Optimal rigid-body angular maneuvers are investigated, using restricted control moments—a problem inspired in the context of rotational maneuvers for <i>super-maneuverable</i> aircraft. Most of the analysis is based on the formulation with no direct control over the roll component of angular velocity. The present research effort is conducted in two phases. In the first phase, optimal control of angular <i>rates</i> is closely examined. The second phase deals with the problem of optimal <i>attitude</i> control. Optimal rigid-body angular <i>rate</i> control is first examined via an <i>approximate</i> dynamic model. The proposed model admits analytical solutions of the optimality conditions. The analysis reveals that over a large range of boundary conditions, there are, in general, <i>several</i> distinct extremal solutions. Second-order necessary conditions are investigated to establish local optimality of candidate minimizers. Global optimality of the extremal solutions is discussed. Next, the optimal angular <i>rate</i> problem is studied using the <i>exact</i> dynamic model. Numerical solutions of optimality conditions are obtained which corroborate and extend the findings of the <i>approximate</i> problem. The qualitative feature of <i>multiple extremal solutions</i> is retained. Several of these extremal solutions did not satisfy the Jacobi necessary condition. The choice of <i>minimizing</i> solution could be narrowed down to two sub-families of extremal solutions. A locus of Darboux Points is obtained which demarcates the domain over which these two sub-families are globally minimal. The above studies look at <i>minimum control effort</i> families of extremal solutions. As a next step, we examine the <i>minimum time</i> control of angular rates, with prescribed hard bounds on available control. Existence of singular subarcs in time-optimal trajectories is explored. Qualitative features exhibited by the <i>exact</i> problem are preserved. In addition, the control space is deformed to allow roll control and its effect on extremal solutions is investigated. In the next phase, we introduce the <i>kinematics</i> into the optimal control problem. Minimum time <i>attitude</i> control of a rigid-body is investigated with prescribed hard bounds on available control. The attitude of the rigid-body is defined using Euler parameters. Existence of singular subarcs in time-optimal trajectories is explored. A numerical survey of first-order necessary conditions reveals that there are <i>several</i> distinct extremal solutions. The character of extremal solutions depend whether <i>pitch</i> or <i>yaw</i> motion assumes the dominating role in controlling <i>roll</i> motion. Moreover, certain <i>spatial symmetries</i> are identified. Maneuvers such as a <i>Roll Around the Velocity Vector</i> and <i>Fuselage Pointing</i> are analyzed. / Ph. D.

On Cu(111) surface and in interaction with a single hexa-tert-butylphenylbenzene moleculegear, the rotation of a graphene nanodisk was studied using the large-scale atomic/molecular massively parallel simulator molecular dynamics simulator. To ensure a transmission of rotation to the molecule-gear, the graphene nanodisk is functionalized on its circumference by tertbutylphenyl chemical groups. The rotational motion can be categorized underdriving, driving and overdriving regimes calculating the locking coefficient of this mechanical machinery as a function of external torque applied to the nanodisk. The rotational friction with the surface of both the phononic and electronic contributions is investigated. For small size graphene nanodisks, the phononic friction is the main contribution. Electronic friction dominates for the larger disks putting constrains on the experimental way of achieving the transfer of rotation from a graphene nanodisk to a single molecule-gear.

Based on the success of diacyl-tert-butylhydrazines RH-5849 and RH-1266 in controlling agricultural crop pests, we endeavored to synthesize our own diacylbenzyl- and arylhydrazine derivatives for use against the malaria vector Anopheles gambiae. In the process of producing a library of compounds for assay against An. gambiae, it became clear that employing regioselective acylation techniques (in molecules that feature two nucleophilic, acyclic nitrogen atoms α to one another) would be imperative. Synthesis of the library derivatives proceeded rapidly and after topical assay, we found three compounds that were more toxic than the RH-series leads. One of the three displayed an LD50 value of half that of RH-1266, though patch clamp assay concluded that toxicity was not necessarily linked to inhibition of mosquito K+ channel Kv2.1. The acylation of monoarylhydrazines appears simple, but its regioselectivity is poorly understood when assumed as a function of basicity correlating to nucleophilic strength. We determined the ratio of the rate constants for distal to proximal N-acylation using 19F NMR spectroscopic analysis of reactions of 4-fluorophenylhydrazine with limiting (0.2 equiv) acylating agent in the presence of various bases. Acid anhydrides gave consistent preference for distal acylation. The selectivity of acylation by acyl chlorides when using pyridine gives strong distal preference, whereas use of triethylamine or aqueous base in conjunction with aroyl chlorides showed a moderate preference for proximal acylation. This observation yielded a convenient one-step method to synthesize proximal aroylarylhydrazines in yields comparable or superior to that provided by the standard three-step literature approach. Combined with NMR evidence of the distal nitrogen as the unambigiously stronger base of the two nitrogens, we propose a single electron transfer mechanism that predicts the regiochemistry of arylhydrazines toward acylating agents better than the nucleophilicity model based on pKa values. While synthesizing the acylhydrazine library for assay against An. gambiae, NMR spectroscopy revealed rotational isomerisms of two types: chiral helicity (M)/(P) and acyl (E)/(Z)-isomerism due to hindered rotation. Variable temperature NMR allowed the measurement of N-N bond rotational barriers, as well as estimate the barrier of (E)/(Z) interconversion. We obtained the X-ray crystal structures of four diacylhydrazines to test this hypothesis and revealed both the twist conformation around the N-N bond axis and (E)/(Z)-isomerism around the proximal acyl group. Computation (which agreed with the crystal structures) allowed us to estimate which (E)/(Z)-isomers were most likely being observed in solution at room temperature by NMR spectroscopy. In addition, we were able to calculate transition structures corresponding to N-N bond rotational barriers of (E,Z)- and (Z,Z)-isomers of model molecules and rationalize the difference in coalescence temperatures between (E,Z)- and (Z,Z)-isomers. / Ph. D.

The determination of the mechanisms setting the strength and structure of the large scale circulation is a fundamental and long-standing problem in physical oceanography. In this thesis, we seek to explore the mechanisms contributing to the steady state and variability of the large scale flow, with a focus on better understanding the dynamics of the Atlantic meridional overturning circulation (AMOC). In the first part of this thesis, we explore the linear sensitivity of the monthly mean subtropical AMOC to surface fluxes of buoyancy and momentum. Our approach is to use a numerical adjoint. Key insights are provided into the memory of the AMOC to historic atmospheric forcing. We find that significant memory to wind forcing is confined to timescales of less than a year. In contrast, we identify significant memory to surface buoyancy forcing spanning multi-decadal timescales and characterised by a large scale oscillation in the sign of sensitivity between the eastern and western North Atlantic basin. An important result is that to understand the origins of seasonal variability in the modelled AMOC, we must examine the response to a multidecadal history of atmospheric forcing. In the second part of this thesis, a new tool is presented that enables a clean diagnosis of the force balance controlling the circulation regime for a Boussinesq fluid. Specifically, the tool is based on the development of the "rotational momentum" equations and sets of scalar "velocity potentials" and analogous "force functions". The latter allow the projection of all forces onto the acceleration of the vertical shears and external modes of overturning to be visualised in isolation. The rotational momentum decomposition is applied to the modelled circulation in idealised Atlantic and global configurations of the MITgcm, with a focus on elucidating the dynamics of the simulated AMOC. We discuss the key role played by the rotational buoyancy forcing right on the western boundary.

Focusing on reducing the air consumption of an air flotation rail system, a flowrate-amplified flotation element was recently developed. This new flotation element ulitises the rotational flow to intake extra air via an intake hole, and thus, effectively improves the flotation height. Compared to a conventional flotation element, the flowrate-amplified flotation element can reduce air consumption by approximately 50% for the same load and flotation height. To gain an understanding of the flow phenomenon in the flowrate-amplified flotation element, experiments and CFD simulations are conducted in this study. Based on the results, we found that the flowrate-amplified flotation element could take a part of the kinetic energy of the rotating air to suck in extra air. The intake hole greatly affects the pressure field and velocity field of the flotation element. Additionally, the effects of the variant gap height and supplied flow rate were also discussed. The results indicate that the pressure distribution decreases as the gap height increases and increases as the supplied flow rate increases.

This thesis presents a development to the technique of rotational Raman lidar by, incorporating an imaging spectrometer in conjunction with a clocking CCD detection system. This allowed the rotational Raman spectra of nitrogen and oxygen to be simultaneously recorded as a function of altitude. The rotational Raman spectra were uses to calculate temperature profiles. Recording the complete band envelopes of the rotational Raman spectra removed the need for an external reference, such as a radiosonde. Results are presented from measurements made in Cambridge in chapter 4 and Ny-Alesund in chapter 6. Chapter 7 presents some conventional lidar backscatter measurements made using a PMT in Birmingham during the winter part of the pollution in the Urban Midlands Area (PUMA) campaign. These measurements were used to determine the cloud base and the planetarty boundary layer height. Two automated algorithms were tested at retrieving the PBL height, the inflection point method and the centroid method.

Die vorliegende Arbeit untersucht in einer Population von 132 gesunden Probanden die Hämostase mittels Calibrated Automated Thrombogram (CAT) und Rotationsthromboelastometrie (ROTEM). CAT wurde im plätchenarmen Plasma mit einer tissue factor (TF) von 1 und 5 pM durchgeführt. Lag time, Thrombin peak, Time to thrombin peak und das endogene Thrombin Potential (ETP) wurden ermittelt. ROTEM wurde ohne Aktivator durchgeführt (NATEM) und die Daten für Gerinnungszeit (clotting time, CT), Gerinnselbildungszeit, Alpha Winkel und maximale Gerinnselfestigkeit (MCF) mit den Daten der Thrombingenerierung korreliert. Es zeigte sich eine positive aber nicht lineare Korrelation bezüglich Alter versus lag time und time to peak, sowie eine annähernd lineare Korrelation bezüglich Alter versus thrombin peak und ETP. Für ROTEM konnte eine positive Korrelation bezüglich Alter versus MCF und Alpha Winkel, aber eine negative Korrelation bezüglich Alter versus CT dargestellt werden. In der Gegenüberstellung beider Assays korrelierten Thrombin peak und ETP (aktiviert mit einer TF Konzentration von 5 pM) signifikant mit dem Alpha Winkel und der MCF. Alle signifikanten Korrelationen zeigten lediglich eine moderate Regressionssteigung. / Published data on thrombin generation variables and their correlation with thromboelastometry in the healthy population are scarce. This study aimed at assessing thrombin generation in adults and its correlation to classical rotational thromboelastometry (ROTEM). Methods: Thrombin generation was measured in platelet-poor plasma from healthy volunteers using the calibrated automated thrombogram (CAT) with 1 and 5 pmol/l tissue factor final concentration. Lag time, thrombin peak, time to thrombin peak and endogenous thrombin potential (ETP) were analyzed. ROTEM was performed without activator (NATEM) and data for clotting time, alpha angle, clot formation time and maximum clot firmness were correlated with those of thrombin generation. Results: Altogether 132 persons (72 men, 60 women; median age: 48.0 years) were included. There was a positive non-linear correlation for age versus lag time (p < 0.001) and time to peak (p = 0.001), and almost linear correlation for age versus thrombin peak (p = 0.024) and ETP (p = 0.001), although with a moderate regression slope. Regarding ROTEM, there was a positive correlation between age and maximum clot firmness and alpha angle (p = 0.001), but a negative correlation between age and clotting time (p = 0.039). Comparing both assays, thrombin peak and ETP measured with a final tissue factor concentration of 5 pmol/l correlated significantly with alpha angle and maximum clot firmness. Conclusion: The age-related changes in CAT and ROTEM variables among adults are not linear. There is a significant correlation, although with a moderate slope, between data from CAT measured with 5 pmol/l tissue factor and ROTEM.

Elite swimmers can be distinguished from novice swimmers by freestyle stroke technique. Elite swimmers move through multiple coordination modes, increases in stroke lengths, stroke rates, and body roll allowing for a more symmetrical stroke and increased speed compared with novice swimmer during 100m freestyle. Coaches strive to improve swimmers’ performance by providing feedback about stroke technique, mostly from the pool deck where view of the full stroke cycle is obstructed by the water. Tools to assess swimming are often expensive and require extra training, which does not provide a pragmatic solution. A dryland rotational swimbench would provide a means to evaluate freestyle swimming. The aim of the present study is to evaluate the sensory motor system of elite and novice level swimmers by comparing kinematic, coordinative structures and spatial-temporal characteristics of freestyle stroke on a dryland swimbench with a rotational component. Thirty elite and novice collegiate and masters swimmers were instrumented with reflective markers bilaterally on the upper extremity and torso. A series of four ten second trials of freestyle sprint swimming were performed on the swimbench. Repeated measures were used for statistical analysis for comparison between and within groups. Bonferroni corrections were used as post-hoc analysis. Results indicated no significant difference between elite and novice swimmers’ sensory-motor system, kinematics or spatio-temporal systems on a rotational swimbench. Similarities could be accounted for by swimmers perceiving a novel task due to differences in sensory feedback, and mechanical limitations of the bench. It is noteworthy that catch-up/opposition coordination are more common than superposition which provides support for the swimbench providing a more similar representation to in water swimming.

In this dissertation, techniques of high-resolution rotational spectroscopy have been used to measure the spectra of molecules in both laboratory and astronomical settings. In the laboratory, small metal-bearing molecules containing zinc, iron, nickel, titanium, yttrium, and scandium have been studied at microwave and millimeter/submillimeter wavelengths in order to determine their rotational, fine, and hyperfine constants. These molecules were synthesized in situ in direct-absorption and Fourier-transform microwave spectrometers using Broida-type ovens and laser ablation methods. From the spectroscopic parameters, information about fundamental physical propertes and electronic character could be obtained. Radio telescopes were used to measure the spectra of molecules in different interstellar environments. A new molecule, FeCN, was detected toward the circumstellar envelope of the carbon-rich asymtotic giant branch star, IRC+10216, marking the first iron-bearing molecule detected in the interstellar medium. The telescopes were also used to conduct a study of the evolved planetary nebula, NGC 7293, or the Helix Nebula. In the Helix, CO, HCO⁺, and H₂CO were observed at several positions offset from the central star to obtain densities and kinetic temperatures throughout the Helix. A map of the HCO⁺ J = 1→ 0 transition was also constructed, showing that HCO⁺ is widespread throughout the Helix, instead of being photodissociated and destroyed, as theoretical models of planetary nebulae predict.

No description available.