Estimation of the ground motion parameters is extremely important for engineers to make the structures safer and more economical, so it is one of the main issues of Earthquake Engineering. Peak values of the ground motions obtained either from existing records or with the help of attenuation relationships, have been used as a useful parameter to estimate the effect of an earthquake on a specific location. Peak Ground Velocities (PGV) of a ground motion is used extensively in the recent years as a measure of intensity and as the primary source of energy-related analysis of structures. Consequently, PGV values are used to construct emergency response systems like Shake Maps or to determine the deformation demands of structures. Despite the importance of the earthquakes for Turkey, there is a lack of suitable attenuation relationships for velocity developed specifically for the country. The aim of this study is to address this deficiency by developing an attenuation relationship for the Peak Ground Velocities of the chosen database based on the strong ground motion records of Turkey. A database is processed with the established techniques and corrected database for the chosen ground motions is formed. Five different forms of equations that were used in the previous studies are selected to be used as models and by using nonlinear regression analysis, best fitted mathematical relation for attenuation is obtained. The result of this study can be used as an effective tool for seismic hazard assessment studies for Turkey. Besides, being a by-product of this study, a corrected database of strong ground motion recordings of Turkey may prone to be a valuable source for the future researchers.

The most prevalent method for the prevention of freeze-thaw and salt scaling damage in cement based materials is through the entrainment of air voids using air entraining chemical admixtures (AEA's). However, the common field methods for measuring air content in fresh concrete cannot distinguish between entrained and entrapped air voids, and the actual air content in the hardened concrete can vary from that determined by these tests due to a variety of factors such as workability, placing operations, consolidation efforts, and environmental conditions. Previous research has shown the ability of ultrasonic attenuation to distinguish between entrained and entrapped air voids in hardened cement paste, providing a foundation for an inversion procedure to calculate the size and volume content of the two scatterer sizes. While additional challenges are present with measurements in fresh paste, the use of an immersion setup can overcome the limitations of cement paste containment vessels and provide a means to measure air content from batching to placement. An immersion apparatus to monitor ultrasonic wave attributes including attenuation in fresh cement paste is designed and built. Results comparing air entrained and non-air entrained cement pastes are presented. Ultrasonic wave attributes are studied as a function of time and level of chemical air entrainer. Finally, recommendations are made to improve the accuracy of the immersion apparatus in order to develop an in situ, quality control procedure to quantify the air content of fresh cement paste from batching to placement.

Die Charakterisierung von Nanopartikeln erfordert eine Messung des Dispersitätszustandes bei allen Schritten der Herstellung - von der Synthese bis zum fertigen Produkt. Dafür ist eine leistungsfähige Partikelmesstechnik notwendig, deren Methoden bei der Beschreibung des komplexen Materialverhaltens helfen können. Die Ultraschalldämpfungsspektroskopie ist eine Messmethode, die zur prozessbegleitenden Charakterisierung hochdisperser Pulver und Suspensionen geeignet ist. Mit Vergleichen von Messungen und Modellrechungen wurde festgestellt, dass für die Ultraschalldämpfungs-Modellierung in Dispersionen homogener Partikel ein auf dem Phänomen der elastischen Streuung basierendes Modell praktisch relevant ist. Dies betrifft sowohl die Anwendung zur Messung in Suspensionen als auch in Emulsionen homogener Partikel. Bei einem Vergleich von Modellrechungen und Messungen für ein System poröser Partikel bzw. Aggregate wurde das Modell der Streuung an poroelastischen Kugeln als geeignet zur Beschreibung der Dämpfung disperser Systeme identifiziert. Bei Vorhandensein grober Partikel in Suspensionen nanoskaliger Systeme ist somit eine korrekte Auswertung der Partikelgröße möglich; der bislang übliche Messbereich wurde erweitert. Sekundärer Schwerpunkt der Arbeit ist die Diskussion der numerischen Modellanwendung. Es werden weiterhin Lösungsmöglichkeiten zur Dämpfungsberechnung und zur Berechnung der Größenverteilungen beschrieben. Des Weiteren wurden Anregungen für Entwickler von Ultraschallspektrometern abgeleitet.

<p>The purpose of this thesis is to investigate an alternative control strategy for a multi-variate non-linear process in a paper machine called the headbox. The proposed solution was intended to be able to be adopted on two different headbox types, currently controlled by different concepts. </p><p>The methodology was to first create black-box models of the two different systems based on measurements, at one working point. Secondly, various control strategies were investigated. A more sophisticated multi-input multi-output controller MPC, or model predictive control, and a less sophisticated one, a single-input single-output, decentralised PI-controller. With help of simulations the performances of the both strategies were tested. Finally, only the decentralised control solution was implemented and evaluated through trial runs on a pilot machine. </p><p>The main issue regarding the decentralised controller was the input-ouput pairing. Since the multi-variate system had four outputs and only three inputs, analysis had to be made in order to select three of those four, to form a square system. This analysis was based on the relative gain array (RGA). </p><p>The resulting performance of the decentralised controller showed stability and adequate response times, surpassing the older system and making one component obsolete through the pairing changes. The MPC controller showed even better performance during simulations and shall also be taken into account if further investigatin is possible.</p>

<p>Free Space Optics (FSO) has received a great deal of attention lately both in the military and civilian information society due to its potentially high capacity, rapid deployment, portability and high security from deception and jamming. The main issue is that severe weather can have a detrimental impact on the performance, which may result in an inadequate availability. </p><p>This report contains a feasibility study for an all-optical free-space link intended for short-range communication (200-500 m). Laboratory tests have been performed to evaluate the link design. Field tests were made to investigate availability and error performance under the influence of different weather conditions. Atmospheric impact due to turbulence related effects have been studied in detail. The most crucial part of the link design turned out to be the receiver optics and several design solutions were investigated. The main advantage of an all-optical design, compared to commercially available electrooptical FSO-systems, is the potentially lower cost.</p>

Over one million acres of land and water in Florida has been classified as impaired by mercury. Approximately 80% of national fish advisories are issued due to mercury contamination. There have been a number of consumption advisories in the Tampa Bay Region for locally eaten fish such as largemouth bass ( Micropterus salmoides), bowfin (Amia calva), and alligator gar (Lepisosteus osseus). The main purpose of this study was to determine if there is adequate dissemination of mercury related risk information by government agencies to recreational and subsistence fishermen in the Tampa Bay Region. This research revealed that government agencies utilized simplified models when addressing mercury consumption risks in Tampa Bay. Most of the popular fishing sites and public parks in the Tampa Bay Region have no advisory signs warning fishers of possible mercury contamination in fish. The majority of survey respondents (88.4%) consumed the fish they caught. There was statistically significant evidence suggesting online sources of public health information influenced viewing of fish advisories. This study determined factors: sex of licensee, above median levels of income and type of license also influenced viewing of fish advisories. Results indicated that women were less likely to view fish advisories than men. In addition, the viewing of fish advisory information by women of reproductive age was not significantly different to all other female age groups. Behavior among participants varied and was dependent on individual perception of mercury risks and nutritional benefits associated with consumption of fish.

Consumers in marine and estuarine environments have a strong reliance on planktonic and benthic primary production. These two basal resources form the foundation of aquatic food webs, yet the abundance of phytoplankton and benthic algae are frequently inversely related due to competition for light and nutrients. As a result, optimal habitats for benthic and planktonic consumers vary spatially and temporally. To investigate these trends, three studies were conducted focusing on light attenuation and basal resources in a bay, river, and on a continental shelf. δ13C and δ15N stable isotopes can be used as endogenous tracers to determine both the trophic level and basal resource use of consumers. δ13C values of primary producers are determined by the isotopic values of available CO2 and by the degree of photosynthetic fractionation (εp) that occurs during photosynthesis. εp by aquatic algae is greater in high CO2concentrations, high light, during slow growth rates, and for cells with a small surface area to volume ratio. Interaction among these parameters complicates prediction of algal εp in a natural setting, prompting the investigation as to which factors would impact εp and δ13C in a dynamic estuary. Community-level fractionation of an assemblage of filamentous algae, pennate diatoms, and centric diatoms grown on glass plates was found to be positively correlated with photosynthetically active radiation (PAR), resulting in higher δ13C values for organic matter in low-light conditions. These results support the concept that the low-light benthic environment may contribute to the widely observed phenomenon of ~5 / higher δ13C values in benthic algae compared to phytoplankton. Spatial and temporal variability in the isotopic baseline provides evidence of shifting biogeochemical controls on primary production. The West Florida Shelf in the eastern Gulf of Mexico transitions from a eutrophic ecosystem near the Mississippi River to an oligotrophic ecosystem in offshore continental shelf waters. Spatiotemporal variability in the δ13C and δ15N signatures of primary producers and fish populations were examined along this gradient. Muscle δ15N from three widely distributed fish species exhibited strong longitudinal isotopic gradients that coincided with the principal trophic gradient, whereas δ13C values of fish muscle and benthic algae were correlated with depth. The three fish species had relatively high site fidelity, as isotopic gradients were consistent between seasons and years. Isotopic mixing models showed all three fish species had a significant reliance on benthic algae as a basal resource. Dynamic models of the West Florida Shelf isotopic baseline were created using spatial data and satellite-derived water quality characteristics as predictors. Models were constructed using data from three fish species and tested on four other species to determine if the models could be extrapolated to new taxa. Both dynamic and static δ15N models had similar predictive capabilities, indicating a fairly stable δ15N baseline. The satellite-derived dynamic variables explained more variation in baseline δ13C than static spatial descriptors. Planktonic primary production can directly impact benthic food chains through phytoplankton deposition. A novel phytoplankton deposition detection method that combined water-column and benthic fluorometry with surficial sediment sampling was developed and assessed in a two-year study of the Caloosahatchee River estuary. Classifications based upon this detection method showed phytoplankton deposition dominated the upstream region and deposition was associated with reduced dissolved oxygen concentrations. Benthic algae dominated in downstream regions, particularly during low freshwater flow conditions when light absorption by colored dissolved organic matter was low. This same Caloosahatchee River estuary study was used to determine if zooplankton aggregate in regions with optimal basal resource availability. The isopod Edotia triloba was found to associate with chlorophyll peaks when freshwater velocity was constant. Chlorophyll peaks were offset downstream or upstream from isopod aggregations when freshwater flow was accelerating or decelerating, implying that phytoplankton and isopods have different response times to changes in flow. Temporal and spatial fluctuations in water quality and primary production introduce instability to aquatic consumers that primarily rely on one basal resource. The current global trends in eutrophication and increasing planktonic production are likely to be a liability for benthic consumers due to increased benthic hypoxia and light attenuation. The results of these studies indicate that both the location of consumers and their isotopic signatures can be impacted by factors, such as light attenuation, that control benthic and planktonic primary production.

The propagation of acoustic waves through water-saturated granular sediments has been widely studied, yet existing propagation models can not adequately predict the speed and attenuation of sound across the range of frequencies of interest in underwater acoustics, especially in loosely packed sediments that have been recently disturbed by storms or wave action. Advances in modeling are currently dependent on experimental validation of various components of existing models. To begin to address these deficiencies, three well-controlled laboratory experiments were performed in gravity-settled glass beads and reconstituted sand sediments. Sound speed and attenuation measurements in the 0.5 kHz to 10 kHz range are scarce in the literature, so a resonator method was used to investigate a reconstituted sand sediment in this range. The literature contains laboratory and in situ measurements of sound speed and attenuation at higher frequencies, but existing models can not predict both the speed of sound and attenuation simultaneously in some sediments. A time-of-flight technique was used to determine the speed of sound and attenuation in monodisperse water-saturated glass beads, binary glass bead mixtures, and reconstituted sediment samples in the frequency range 200 kHz to 900 kHz to investigate the effect of sediment inhomogeneity. The effect of porosity, independent of changes in other sediment physical properties, has not been demonstrated in the experimental literature. Therefore, a fluidized bed technique was used to independently vary the porosity of monodisperse glass bead samples from 0.37 to 0.43 and a Fourier phase technique was used to determine the speed and attenuation of sound. Collecting these results together, measured sound speeds showed positive dispersion below 50 kHz while negative dispersion was observed above 200 kHz for some samples. Attenuation measurements showed an approximately f⁰̇⁵ dependence in the low frequency regime and an approximately f³̇⁵ dependence for large-grained samples in the high frequency regime. The laboratory experiments presented in this work demonstrate that both sound speed and attenuation in idealized loosely packed water-saturated sediments can not be simultaneously predicted by existing models within the uncertainties of the model input parameters, but the independent effect of porosity on sound speed can be predicted. / text

Long range stand-off Raman and Laser-Induced Breakdown Spectroscopy (LIBS) lidar signal simulations have been carried out using a modified UV-visible atmospheric transmission program and a modified lidar equation. The Hitran-PC atmospheric transmission program which normally operates over the wavelength range of 400 nm to the far-IR was modified to provide UV atmospheric attenuation (200 nm -- 400 nm) using the optical cross section data contained in the HITRAN database. The two-way lidar equation was modified in order to simulate the one-way propagation of the Raman and LIBS spectral, and thus provide calculations of the expected Raman or LIBS signal as a function of range. Estimation of the LIBS and Raman spectral intensity was then calculated for several remote sensing cases. In particular, the atmospheric attenuation spectra generated with the modified Hitran-PC program were combined with the calculated LIBS and Raman lidar emission spectra at the remote excitation site using a modified lidar equation to determine for the first time to our knowledge the power and S/N ratio versus range of the LIBS and Raman Lidar complete spectrum as a function of wavelength in the UV -- IR region. Previous simulations had only made S/N versus range calculations at a single wavelength or for the total integrated emission. These results are important as they can be used for future design of stand-off LIBS and Raman lidar systems, and for comparisons with experimental measurements. In particular, we are planning to use our simulations for comparison of 266 nm excited LIBS and Raman lidar measurements of energetic compounds at ranges of a few tens of meters.

The decline of coral reef habitats has been witnessed on a global scale, with some of the most dramatic decline occurring in the florida keys. as remote sensing can provide a synoptic view of coral reef ecosystems, 28 landsat images (1984-2002) were utilized to study water clarity and habitat change. first, the data were used to derive the diffuse attenuation coefficient (kd, m-1), a measure of water clarity, for 29 sites throughout the florida keys national marine sanctuary (fknms). landsat-derived kd values from bands 1 (blue) and 2 (green) provided useful information for 26 of 29 sites, whereas band 3 (red) provided no consistent data due to the high absorption of red light by water. it was not possible to assess long-term temporal trends as data were acquired, at most, twice a year. spatial variability was high between sites and between regions (upper, middle and lower keys) for bands 1 (0.019 m-1 - 0.060 m-1) and 2 (0.036 m-1 - 0.076 m-1). the highest kd values were f ound in the upper keys, followed by the middle and lower keys, respectively. this trend was corroborated by in situ monitoring of kd(par). second, the data were used to assess benthic habitat changes in eight coral reef sites located in the fknms. a mahalanobis distance classification was trained for four classes using in situ ground-truth data. overall coral habitat decline was 61% (3.4%/y), from 19% (1984) to 7.7% (2002). in situ monitoring data acquired by the coral reef evaluation and monitoring project (cremp) for the eight reef sites (1996-2002) showed a loss in coral cover of 52%, whereas the landsat-derived coral-habitat cover declined 37% for the same time period. a trend comparison between the full cremp percent coral cover data (1996-2004) and the full landsat-derived coral habitat class (1984-2002) showed no significant difference between the rates of change (ancova f-test, p = 0.303). The derivation of Kd and benthic habitat maps produced from Landsat data could provide c oastal marine managers another tool to help in the decision-making process.