On the beam tilting and bit rate selection in mobile systems

Beam tilting of a mobile Base Station (BS), as a technique that limits the transmitted signals to each cell, introduces a way of increasing the system bit rate over a wider range than that without beam tilting. In this paper, the general approach of a BS antenna is being evaluated giving the system's response for different half power beamwidths (HPBW) and different types of propagation environments. The critical rate of the system versus the level of diffuse reflection, the communication distance, the excess distance and the height of the BS antenna are being examined.     

A method for fast digital simulation of induction motor drive systems including the power electronic circuit

Contents A method for fast digital simulation of induction motor drive systems based on a simple numerical algorithm is proposed. An efficient technique is used for the automatic formulation of the power electronic circuit which is based on the fundamental loop matrix modification. A discrete-time model of the induction machine, which can be directly interfaced with the power electronic circuit, is introduced. Computer results of a drive system that illustrate the capabilities of the method are also presented.

---

Eine Methode für schnelle Simulation von Antriebssystemen mit Induktionsmotor einschliesslich Leistungselektronikschaltung

Übersicht Eine Methode für schnelle digitale Simulation eines Antriebssystems mit Induktionsmotor basierend auf einfachen numerischen Algorithmen wird vorgeschlagen. Eine wirkungsvolle Technik für die automatische Formulierung der Gleichungen für die Leistungselektronikschaltungen wird verwendet, die auf einer Modifikation der fundamentalen Maschenmatrix beruht. Ein zeitdiskretes Modell für die Induktionsmaschine wird eingeführt, das direkt mit der Leistungselektronikschaltung verbunden werden kann. Rechenresultate für ein Antriebssystem zur Illustration der Methodenfähigkeit werden ebenfalls vorgestellt.

     

In vitro activity of vitamins, flavonoids, and natural phenolic antioxidants against the oxidative deterioration of oil-based systems

It is well-known, that lipid antioxidants can retard the oxidative rancidity of foods caused by atmospheric oxidation, and thus protect oils, fats, and fat-soluble components from their quality degradation. In the last few years, much emphasis has been put on the promotion and use of natural antioxidants, commonly occurring in many fruits and vegetables and thereby produced from various natural extracts. This review gives a summary of previously reported work together with more recent trends in the field of natural antioxidants. Focus is given on the mechanism of actions and the inhibitory effect of certain vitamins against the oxidative degradation of oil-based systems. Moreover, the use of natural phenolics (flavonoids, olive-oil penolics, herb extracts etc.) as antioxidants in numerous lipid food applications is discussed.     

Worst case temperature rise in a one-dimensional tissue model exposed to radiofrequency radiation

This paper investigates the temperature rise in a 1-D layered tissue model, which is irradiated with nonionizing radiation. Of the numerous tissue configurations that correspond to realistic body trunk and limb representations, only those are examined which maximize the averaged specific absorption rate (SAR). The results show that the old IEEE standard on safety was more conservative in terms of temperature rise than the Non-Ionizing Radiation Protection guidelines. They also indicate that the removal of heat exchange from the skin surface can induce a significant temperature rise in it, which is, however, mostly due to imposing the adiabatic conditions themselves, rather than the electromagnetic energy absorption.     

Influence of atomic layer deposition chemistry on high-k dielectrics for charge trapping memories

In this work we report the performance of the SiO₂/Si₃N₄/HfO₂ and SiO₂/Si₃N₄/ZrO₂ stacks with emphasis on the influence of atomic layer deposition chemistry used for forming the HfO₂ and ZrO₂ blocking layers. Two Hf precursors were employed – tetrakis(ethylmethylamino)hafnium (TEMAH) and bis(methylcyclopentadienyl)methoxymethyl hafnium (HfD-04). For ZrO₂, tetrakis(ethylmethylamino)zirconium (TEMAZ) and bis(methylcyclopentadienyl)methoxymethyl zirconium (ZrD-04) were used as metal precursors. Ozone was used as the oxygen source. The structural characteristics of the stacks were examined by transmission electron microscopy and grazing incidence X-ray diffraction. The electrical properties of the stacks were studied using platinum-gated capacitor structures. The memory performance of the stacks was evaluated by write/erase (W/E) measurements, endurance and retention testing. Endurance measurements revealed the most important difference between the stacks. The films grown from TEMAH and TEMAZ could withstand a significantly higher number of W/E pulses (>3 × 10⁵ in the 10 V/?11 V, 10 ms regime), in comparison to the stacks made from HfD-04 and ZrD-04 precursors (<5 × 10³ W/E cycles). This difference in endurance characteristics is attributed mainly to the different deposition temperatures suited for these two precursors and the nature of the layer formed at the Si₃N₄/HfO₂ and the Si₃N₄/ZrO₂ interfaces.     

Quantifying the Poorly Known Role of Groundwater in Agriculture: the Case of Cyprus

Agriculture in the Mediterranean region is constrained by limited water resources and in many countries irrigation demand exceeds the renewable water supply. This paper presents a comprehensive approach to (a) quantify the consumptive green (soil moisture provided by precipitation) and blue (irrigation) water use for crop production, (b) distinguish the contribution of groundwater to irrigation supply and (c) estimate groundwater over-abstraction. A spatiotemporally explicit soil water balance model, based on the FAO-56 dual crop coefficient approach, which includes the computation of evaporation losses of the different irrigation systems, was applied to the 5,760-km² area of the Republic of Cyprus for the agro-meteorological years 1995–2009. The model uses national agricultural statistics, community-level data from the agricultural census and daily data from 34 meteorological stations and 70 precipitation gauges. Groundwater over-abstraction is quantified per groundwater body, based on the sustainable abstraction rates specified in the Cyprus River Basin Management Plan, as prepared for the EU Water Framework Directive. It was found that, on average, total agricultural water use was 506 Mm³/year, of which 62 % is attributed to green water use and 38 % to blue water use. Groundwater contributed, on average, 81 % (151 Mm³/year) to blue water use and exceeded the recommended abstraction rates by 45 % (47 Mm³/year). Even though the irrigated area decreased by 18 % during the 2008 drought year, relative to the wettest year (2003), total blue water use decreased by only 1 %. The limited surface water supply during the driest year resulted in a 37 % increase in groundwater use, relative to the wettest year, and exceeded the sustainable abstraction rate by 53 % (55 Mm³/year). Overall, the model provides objective and quantitative outcomes that can potentially contribute to the improvement of water resource management in Mediterranean environments, in the light of climate change and expected policy reforms.     

Active load alleviation potential of adaptive wind turbine blades using shape memory alloy actuators

Upscaling of wind turbine blades calls for implementation of innovative active load control concepts that will facilitate the flawless operation of the machine and reduce the fatigue and ultimate loads that hinder its service life. Based on aeroelastic simulations that prove the enhanced capabilities of combined individual pitch and individual flap control at global wind turbine scale level, a shape adaptive concept that encompasses an articulated mechanism consisting of two subparts is presented. Shape memory alloy (SMA) actuators are investigated and assessed as means to control the shape adaptive mechanism at airfoil section level in order to alleviate the developed structural loads. The concept is embedded in the trailing edge region of the blade of a 10‐MW horizontal axis wind turbine and acts as a flap mechanism. Numerical simulations are performed considering various wind velocities and morphing target shapes and trajectories for both normal and extreme turbulence conditions. The results prove the potential of the concept, since the SMA controlled actuators can accurately follow the target trajectories. Power requirements are estimated at 0.22% of the AEP of the machine, while fatigue and ultimate load reduction of the flap‐wise bending moment at the blade root is 27.6% and 7.4%, respectively.     

Application of failure mode and effect analysis (FMEA), cause and effect analysis and Pareto diagram in conjunction with HACCP to a potato chips manufacturing plant

Failure mode and effect analysis (FMEA) model has been applied for the risk assessment of potato chips manufacturing. A tentative approach of FMEA application to the snacks industry was attempted in order to analyse the critical control points (CCPs) in the processing of potato chips. Preliminary hazard analysis was used to analyse and predict the occurring failure modes in a food chain system (potato processing and potato chips processing plant), based on the functions, characteristics and/or interactions of the ingredients or the processes, upon which the system depends. CCPs have been identified and implemented in the cause and effect diagram (also known as Ishikawa, tree diagram and fishbone diagram). Finally, Pareto diagrams were employed towards the optimisation potential of FMEA.     

Three-points interfacial quadrature for geometrical source terms on nonuniform grids

This paper deals with numerical (finite volume) approximations, on nonuniform meshes, for ordinary differential equations with parameter-dependent fields. Appropriate discretizations are constructed over the space of parameters, in order to guarantee the consistency in presence of variable cells’ size, for which L ^p -error estimates, 1≤p<+∞, are proven.     

Statistical Learning Theory: A Primer

In this paper we first overview the main concepts of Statistical Learning Theory, a framework in which learning from examples can be studied in a principled way. We then briefly discuss well known as well as emerging learning techniques such as Regularization Networks and Support Vector Machines which can be justified in term of the same induction principle.