Mono- and dinuclear chromiumtricarbonyl and manganesetricarbonyl complexes of dibenzo[a,e]cyclooctatetraene (DBCOT) were synthesized and characterized. In the bis(chromiumtricarbonyl)DBCOT synthesis, the main product was the syn,anti isomer where the two Cr(CO)3 moieties coordinate to opposite faces of the DBCOT backbone. This complex exhibits three dynamic processes in solution. A ring inversion of the organic skeleton occurs while the two chromiumtricarbonyl moieties undergo tripod rotation. This is the first study where eight-membered ring inversion is studied for a pi-coordinated metallic system. The rate of inversion at various temperatures was determined by 1H NMR line shape analysis at two different field strengths (300 and 600 MHz). Compared with other cyclooctatetraene compounds reported, there is a large positive entropy of activation and a relatively high enthalpy of activation in this system. DFT calculations, using the B3LYP/6-31G** basis set, were performed to gain a better understanding of the experimental results. It is proposed that free rotation of both Cr(CO)3 groups in the planar transition state are responsible for the large entropy of activation for ring inversion in hexahapto,hexahapto-dibenzo[a,e]cyclooctatetraene-syn,anti-bis(tricarbonylchromium). The relatively large enthalpy of activation is due to a stabilizing interaction between the endo carbonyl groups on the syn-Cr(CO)3 and the remote arene. In the monometallic DBCOT complexes, the metal can either be inside or outside the tub conformation. Interestingly, the crystal structures show opposite orientations for the isoelectronic chromium and manganese systems. The Cr(CO)3 group is positioned anti relative to the DBCOT backbone while the Mn(CO)3+ is syn. It should be noted that the optimized gas phase geometries obtained through DFT calculations agree with the crystallographic results. Electrochemical studies were performed to investigate the change in redox behavior associated with coordination of mono and bis-chromium units to the DBCOT backbone. Four new organometallic crystal structures are reported in this dissertation. Different tripod orientations, DBCOT backbone angles, and metal orientation relative to the interior of the organic skeleton are found. C-H...O, C-H...pi, and charge assisted C-H...F hydrogen bonding interactions were observed in the solid state packing. The structural motifs found suggest these complexes could serve as organometallic synthons in supramolecular chemistry.

The Lattrell-Dax method of nitrite-mediated substitution of carbohydrate triflates is an efficient method to generate structures of inverse configuration. In this study it has been demonstrated that a neighboring equatorial ester group plays a highly important role in this carbohydrate epimerization reaction, inducing the formation of inversion compounds in good yields. Based on this effect, efficient synthetic routes to a range of carbohydrate structures, notably β-D-mannosides and β-D-talosides, were designed. By use of the ester activation effect for neighboring groups, a double parallel as well as a double serial inversion strategy was developed. / QC 20101111

The ocean influences global weather patterns, stores and transports heat, and supports entire ecosystems. An area of interest is the relationship between the observed backscattered power received by a surface-based marine radar and the ocean surface topography. Current methods for obtaining surface elevation maps involve either in situ devices, which only provide point measurements, or an interferometric radar, which can be costly. During the late 1990's and early 2000's a radar was built at UMass, called the Focused Phased Array Imaging Radar II (FOPAIR II), and deployed at a several locations. A method is discussed to determine a transfer function between displacement and backscattered power for each of the range bins used by the radar and evaluate it's accuracy by applying the transfer function to separate data sets. In addition, it is known that horizontal polarized (H-Pol) backscatter exhibits a very different characteristic than vertical polarization (V-Pol). The horizontal polarization data exhibits less echo power except for intermittent bright spots, colloquially called “sea spikes'', that only briefly occur. Determining if there is correlation between these bright returns and a characteristic of the of the surface topography is investigated.

付記する学位プログラム名: 京都大学卓越大学院プログラム「先端光・電子デバイス創成学」 / 京都大学 / 新制・課程博士 / 博士(理学) / 甲第24401号 / 理博第4900号 / 新制||理||1700(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 川上 則雄, 教授 石田 憲二, 教授 田中 耕一郎 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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Seismic inversion is the leading method to map and quantify changes in time-lapse (4D) seismic datasets, with applications ranging from monitoring hydrocarbon-producing fields to geological CO2 storage. However, the process of inverting seismic data for reservoir properties is a notoriously ill-posed inverse problem due to the band-limited and noisy nature of seismic data. This comes with additional challenges for 4D applications, given the inaccuracies in the repeatability of time-lapse acquisition surveys. Consequently, adding prior information to the inversion process in the form of properly crafted regularization terms is essential to obtain geologically meaningful subsurface models and 4D effects. In this thesis, I propose a joint inversion-segmentation algorithm for 4D seismic inversion, which integrates total variation and segmentation priors as a way to counteract the missing frequencies and noise present in 4D seismic data. I validate the algorithm with synthetic and field seismic datasets and benchmark it against state-of-the-art 4D inversion techniques. The proposed algorithm shows three main advantages: 1. it produces high-resolution baseline and monitor acoustic impedance models, 2. by leveraging similarities between multiple seismic datasets, the proposed algorithm mitigates the non-repeatable noise and better highlights the real seismic time-lapse changes, and 3. it simultaneously provides a volumetric classification of the acoustic impedance 4D difference model based on user-defined classes, i.e., percentages of seismic time-lapse changes. Such advantages may enable more robust stratigraphic/structural and quantitative 4D seismic interpretation and provide more accurate inputs for dynamic reservoir simulations.

Op amps are among the most-used components in electronic design. Their performance is important and is often measured in terms of gain, bandwidth, power consumption, and chip area. Although BJT amplifiers can achieve high gains and bandwidths, they tend to consume a lot of power. CMOS amplifiers utilizing the strong inversion region alone use less power than BJT amplifiers, but generally have lower gains and bandwidths. When CMOS SPICE models were improved to accurately simulate all regions of inversion, researchers began to test the performance of amplifiers operating in the weak and moderate inversion regions. Previous work had dealt with exploring the parameters of composite cascode stages, including inversion coefficients. This thesis extends the work to include conventional cascode stages and presents an efficient method for exploring design parameters. A high-gain (137.7 dB), low power (4.347 µW) operational amplifier based on the conventional cascode stage is presented.

We propose an exact filtered backprojection algorithm for inversion of the cone beam data in the case when the trajectory is composed of a distorted circle and a line segment. The length of the scan is determined by the region of interest , and it is independent of the size of the object. With few geometric restrictions on the curve, we show that we have an exact reconstruction. Numerical experiments demonstrate good image quality.

The main objective of this thesis is to develop novel misfit functions for full-waveform inversion such that (a) the estimation of the long-wavelength model will less likely stagnate in spurious local minima and (b) the inversion is immune to wavelet inaccuracy. First, I investigate the pros and cons of misfit functions based on optimal transport theory to indicate the traveltime discrepancy for seismic data. Even though the mathematically well-defined optimal transport theory is robust to highlight the traveltime difference between two probability distributions, it becomes restricted as applied to seismic data mainly because the seismic data are not probability distribution functions. We then develop a misfit function combining the local cross-correlation and dynamic time warping. This combination enables the proposed misfit automatically identify arrivals associated with a phase shift. Numerical and field data examples demonstrate its robustness for early arrivals and limitations for later arrivals.%, which means that a proper pre-processing step is still required. Next, we introduce differentiable dynamic time warping distance as the misfit function highlighting the traveltime discrepancy without non-trivial human intervention. Compared to the conventional warping distance, the differentiable version retains the property of representing the traveltime difference; moreover, it can eliminate abrupt changes in the adjoint source, which helps full-waveform inversion converge to geologically relevant estimates. Finally, we develop a misfit function entitled the deconvolutional double-difference measurement. The new misfit measures the first difference by deconvolution rather than cross-correlation. We also present the derivation of the adjoint source with the new misfit function. Numerical examples and mathematical proof demonstrate that this modification makes full-waveform inversion with the deconvolutional double-difference measurement immune to wavelet inaccuracy.