Πραγματοποιήθηκε πείραμα με στόχο τη μελέτη των περιβαλλοντικών συνθηκών πειραματικής καλλιέργειας ηλίανθου σε υπόστρωμα τέφρας. Για την μελέτη του θέματος εγκαταστάθηκε πειραματικός αγρός στην παραλιακή περιοχή του χωριού Μηλάκι του δήμου Ταμυνέων (Αλιβερίου) στο νομό Ευβοίας. Η σπορά του ηλίανθου έγινε με την φύτευση σπόρου με το χέρι στις 27 Απριλίου του 2009 σε δυο διαφορετικά υποστρώματα, της ήδη υπάρχουσας στην περιοχή, τέφρας και σε κανονικό εδαφικό υπόστρωμα το οποίο μεταφέρθηκε στην περιοχή. Για τις ανάγκες του πειράματος χρησιμοποιήθηκαν και στα δυο υποστρώματα τα πιο κάτω εδαφοβελτιωτικά (γύψος, τύρφη, περλίτης, πριονίδι) καθώς και αναμείξεις αυτών. Η μέγιστη τιμή του ολικού ύψους των φυτών στο υπόστρωμα της τέφρας, παρατηρείται στις 18 Ιουλίου του 2009, ενώ για την παράμετρο της διαμέτρου των ανθοκεφαλών η μέγιστη τιμή της παρατηρείται στις 2 Αυγούστου του 2009. Τα ίδια συμπεράσματα προκύπτουν και από τα δεδομένα που ελήφθησαν από το κανονικό εδαφικό υπόστρωμα. Υπολογίστηκαν οι συντελεστές συσχέτισης των φυτικών παραμέτρων στα διάφορα πειραματικά πεδία. Αυτές έδειξαν ότι οι θετικές αλλά και οι αρνητικές συσχετίσεις μεταξύ των ίδιων συγκρινόμενων παραμέτρων (Μεσοδιάστημα Κοτύλη – 1ο φύλλο, Μεσοδιάστημα 1ο φύλλο – 2ο φύλλο, Ολικό ύψος, Φυλλική επιφάνεια 1ου φύλλου, Φυλλική επιφάνεια 2ου φύλλου, Διάμετρος ανθοκεφαλής, Βάρος φυτού), είναι μεγαλύτερες στο υπόστρωμα της τέφρας από αυτό του κανονικού εδαφικού υποστρώματος. Εξαίρεση αποτελούν δυο περιπτώσεις, όπου στο υπόστρωμα της τέφρας εμφανίζεται αρνητική συσχέτιση ενώ στο κανονικό εδαφικό υπόστρωμα εμφανίζεται θετική συσχέτιση. Διαπιστώθηκε ότι στο υπόστρωμα της τέφρας, οι μεγαλύτερες τιμές των παραμέτρων που μετρήθηκαν κατά τη διάρκεια του πειράματος παρατηρήθηκαν στα πειραματικά τετράγωνα με τα παρακάτω εδαφοβελτιωτικά: T5A, G.T4A, G.T5A, G.T.PL3A και G.T.PL4A. Στο κανονικό εδαφικό υπόστρωμα, διαπιστώθηκε ότι οι μεγαλύτερες τιμές των παραμέτρων που μετρήθηκαν κατά τη διάρκεια του πειράματος παρατηρήθηκαν στα πειραματικά τετράγωνα με τα παρακάτω εδαφοβελτιωτικά: G.T5B, G.T.PL4B, G.T.PL5B, G.T.PL.PN4B και G.T.PL.PN5B. / An experiment was realised amining at the study of environmental conditions experimental growing of sunflower in sublayer of ash. For the study of this subject was installed experimental field in the coastal region of the village Milaki at the municipality Tamyneon (Aliveriou) in the prefecture of Evia. The seeding of sunflower became with the planting of seed by hands on 27 April 2009 in two different sublayers, the already existing in the region, ash and in regular territorial sublayer which was transported in the region. For the needs of experiment they were also used in the two sublayers the below ameliorative of ground (gypsum, peat, perlite, sawdust) as well as mixtures of these. The biggest price of the total height of plants in the sublayer of ash, is observed on 18 July 2009, while for the parameter of heads diameter her biggest price is observed on 2 August 2009. The same conclusions also result from the data that were received from the regular territorial sublayer. They were calculated the correlation factors of the plant parameters in the various experimental fields. These showed that positive but also negative correlations between the same compared parameters (Cotyledon – first leaf interval, First leaf – second leaf interval, Total height, Leaf surface of first leaf, Leaf surface of second leaf, Head diameter, Weight of plant) are bigger in the sublayer of the ash from that of the regular territorial sublayer. Exception constitutes two cases, where in the sublayer of ash is presented negative correlation while in the regular territorial sublayer is presented positive correlation. It was realised that in the sublayer of ash, the biggest prices of the parameters that were measured at the duration of experiment were observed in the experimental squares with the following ameliorative of ground: T5A, G.T4A, G.T5A, G.T.PL3A και G.T.PL4A. In the regular territorial sublayer, was realised that the biggest prices of the parameters that were measured at the duration of experiment were observed in the experimental squares with the following ameliorative of ground: G.T5B, G.T.PL4B, G.T.PL5B, G.T.PL.PN4B και G.T.PL.PN5B.

Wireless local area networks (WLANs) and wireless sensor networks (WSNs) technologies have been comprehensively developed and deployed during recent years. Since commercial WLAN and WSN products share the same free of license frequency band, the low power, low rate ZigBee based WSNs are vulnerable to the interference from Wi-Fi WLANs. Therefore, it is important to evaluate the performance of ZigBee WSNs that are subjected to interference generated by collocated Wi-Fi WLANs and to design effective counter-measuring techniques should performance improvement is needed. In this research, a versatile testbed for conducting various experiments is established and the ZigBee system’s performance with different clear channel assessment (CCA) modes and energy detection (ED) thresholds are evaluated through extensive experimental measurements in the testbed. It can be concluded from the results that CCA has significant impact on ZigBee’s performance. An existing theoretical analysis approach that is based on the collision time model between ZigBee and Wi-Fi packets is suitably modified to provide analytical evaluation means of the cases we examined. In order to mitigate the interference from the collocated Wi-Fi system, a novel and effective interference-aware adaptive CCA (IAACCA) scheme is proposed and implemented as firmware flashed into Crossbow motes. Experiments confirmed the ability of IAACCA to countermeasure effectively interference generated by Wi-Fi and thus improve the performance of ZigBee WSNs. Finally, a thorough statistical analysis is performed to understand the factors impacting the performance of ZigBee system and is used to further verify our experimental methods.

Wireless local area networks (WLANs) and wireless sensor networks (WSNs) technologies have been comprehensively developed and deployed during recent years. Since commercial WLAN and WSN products share the same free of license frequency band, the low power, low rate ZigBee based WSNs are vulnerable to the interference from Wi-Fi WLANs. Therefore, it is important to evaluate the performance of ZigBee WSNs that are subjected to interference generated by collocated Wi-Fi WLANs and to design effective counter-measuring techniques should performance improvement is needed. In this research, a versatile testbed for conducting various experiments is established and the ZigBee system’s performance with different clear channel assessment (CCA) modes and energy detection (ED) thresholds are evaluated through extensive experimental measurements in the testbed. It can be concluded from the results that CCA has significant impact on ZigBee’s performance. An existing theoretical analysis approach that is based on the collision time model between ZigBee and Wi-Fi packets is suitably modified to provide analytical evaluation means of the cases we examined. In order to mitigate the interference from the collocated Wi-Fi system, a novel and effective interference-aware adaptive CCA (IAACCA) scheme is proposed and implemented as firmware flashed into Crossbow motes. Experiments confirmed the ability of IAACCA to countermeasure effectively interference generated by Wi-Fi and thus improve the performance of ZigBee WSNs. Finally, a thorough statistical analysis is performed to understand the factors impacting the performance of ZigBee system and is used to further verify our experimental methods.

Wireless local area networks (WLANs) and wireless sensor networks (WSNs) technologies have been comprehensively developed and deployed during recent years. Since commercial WLAN and WSN products share the same free of license frequency band, the low power, low rate ZigBee based WSNs are vulnerable to the interference from Wi-Fi WLANs. Therefore, it is important to evaluate the performance of ZigBee WSNs that are subjected to interference generated by collocated Wi-Fi WLANs and to design effective counter-measuring techniques should performance improvement is needed. In this research, a versatile testbed for conducting various experiments is established and the ZigBee system’s performance with different clear channel assessment (CCA) modes and energy detection (ED) thresholds are evaluated through extensive experimental measurements in the testbed. It can be concluded from the results that CCA has significant impact on ZigBee’s performance. An existing theoretical analysis approach that is based on the collision time model between ZigBee and Wi-Fi packets is suitably modified to provide analytical evaluation means of the cases we examined. In order to mitigate the interference from the collocated Wi-Fi system, a novel and effective interference-aware adaptive CCA (IAACCA) scheme is proposed and implemented as firmware flashed into Crossbow motes. Experiments confirmed the ability of IAACCA to countermeasure effectively interference generated by Wi-Fi and thus improve the performance of ZigBee WSNs. Finally, a thorough statistical analysis is performed to understand the factors impacting the performance of ZigBee system and is used to further verify our experimental methods.

Incipient motion criterion in sediment transport is very important, as it defines the flow condition that initiates sediment motion, and is also frequently employed in models to predict the sediment transport at higher flow conditions as well. In turbulent flows, even a reasonably accurate definition of incipient motion condition becomes very difficult due to the random nature of the turbulent process, which is responsible for sediment motion under incipient conditions. This work investigates two aspects, both of which apply to incipient sediment transport conditions. The first one deals with the role of turbulence in initiating sediment motion. The second part deals with the nature of sediment-fluid interaction for more general and complex flows where the number of sediment particles that form the rough surface is varied. The first part of this work that investigates the role of turbulence in initiating sediment motion, uses a video camera to simultaneously monitor and record the sediment (glass ball) motion and corresponding fluid velocity events measured by a three-component laser Doppler Velocimeter (LDV). The results of the single ball experiment revealed that the number of LDV flow measurements increase dramatically (more than four folds) just prior to the ball motion. The fluid mean velocity and its root-mean-square (rms) values also are significantly higher than the values that correspond to the flow conditions that yield no ball motion. The second part of the work, investigation of the fluid-sediment interaction, includes five tests with varying number of sediment particles. In order to understand the nature and extent of fluid-solid interaction, velocity profile measurements using the 3-D laser system were carried out at three locations for each of these five cases. Plots of mean velocities, rms quantities located the universal layer at about 1.5 ball diameters above the porous bed. However, at higher sediment particle concentrations, this distance reduced and the beginning of the universal layer approached the top of the porous bed. / Ph. D.

Communication underwater is challenging because of the inherent characteristics of the media. First, common radio frequency (RF) signals utilized in wireless communications cannot be used under water. RF signals are attenuated in such as way that RF communication underwater is restricted to very few meters. As a result, acoustic-based communication is utilized for underwater communications; however, acoustic communication has its own limitations. For example, the speed of sound is five orders of magnitude lower than the speed of light, meaning that communications under water experience long propagation delays, even in short distances. Long propagation delays impose strong challenges in the design of Data Link Layer (DLL) protocols. The underwater communication channel is noisy, too. The bit error rate (BER) can also change depending on depth and other factors, and the errors are correlated, like in wireless communications. As in wireless communications, transducers for acoustic communication are half duplex, limiting the application of well-known detection mechanisms in Medium Access Control (MAC) layer protocols. Further, known problems like the hidden and exposed terminal problem also occur here. All these aspects together make the underwater communication channel to have the worst characteristics of all other known channels. Because of these reasons, underwater scenarios are complicated to implement, especially when they have underwater autonomous vehicles exchanging information among them. This dissertation proposes data link layer protocols in support of swarming of underwater autonomous vehicles that deal with the problems mentioned before. At the MAC sublayer, a MAC protocol called 2MAC is introduced. 2MAC improves the throughput of the network using the multichannel capabilities of OFDM at the physical layer. At the logical link control sublayer, a protocol named SW-MER is proposed. SW-MER improves the throughput and the reliability combining the well-known stop and wait protocol with the sliding window strategy, and using an exponential retransmission strategy to deal with errors. 2MAC and SW-MER are evaluated and compared with other protocols using analytical means and simulations. The results show that by using 2MAC, packet collisions are considerably reduced and the throughput improved. In addition, the use of SW-MER improves the packet delivery ratio over existing mechanisms. In general, the evaluations indicate that the proposed data link layer protocols offer a better communication alternative for underwater autonomous vehicles (UAV) than traditional protocols.

The diploma thesis deals with the theoretical definition of passive optical networks, furthermore the description of methods of channel bundling in passive optical networks and the coexistence and migration between standards. The main essence of this work is the XG-PON (10-Gigabit-capable Passive Optical Network) standard. This standard is generally defined along with a description of the physical layer. The transport layer is detailed analysis. There is a description of conditions, under which the Optical Network Unit pass through, when is activated. Additionally, this diploma thesis focuses on the processes of connecting Optical Network Units to the Passive Optical Networks and the timing relationships between Optical Network Units and Optical Line Terminal. The simulations demonstrate that as the number of simultaneous connections to Optical Network Unit increase, longer wait time for each additional connection becomes. This also solves the collision conditions, that might arise in communication and the equalization delay. Finally, the diploma thesis deals with the influence of a refractive index on timing relationships.

<p>A new theory for predicting the windprofile over a canopy has been evaluated. The theory was first presented by Harman and Finnigan (2007). The theory relies on the forming of a mixing-layer above the canopy, due to different mean wind in and above the canopy. Characteristics from both mixing-layer and Monin Obukhov similarity theory have been used to develop the governingequations that give the wind profile. The theory has been used to calculate wind profiles for sixdifferent atmospheric stabilities. In order to evaluate the theory, profiles from the theory have beencompared to measurements from Jädraås forest, Sweden. Profiles from Monin Obukhov similarity theory were also used for comparison.In general the mixing-layer theory gives better results than Monin Obukhov similarity theory. Agreement with measurements is good in neutral conditions, but fails when the atmospheric stability is altered, especially in convective conditions. This is believed to be due to the canopy lacking in thickness. The mean wind speed is systematically underestimated and this is also believed to be caused by insufficient thickness of the canopy. A correction for this behaviour is proposed. The theory gives higher values of the mean wind speed in convective conditions with the correction and the calculated values of mean wind speed are closer to the measurements.</p>

A new theory for predicting the windprofile over a canopy has been evaluated. The theory was first presented by Harman and Finnigan (2007). The theory relies on the forming of a mixing-layer above the canopy, due to different mean wind in and above the canopy. Characteristics from both mixing-layer and Monin Obukhov similarity theory have been used to develop the governingequations that give the wind profile. The theory has been used to calculate wind profiles for sixdifferent atmospheric stabilities. In order to evaluate the theory, profiles from the theory have beencompared to measurements from Jädraås forest, Sweden. Profiles from Monin Obukhov similarity theory were also used for comparison.In general the mixing-layer theory gives better results than Monin Obukhov similarity theory. Agreement with measurements is good in neutral conditions, but fails when the atmospheric stability is altered, especially in convective conditions. This is believed to be due to the canopy lacking in thickness. The mean wind speed is systematically underestimated and this is also believed to be caused by insufficient thickness of the canopy. A correction for this behaviour is proposed. The theory gives higher values of the mean wind speed in convective conditions with the correction and the calculated values of mean wind speed are closer to the measurements.

AN ABSTRACT OF THE DISSERTATION OF Mohamed Zaneer Segu Mohideen, for the Doctor of Philosophy degree in Chemistry, presented on November 3 2008, at Southern Illinois University Carbondale. TITLE: TARGET MODIFICATION FOR ENHANCED PERFORMANCE MATRIX ASSISTED LASER DESORPTION IONIZATION (MALDI) MASS SPECTROMETRY MAJOR PROFESSOR: Dr. Gary R Kinsel MALDI MS, a powerful tool for the analysis of biomolecules, has undergone major advancement in instrumentation to yield improvements in robustness, sensitivity and throughput since its invention. Despite these developments in instrumentation, the performance of MALDI is in question when it comes to the analysis of complex protein/peptide mixtures. For these types of mixtures the performance of MALDI can be improved by either simplifying the sample complexity, modifying the sample preparation approach to increase the ionization efficiency of mixture components or seeking further enhancements to instrument performance. In this work these improvements are pursued through modifications to the MALDI target itself. In the MALDI analysis of high MW proteins a primary limitation is thought to be related to inefficient desorption of these compounds as proteins are expected to experience relatively stronger interaction with the MALDI target surface. This insight led to investigations of the use of various sublayers, deposited directly on the MALDI target, as a means to improve high molecular weight protein MALDI ion signals. In the first approach the protein / matrix mixture is applied on a laser desorbable polyaromatic hydrocarbon layer which serves as a barrier to protein surface binding interactions. These sublayers are also shown to be useful for on probe sample purification from salts that are known to interfere with MALDI performance. In the second approach the sublayer is formed from bovine serum albumin, a protein that is known to have strong binding affinity for surfaces and is also expected to form a barrier to protein surface binding interactions. Enhancements in MALDI performance and reductions in the limit of detection for proteins on these albumin precoated probes clearly demonstrate the influence of surface-protein interaction in the analysis of these species by MALDI MS. In further studies, methods to improve on-MALDI-target approaches to the simplification of sample complexity are investigated. These on-target separation approaches have been previously developed and shown to be successful for reducing sample complexity in the Kinsel Research Group. However, one significant limitation to this separation approach is the limited surface binding capacity of the MALDI probe. This limitation led to theoretical and experimental studies of methods to improve the surface protein binding capacity. Studies performed show that the surface binding capacity can be improved significantly through attachment of gold beads and through physical / chemical roughening of the target surface. Both approaches are shown to yield higher performance MALDI probes with lowered limits of detection for deposited / affinity captured proteins.