Accessibility and Development Prospects: The Web Implications for Local Economy Extroversion in Greece

In the contemporary age of access the role of “immaterial networking” has been highly reinforced, driving the emergence of the internet as an essential tool for the social and economic daily routine. The main spatial and developmental features of Greek small and medium sized centres play a major influential role on the development and use of internet applications. The research conducted has examined this interaction and identified two main tendencies. Dynamic and powerful centres, which are near the basic development axes, have a dominant position in the web, as far as both connectivity and use is concerned. Moreover, in some small and medium sized peripheral centres local enterprises tend to overcome their lack of accessibility through increasing the use of the internet. How can we measure this potential and come to more reliable conclusions? Is this procedure related to a local economy extroversion?     

Reply to `Comments on the robust stability analysis of adaptivecontrollers using normalizations'

The author addresses a statement in the above-titled paper by P.P. Khargonekar and R. Ortega (see ibid., vol.34, no.4, p.478, April (1989)) that the proofs in four earlier papers, including two of which he is a coauthor, failed to establish that the proposed adaptive controllers provide a nonvanishing robustness margin for the considered class of unmodeled dynamics. He shows that the results in those papers are correct and that the above statement and its implications are misleading. He also rebuts an incorrect statement that μ* is inversely proportional to the initial condition |η(0)| of the unmodeled dynamics, leading the reader to the conclusion that the results of the four papers cannot be global with respect to |η(0)|     

An Integration of Statistics Temporal Methods to Track the Effect of Drought in a Shallow Mediterranean Lake

During the last decades, a progressive decrease of water level in shallow Mediterranean lakes was recorded. This contribution tried to identify whether the rapid decrease of the Lake Doiran (N. Greece) water level was associated with drought phenomena. Drought characteristics over the study area were revealed by employing the Standardized Precipitation Index (SPI) in different time scales. Negative trends of the SPI drought index were recognized by using the Mann-Kendall non parametric test, which suggested that drought conditions were intensified through time. The impact of the intense drought phenomena to the lake??s water level became evident by employing the Pearson correlation coefficient. A year ahead forecast of future drought conditions was achieved by training a hybrid ARIMA/ANN model. The predicted results indicated that mild drought conditions should be anticipated in the future and the water level would further drop as well.     

The time dependent resistance and inductance of the electricdischarges in pulsed gas lasers

A method of finding the time dependent resistances and inductances in the discharges in pulsed gas lasers is described in this work. According to this method the waveforms of the laser circuit voltages are digitized and their first and second derivatives are calculated. These are substituted into the differential equations governing the behavior of the system and relationships among the resistances and inductances are formed for every time. Using relationships from a sequence of four very closed adjacent time instants and considering that during this short time interval the resistances and inductances are varied linearly, their values can be found for this particular time interval. Repeating the same procedure for other time intervals and scanning the entire time region of the discharge, the time histories of the resistances and inductances of the discharges are revealed. These show strong variations in the “formation phase” of the discharge (first 50 nsec). Specifically the resistances drop rapidly (first 10 nsec) from very high values to low values, while the inductances increase to high values and subsequently decrease, forming an abrupt high peak. The steep drop of the resistances is due to the electron avalanche multiplication, while the peak of the inductances is due to the centripetal magnetic forces (Laplace forces), which cause a temporary constriction of the plasma. In the “main phase” of the discharge the resistances present a damping oscillation with the same frequency as the voltages, while the inductances present light fluctuations around constant values     

Quantitative measurement of channel temperature of GaAs devices for reliable life-time prediction

The channel temperature of Gallium Arsenide (GaAs) devices was quantitatively measured using scanning thermal microscopy (SThM), which is a variation of atomic force microscopy (AFM). The temperature of the devices was also characterized by infrared (IR) imaging and thermal modeling. The measured SThM temperature values were close to the calculated values from the model, and were higher than those found by IR, as predicted. In contrast to most published AFM results which have reported only qualitative and indirect semi-quantitative thermal information about the sample, the results presented here can be used directly to determine accurately the device-temperature. These results are useful to the reliability community in that they help to predict a more accurate semiconductor device lifetime. By careful calibration of an AFM thermistor probe tip, a quantitative temperature measurement of the channel temperature of the GaAs PHEMTs and MESFETs can be made. The result of the measurement can be substantiated by applying a suitable thermal calculation, such as the Cooke model. A secondary measurement technique, such as IR microscopy, can also be useful in providing further information about the thermal response of the device. Published results using AFM techniques have been unable to determine the channel temperature quantitatively. The method in this paper applies to other types of electronic devices for which the channel (or junction) temperature can be probed from the top surface of the device.     

The inductance and resistance of the laser discharge in a pulsedgas laser

Theoretical consideration of the discharge of a laser channel takes place in this work. This leads to formulas for the resistance and inductance. The resistance depends on the total charge in the discharge volume while the inductance depends on the dimensions of the discharge volume. Generally, the inductance increases as electrode length and discharge thickness decreases and more so as these become equal. On the other hand the inductance increases as interelectrode distance increases. However, discharge dimensions depend on the drift velocity of the flowing charges creating centripetal Lorenztian forces which constrict the volume of the laser channel. Consequently, the microscopic parameters of the plasma, total charge and drift velocity are responsible for the electrical macroscopical characteristics' resistance and inductance respectively. Nevertheless, these microscopic parameters are formed through the external driving circuit and especially through its capacitance which strongly influences the discharge of the laser channel. Particularly, the values of the capacitances form the total charge, while the coupling of the capacitances in the circuit forms the drift velocity. These were inferred dealing with the two most common circuits used in pulsed gas lasers, namely the “doubling circuit” and the “charge transfer circuit” for all possible combinations of capacitance allocation     

Fabrication, characterization and simulation of high performance Si nanowire-based non-volatile memory cells

We report the fabrication, characterization and simulation of Si nanowire SONOS-like non-volatile memory with HfO(2) charge trapping layers of varying thicknesses. The memory cells, which are fabricated by self-aligning in situ grown Si nanowires, exhibit high performance, i.e. fast program/erase operations, long retention time and good endurance. The effect of the trapping layer thickness of the nanowire memory cells has been experimentally measured and studied by simulation. As the thickness of HfO(2) increases from 5 to 30 nm, the charge trap density increases as expected, while the program/erase speed and retention remain the same. These data indicate that the electric field across the tunneling oxide is not affected by HfO(2) thickness, which is in good agreement with simulation results. Our work also shows that the Omega gate structure improves the program speed and retention time for memory applications.     

Rejection of unknown periodic disturbances for continuous‐time MIMO systems with dynamic uncertainties

Rejection of unknown periodic disturbances in multi‐channel systems has several industrial applications that include aerospace, consumer electronics, and many other industries. This paper presents a design and analysis of an output‐feedback robust adaptive controller for multi‐input multi‐output continuous‐time systems in the presence of modeling errors and broadband output noise. The trade‐off between robust stability and performance improvement as well as practical design considerations for performance improvements are presented. It is demonstrated that proper shaping of the open‐loop plant singular values as well as over‐parameterizing the controller parametric model can significantly improve performance. Numerical simulations are performed to demonstrate the effectiveness of the proposed scheme. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of Floating-Body and Stress Bias on NBTI and HCI on 65-nm SOI pMOSFETs

Grounded-body (GB) core-logic/high-speed (HS) and input/output (I/O) silicon-on-insulator pMOSFETs from 65-nm technology are shown to degrade more than floating-body (FB) devices under negative bias temperature instability (NBTI) stress. However, in both cases, worst case degradation occurs when stressed under equal gate and drain voltages (V_g = V_d), whereby degradation is simultaneously induced by both NBTI and hot carrier injection (HCI) simultaneously ("concurrent HCI-NBTI"), the relative importance of each mechanism depending on the type of device and the bias level. The degradation of I/O pMOSFETs stressed under V_g = V_d at room temperature shows predominantly NBTI-like behavior at higher stress voltages, whereas it shows concurrent HCI-NBTI behavior at lower stress voltages. By contrast, the degradation of HS pMOSFETs stressed under V_g = V_d shows concurrent HCI-NBTI behavior over the entire stress bias range. In both cases, FB devices degrade more than GB devices for higher stress voltage values, but the FB effects weaken and the degradations become comparable for lower stress bias.