Intrinsic selectivities and yields in the catalytic hydrogenation of polyenoic fatty acid methyl esters

Precise values of the intrinsic selectivities and yields for the hydrogenation products of methyl linolenate (Ln) and methyl linoleate (L) obtained under carefully controlled conditions using a commercial Ni catalyst are presented and analyzed in detail. The existence of a preferential adsorption of Ln and a significant co-hydrogenation of its double bonds are confirmed as being the dominant features under typical vegetable oil processing conditions. It is shown that the values of the selectivities that are obtained from the classical consecutive reactions network account for the intrinsic selectivity of the catalyst only while hydrogenating feedstocks with moderate to low (<10%) contents of Ln. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional del Lltoral (U.N.L.)     

Performance of Efficient Signal Detection for LED-ID Systems

In this paper, effects of reader-to-reader interference are investigated for LED identification (LED-ID) system in a multi-reader environment. The LED-ID readers typically use different channels to avoid collision between readers. However, in-channel collision usually happens in terms of interrogation range. A reader-to-reader interference scenario is proposed, and nominal interrogation range of a desired reader is derived from this model. In order to evaluate the LED-ID reader-to-reader interference quantitatively, an efficient detection scheme is proposed and simulated by employing spreading sequence. The spreading sequence is inserted between each user’s frame formats. In the receiver, the desired signal is detected by using correlation among inserted spreading sequences. From simulation results, it is confirmed that the proposed scheme is very effective to enhance reliability of LED-ID communication systems.     

An energy efficient middleware for an ad-hoc AAL wireless sensor network

DIA (Dispositivo Inteligente de Alarma, in Spanish) is an AAL (Ambient Assisted Living) system that allows to infer a potential dangerous action of an elderly person living alone at home. This inference is obtained by a specific sensorisation with sensor nodes (portables and fixes) and a reasoning layer embedded in a PC that learns of the users behaviour patterns and advices when actual one differs significantly of the normal patterns. In AAL systems, energy is a limited resource therefore sensor devices need to be properly managed to conserve energy. In this paper, we introduce the design and implementation of innovative and specific mechanisms at the sensory layer middleware which is capable of, first to discriminate spurious motion detections assuming that these signals do not resemble the patterns of real motion detections and, second to reduce the dynamics of messages by a sensor signal processing in order to compress the whole information in one single event. The middleware achieves power saving by modifying the raw information from sensors and adapting it to the predefined semantic of the reasoning layer. It manages the important task of data processing from sensors (raw information), and transfers the pre-processed information into the top layer of reasoning in a more energy efficient way. We also address the trade-off between reducing power consumption and reducing delay for incoming data. We present results from experiments using our implementation of these mechanisms at the middleware that comprises from node firmware to the PC driver. The number of messages of the proposed method with respect to the raw data is reduced by approximately 98.5%. The resources used in the PIR signal processing is reduced by approximately 85%. The resulting delay introduced is small (10–19 s) but system dynamics is slow enough to avoid contextualisation errors or reduction of system performance. We consider these results as very satisfactory.     

Variational optical flow computation in real time.

This paper investigates the usefulness of bidirectional multigrid methods for variational optical flow computations. Although these numerical schemes are among the fastest methods for solving equation systems, they are rarely applied in the field of computer vision. We demonstrate how to employ those numerical methods for the treatment of variational optical flow formulations and show that the efficiency of this approach even allows for real-time performance on standard PCs. As a representative for variational optic flow methods, we consider the recently introduced combined local-global method. It can be considered as a noise-robust generalization of the Horn and Schunck technique. We present a decoupled, as well as a coupled, version of the classical Gauss-Seidel solver, and we develop several multgrid implementations based on a discretization coarse grid approximation. In contrast, with standard bidirectional multigrid algorithms, we take advantage of intergrid transfer operators that allow for nondyadic grid hierarchies. As a consequence, no restrictions concerning the image size or the number of traversed levels have to be imposed. In the experimental section, we juxtapose the developed multigrid schemes and demonstrate their superior performance when compared to unidirectional multgrid methods and nonhierachical solvers. For the well-known 316 x 252 Yosemite sequence, we succeeded in computing the complete set of dense flow fields in three quarters of a second on a 3.06-GHz Pentium4 PC. This corresponds to a frame rate of 18 flow fields per second which outperforms the widely-used Gauss-Seidel method by almost three orders of magnitude.     

A Framework for MPEG‐4 Contents Delivery over DMB

Digital Multimedia Broadcasting (DMB) is an upcoming standard in Korea used to provide mobile multimedia broadcasting service based on the Eureka‐147 Digital Audio Broadcasting (DAB) system. The current dominant multimedia coding standard, MPEG‐4, is foreseen to play an important role in forthcoming DMB services. However, the current approaches for transporting MPEG‐4 content over DMB networks are not optimized. To address this issue we propose a novel MPEG‐4 stream multiplexer, called M4SMux, which provides better stream multiplexing and delivery over DMB networks. M4SMux features an MPEG‐4 elementary‐stream interleaving mechanism that reduces the multiplexing overhead and a multiplex configuration mechanism that utilizes M4SLinkTable for easy content access. In addition, we propose an error correction method which enhances transport efficiency.     

Characterization of MIS structures and PTFTs using TiOx deposited by spin-coating

This paper presents a method to deposit titanium oxide (TiOx) films from a sol containing IV titanium isopropoxide Ti[OCH(CH₃)₂]₄, 2-methoxyethanol, CH₃OCH₂CH₂OH and ethanolamine H₂NCH₂CH₂OH, in order to obtain layers with thickness above 220 nm with the required characteristics to be used in Metal–Insulator–Semiconductor, MIS, structures and polymeric thin film transistors, PTFTs. The effect of using different component ratios is described. The dielectric constant was in the order of 12, the critical electric field was 5 × 10⁵ V/cm and the density of states at the interface was less than 1 × 10¹¹ cm⁻². The analysis of MIS structures prepared with these TiOx layers shows that they are suitable for using in PTFTs. The fabrication of independent bottom gate PTFTs with poly(3-hexylthiophene), P3HT, on top of the TiOx layer is described, obtaining a major reduction in the operation voltage range from −30 V to −4 V, while maintaining the typical mobility for P3HT PTFTs.     

Combined multidimensional signaling and transmit diversity forhigh-rate wide-band CDMA

Multidimensional signaling is newly designed to provide a diversity gain of order 2 using two transmit antennas in uplink transmission of wide-band CDMA (W-CDMA) while achieving high and multiple data rates at the same time. The rate can be easily changed on the slot basis in a frame transmission by adapting the order of multidimensional signaling to the incoming traffic. The multidimensional signaling of order zero simply reduces to conventional multicode scheme, so there exists a tradeoff between rate and complexity. Also, the use of multidimensional signaling results in far reduced envelope variations at the maximum rate. With the transmit diversity, the uplink signal-to-interference ratio (SIR) will be further stabilized to meet the requirements of multimedia traffic. Statistics of interferences are characterized in terms of their second- and fourth-order moments from which diversity gain is theoretically verified. For realistic multipath fading channels, considering both equal and unequal average path powers, the average probability of symbol error is obtained in compact form, in which the two schemes, multidimensional signaling with and without transmit diversity are compared, and then with nonmulticode scheme in view of the bit error rate (BER). Numerical and simulation results show that the multidimensional signal with transmit diversity provides a significant gain over that with no diversity, and furthermore outperforms nonmulticode scheme subject to the same signal energy per bit and chip rate     

Trisneopentylgallium as a precursor for atomic layer epitaxy of GaAs

We report the use of a new precursor, trisneopentylgallium (NPG) for the growth of GaAs by atomic layer epitaxy (ALE). In contrast to most other alkyl gallium precursors such as triethylgallium, which decompose via a β-hydride elimination mechanism, this compound undergoes homolysis similar to that of trimethylgallium (TMGa), the normal choice as an ALE precursor. Clear self-limiting growth behavior similar to that of TMGa was observed over a reasonably wide range of growth conditions (430–500°C). Carbon incorporation was not significantly reduced compared with TMGa suggesting that the adsorbed neopentyl radicals undergo decomposition to result in a methyl terminated surface identical to that obtained for growth with TMGa.     

Technology trends toward a system-in-a-module in power electronics

Currently, assemblies of power semiconductor switches and their associated drive circuitry are available in modules. From a few 100 watts downward, one finds silicon monolithic technology as the integration vehicle, while upward into the multi-kilowatt range, mixed mode module construction is used. This incorporates monolithic, hybrid, surface mount and wirebond technology. However, a close examination of the applications in motor drives and power supplies indicates that there has been no dramatic volume reduction of the subsystem. The power semiconductor modules have shrunk the power switching part of the converter, but the bulk of the subsystem volume still comprises the associated control, sensing, electromagnetic power passives and interconnect structures. The paper addresses the improvement of power processing technology through advanced integration of power electronics. The goal of a subsystem in a module necessitates this advanced integration. The central philosophy of this technology development research is to advance the state of the art by providing the concept of integrated power electronics modules (IPEMs). The technology underpinning such an IPEM approach is discussed. The fundamental functions in electronic power processing, the materials, processes and integration approaches and future concepts are explained.     

Dynamic rate adaptation based on multidimensional multicode DS-CDMA in cellular wireless networks

Dynamic rate adaptation for uplink data transmission in a cellular multidimensional multicode (MDMC) direct-sequence code-division multiple-access packet data network is modeled and analyzed. An analytical framework is developed to evaluate the performances of radio link level dynamic rate adaptation schemes under multipath fading and log-normal shadowing. The radio link level throughput under optimal dynamic rate adaptation (having exponential computational complexity) and different heuristic-based suboptimal rate adaptation schemes can be assessed under the presented analytical framework. The performance of MDMC signaling is compared with that of the single-code variable spreading factor (VSF) signaling. To this end, based on an equilibrium point analysis of the system in steady-state, a base station-assisted and mobile-controlled dynamic rate adaptation scheme is presented.