Low-complexity MIMO blind, adaptive channel shortening

Channel shortening is often employed as a means of mitigating intersymbol and intercarrier interference (ISI and ICI) in systems using multicarrier modulation. The Multicarrier Equalization by Restoration of RedundancY (MERRY) algorithm has previously been shown to blindly and adaptively shorten a channel to the length of the guard interval in a multicarrier system. This paper addresses synchronization and complexity reduction issues that were not dealt with in previous work and provides extensions to and generalizations of the MERRY algorithm. A modification is presented that removes the square root and division needed at each iteration without introducing additional complexity, with the added benefit of allowing the use of constraints other than a unit norm equalizer; an extension is proposed that allows for the use of more data in the MERRY update; the algorithm is generalized to the multiple-input multiple output (MIMO) and fractionally spaced cases; a low-complexity, blind symbol synchronization technique is proposed, and a method is proposed for blind initialization of the algorithm to avoid slow modes of convergence. Each extension to the basic MERRY algorithm is accompanied by an illustrative simulation example.     

An automatic nonrigid registration for stained histological sections.

Automatic computer-based analyses of histological sections which are differently stained require that they are related to each other. Most registration methods are only able to perform rigid-body motion and are sensitive to noise and artifacts. Histological images, however, are accompanied by several artifacts and different contrasts, which require a nonrigid registration. In this paper, we present a hierarchical nonrigid registration algorithm able to align images, which contain minor image artifacts. The algorithm requires no a priori knowledge of the true image. The hierarchical design of the algorithm enhances robustness and accuracy, and saves computational costs. The proposed algorithm is decomposed into a fast, coarse, rigid registration step and a slower, but finer, nonrigid step. For the coarse registration, we use image pyramids, while for the second step, we combine a point-based registration with an elastic thin-plate spline interpolation. Accuracy tests, performed for 20 histological images obtained from human arteries, have shown that the error measure is acceptable, and that the image noise does not cause a problem. The associated convergence rate of the mean pixel displacement error during the rigid and nonrigid registrations is satisfying. The algorithm can be applied to various multicontrast elastic registration problems in medical imaging and may be extended to three dimensions.     

Reliability of gate dielectrics and metal–insulator–metal capacitors

In this review paper reliability characterisation methods of SiO₂ as gate dielectric and metal–insulator–metal capacitors with various dielectrics are discussed. It includes the test structure design, the stress and measurement sequences, the raw data analysis and the extrapolation models of measured time to breakdown to lifetimes at operating conditions and targeted product failure rates. For each topic various references are given where further details are described. Especially pitfalls of approaches and problem areas are highlighted.     

Required bandwidth, unwanted emission, and data power efficiencyfor residual and suppressed carrier systems-a comparative study

This paper presents a new concept for required bandwidth along with a method for computing this bandwidth and the associated undesired emission for the classes of PCM/PSK/PM, PCM/PM and BPSK signals. The PCM/PSK/PM signals considered here employ either a square wave or sine-wave subcarrier with NRZ data format. On the other hand, the PCM/PM and BPSK signals use either a Bi-phase or an NRZ data format. Furthermore, the maximum allowable required bandwidth in the presence of noise and the data power efficiency for these modulation schemes will also be investigated. The term “data power efficiency” as considered in this paper consists of two principal components, namely, the amount of power contained in the data channel, and the symbol signal-to-noise ratio (SSNR) degradation due to the presence of intersymbol interference (ISI) for a specified required bandwidth. This paper evaluates both of these components numerically for the modulation schemes considered and the results are then compared. Furthermore, the impact of baseband filtering on the required bandwidth is also investigated in this paper     

Multimodal acting in mixed reality interactive storytelling

In this paper, an experimental mixed reality using a multimodal approach is introduced which lets users play characters in interactive narratives as though acting on a stage. Users interact with characters through speech, attitude, and gesture, enhancing their immersion in the virtual world. This system provides a small-scale but complete integration of multimodal communication in interactive storytelling. It uses a narrative's semantic context to focus multimodal input processing-that is, the system interprets users' acting (the multimodal input) in the mixed reality stage in terms of narrative functions representing users' contributions to the unfolding plot.     

Narrow-channel GaInP/InGaAs/GaAs MODFETs for high-frequency andpower applications

We have developed a new concept of narrow (50-80 Å) channel MODFETs. It is shown theoretically and experimentally that only the ground energy level is populated in the narrow-channel device. A new technique to measure mobility at the highest energies of the two-dimensional electron gas (2-DEG) was introduced. With the help of this technique it is shown that, in wide wells, electrons in the excited energy levels have low mobility and consequently degrade device performance. It is shown theoretically and experimentally that the narrow-channel device has a higher electron sheet density and mobility and consequently better performance than a conventional wide-channel MODFET. Excellent quality Ga_xIn_1-xP/In_yGa_1-yAs/GaAs MODFETs with a pseudomorphic barrier and a pseudomorphic channel were grown by MBE and OMVPE. Higher than 3.4·10¹² cm^-2 electron sheet densities for single-side-doped MODFETs on GaAs substrate were measured. One-tenth micron gate length MODFETs achieved f _T's over 100 GHz and f_max's over 180 GHz. These results are comparable to the previously reported results for GaInP MODPET with graded barriers, however the device structure is much simpler     

Subnanometer Analysis and Modeling of MBE Grown InP Based MODFETs

InGaAs/InAlAs double-doped double-strained modulation-doped field-effect transistors OD-SMODFETs)1 were grown by solid source molecular beam epitaxy. The structures were characterized using high resolution x-ray diffraction, Hall effect, and cross-sectional scanning tunneling microscopy. A record two-dimensional electron gas (2DEG) sheet density of 8.5 × 10¹²/cm² and 8.1 × 10¹²/cm² for 300 and 77K, respectively, was achieved. The mobility was 6500 and 12000 cm²/ Vs for 300 and 77K, respectively. To the author’s knowledge,² the previous record 2DEG result was 6.58 × 10¹²/cm². The electron mobility was limited by alloy scattering and interface roughness caused by the presence of “clustering.” Using cross-sectional scanning tunneling microscopy to verify the presence of these clusters, we have the first images of the lattice matched InAlAs (spacer)-InGaAs (quantum well) interface. These images reveal clusters that have approximate spherical or cylindrical shapes with equivalent cubic dimensions ranging from 25 to 45Å.     

Application of Reconfigurable CORDIC Architectures

Reconfiguration enables the adaption of Coordinate Rotation DIgital Computer (CORDIC) units to the specific needs of sets of applications, hence creating application specific CORDIC-style implementations. Reconfiguration can be implemented at a high level, taking the entire CORDIC unit as a basic cell (CORDIC-cells) implemented in VLSI, or at a low level such as Field-Programmable Gate Arrays (FPGAs). We suggest a design methodology and analyze area/time results for coarse (VLSI) and fine-grain (FPGA) reconfigurable CORDIC units. For FPGAs we implement CORDIC units in Verilog HDL and our object-oriented design environment, PAM-Blox. For CORDIC-cells, multiple reconfigurable CORDIC modules are synthesized with state-of-the-art CAD tools. At the algorithm level we present a case study combining multiple CORDICs based on a geometrical interpretation of a normalized ladder algorithm for adaptive filtering to reduce latency and area of a fully pipelined CORDIC implementation. Ultimately, the goal is to create automatic tools to map applications directly to reconfigurable high-level arithmetic units such as CORDICs.     

Ochratoxin A in dried vine fruit: method development and survey

A method is described for the determination of concentrations of the mycotoxin ochratoxin A in dried vine fruits (currants, raisins and sultanas) using acidic methanolic extraction,immunoaffinity chromatography clean-up and HPLC determination. The limit of detection was estimated as 0.2mug/kg, and recoveries of 63-77% were achieved at 5mug/kg. HPLC-mass spectrometric confirmation of the identity of ochratoxin was obtained. Ochratoxin A and aflatoxins were determined in 60 samples of retail dried vine fruits purchased in the United Kingdom. Ochratoxin A was found in excess of 0.2mug/kg in 19 of 20 currant, 17 of 20 sultana and 17 of 20 raisin samples examined, an overall incidence of 88% . The maximum level found was 53.6mug/kg. No aflatoxin was found in any sample analysed, using a method with a detection limit of 0.2mug/kg for each of aflatoxin B1, B2, G1 and G2.