Simplified methods of analysis described in codes and specifications for seismically isolated structures are always used either directly in special cases or for checking the results of nonlinear response history analysis (RHA). Important predictions for seismically isolated structures by simplified methods are the maximum displacements and base shears of the isolation system. In this study, the maximum isolator displacements and base shears determined by nonlinear RHA are compared with those determined by the equivalent lateral force (ELF) procedure in order to assess the accuracy of the simplified method in the case of bi-directional excitations with near-field characteristics. However, although there are currently many methods for ground motion selection and scaling, little guidance is available to classify which method is more appropriate than the others in any applications. Features of this study are that the ground motions used in analysis are selected and scaled using contemporary concepts and that the ground excitation is considered biv directional. The variations in response of isolated structures due to application of ground motions uni-directionally and bi-directionally are also studied by employing a scaling procedure that is appropriate for the bi-directional analysis. The proposed new scaling methodology is an amplitude scaling method that is capable of preserving the horizontal orthogonal components and it is developed especially for dynamic analysis of isolated structures. Analyses are conducted for two different symmetric reinforced concrete isolated structure for two different soil conditions in structural analysis program SAP2000. Effect of asymmetry in superstructure on isolator displacement is also investigated with further analyses considering 5% mass eccentricity at each floor level. Furthermore, once the significance of the orthogonal horizontal component on the response of isolation system is shown, the biaxial interaction of hysteretic behavior of lead rubber bearings is implemented in OpenSees by developing a subroutine which was not readily available.

The studies conducted on hole cleaning have been started with single phase drilling fluids for vertical holes in 1930&rsquo / s, and have reached to multiphase drilling fluids for directional and horizontal wells today. The influence of flow rate and hole inclination on cuttings transport has been well understood, and many studies have been conducted on effective hole cleaning either experimentally or theoretically. However, neither the hydraulic behavior nor the hole cleaning mechanism of gasified drilling fluids has been properly understood. The aims of this study are to investigate and analyze the hole cleaning performance of gasified drilling fluids in horizontal, directional and vertical wells experimentally, to identify the drilling parameters those have the major influence on cuttings transport, to define the flow pattern types and boundaries as well as to observe the behavior of cuttings in detail by using digital image processing techniques, and to develop a mechanistic model based on the fundamental principles of physics and mathematics with the help of the experimental observations. A mechanistic model is developed with the help of the obtained experimental data. Developed model is used for estimating optimum flow rates for liquid and gas phases for effective cuttings transport as well as for determining the total pressure losses and void fraction of each phase for a given drilling conditions. The v mechanistic model obtained using the experimental data within the scope of this study will be used to develop the hydraulic program and equipment selection to be used in the field during underbalanced drilling applications.

Low noise, directional microphones are critical for hearing aid applications. This thesis is focused on further development of a biomimetic micromachined directional microphone based on the ear structure of the Ormia Ochracea, a parasitic fly able to locate sound sources in the audio frequency range with high accuracy. The development efforts have been on implementing a version of the microphone for a behind the ear (BTE) package while improving the overall optical efficiency and noise level, demonstrating pulsed laser operation for reduced power consumption, and electrostatic control of the microphone diaphragm position for stable operation over a long time. The new packaging method for the microphone addressed the need for tighter placement tolerances along with a redesigned diaphragm and integration of a microscale optical lens array to improve the optical efficiency of the device. The completed packages were characterized for sensitivity improvement and optical efficiency. The overall optical efficiency was significantly increased from less than 1% to the photo diode array collecting 50% of the emitted optical power from the Vertical Cavity Surface Emitting Laser (VCSEL). This, coupled with the new diaphragm design, improved the acoustic performance of the microphones. Consequently, the noise levels recorded on the devices were about 31 dBA SPL, more than 15dB better than conventional directional microphones with nearly 10 times larger port spacing. Since the application for this technology is hearing aids, the power consumed by the working device needs to be at an acceptable level. The majority of the power used by the microphone is from continuously operating the VCSEL with 2mW optical output power. To reduce this power requirement, it was suggested to pulse the VCSEL at high enough frequency with low duty cycle so that the acoustic signals can be recovered from its samples. In this study, it was found that the VCSEL can be pulsed with little to no degradation in signal to noise ratio as long as the thermal mechanical noise dominated the noise spectrum. The results also indicated that a pulse train with a duty cycle of around 20% can be used without a major loss of performance in the device, meaning the device can effectively run at 1/5 of its original power under pulsed operation mode. Finally, a control technique to overcome some inherent problems of the microphone was demonstrated. Since the optical sensitivity of the microphone depends on the gap between the diaphragm grating and the integrated mirror, it is important to keep that bias gap constant during long term operation against environmental variations and charging effects. Using a simple electrostatic bias controller scheme, the sensitivity variation of the microphone was improved by a factor of 7.68 with bias control. Overall, this thesis has addressed several important aspects of a micromachined biomimetic microphone and further demonstrated its feasibility for hearing aid applications.

Ad hoc network is intrinsically autonomous and self-configuring network that does not require any dedicated centralized management. For specialized applications such as, military operations, search-and-rescue missions, security and surveillance, patient monitoring, hazardous material monitoring, 4G (4th Generation) coverage extension, and rural communication; ad hoc networks provide an intelligent, robust, flexible and cost effective solution for the wireless communication needs. As in centralized wireless systems, ad hoc networks are also expected to support high data rates, low delays, and large node density in addition to many other QoS (Quality of Service) requirements. However, due to unique ad hoc network characteristics, spectrum scarcity, computational limit of current state-of-the-art technology, power consumption, and memory; meeting QoS requirements is very challenging in ad hoc networks. Studies have shown cross layer to be very effective in enhancing QoS performance under spectrum scarcity and other constraints. In this dissertation, our main goal is to enhance performance (e.g., throughput, delay, scalability, fairness) by developing novel cross layer techniques in single-hop single channel general ad hoc networks. Our dissertation mainly consists of three main sections. In the first section, we identify major challenges intrinsic to ad hoc networks that affect QoS performance under spectrum constraint (i.e., single channel). In the later parts of the dissertation, we investigate and propose novel distributed techniques for ad hoc networks to tackle identified challenges. Different from our main goal, albeit closely related; in the first section we propose a conceptual cross layer frame work for interaction control and coordination. In this context, we identify various functional blocks, and show through simulations that global and local perturbations through parametric correlation can be used for performance optimization. In the second section, we propose MAC (Medium Access Control) scheduling approaches for omni-directional antenna environment to enhance throughput, delay, scalability and fairness performance under channel fading conditions. First, we propose a novel cooperative ratio-based MAC scheduling scheme for finite horizon applications. In this scheduling scheme, each node cooperatively adapts access probability in every window based on its own and neighbors` backlogs and channel states to enhance throughput, scalability and fairness performance. Further, in the second section, we propose two novel relay based MAC scheduling protocols (termed as 2rcMAC and IrcMAC) that make use of relays for reliable transmission with enhanced throughput and delay performance. The proposed protocols make use of spatial diversity due to relay path(s) provided they offer higher data rates compared to the direct path. Simulation results confirm improved performance compared to existing relay based protocols. In the third section, we make use of directional antenna technology to enhance spatial reuse and thus increase network throughput and scalability in ad hoc networks. In this section, we introduce problems that arise as a result of directional communication. We consider two such problems and propose techniques that consequently lead to throughput, delay and scalability enhancement. Specifically, we consider destination location and tracking problem as our first problem. We propose a novel neighbor discovery DMAC (Directional MAC) protocol that probabilistically searches for the destination based on elapsed time, distance, average velocity and beam-width. Results confirm improved performance compared to commonly used random sector and last sector based directional MAC protocols. Further, we identify RTS/CTS collisions as our second problem which leads to appreciable throughput degradation in ad hoc networks. In this respect, we investigate and propose a fully distributed asynchronous polarization based DMAC protocol. In this protocol, each node senses its neighborhood on both linear polarization channels and adapts polarization to enhance throughput and scalability. Throughput and delay comparisons against the basic DMAC protocol clearly show throughput, scalability and delay improvements.

There is growing interest in developing reliable, high performance, underwater acoustic networks (UWANs). However, the acoustic communication channel, with its slow sound propagation, high signal attenuation, and low bandwidth, presents significant challenges to network designers. One advantage offered by the acoustic channel is the ability to form directional communication beams, which improve signal strength and reduce interference. The work presented here describes a novel medium access control protocol for UWANs designated Beam-Enabled Acoustic Link Establishment (BEALE). BEALE addresses the inherent challenges of the acoustic channel by incorporating two techniques: link-level scheduling and dynamic directional beam steering. BEALE neighbors exchange packets based on a link-level schedule negotiated between the two nodes. This scheduling allows nodes to steer transmit and receive beams in the appropriate direction at the appropriate time while minimizing control overhead. Using steered, directional beams increases the gain between sender and receiver, reduces the senders interference with other nodes, and, at the receiver, rejects possible interference from other nodes and noise sources common in the ocean, resulting in increased spatial reuse. The core protocol has been modeled in a UWAN simulator developed specifically for this research. The results demonstrate significant improvement in throughput and packet loss over two benchmark UWAN random access protocols when evaluated over a variety of spatial node topologies and traffic patterns. The core BEALE protocol is further enhanced herein by a Half-Duplex Sliding Window algorithm. The HDX Sliding window is shown through point-to-point simulation to markedly improve bandwidth utilization and error rate in large Bandwidth Delay Product (BDP) situations. Extension of the HDX Sliding Window to more complex multi-flow, two-way and multi-hop cases requires an additional level of communication coordination provided by the BEALE Sliding Window Scheduler presented here. The functional challenges and novel concept of the scheduler are described in detail. The BEALE protocol performance promotes a rich list of potential future research, such as rigorous characterization of the BEALE Sliding Window Scheduler, BEALE accommodation of mobile nodes, conceptual operability of a BEALE-enabled network of a central multi-beam sink node supporting large numbers of simple source nodes, and rate adaptation. / text

In this thesis, a cavity-backed slot antenna array is designed for relatively wide instantaneous bandwidth, high gain and low sidelobes. The array consists of four, rectangular, slot elements, arranged side-by-side in a linear array and developed around 5GHz. Two feed points, at opposing sides of the printed array, each excite two of the slot elements through a series feed. This bidirectional feed presents symmetry to the design and prevents the tendency of beam-drift versus frequency as is common with many series-fed arrays. While being fed in-phase, the array will maintain boresight at broadside over the entire operating bandwidth. Also, the additional port allows for the potential introduction of a phase offset and, therefore, beam tilt. Finally, the printed array is designed to function within a quarter-wave, metallic cavity to achieve unidirectional radiation and improve gain.

Faithful chromosome segregation is essential for all living organisms. Bacterial chromosome segregation utilizes highly conserved directional SpoIIIE/FtsK translocases to move large DNA molecules between spatially separated compartments. These translocases employ an accessory DNA-interacting domain (gamma) that dictates the direction of DNA transport by recognizing specific DNA sequences. To date it remains unclear how these translocases use DNA sequence information as a trigger to expend chemical energy (ATP turnover) and thereby power mechanical work (DNA movement). In this thesis, I undertook a mechanistic study of directional DNA movement by SpoIIIE from the Gram-positive model bacterium Bacillus subtilis. Specifically, I was interested in understanding the information transfer within the protein from sequence recognition, to ATP turnover, and ultimately to chromosome translocation. How do DNA sequences trigger directional chromosome movement?

Darbe analizuojama inžinerinių tinklų įrengimas horizontalaus valdomo gręžimo metodu. Pirmiausia pateikiama literatūros apžvalga, kurioje aptariami veiksniai, lemiantys žemės kasimo darbus. Aprašomas atviras žemės kasimo būdas, kuris dažniausiai naudojamas atliekant žemės kasimo darbus. Aptariamos betranšėjės technologijos, kurios naudojamos kaip alternatyva atviram žemės kasimo būdui specifinėse vietose. Tyrimo metodikoje ir organizavime dalyje pateikiami gręžimo darbų projektai bei jų analizės, gręžimo darbų pasirengimo etapai, gręžimo mašinų ir kitos įrangos, naudojamos tyrime, charakteristikos. Aptariami gręžimo mašinų parinkimo metodai konkrečiam gręžimui ir aprašomi gręžimo darbai. Tyrimų rezultatų analizės dalyje pateikiama gręžimo mašinų charakteristikų analizė bei pasirinktų trijų gręžimų ,,Kryptinio gręžimo matavimo protokolai“ bei pagal juos sudaryti išilginiai gręžimo profiliai. Pateikiamos tyrimo išvados ir rekomendacijos dėl inžinerinių tinklų įrengimo horizontalaus valdomo gręžimo metodu. / The paper analyzes the engineering networks in horizontal directional drilling method. Firstly there is the literature review, which discusses the factors that determine the excavation. Describe the open method of excavating the land, which is mainly used in the excavation. Discussed in trenchless technology, which are used as an alternative way of moving to an open ground in specific areas. The study methodology and the organization of the work submitted for drilling projects, and their analysis, the preparation stages of drilling, drilling machines and other equipment used in the study, characteristics. Considered boring machine selection methods described in the particular drilling and boring work. Research results presented in the analysis of drilling machines and the analysis of selected characteristics of the three drilling, directional drilling measurement protocols, and to set them up under the longitudinal drilling profiles. Presented the study findings and recommendations of the engineering networks in horizontal directional drilling method.

The Arctic tundra, covering approx. 5.5 % of the Earth’s land surface, is one of the last ecosystems remaining closest to its untouched condition. Remote sensing is able to provide information at regular time intervals and large spatial scales on the structure and function of Arctic ecosystems. But almost all natural surfaces reveal individual anisotropic reflectance behaviors, which can be described by the bidirectional reflectance distribution function (BRDF). This effect can cause significant changes in the measured surface reflectance depending on solar illumination and sensor viewing geometries. The aim of this thesis is the hyperspectral and spectro-directional reflectance characterization of important Arctic tundra vegetation communities at representative Siberian and Alaskan tundra sites as basis for the extraction of vegetation parameters, and the normalization of BRDF effects in off-nadir and multi-temporal remote sensing data. Moreover, in preparation for the upcoming German EnMAP (Environmental Mapping and Analysis Program) satellite mission, the understanding of BRDF effects in Arctic tundra is essential for the retrieval of high quality, consistent and therefore comparable datasets. The research in this doctoral thesis is based on field spectroscopic and field spectro-goniometric investigations of representative Siberian and Alaskan measurement grids. The first objective of this thesis was the development of a lightweight, transportable, and easily managed field spectro-goniometer system which nevertheless provides reliable spectro-directional data. I developed the Manual Transportable Instrument platform for ground-based Spectro-directional observations (ManTIS). The outcome of the field spectro-radiometrical measurements at the Low Arctic study sites along important environmental gradients (regional climate, soil pH, toposequence, and soil moisture) show that the different plant communities can be distinguished by their nadir-view reflectance spectra. The results especially reveal separation possibilities between the different tundra vegetation communities in the visible (VIS) blue and red wavelength regions. Additionally, the near-infrared (NIR) shoulder and NIR reflectance plateau, despite their relatively low values due to the low structure of tundra vegetation, are still valuable information sources and can separate communities according to their biomass and vegetation structure. In general, all different tundra plant communities show: (i) low maximum NIR reflectance; (ii) a weakly or nonexistent visible green reflectance peak in the VIS spectrum; (iii) a narrow “red-edge” region between the red and NIR wavelength regions; and (iv) no distinct NIR reflectance plateau. These common nadir-view reflectance characteristics are essential for the understanding of the variability of BRDF effects in Arctic tundra. None of the analyzed tundra communities showed an even closely isotropic reflectance behavior. In general, tundra vegetation communities: (i) usually show the highest BRDF effects in the solar principal plane; (ii) usually show the reflectance maximum in the backward viewing directions, and the reflectance minimum in the nadir to forward viewing directions; (iii) usually have a higher degree of reflectance anisotropy in the VIS wavelength region than in the NIR wavelength region; and (iv) show a more bowl-shaped reflectance distribution in longer wavelength bands (>700 nm). The results of the analysis of the influence of high sun zenith angles on the reflectance anisotropy show that with increasing sun zenith angles, the reflectance anisotropy changes to azimuthally symmetrical, bowl-shaped reflectance distributions with the lowest reflectance values in the nadir view position. The spectro-directional analyses also show that remote sensing products such as the NDVI or relative absorption depth products are strongly influenced by BRDF effects, and that the anisotropic characteristics of the remote sensing products can significantly differ from the observed BRDF effects in the original reflectance data. But the results further show that the NDVI can minimize view angle effects relative to the contrary spectro-directional effects in the red and NIR bands. For the researched tundra plant communities, the overall difference of the off-nadir NDVI values compared to the nadir value increases with increasing sensor viewing angles, but on average never exceeds 10 %. In conclusion, this study shows that changes in the illumination-target-viewing geometry directly lead to an altering of the reflectance spectra of Arctic tundra communities according to their object-specific BRDFs. Since the different tundra communities show only small, but nonetheless significant differences in the surface reflectance, it is important to include spectro-directional reflectance characteristics in the algorithm development for remote sensing products. / Die arktische Tundra ist mit circa 5,5 % der Landoberfläche eines der letzten großen verbliebenen fast unberührten Ökosysteme unserer Erde. Nur die Fernerkundung ist in der Lage, benötigte Informationen über Struktur und Zustand dieses Ökosystems großräumig und in regelmäßigen Zeitabständen zur Verfügung zu stellen. Aber fast alle natürlichen Oberflächen zeigen individuelle anisotrope Reflexionsverhaltensweisen, welche durch die bidirektionale Reflektanzverteilungsfunktion (englisch: BRDF) beschrieben werden können. Dieser Effekt kann zu erheblichen Veränderungen im gemessenen Reflexionsgrad der Oberfläche in Abhängigkeit von den solaren Beleuchtung- und Blickrichtungsgeometrien führen. Zielstellung dieser Arbeit ist die hyperspektrale und spektro-direktionale Charakterisierung der Oberflächenreflexion wichtiger und repräsentativer arktischer Pflanzengesellschaften in Sibirien und Alaska, als Grundlage für die Extraktion von Vegetationsparametern und die Normalisierung von BRDF-Effekten in Off-Nadir und multi-temporalen Fernerkundungsdaten. In Vorbereitung auf die bevorstehende nationale EnMAP Satellitenmission ist ein Grundverständnis der BRDF-Effekte in der arktischen Tundra von wesentlicher Bedeutung für die Erstellung von hochqualitativen, konsistenten und damit vergleichbaren Datensätzen. Die in dieser Arbeit genutzten Daten beruhen auf geländespektroskopische und geländespektro-goniometrische Untersuchungen von repräsentativen Messflächen in Sibirien und Alaska. Die Entwicklung eines leichten, transportablen und einfach anzuwendenden Geländespektro-Goniometers, welches dennoch zuverlässig Daten liefert, war die erste Aufgabe. Hierfür habe ich ein Gerät mit der Bezeichnung ManTIS („Manual Transportable Instrument platform for ground-based Spectro-directional observations“) entwickelt. Die Ergebnisse der geländespektro-radiometrischen Messungen entlang wichtiger ökologischer Gradienten (regionales Klima, pH-Wert des Bodens, Bodenfeuchte, Toposequenz) zeigen, dass die Pflanzengesellschaften sich anhand ihrer Nadir-Reflektanzen unterscheiden lassen. Insbesondere die Möglichkeit der Differenzierung im sichtbaren (VIS) blauen und roten Wellenlängenbereich. Die Nah-Infrarot (NIR) Schulter und das NIR-Reflektanzplateau sind trotz ihrer niedrigeren Reflektanzwerte eine wertvolle Informationsquelle, die genutzt werden kann um die Pflanzengesellschaften entsprechend ihrer Biomasse und der Vegetationsstruktur voneinander zu unterscheiden. Im Allgemeinen zeigen die verschiedenen Pflanzengesellschaften der Tundra: (i) eine niedrige maximale NIR-Reflektanz; (ii) ein schwaches oder nicht sichtbares lokales Reflektanzmaximum im grünen VIS-Spektrum; (iii) einen schmalen „red-edge“ Bereich zwischen dem roten und NIR-Wellenlängenbereich und (iv) kein deutliches NIR-Reflektanzplateau. Diese gemeinsamen Nadir-Reflektanzeigenschaften sind entscheidend für das Verständnis der Variabilität der BRDF-Effekte in der arktischen Tundra. Keine der untersuchten Pflanzengesellschaften wies isotrope Reflektanzeigenschaften auf. Im Allgemeinen zeigt Tundravegetation: (i) die höchsten BRDF-Effekte in der solaren Hauptebene; (ii) die maximalen Reflexionsgrade in den rückwärts gerichteten Blickrichtungen; (iii) höhere Grade an Anisotropie im VIS-Spektrum als im NIR-Spektrum und (iv) schüsselförmige Reflexionsgradverteilungen in den längeren Wellenlängenbereichen (>700 nm). Die Analyse des Einflusses von hohen Sonnenzenitwinkeln auf die Anisotropie der Rückstrahlung zeigt, dass sich mit zunehmenden Sonnenzenitwinkeln die Anisotropie-Eigenschaften in azimutal-symmetrische schüsselförmige Reflexionsgradverteilungen ändern. Auch ergeben die spektro-direktionalen Analysen, dass Fernerkundungsprodukte wie der NDVI oder die relative Absorptionstiefe stark von BRDF-Effekten beeinflusst werden. Die anisotropen Eigenschaften der Fernerkundungsprodukte können sich erheblich von den beobachteten BRDF-Effekten in den ursprünglichen Reflektanzdaten unterscheiden. Auch lässt sich aus den Ergebnissen ableiten, dass der NDVI relativ gesehen die blickrichtungsabhängigen BRDF-Effekte minimieren kann. Für die untersuchten Pflanzengesellschaften der Tundra weichen die Off-Nadir NDVI-Werte nie mehr als 10 % von den Nadir-NDVI-Werten ab. Im Resümee dieser Studie wird nachgewiesen, dass Änderungen in der Sonnen-Objekt-Sensor-Geometrie direkt zu Reflektanzveränderungen in den Fernerkundungsdaten von arktischen Pflanzengesellschaften der Tundra entsprechend ihrer objekt-spezifischen BRDF-Charakteristiken führen. Da die verschiedenen Arten der Tundravegetation nur kleine, aber signifikante Unterschiede in der Oberflächenreflektanz zeigen, ist es wichtig die spektro-direktionalen Reflexionseigenschaften bei der Entwicklung von Algorithmen für Fernerkundungsprodukte zu berücksichtigen.

Polymer pipes, typically high density polyethylene (HDPE), can be pulled-into-place, avoiding traditional cut-and-cover construction, using pipe bursting and horizontal directional drilling (HDD) pipe installation techniques. Of particular interest, are the ground displacements, induced by cavity expansion, associated with these techniques and the strains that develop in existing pipes in response to these displacements. Further, the axial stress-strain response of the new HDPE pipe during and after the cyclic pulling force history required to pull the pipe into place is of interest. Surface displacements and strains in an adjacent polyvinyl chloride (PVC) pipe induced by static pipe bursting were measured during the replacement of a new unreinforced concrete pipe. For the pipe bursting geometry tested, the maximum vertical surface displacement measured at the ground surface was 6 mm, while the distribution of vertical surface displacements extended no more than 2 m on either side of the centreline. The maximum longitudinal strain measured in the PVC pipe was less than 0.1% and its vertical diameter decreased by only 0.5%, suggesting that pipe bursting did not jeopardize the long-term performance of the water pipe tested. In addition, results from identical stress relaxation and creep tests performed on whole pipe samples and coupons trimmed from a pipe wall were compared, and these demonstrated that the coupons exhibited higher modulus than the pipe samples. Therefore, isolated pipe samples, as opposed to coupons, were tested to quantify the stress-strain response of HDPE pipe during the simulated installation, strain recovery, and axial restraint stages of HDD. Axial strains were found to progressively accumulate when an HDPE pipe sample was subjected to the cyclic stress history used to simulate an HDD installation. It was shown that existing linear and nonlinear viscoelastic models can serve as predictive design tools for estimating the cyclic strain history of HDPE pipe during installation. For the specific conditions examined, the tensile axial stresses redeveloped in the pipe samples, once restrained, were not large enough to lead to long-term stress conditions conducive to slow crack growth even when the short-term performance limits were exceeded by a factor of 1.5. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2009-04-01 18:19:24.434