A self-organizing map with twin units capable of describing a nonlinear input-output relation applied to speech code vector mapping

This paper describes a new type of self-organizing map (SOM) with twin units as opposed to the single unit type conventional SOM proposed by Kohonen. The present self-organizing map with twin units (TW-SOM) can describe a nonlinear input-output relation with high accuracy. It is applied to voice conversion problem from bone conduction voice to air conduction voice (nonlinear code vector mapping), and its superiority over the conventional method using Linde-Buzo-Gray (LBG) algorithm is discussed. The tone quality of the converted voice is examined not only from the quantization distortion viewpoint, but also from the auditory sensation viewpoint through actual listening tests. The enhancement of the tone quality was experimentally confirmed.     

Next-generation 10 GBaud module based on emerging SFP+ with host-based EDC [Topics in Optical Communications]

There has been an ongoing trend to require transceivers for use in datacom and telecom switches to be small and have low power dissipation to enable large port count switches. At speeds between 1 and 4 GBaud the SFP form factor is by far the most commonly used. Up to now 10 GBaud transceivers have used larger devices with larger power dissipations. This article describes the SFP+ module being specified by the SFF Committee (SFF 8431) that will enable the same port densities as the SFP module. The adaptive equalizers and high-speed transmission channels required in the switches to make the SFP+ module work successfully are also described     

CMOS Multistage Preamplifier Design for High-Speed and High-Resolution Comparators

This brief describes a design technique for multistage preamplifiers of the type commonly used in high-performance comparators. Following the examination of multistage preamplifier responses in both the spectral and time domains, and a consideration 1/f noise attenuation in topologies employing offset storage capacitors, a procedure for optimizing both the number of stages and the offset storage capacitance is presented. As a demonstration vehicle, a comparator with a 13-Msample/s conversion rate and 200-muV minimum input resolution is designed for realization in a 0.4-mum CMOS technology under the constraint of a power dissipation of 250 muW when operating from a 2.5-V supply. In this design, the effective input signal is 33 muV for the minimum input resolution of 200 muV due to signal corruption from circuit noise and residual error from incomplete settling     

EXPLOITATION PROCEDURE BASED ON EIGENVECTOR REVISITED: THE CONCEPT OF WEIGHTED PREFERENCE FLOWS IN MULTICRITERIA OUTRANKING ANALYSIS

The outranking analysis has been frequently used to deal with the complex decisions involving qualitative criteria and imprecise data. So far, various versions of ELECTRE have been proposed for ranking alternatives in the outranking analysis. Among others, ELECTRE III has been widely used. A distillation procedure using a qualification index is proposed to rank alternatives from the fuzzy outranking relation. A weakness of ELECTRE III, however, is to involve the arbitrariness in the selection of the discrimination threshold function for the distillation procedure.

On the other hand, various variants of PROMETHEE has also been proposed for the outranking analysis. PROMETHEE intends to be simple and easy to understand. A deficiency of PROMETHEE is that it does not take discordance into account when the outranking relation matrix is constructed.

This note revisits an exploitation procedure based on eigenvector using the “weighted” preference in-and out-flows of each alternative in the outranking analysis. The basic idea is that it should be better to outrank a “strong” alternative than a “weak” one and, conversely, it is less serious to be outranked by a “strong” alternative than by a “weak” one in a PROMETHEE context. It has a completely different interpretation with the AHP (Analytic Hierarchy Process) since the components of the fuzzy (valued) outranking relation matrix are neither ratios nor reciprocal as in the AHP.     

Downscaling MODIS LST in the East African mountains using elevation gradient and land-cover information

Land-surface temperature (LST) is strongly affected by altitude and surface albedo. In mountain regions where steep slopes and heterogeneous land cover are predominant, LST can vary significantly within short distances. Although remote sensing currently provides opportunities for monitoring LST in inaccessible regions, the coarse resolution of some sensors may result in large uncertainties at sub-pixel scales. This study aimed to develop a simple methodology for downscaling 1 km Moderate Resolution Spectroradiometer (MODIS) LST pixels, by accounting for sub-pixel LST variation associated with altitude and land-cover spatial changes. The approach was tested in Mount Kilimanjaro, Tanzania, where changes in altitude and vegetation can take place over short distances. Daytime and night-time MODIS LST estimates were considered separately. A digital elevation model (DEM) and normalized difference vegetation index (NDVI), both at 250 m spatial resolution, were used to assess altitude and land-cover changes, respectively. Simple linear regressions and multivariate regressions were used to quantify the relationship between LST and the independent variables, altitude and NDVI. The results show that, in Kilimanjaro, altitude variation within the area covered by a 1 km MODIS LST pixel can be up to ±300 m. These altitude changes can cause sub-pixel variation of up to ±2.13°C for night-time and ±2.88°C for daytime LST. NDVI variation within 1 km pixels ranged between –0.2 and 0.2. For night-time measurements, altitude explained up to 97% of LST variation, while daytime LST was strongly affected by land cover. Using multivariate regressions, the combination of altitude and NDVI explained up to 94% of daytime LST variation in Kilimanjaro. Finally, the downscaling approach proposed in this study allowed an improved representation of the influence of landscape features on local-scale LST patterns.     

Feasibility study on cellular network analysis with patterned cell culture microdevice

In order to realize cellular network analysis on a chip-based system, our group has been developing a patterned cell culture microdevice with pillars in an array for tapping cells into space surrounded by the pillars. The pillar structures has advantages to trap both adhesive and non-adhesive cells and to precisely control positions of cells and distances between cells for understanding effects of various cell patterns on functions of a cellular network such as cell proliferation, differentiation, and network formation. In this paper, HeLa cell cultivation with the patterned cell culture microdevice having a pillar array fabricated by dry film of thick negative photoresist SU-8 on a glass substrate was executed as a feasibility study on a cellular network analysis. The results revealed that the device performance was found to be enough to culture HeLa cells for more than 48 h. In addition, relative extensibility of blocks of multiple cells compared with single cells tapped on the device was observed. Thus, the patterned cell culture microdevice proposed here could be applicable to analysis of cellular functions.     

The control performance improvement of the optical disk system by correction pulse control

This paper proposes a control system which improves OPU (Optical Pick Up) control performance in an optical disk system. This system can be realized by adding a correction pulse control block which is based on a position error signal onto a conventional position control loop composed of the PID control rule. Using this function, the position error resulting from a physical distortion and acceleration disturbance to the disk can be decreased sharply. Furthermore, this system can decrease the deviation caused by the shock disturbance which cannot be controlled by the PID control rule. In addition, it becomes possible to decrease the overshoot in the impulse response sharply, and realize stable capture of a target position. Since this system can be created with a simple algorithm, it is possible to use it in a wide range of applications. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(2): 53–67, 2007; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20570     

Super‐reflective color LCD with PDLC technology

Abstract— A novel reflective color LCD without polarizers has been developed using a PDLC film and a retro‐reflector. Bright color images including moving images are achievable with ambient light. This novel LCD will enable the new application area of electronic paper.     

GaInAs-GaInNAs-GaInAs intermediate layer structure for longwavelength lasers

Proposes two new structures, the GaInAs-GaInNAs intermediate layer (IML) and the GaInN_xAs graded wells, which show better optical properties than the commonly used GaInNAs-GaAs rectangular quantum-wells. A 1240-nm emitting IML laser has been achieved with a low-threshold current density (200 A/cm²/well) and a relatively high characteristic temperature (T_o=100 K). The IML structure is very promising for long wavelength GaAs-based laser applications