Coupling Measurements of an Antenna System Suitable for Relay-Aided WiMAX Network

YesIn this paper two novel antennas, suitable for access and backhaul links, are designed, fabricated and tested for a Relay Station in a WiMAX wireless network. A single modi¯ed E-shaped patch antenna is described, presenting 10 dB gain over 12.4% bandwidth. This antenna element is used for the design of a 4 £ 4 planar array which provides experimental gain of 21.2 dB. The antenna system on the Relay Station operates at 3.4 GHz and includes one single antenna element for access link realization and an antenna array for the backhaul link realization. These antennas are installed in two con¯guration arrangements and tested in terms of their radiation performances and coupling e®ects. The simulated and measured results are quite satisfactory and in good agreement at which the maximum coupling between the access and backhaul antennas is found below ¡25 dB for all tested cases

Sustainable and Regenerative Development of Water Mills as an Example of Agricultural Technologies for Small Farms

Nowadays, the reuse of built agricultural/industrial heritage has been a common practice worldwide. These structures represent excellent symbols of the great agricultural/industrial past. These agricultural/hydro-technologies also serve as monuments of socio-cultural identities, especially in rural areas and on small farms. One example of a successful application of agricultural technologies for small farms is the water mill. By harnessing the water energy, they were used for traditional flour and other goods production (e.g., olive oil) and works requiring energy, with the main role in the evolution of the traditional/cultural landscape. Water mills have been used to drive a mechanical process of milling, hammering, and rolling and are a portion of the agricultural, cultural, and industrial heritage. For approximately two millennia, the vertical mill water wheel prepared the initial source of mechanical power in many regions of the world. Water mills were the first device that converted natural resources of energy into mechanical energy in order to operate some form of machinery. The preservation/management of water mills is challenging due to their long-term abandonment and the lack of information/knowledge about their value. The other obstacles that are faced in their retrofitting and/or preservation are the lack of sufficient economic incentives and complex authorizations/legislations. Sustainability and regeneration of water mills through the centuries are then reviewed for history and agricultural/industrial “archaeology”. The history of water-powered mills in prehistoric and historic times, including ancient Persia/Iran, ancient China, ancient India, the Islamic world, Venetian Crete, medieval Europe, America, and finally present times, is discussed. The outcome of this review allows the understanding of the importance of conservation, optimization, and development of water mills. It will help to know more and achieve sustainable/regenerative development for small farms with respect to water and energy crises at present and in the future

Improved QC-STBC OFDM system using null interfeence elimination

YesThe quasi-orthogonal space time block coding (QO-STBC) over orthogonal frequency division multiplexing (OFDM) is investigated. Traditionally, QO-STBC does not achieve full diversity since the detection matrix of QO-STBC scheme is not a diagonal matrix. In STBC, the decoding matrix is a diagonal matrix which enables linear decoding whereas the decoding matrix in traditional QO-STBC does not enable linear decoding. In this paper it is shown that there are some interfering terms in terms of non-diagonal elements that result from the decoding process which limit the linear decoding. As a result, interference from the application of the QO-STBC decoding matrix depletes the performance of the scheme such that full diversity is not attained. A method of eliminating this interference in QO-STBC is investigated by nulling the interfering terms towards full diversity for an OFDM system. It was found that the interference reduction technique permits circa 2dB BER performance gain in QO-STBC. The theoretical and simulation results are presented, for both traditional QO-STBC and interference-free QO-STBC applying OFD

Beam-forming module for backhaul link in a Relay-aided 4G network

YesA novel beam-forming module based on Wilkinson power divider technology, including attenuators and phase shifter chips is designed, fabricated and evaluated to be incorporated in a Relay Station connecting it with the Base Station under a 4G network. The proposed module is a 1:8 port circuit, utilizing two substrates, providing approximately 700 MHz bandwidth over 3.5 GHz frequency band and less than −20 dB transmission line coupling. Moreover an external control unit that feeds the beam-forming module with code-words that define the proper amplitude/phase of the excitation currents is established and described. The presented module is connected to a planar array and tested for two beam-forming scenarios, providing satisfactory radiation patterns

Predictable Artificial Intelligence

We introduce the fundamental ideas and challenges of Predictable AI, a nascent research area that explores the ways in which we can anticipate key indicators of present and future AI ecosystems. We argue that achieving predictability is crucial for fostering trust, liability, control, alignment and safety of AI ecosystems, and thus should be prioritised over performance. While distinctive from other areas of technical and non-technical AI research, the questions, hypotheses and challenges relevant to Predictable AI were yet to be clearly described. This paper aims to elucidate them, calls for identifying paths towards AI predictability and outlines the potential impact of this emergent field.Comment: 11 pages excluding references, 4 figures, and 2 tables. Paper Under Revie

A New Approach for Designing Orthogonal Wavelets for Multicarrier Applications

yesThe Daubechies, coiflet and symlet wavelets, with properties of orthogonal wavelets are suitable for multicarrier transmission over band-limited channels. It has been shown that similar wavelets can be constructed by Lagrange approximation interpolation. In this work and using established wavelet design algorithms, it is shown that ideal filters can be approximated to construct new orthogonal wavelets. These new wavelets, in terms of BER behave slightly better than the wavelets mentioned above, and much better than biorthogonal wavelets, in multipath channels with additive white Gaussian noise (AWGN). It is shown that the construction, which uses a simple simultaneous solution to obtain the wavelet filters from the ideal filters based on established wavelet design algorithms, is simple and can easily be reproduced

Preventing Groundwater Pollution Using Vulnerability and Risk Mapping: The Case of the Florina Basin, NW Greece

The alluvial aquifer system of the Florina basin (320 km2) in North Greece is a representative area where irrigated agriculture is applied. Groundwater is the main source of water. The highest and mean nitrate concentrations in groundwater are 67.9 mg/L and 25 mg/L, respectively. High values could be associated with the use of nitrogen fertilizers from agricultural activities. This study deals with the evaluation of the groundwater quality. For this reason, hydrochemical analyses from 29 groundwater samples and water level measurements were performed for the wet and dry periods of 2016. The suitability of groundwater quality for irrigation purposes is examined by using different indices (Chlorinity Index, SAR, Sodium Percentage, Potential Salinity and Kelly’s index). In addition, the DRASTIC method was modified by using statistical methods, land use map and nitrate concentrations and applied in order to assess the groundwater vulnerability to external pollution. Notably, there was no correlation between the standard DRASTIC method and nitrate concentrations. However, the modified version and the obtained risk map showed high correlation with nitrate concentrations (ρ = 0.55) and the Groundwater Quality; hence, it is suggested as the base for a protection plan of the alluvial aquifer

HYDROGEOLOGICAL CONDITIONS OF THE NW PART OF ACHAIA (NW PELOPONNESUS, GREECE)

THE STUDIED AREA (942.8 KM2) IS EXTENDING AT THE NW PART OF ACHAIA (NW PELOPONNESUS). THE HYDROGRAPHIC PATTERN IS MODERATELY DEVELOPED, WITH MEAN SLOPE BETWEEN 6.0% AND 15%. IN THE STUDIED AREA, FOLDED AND FAULTED FORMATIONS OF THE GAVROVO-TRIPOLITZA AND OLONOS-PINDOS ZONES ARE OUTCROPPING. IN THE LOWLANDS OF THE AREA, THE ALPINE FORMATIONS ARE COVERED BY POSTALPINE PLIOCENE SEDIMENTS (SANDY CLAYS, CLAYEY MARLS WITH THIN GRAVEL INTERCALATIONS). QUATERNARY IS REPRESENTED BY PLEISTOCENE CLAYEY CONGLOMERATES, GRAVELS, SANDS AND CLAYS. THE MEAN ANNUAL PRECIPITATION IN THE STUDY AREA AMOUNTS TO 918.8 MM (PERIOD 1975-1991). THE TIME SERIES ANALYSIS OF THE PRECIPITATION DATA SHOWS A CLEARLY NEGATIVE COURSE OF THE MEAN ANNUAL PRECIPITATION IN THE LAST DECADE. A LARGE VOLUME OF WATER (221.7X10 6 M3/YEAR) IS COMPRISING THE RUNOFF THROUGH THE MAIN BRANCHES OF THE HYDROGRAPHIC PATTERN. THE HYDROGEOLOGICAL INVESTIGATION WAS MAINLY APPLIED TO THE PLIOQUATERNARY SEDIMENTARY SEQUENCE, WHERE IMPORTANT UNCONFINED AQUIFERS ARE DEVELOPED, AT VARIOUS DEPTHS. THE QUATERNARY FORMATIONS ARE SHOWING VARYING HYDROGEOLOGICAL PROPERTIES, ACCORDING TO THEIR THICKNESS AND THEIR GRAIN-SIZE DISTRIBUTION. THE BEST AQUIFERS ARE THE PLEISTOCENE AND HOLOCENE FLUVIAL DEPOSITS, WITH HIGH YIELDS IN RELATIVELY LOW DEPTHS. NEGATIVEGROUNDWATER LEVELS (BELOW SEA-LEVEL) ARE OBSERVED IN THE COASTAL ZONE OF THEGLAFKOS AND CHARADROS ALLUVIAL PLAINS DUE TO PROLONGED DROUGHT PERIODS. (ABSTRACT TRUNCATED)Η ΠΕΡΙΟΧΗ ΕΡΕΥΝΑΣ ΚΑΤΑΛΑΜΒΑΝΕΙ ΤΟ ΒΔ/ΚΟ ΤΜΗΜΑ ΤΟΥ ΝΟΜΟΥ ΑΧΑΙΑΣ ΜΕ ΣΥΝΟΛΙΚΗ ΕΚΤΑΣΗ 942.8 KM2. ΤΟ ΜΕΣΟ ΥΨΟΜΕΤΡΟ ΑΝΕΡΧΕΤΑΙ ΣΕ 600 M ΚΑΙ Η ΜΕΣΗ ΚΛΙΣΗ ΚΥΜΑΙΝΕΤΑΙ ΑΠΟ 6.0% ΕΩΣ 15.5 %. ΤΟ ΑΛΠΙΚΑ ΠΤΥΧΩΜΕΝΟ ΥΠΟΒΑΘΡΟ ΤΗΣ ΠΕΡΙΟΧΗΣ ΑΠΟΤΕΛΕΙΤΑΙΑΠΟ ΔΥΟ ΕΠΙΜΗΚΕΙΣ ΙΣΟΠΙΚΕΣ ΖΩΝΕΣ : ΤΗ ΖΩΝΗ ΓΑΒΡΟΒΟΥ-ΤΡΙΠΟΛΗΣ Δ /ΚΑ ΚΑΙ ΤΗ ΖΩΝΗ ΩΛΟΝΟΥ-ΠΙΝΔΟΥ ΣΤΑ Α/ΚΑ. ΤΟ ΠΛΕΙΟΤΕΤΑΡΤΟΓΕΝΕΣ ΕΠΙΚΑΛΥΜΜΑ ΣΥΝΙΣΤΑΤΑΙ ΑΠΟ ΕΝΑΛΛΑΓΕΣ ΑΡΓΙΛΩΝ, ΑΜΜΟΥΧΩΝ ΑΡΓΙΛΩΝ ΚΑΙ ΑΜΜΩΝ ΚΑΙ ΣΤΟ ΑΝΩΤΕΡΟ ΤΜΗΜΑ ΕΜΦΑΝΙΖΕΤΑΙΜΙΑ ΑΔΡΟΜΕΡΕΣΤΕΡΗ ΣΕΙΡΑ ΚΑΙ ΚΡΟΚΑΛΟΠΑΓΗ. ΤΟ ΜΕΣΟ ΕΤΗΣΙΟ ΥΨΟΣ ΒΡΟΧΗΣ ΑΝΕΡΧΕΤΑΙ ΣΕ 918.8 MM (ΠΕΡ. 1975-1991) ΚΑΙ ΑΠΟ ΤΗΝ ΑΝΑΛΥΣΗ ΤΩΝ ΒΡΟΧΟΜΕΤΡΙΚΩΝ ΔΕΔΟΜΕΝΩΝ ΠΡΟΕΚΥΨΕ ΠΤΩΤΙΚΗ ΠΟΡΕΙΑ ΤΩΝ ΕΤΗΣΙΩΝ ΤΙΜΩΝ ΒΡΟΧΟΠΤΩΣΗΣ ΤΗΝ ΤΕΛΕΥΤΑΙΑ ΔΕΚΑΕΤΙΑ. ΕΝΑΣ ΣΗΜΑΝΤΙΚΟΣ ΟΓΚΟΣ ΝΕΡΟΥ (221.7 Χ10 6 M3/YEAR) ΑΠΟΡΡΕΕΙ ΜΕΣΩ ΤΩΝ ΚΥΡΙΩΝΚΛΑΔΩΝ ΤΟΥ ΥΔΡΟΓΡΑΦΙΚΟΥ ΔΙΚΤΥΟΥ (ΠΟΤΑΜΟΙ, ΧΕΙΜΑΡΡΟΙ) ΣΤΗ ΘΑΛΑΣΣΑ. ΣΤΙΣ ΠΛΕΙΟΠΛΕΙΣΤΟΚΑΙΝΙΚΕΣ ΑΠΟΘΕΣΕΙΣ ΤΗΣ ΠΕΔΙΝΗΣ ΠΕΡΙΟΧΗΣ ΑΝΑΠΤΥΣΣΟΝΤΑΙ ΕΠΑΛΛΗΛΟΙ ΥΔΡΟΦΟΡΟΙ ΟΡΙΖΟΝΤΕΣ ΠΟΥ ΧΑΡΑΚΤΗΡΙΖΟΝΤΑΙ ΑΠΟ ΑΝΙΣΟΤΡΟΠΙΑ ΚΑΙ ΑΝΟΜΟΙΟΓΕΝΕΙΑ. ΟΙ ΤΕΤΑΡΤΟΓΕΝΕΙΣ ΣΧΗΜΑΤΙΣΜΟΙ ΕΜΦΑΝΙΖΟΥΝ ΠΟΙΚΙΛΛΟΥΣΑ ΥΔΡΟΓΕΩΛΟΓΙΚΗ ΣΥΜΠΕΡΙΦΟΡΑ ΑΝΑΛΟΓΑ ΜΕ ΤΟ ΠΑΧΟΣ ΤΟΥΣ ΚΑΙ ΤΗΝ ΚΟΚΚΟΜΕΤΡΙΚΗ ΤΟΥΣ ΣΥΣΤΑΣΗ. ΟΙ ΣΥΓΧΡΟΝΕΣ ΠΟΤΑΜΙΕΣ ΑΠΟΘΕΣΕΙΣ ΑΠΟΤΕΛΟΥΝ ΤΑ ΚΑΛΥΤΕΡΑ ΥΔΡΟΦΟΡΑ ΣΤΡΩΜΑΤΑ ΕΞ' ΑΥΤΩΝ ΚΑΙ ΔΙΝΟΥΝ ΑΞΙΟΛΟΓΕΣ ΠΑΡΟΧΕΣ ΑΠΟ ΜΙΚΡΑ ΣΧΕΤΙΚΑ ΒΑΘΗ. ΠΑΡΑΤΗΡΕΙΤΑΙ ΜΙΑ ΤΑΠΕΙΝΩΣΗ ΤΗΣ ΣΤΑΘΜΗΣ ΤΩΝ ΥΠΟΓΕΙΩΝ ΝΕΡΩΝ ΤΑ ΤΕΛΕΥΤΑΙΑ ΧΡΟΝΙΑ ΠΟΥ ΣΧΕΤΙΖΕΤΑΙ ΜΕ ΤΗ ΜΕΙΩΣΗ ΠΡΟΣΦΟΡΑΣ ΝΕΡΟΥ.(ΠΕΡΙΚΟΠΗ ΠΕΡΙΛΗΨΗΣ

Groundwater Resources Management: Reconciling Demand, High Quality Resources and Sustainability

The prospect of the global population reaching 9 billion by 2050, in addition to growing urbanisation, intensive irrigated agriculture and climate change, will add extra pressures on water resources and the environment [...