Impact of bounded delay on throughput in multi-hop networks

This paper presents a closed form solution relating to the impact of bounded delays on throughput in multi-hop networks. In contrast to contemporary literature that largely focuses on average delay to estimate the Quality of Service, our model focuses on an upper bound of delay, referred to as delay threshold in this paper. Traffic that exceeds the delay threshold is treated as lost throughput. The results obtained can be used in scaling resources in a multi-hop network for attaining specified levels of throughput under different thresholds of acceptable delays. Both single-hop and multi-hop transfers are addressed. The theoretical analysis presented in this paper is further corroborated by simulation. The findings presented in this paper will be very relevant to multi-hop network applications where received data that are older than a specified threshold period are not relevant and must be discarded.     

Elektromagnetisches Geräusch von Reluktanzmaschinen mit segmentiertem Läufer

Übersicht Zur Ermittlung der wichtigsten Radialkraftwellen wird anhand der in Teil 1 ausgeführten Feldberechnung eine Übersicht über die Polpaarzahlen und Frequenzen der Oberfelder erstellt. Das sich hieraus ergebende Tonfrequenzspektrum wird mit experimentellen Untersuchungen an einem 22kW-Reluktanzmotor verglichen. Die ungleichmäßige Nutteilung des Dämpferkäfigs ergibt ein dichtes Frequenzspektrum, das in Verbindung mit mechanischen Eigenfrequenzen zu hohen Geräuschpegeln führt.

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Electromagnetic noise of reluctance machines with segmental-rotor. Part 2: Radial electromagnetic force waves and noise

Contents A survey is made on the basis of the field calculation performed in part 1 of the numbers of pole-pairs and frequencies of the harmonic magnetic fields in order to find out the most important radial force waves. The resulting audio frequency spectrum is compared to experimental investigations of a 22 kW-reluctance motor. The unequal slot pitch of the squirrel-cage damper results in a dense frequency spectrum which, in connection with the mechanical natural frequencies, causes high noise levels.

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Teil 1 erschien Arch. Elektrotech. 73 (1990) 253–260     

A 24-GHz Transmitter With On-Chip Dipole Antenna in 0.13-$mu$m CMOS

A fully integrated dual-conversion transmitter chain with an on-chip dipole antenna and an integer-N synthesizer operating in the 24-GHz Instrument, Scientific and Medical (ISM) band was fabricated in 0.13-mum CMOS. The choice of 24-GHz operation enables the integration of a 4-mm long antenna on chip. The transmitter chain can support data rate of 100 Mb/s. It provides 6-dBm output power to a 100-Omega load at 22.4 GHz with 152-mW power dissipation including that of a frequency synthesizer. At this output power level, the dual conversion architecture can mitigate the VCO pulling even when an antenna and a power amplifier are integrated on the same substrate as the VCO. The out-of-band emissions due to the modulation side lobes and image have been sufficiently suppressed. The stray emissions of local oscillator can also be reduced using circuit techniques. The signal from the transmitter has been picked up 95 meters away with a horn antenna, which suggests that wireless communications between a single chip radio and a base station 100 meters away is possible.     

Electron microscopic observations of Bi and Tl bearing cuprate high temperature superconductors

The second generation of high temperature superconductors typified by Bi₂Sr₂Ca _n−1Cu _n O_2n+4 and Tl₂Ba₂Ca _n−1Cu _n O_2n+4 exhibits curious structural properties which have direct relevance to the superconducting behaviour particularly transition temperature (T _c ). The present paper reports on investigations of structural properties at microlevel in Bi-bearing HTCS. We have found curious structural characteristics which manifests itself in the form of transformation froma _p ×a _p ×c to (2)^1/2 a _p ×(2)^1/2 a _p ×c through the loss of calcium atoms and the formation of five-fold modulated phase alongb through the loss of Ca and Sr atoms. We have also found the evidence of high periodicities (n=4) Bi₂Sr₂Ca₃Cu₄O₁₂. The microstructural characteristics of HTCS showing the higherT _c (R=0) ∼ 120 K exhibits unusual characteristics.     

Global estimates of evapotranspiration and gross primary production based on MODIS and global meteorology data

The simulation of gross primary production (GPP) at various spatial and temporal scales remains a major challenge for quantifying the global carbon cycle. We developed a light use efficiency model, called EC-LUE, driven by only four variables: normalized difference vegetation index (NDVI), photosynthetically active radiation (PAR), air temperature, and the Bowen ratio of sensible to latent heat flux. The EC-LUE model may have the most potential to adequately address the spatial and temporal dynamics of GPP because its parameters (i.e., the potential light use efficiency and optimal plant growth temperature) are invariant across the various land cover types. However, the application of the previous EC-LUE model was hampered by poor prediction of Bowen ratio at the large spatial scale. In this study, we substituted the Bowen ratio with the ratio of evapotranspiration (ET) to net radiation, and revised the RS-PM (Remote Sensing-Penman Monteith) model for quantifying ET. Fifty-four eddy covariance towers, including various ecosystem types, were selected to calibrate and validate the revised RS-PM and EC-LUE models. The revised RS-PM model explained 82% and 68% of the observed variations of ET for all the calibration and validation sites, respectively. Using estimated ET as input, the EC-LUE model performed well in calibration and validation sites, explaining 75% and 61% of the observed GPP variation for calibration and validation sites respectively.Global patterns of ET and GPP at a spatial resolution of 0.5° latitude by 0.6° longitude during the years 2000-2003 were determined using the global MERRA dataset (Modern Era Retrospective-Analysis for Research and Applications) and MODIS (Moderate Resolution Imaging Spectroradiometer). The global estimates of ET and GPP agreed well with the other global models from the literature, with the highest ET and GPP over tropical forests and the lowest values in dry and high latitude areas. However, comparisons with observed GPP at eddy flux towers showed significant underestimation of ET and GPP due to lower net radiation of MERRA dataset. Applying a procedure to correct the systematic errors of global meteorological data would improve global estimates of GPP and ET. The revised RS-PM and EC-LUE models will provide the alternative approaches making it possible to map ET and GPP over large areas because (1) the model parameters are invariant across various land cover types and (2) all driving forces of the models may be derived from remote sensing data or existing climate observation networks.     

Design and Self-Consistent Schrodinger-Poisson Model Simulation of Ultra-Thin Si-Channel Nanowire FET

Silicon - Since at the regime of nanometer, the quantum confinement effects are observed and the wave nature of electrons is more dominant. Therefore, the classical approach of current formulation...     

Investigation of N + SiGe Gate Stacked V-TFET Based on Dopingless Charge Plasma for Gas Sensing Application

Silicon - In this paper, a novel n + SiGe pocket layer gate stacked VTFET doping less charge plasma is proposed and analyzed using Silvaco TCAD simulation software. The proposed device...