Photoelectrocatalytic humic acid degradation kinetics and effect of pH,applied potential and inorganic ions

This study addresses the removal of humic acid (HA) dissolved in an aqueous medium by a photoelectrocatalytic process. UV₂₅₄ removal and the degradation of color (Vis₄₀₀) followed pseudo‐first order kinetics. Rate constants were 1.1 × 10^?1 min^?1, 8.3 × 10^?2 min^?1 and 2.49 × 10^?2 min^?1 (R² > 0.97) for UV₂₅₄ degradation and 1.7 × 10^?1 min^?1, 6.5 × 10^?2 min^?1 and 2.0 × 10^?2 min^?1 for color removal from 5 mg dm^?3, 10 mg dm^?3 and 25 mg dm^?3 HA respectively. Following a 2 h irradiation time, 96% of the color, 98% of the humic acid and 85% of the total organic carbon (TOC) was removed from an initial 25 mg dm^?3 HA solution in the photoanode cell. Photocatalytic removal on the same photoanode was also studied in order to compare the two methods of degradation. Results showed that the photoelectrocatalytic method was much more effective than the photocatalytic method especially at high pH values and with respect to UV₂₅₄ removal. The effect of other important reaction variables, eg pH, external potential and electrolyte concentration, on the photoelectrocatalytic HA degradation was also studied. Copyright © 2003 Society of Chemical Industry     

Millimeter-wave Ground-based Synthetic Aperture Radar Imaging for Foreign Object Debris Detection: Experimental Studies at Short Ranges

In this paper, millimeter-wave imaging of foreign object debris (FOD)-type objects on the ground is studied with the help of ground-based synthetic aperture radar (GB-SAR) technique. To test the feasibility of detecting runway FODs with this technique, some preliminary experiments are conducted within short antenna-to-target ranges of small imaging patches. An automated stripmap GB-SAR system with stepped-frequency transmission is constructed together with a quasi-monostatic data collection operation. The imaging experiments for various braces and screws are then carried out by using 32–36?GHz and 90–95?GHz frequency bands of the millimeter-wave. Images reconstructed by a matched-filter based algorithm are analyzed to determine the proper system parameters for an efficient imaging and to comprehend the factors against a successful detection. Results demonstrate the capability of GB-SAR imaging in accurately locating these FOD-like targets under near-range operating conditions.     

TiN and TaN diffusion barriers in copper interconnect technology: Towards a consistent testing methodology

The present status of work on diffussion barriers for copper in multilevel interconnects is surveyed briefly, with particular emphasis on TiN and TaN, and silicon dioxide as the interlayer dielectric. New results are presented for these materials, combining thermal annealing and bias temperature stress testing. With both stress methods, various testing conditions are compared using capacitance-vs-voltage (C-V) and leakage current-vs-voltage (I-V) measurements to characterize the stressed samples. From an evaluation of these data and a comparison with other testing approaches, conditions for a consistent testing methodology of barrier reliability are outlined.     

Stochastic differential equations and geometric flows

In previous years, curve evolution, applied to a single contour or to the level sets of an image via partial differential equations, has emerged as an important tool in image processing and computer vision. Curve evolution techniques have been utilized in problems such as image smoothing, segmentation, and shape analysis. We give a local stochastic interpretation of the basic curve smoothing equation, the so called geometric heat equation, and show that this evolution amounts to a tangential diffusion movement of the particles along the contour. Moreover, assuming that a priori information about the shapes of objects in an image is known, we present modifications of the geometric heat equation designed to preserve certain features in these shapes while removing noise. We also show how these new flows may be applied to smooth noisy curves without destroying their larger scale features, in contrast to the original geometric heat flow which tends to circularize any closed curve.     

Neodymium-doped tantalum pentoxide waveguide lasers

The fabrication, spectroscopic properties, and laser performance of Nd/sup 3+/-doped Ta/sub 2/O/sub 5/ channel waveguide lasers are described. Lasing is obtained at both 1.066 and 1.375 /spl mu/m with threshold pump powers as low as 2.7 mW. The rib waveguides are reactive-ion-etched into Nd:Ta/sub 2/O/sub 5/ layers formed by reactive magnetron sputtering. These high-index low-loss rare-earth-doped waveguides are fabricated on silicon substrates and offer the potential for integration with photonic crystal structures for compact optical circuits.     

The polarization-dependent relation between radar backscatter fromthe ocean surface and surface wind vector at frequencies between 1 and18 GHz

A series of airborne scatterometer measurements carried out with the DUTSCAT multifrequency airborne scatterometer are discussed. This study deals with the first results obtained from the analysis of these measurements. The objective of this activity is to establish a multifrequency dual-polarization radar signature database, and with it a multidimensional version of the current CMOD1 model. The main features of the data set are the following. The wind exponent of the upwind normalized radar cross section (NRCS) increases with frequency and incidence angle in the case of HH polarization. The upwind/downwind ratio is mainly negative at 20° of incidence angle, always at C-, X-, and Ku1-bands     

RF-MEMS load sensors with enhanced Q-factor and sensitivity in a suspended architecture

In this paper, we present and demonstrate RF-MEMS load sensors designed and fabricated in a suspended architecture that increases their quality-factor (Q-factor), accompanied with an increased resonance frequency shift under load. The suspended architecture is obtained by removing silicon under the sensor. We compare two sensors that consist of 195 μm × 195 μm resonators, where all of the resonator features are of equal dimensions, but one’s substrate is partially removed (suspended architecture) and the other’s is not (planar architecture). The single suspended device has a resonance of 15.18 GHz with 102.06 Q-factor whereas the single planar device has the resonance at 15.01 GHz and an associated Q-factor of 93.81. For the single planar device, we measured a resonance frequency shift of 430 MHz with 3920 N of applied load, while we achieved a 780 MHz frequency shift in the single suspended device. In the planar triplet configuration (with three devices placed side by side on the same chip, with the two outmost ones serving as the receiver and the transmitter), we observed a 220 MHz frequency shift with 3920 N of applied load while we obtained a 340 MHz frequency shift in the suspended triplet device with 3920 N load applied. Thus, the single planar device exhibited a sensitivity level of 0.1097 MHz/N while the single suspended device led to an improved sensitivity of 0.1990 MHz/N. Similarly, with the planar triplet device having a sensitivity of 0.0561 MHz/N, the suspended triplet device yielded an enhanced sensitivity of 0.0867 MHz/N.     

What installed mobile applications tell about their owners and how they affect users’ download behavior

The rapid growth in the mobile application market presents a significant challenge to find interesting and relevant applications for users. An experimental study was conducted through the use of a specifically designed mobile application, on users’ mobile phones. The goals were; first, to learn about the users’ personality and the applications they downloaded to their mobile phones, second to recommend applications to users via notifications through the use of experimental mobile application and learn about user behavior in mobile environment. The question of how the personality features of users affect their compliance to recommendations is explored in this study. It is found that conscientiousness is positively related with accepting recommended applications and being agreeable is related with the preference for the applications of editor’s choice. Furthermore, in this study, applications owned by the user and the composition of applications under categories and their relation with personality features are explored. It is shown that the number of user owned applications and their category differ according to gender and personality. Having similar applications and the number of applications owned under specific categories increase the probability of accepting recommended applications.     

Application of an asymmetrical four point bend shear test to solder joints

The asymmetrical four-point bend shear (AFPB) test method was used to measure the shear strength and creep properties through the stress relaxation experiments using three different Pb-free solder joint compositions in an assolidified condition. Since it was difficult to shear the uniform specimens and the local bending usually occurs at the inner loading points, the notches were introduced at the joint line to preferentially weaken this region. The stress analysis by finite element modeling showed that the straight notches transform the parabolic shear stress distribution in the uniform specimen into a relatively uniform shear distribution along the bond line in the notched specimens. Therefore, the shear strength results from the notched specimens are expected to be much more accurate. Experiments showed that both the Sn-3.6Ag-1Cu (wt.%) and Sn-3.6Ag-1Cu-0.45Co joints have superior strength and creep properties as compared to the Sn-3.5Ag joint. However, there was no statistical difference between the shear strength of the Sn-3.6Ag-1Cu and Sn-3.6Ag-1Cu-0.45 Co joints. Moreover, the difference between the creep resistance of these two types of joints was small.