A New Linear Group-Wise SIC Multiuser Detector

In this work, we introduce a new linear group-wise SIC multi-user detector that can converge to either the decorrelator or the least minimum mean-square error (LMMSE) detector. We study the convergence behavior of the proposed scheme and show that the latter is equivalent to the block Gauss-Seidel iterative method if the group-detection scheme used is the decorrelator detector. Moreover, we prove that the latter is convergent if the group-detection matrix is positive definite. Our simulation results are in excellent agreement with the proposed theory     

Range image segmentation using local approximation of scan lines with application to CAD model acquisition

Abstract. Automatic acquisition of CAD models from existing objects requires accurate extraction of geometric and topological information from the input data. This paper presents a range image segmentation method based on local approximation of scan lines. The method employs edge models that are capable of detecting noise pixels as well as position and orientation discontinuities of varying strengths. Region-based techniques are then used to achieve a complete segmentation. Finally, a geometric representation of the scene, in the form of a surface CAD model, is produced. Experimental results on a large number of real range images acquired by different range sensors demonstrate the efficiency and robustness of the method. Received: 1 August 2000 / Accepted: 23 January 2002 Correspondence to: I. Khalifa     

Silicon-on-insulator for high-temperature applications

The silicon-on-insulator (SOI) CMOS technology is one of the best candidates for high- temperature applications due to its low leakage current, steep subthreshold slope, absence of latch-up phenomenon and temperature-resistant threshold voltage. However, the most critical elements for high temperature applications are transmission lines, especially thin-film microstrip lines. In the paper, the impact of high-temperature operation on the RF performance of some SOI circuits is analysed up to 250degC.     

Observation of infrared intersubband emission in optically pumpedquantum wells

Mid-infrared intersubband emission is investigated in GaAs/AlGaAs asymmetric coupled quantum wells exhibiting an energy separation between the ground and first excited subbands close to the LO-phonon energy. The authors show that an infrared emission occurs between excited subbands under intersubband optical pumping     

Cross-linked high amylose starch for controlled release of drugs: recent advances

Cross-linked high amylose starches have been developed as excipients for the formulation of controlled-release solid dosage forms for the oral delivery of drugs. Advantages of this new class of excipients include cost-effectiveness, readily accessible industrial manufacturing technology, high active ingredient core loading and the possibility of achieving a quasi zero-order release for most drugs. In addition to the latter, other features distinguish cross-linked high amylose starches from other excipients used to prepare hydrophilic matrices. Among these are the absence of erosion, the limited swelling and the fact that increasing cross-linking degrees results in increased water uptake rate, drug release rate and equilibrium swelling. Thus the goal of the present study was to gain some insights into the mechanism of drug release control by matrices of cross-linked high amylose starch. Water transport kinetics and dimensional changes were studied in matrices placed in water at 37 degrees C by an image analysis technique. The results show that in the first 5 min, a gel layer is formed at the surface of the tablet, after which the gel front seems to halt its progression toward the center of the tablet. Water continues to diffuse through the front and to invade the core. As a consequence, this latter swells, with a predominance for radial swelling. Equilibrium swelling is reached over 3 days, when the water concentration in the tablet becomes homogeneous and the whole tablet gelifies. Solid-state 13C-NMR were acquired on cross-linked high amylose starch powders, tablets and hydrated tablets with varying cross-linking degrees. They show a predominance of the V-type single helix arrangement of amylose in the dry state irrespective of the cross-linking degree. Upon hydration, the homologues with a low cross-linking degrees show a transition from the V to the B-type double helix arrangement. It is therefore hypothesized that the capacity of amylose to undergo the V to B transition is an important factor in controlling water transport and drug release rate. Finally applications to different drugs are reviewed briefly. They illustrate the versatility of this technology as generic versions of zero order OROS drug (Efidac) and Fickian release conventional matrices (Voltaren SR) were developed and successfully tested in pilot clinical studies to be bioequivalent to the references. These studies further showed that cross-linked high amylose starch matrices have the lowest inter-subject variability among the systems tested and show a total absence of food effect.     

A hardware Memetic accelerator for VLSI circuit partitioning

During the last decade, the complexity and size of circuits have been rapidly increasing, placing a stressing demand on industry for faster and more efficient CAD tools for VLSI circuit layout. One major problem is the computational requirements for optimizing the place and route operations of a VLSI circuit. Thus, this paper investigates the feasibility of using reconfigurable computing platforms to improve the performance of CAD optimization algorithms for the VLSI circuit partitioning problem. The proposed Genetic algorithm architecture achieves up-to 5× speedup over conventional software implementation while maintaining on average 88% solution quality. Furthermore, a reconfigurable computing based Hybrid Memetic algorithm improves upon this solution while using a fraction of the execution time required by the conventional software based approach.     

The economic impact of cowpea research in West and Central Africa: A regional impact assessment of improved cowpea storage technologies

Researchers from the Bean/Cowpea Collaborative Research Support Program (CRSP), a program supported by the USAID, developed several non-chemical cowpea grain storage technologies in the 1980s. These included hermetic storage in airtight containers, improved ash storage, and the solar heater. Impact studies conducted at the country level showed that the research program was economically a good investment. As the CRSP new storage technologies spread throughout West and Central Africa, a regional assessment including spillover effects became necessary to fully comprehend the impact and guide future research investments. Therefore, this study sought to measure the economic impact of the new CRSP cowpea storage technologies at a regional level. Surveys in seven countries were used to estimate storage technology adoption. Economic surplus was used to estimate annual benefits and internal rate of return (IRR), and net present value (NPV) were calculated to summarize the net benefits. From the perspective of recipients' countries the project was a good investment. The IRR, is found to be much greater than the cost of capital. The regional IRR was found to be about 29%, much higher than the real interest rate on government bonds in West Africa at the time. For example the real interest rate on bonds issued by the government of Ghana in 2004 and 2005 was 8.9% and 5.4% respectively. The IRR is also higher than the private bank real lending rates in West Africa. From the perspective of the principal donor, the US government, the project was a good investment given that the average real interest rate on US government’s bonds was 4.8% during the period. The net present value of the investment amounts to more than 295 million US dollars which yields an annualized value of about 17 million.