This research was carried out in support of fieldwork in the Gulf of Mexico in summers 2004 and 2005 as part of the multidisciplinary Sperm Whale Seismic Study (SWSS). Important aspects of SWSS research include oceanographic habitat characterization and studies of sperm whale foraging and diving patterns. During the SWSS 2005 cruise, acoustic volume backscatter data were collected using a 38 kHz ADCP for comparison with XBT, MODIS ocean color data, and whale dive profiles extrapolated from analysis of towed passive acoustic hydrophone array recordings of whale vocalizations. This unique data set, collected from a cyclonic eddy, was compared with non-upwelling conditions surveyed in the western Gulf and the Mississippi Canyon in summer 2004. My focus was to examine the relationship between acoustic backscatter intensity from the deep scattering layer (DSL; usually 400-600 m deep) and the depths to which whales dived. The results of the study investigate differences in DSL characteristics between divergent zones and non-divergent zones, and examine connections relating to variations in sperm whale dive patterns. The analysis of 38 kHz ADCP data showed that there were significant differences in some characteristics of the main DSL dependent on time of day. There were no significant differences in characteristics of the main DSL between divergent and non-divergent areas or between 2004 and 2005. The comparison of the 38 kHz ADCP and the 70 kHz Simrad echosounder data yielded a relationship of 4 ADCP counts for every 1 dB of Sv. This relationship was a promising start to a potential calibration for the ADCP instrument. Lastly, the analysis of localized sperm whale dive profiles identified three basic dive profiles; Deep (> 800 m), Mid-water dives to DSL depths (500 - 800 m) and Shallow (<500 m). The analysis also showed that whale dive behavior did not change based on time of day or location. It showed that whales are diving above the DSL as well as through and below, however these dives are independent of differences in DSL characteristics.

Wireless network analysis and simulations rely on accurate physical layer models. The increased interest in wireless network design and cross-layer design require an accurate and efficient physical layer model especially when a large number of nodes are to be studied and building the real network is not possible. For analysis of upper layer characteristics, a simplified physical layer model has to be chosen to model the physical layer. In this dissertation, the widely used two-state Markov model is examined and shown to be deficient for low to moderate signal-to-noise ratios. The physical layer statistics are investigated, and the run length distributions of the good and bad frames are demonstrated to be the key statistics for accurate physical layer modeling. A four-state Markov model is proposed for the flat Rayleigh fading channel by approximating the run length distributions with a mixture of exponential distributions. The transition probabilities in the four-state Markov model can be established analytically without having to run extensive physical layer simulations, which are required for the two-state Markov model. Physical layer good and bad run length distributions are compared and it is shown that the four-state Markov model reasonably approximates the run length distributions. Ns2 simulations are performed and the four-state Markov model provides a much more realistic approximation compared to the popular two-state Markov model. Achieving good results with the flat Rayleigh fading channel, the proposed four-state Markov model is applied to a few diversity channels. A coded orthogonal fre- quency division multiplexing (OFDM) system with a frequency selective channel and the Alamouti multiple-input multiple-output system are chosen to verify the accuracy of the four-state Markov model. The network simulation results show that the four-state Markov model approximates the physical layer with diversity channel well whereas the traditional two-state Markov model estimates the network throughput poorly. The success of adapting the four-state Markov model to the diversity channel also shows the flexibility of adapting the four-state Markov model to various channel conditions.

Two mechanisms appear to be primarily responsible for the formation of cirrus clouds in Tropical Tropopause Layer (TTL): detrainment from deep convective anvils and in situ initiation. Here we propose to identify TTL cirrus clouds by analyzing water content measurements from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Aura Microwave Limb Sounder (MLS). Using ice water content (IWC) and water vapor (H2O) abundances we identify TTL cirrus clouds that contain too much ice to have been formed in situ — and therefore must be of convective origin. We use two methods to infer amounts of water vapor available for in situ formation. Clouds with IWC greater than this threshold are categorized as being of convective origin; clouds with IWC below the threshold are ambiguous — they could either form from in situ or still be of convective origin. Applying the thresholds from December 2008 to November 2009, we found that at least 19.2% of tropical cirrus were definitively of convective origin at the tropopause (375 K) during boreal winter. At each level, we found three maxima in the occurrence of convective cirrus: western Pacific, equatorial Africa, and South America. Averaged over the entire tropics (30oS to 30oN), we found convective cirrus occurs more frequently in boreal winter and less frequently in boreal summer, basically following the a decreasing trend from DJF, MAM, SON, to JJA. During boreal summer, we found that only 4.6% of tropical cirrus come from convection. Sensitivity tests show that the thresholds derived at 390 K have the largest uncertainty. At lower levels, especially 375 K, our thresholds are robust.

In recent times, there has been an increased focus on the problem of information exchange between two nodes using a relay node. The introduction of physical layer network coding has improved the throughput efficiency of such an exchange. In practice, the reliability of information exchange using this scheme is reduced due to synchronization issues at the relay node. In this thesis, we deal with timing synchronization of the signals received at the relay node. The timing offsets of the signals received at the relay node are computed based on the propagation delays in the transmitted signals. However, due to the random attenuation of signals in a fading channel, the near far problem is inherent in this situation. Hence, we aim to design near far resistant delay estimators for this system. We put forth four algorithms in this regard. In all the algorithms, propagation delay of each signal is estimated using a known preamble sent by the respective node at the beginning of the data packet. In the first algorithm, we carefully construct the preamble of each data packet and apply the MUSIC algorithm to overcome the near far problem. The eigenstructure of the correlation matrix is exploited to estimate propagation delay. Secondly, the idea of interference cancellation is implemented to remove the near far problem and delay is estimated using a correlator. Thirdly, a modified decorrelating technique is presented to negate the near far problem. Using this technique we aim to obtain an estimate of the weak user's delay that is more robust to errors in the strong user's delay estimate. In the last algorithm, pilot signals with desired autocorrelation and cross correlation functions are designed and a sliding correlator is used to estimate delay. Even though this approach is not near far resistant, performance results demonstrate that for the length's of preamble considered, this algorithm performs similar to the other algorithms.

The surface phenemona in polishing process induced by nano-particle was studied in this thesis. The properties of particle, rigidity and geometry, are forced. A perfect polished surface includes lower roughness and thinner damage layer. Besides a perfect surface, how we get higher rate of remove is also an important thing. The goal is to get the relation between induced surface phenomena and properities of nano-particle. The M.D. (Molecular Dynamic) simulation is uesed in this thesis. The specicaly lowered integral timestep is second for simulating the rigidity of nano-particle with saving simulation time and geting accurate in simulation results. In order to simuate the nano-particle rigidity and adhesive effects between nanoparticle and work surface, the modified potential function is used. Considering the types of nano-particle motion which are pure rolling and sliding, the different geometric shapes are used . In the results of simulation about the rigidity of particles, the phenomena induced by rolling particles and rigidity don¡¦t have apparent correlation. For sliding particles, the lower rigidity and lower thick damage layer was. However, if the rigidity is too weak to hold the particle geometric shape, the damage layer thickness is larger. In the results of simulation about particle shapes, the sliding particle with larger front angle will indcue deeper damager layer. It¡¦s because the more workpiece atoms could move to the bottom or rear of the particles to make more damaged atoms. If the length of particle bottom be increased, the interactive behavior between particle and work surface would become more violently to make deeper damaged layer. The rolling particle with scraggy surface can cohere more atoms than the ball particle even in the lower adhesive coefficient, but induced roughness will be higher .

Abstract High quality epitaxial growth of undoped ZnSe, ZnSxSe1-x and ZnSe-ZnS strained quantum well structures were successfully grown on n-type (100)-oriented silicon substrates at 150 &#x00BA;C in a horizontal cold-wall quartz reactor by low-pressure metalorganic atomic layer epitaxy (MOALE) at a pressure of 30 Torr for the first time. Dimethylzinc [Zn(CH3)2, DMZn], hydrogen selenide (H2Se) and hydrogen sulfur (H2S) were used as the reactants. ALE is a suitable technique for the growth of ultra thin semiconductors because it provides accuracy monolayer control of the deposited film thickness, low growth temperature and uniform growth over a large area by its¡§ self-limiting mechanism ¡¨via supplying source materials in a flow pulse sequences alternatively over the substrate. Idea one monolayer per cycle was obtained in wide range of parameters such as substrate temperatures, mole flow rate and pulse duration of reactants. From X-ray diffraction pattern, (400)-oriental single crystal epilayers of ZnSe are evidenced. The surface morphologies of ZnSe in the ALE temperature region 150 - 200 ¢J, extensively smooth and mirror-like surface were obtained. PL spectra of ZnSe epilayer is dominated by the strong near-band-edge at 2.8 eV with FWHM of 36 meV. Schottky diodes were fabricated from the undoped ZnSe layer and the electrical properties were measured at room temperature. From the current-voltage (I-V) characteristics, a high reverse breakdown voltage (>40 V) and an excellent low cut-in voltage of 0.6 - 0.8 V were obtained. On the basis of the observed ZnSe/Si epitaxial film properties, the material is suitable for fabrication of ZnSe-based blue light emitting diodes and for application in direct-current thin-film electroluminescence. The lattice of the ZnSxSe1-x layer with a sulfur content around 93% was found to have the best match to the Si substrate, as confirmed by the good layer thickness, uniformity, surface morphology and narrow linewidth of the X-ray diffraction rocking curve with a minimal FWHM of about 0.16 degree. In addition, strong near-band-edge and weak deep-level emissions in the longer wavelength region dominate PL spectra of the ZnS0.93Se0.07 epilayer at 300K. With respect to Schottky diodes, Au/n-ZnS0.93Se0.07/Al, has a high breakdown voltage, over 40 V at 400 nA and a low cut-in voltage of 0.68 V. The highest Hall mobility of the ZnS0.93Se0.07 is 347 cm2/v-sec. These results indicate a good lattice-match of ZnS0.93Se0.07/Si as a result of low numbers of interface and epitaxial layer defects. The lower temperature of ZnSe-ZnS strained quantum well structures, 150 &#x00BA;C would be lowed enough to eliminate 3-D growth related to the lattice mismatch between ZnSe and ZnS. A good epitaxy and crystallinity was carried out by X-ray diffraction. The formation of the strained quantum well structure is evident from the periodic behavior of each fluctuation profile by SIMS. At least 25 periodic thickness of the ALE growth samples shows a strong blue emissions and nearly neglects the deep-level emission at room temperature. The phenomenon of quantum size effects and the ¡§ blue-shift ¡¨ was evidenced as the well width increases. The results of the PL measurements were found to correlate well with the theoretical one, parabolic well-strain mode. Schottky diodes were fabricated from the Au/ZnSe-ZnS SMQW/n-Si/Al, a high reverse breakdown voltage over 40 (at 20 &#x00B5;A) and an extremely low cut-in voltage of 80 - 120 mV were obtained. The I-V characteristics of the heterojunction are more suitable for the fabrication of the direct-current thin film electroluminescent (EL) device.

Vibrations of small cylinder in a jet flow are investigated experimentally. Because of the flow field in shear layers of jet flow is very complex and filled with vortex structures, so the flow induced vibration phenomena in jet flow is different from the flow induced vibration in uniform flow. The major subject in this experiment is to discuss the major cause of small cylinder vibrations, and the flow field influenced by the cylinder vibration. About flow measurement, velocity measurement by hot-wire is applied. As for the vibration measurement, by using the principle of electromagnetic, a new measurement technology was successfully developed. This new vibration measurement can measure the vibrations in two axial, so as to describe the orbit of vibrations. To find the interrelation of flow field and cylinder vibrations, flow measurement and vibration measurement was carry on at the same time. It is shown that when the jet velocity is increased constantly, small cylinder will vibration intensely. The fixed velocity is called critical velocity. If add a perturb, the vibration will occur in advance. The dominant frequency of cylinder vibration, fr, will be the same with it's nature frequency, fn, in the critical velocity, but when the flow velocity keep on increasing, the dominant frequency, fr, will also increase. Besides, the relation of reduced velocity and mass damping was found in this case. The orbits of vibrations are all like ellipse, and the orbit is different with different reduced velocity. The vibration amplitude be changed into three sections that have different reduced velocity, and different orbit. About the flow field, the velocity profile in potential core is not influenced by vibrations of small cylinder, but the velocity fluctuations in shear layer indeed be inflected. At the fixed velocity region, the dominant frequency of flow is the same with dominant frequency of vibrations when the flow at downstream of small cylinder in shear layer. This phenomena only exist when the vibration amplitude under the fixed range.

We proposes an efficient algorithm for extracting SPICE-compatible circuits of embedded interconnect structures from FDTD-simulated time-domain reflections. A layer-peeling technique (LPT) is used to obtain the time-domain step response of the interconnects under extract (IUE) itself. A pencil matrix method is then used to get the pole-residue representation of the time-domain step response of the IUE. A pole-reducing procedure is implemented based on a bandwidth criterion to simplify pole-residue representation. Finally, the lumped equivalent models of the IUE are synthesized by an equivalent lumped-model extraction technique, in which four types of equivalent model bases are used. The equivalent circuit can be easily implemented in SPICE-like simulator. Several transmission line structures are presented as examples to demonstrate the validity of the proposed algorithm both in time and frequency domains.

Atomic Layer Epitaxy is a stepwise deposition process by supplying the sources materials alternatively. This deposition technique provides the monolayer control of film thickness and the uniform film growth over a large area. ZnSxSe1-x layers were grown epitaxially onto Si and GaAs substrate by using DMZn and H2S , H2Se gases for the reactant source. Owing to the self-limiting characteristics of ALE process, ZnSxSe1-x monolayers could be deposited over a wide range of temperature within growth window. In this study, for obtaining high crystalline quality ZnSxSe1-x epitaxial films, various growth conditions were investigated including substrate temperature, the flow rate of DMZn, H2S and H2Se, H2 purge duration and pulse duration etc.. A thermodynamic analysis based the calculation of Seki et. al [6], was used to investigate the effects by varying the substrate temperature, input mole ratio of group VI source gases on equilibrium partial pressure, solid composition and solid-vapor distribution relation of this alloy. The interaction parameter of ZnSxSe1-x, £[, was estimated by using the delta-lattice parameter (DLP) model suggested by Stringfellow [39]. Finally, it shows that the thermodynamic analysis provides a useful guideline for the growth of ZnSxSe1-x alloy on Si and GaAs substrates.

The Unidata Program Center is an organization working with the University Center for Atmospheric Research (UCAR), in Colorado. It provides a broad variety of meteorological data, which is used by researchers in many real-world applications. This data is obtained from observation stations and distributed to various universities worldwide, using Unidata’s own Internet Data Distribution (IDD) system, and software called the Local Data Manager (LDM). The existing solution for data distribution has many limitations, like high end-toend latency of data delivery, increased bandwidth usage at some nodes, poor scalability for future needs and manual intervention for adjusting to changes or faults in the network topology. Since the data is used in so many applications, the impact of these limitations is often substantial. This thesis removes these limitations by suggesting improvements in the IDD system and the LDM. We present new algorithms for constructing an application-layer data distribution network. This distribution network will form the basis of the improved LDM and the IDD system, and will remove most of the limitations given above. Finally, we perform simulations and show that our algorithms achieve better average end-to-end latency as compared to that of the existing solution. We also compare the performance of our algorithms with a randomized solution. We find that for smaller topologies (where the number of nodes in the system are less than 38) the randomized solution constructs efficient distribution networks. However, if the number of nodes in the system increases (more than 38), our solution constructs efficient distribution networks than the randomized solution. We also evaluate the performance of our algorithms as the number of nodes in the system increases and as the number of faults in the system increases. We find that even if the number of faults in the system increases, the average end-to-end latency decreases, thus showing that the distribution topology does not become inefficient.