found to be favourable, endothermic and spontaneous. Copyright © 2007 Society of Chemical Industry     

A simple continuous-time equalizer for use in magnetic storage readchannels

A four-pole continuous-time equalizer has been developed to minimize the error rate in rigid-disk magnetic storage channels employing peak detection at high recording densities. The design process consisted of two parts. A nominal model of the disk drive characteristics in the time and frequency domains was obtained from digitized waveforms at the output of a read-head amplifier in a disk drive system. The relative performance of candidate equalizers was studied by subjecting them to the measured data waveforms and then either estimating or measuring the resulting bit error rate in a simulated peak detector, operating on the equalized waveforms. The equalizer outperforms more complex structures proposed for this task and is well suited for implementation as an analog CMOS active filter with low power dissipation. Its constellation of four poles and a zero appears to be useful for several types of magnetic media     

Analysis of antimycin A by reversed-phase liquid chromatography/nuclear magnetic resonance spectrometry

A mixture of closely related streptomyces fermentation products, antimycin A, is separated, and the components are identified by using reversed-phase high-performance liquid chromatography with directly linked 400-MHz proton nuclear magnetic resonance detection. Analyses of mixtures of three amino acids, alanine, glycine, and valine, are used to determine optimal measurement conditions. Sensitivity increases of as much as a factor of 3 are achieved, at the expense of some loss in chromatographic resolution, by use of an 80-microL NMR cell, instead of a smaller 14-microL cell. Analysis of the antimycin A mixture, using the optimal analytical high-performance liquid chromatography/nuclear magnetic resonance conditions, reveals it to consist of at least 10 closely related components.     

Varactor characteristics, oscillator tuning curves, and AM-FM conversion

A simple analysis relates the small-signal specification of a varactor's capacitance to an oscillator's tuning curve. The notion of an effective capacitance across the amplitude of oscillation is introduced. The analysis also explains how the varactor converts AM noise on the oscillation into FM, which is phase noise. The analysis is experimentally validated.     

On the Discrete-Time Integral Sliding-Mode Control

A new discrete-time integral sliding-mode control (DISMC) scheme is proposed for sampled-data systems. The new control scheme is characterized by a discrete-time integral sliding manifold which inherits the desired properties of the continuous-time integral sliding manifold, such as full order sliding manifold with pole assignment, and elimination of the reaching phase. In particular, comparing with existing discrete-time sliding-mode control, the new scheme is able to achieve more precise tracking performance. It will be shown in this work that, the new control scheme achieves O(T²) steady-state error for state regulation with the widely adopted delay-based disturbance estimation. Another desirable feature is, the proposed DISMC prevents the generation of overlarge control actions due to deadbeat response, which is usually inevitable due to the existence of poles at the origin for a reduced order sliding manifold designed for sampled-data systems. Both the theoretical analysis and illustrative example demonstrate the validity of the proposed scheme     

An active resistor network for Gaussian filtering of images

The architecture of an active resistive mesh containing both positive and negative resistors to implement a Gaussian convolution in two dimensions is described. With an embedded array of photoreceptors, this may be used for image detection and smoothing. The convolution width is continuously variable by 2:1 under user control. Analog circuits implement a 45×40 mesh on a 2-μm CMOS integrated circuit, and perform an entire convolution in 20 μs on applied images     

Distributed routing with on-line marginal delay estimation

A procedure is presented for estimating online marginal packet delays through links with respect to link flows without making the standard assumptions (exponentially distributed packet lengths, Poisson arrival processes). This procedure is based on a technique known as perturbation analysis. No knowledge of network parameters (arrival rates, link capacities) is required. This is used in the context of a minimum delay distributed routing algorithm for real-time implementation. Experimental results are included to investigate the effect of the algorithm step-size and observation period parameters, demonstrate the adaptivity of the approach, and compare it to well-known analytical approximation     

A 4.5-mW 900-MHz CMOS receiver for wireless paging

An ultralow-power 900-MHz receiver implemented on a single CMOS chip is intended for use in FLEX wireless paging. The receiver uses an indirect conversion to zero intermediate frequency (IF) to suppress the flicker noise corner in the second mixer to less than 1 kHz. Various techniques for low-power design, most of them unique to CMOS, are presented, with theoretical support and experimental verifications. The receiver, fabricated in a 0.25-μm standard CMOS process, achieves 7.4-dS noise figure at 1.6 kHz with -25-dBm IIP3 on a 1.5 V supply. The voltage-controlled oscillator (VCO) has a phase noise of -98 dBc/Hz at 25 kHz offset. The nominal receiver bias current of 3 mA is higher than the expected 2 mA because of unanticipated losses in coupling capacitors     

Long-term bond performance of GFRP bars in concrete under temperature ranging from 20 °C to 80 °C

Eighty pull-out specimens were used to study the effect of temperature ranging from 20 °C to 80 °C in dry environment on bond properties between Glass Fiber Reinforced Polymer (GFRP) bars and concrete. The pullout-test specimens were subjected during 4 and 8 months to high temperatures up to 80 °C and then compared to untreated specimens (20 °C). Experimental results showed no significant reduction on bond strength for temperatures up to 60 °C. However, a maximum of 14% reduction of the bond strength was observed for 80 °C temperature after 8 months of thermal loading. For treated specimens, the coefficient β in the CMR model, which predicts the bond–stress–displacement behavior, seems to be dependant with the temperature.