Static performance and rotordynamic coefficients are provided for a rocker-pivot, tilting-pad journal bearing with 50 and 60 percent offset pads in a load-between-pad configuration. The bearing uses leading-edge-groove lubrication and has the following characteristics: 5-pads, 101.6 mm (4.0 in) nominal diameter, .0814 - .0837 mm (.0032 - .0033 in) radial bearing clearance, .25 to .27 preload, 60.325 mm (2.375 in) axial pad length. Operating conditions included loads from 0 to 3101 kPa (450 psi) and speeds from 7 to 16 krpm. Dynamic tests were conducted over a range of frequencies to obtain complex dynamic stiffness coefficients as functions of excitation frequency. For most test conditions, the direct real dynamic stiffnesses were well fitted with a quadratic function with respect to frequency. This curve fit allowed for the stiffness frequency dependency to be captured by including an added mass matrix [M] to a conventional [K][C] model, producing a frequency independent [K][C][M] model. The direct imaginary dynamic stiffness coefficients increased linearly with frequency, producing frequency independent direct damping coefficients. Compared to the 50 percent offset, the 60 percent offset configuration’s direct stiffness coefficients were larger at light unit loads. At high loads, the 50 percent offset configuration had a larger direct stiffness in the loaded direction. Negative direct added-mass coefficients were regularly obtained for both offsets, especially in the unloaded direction. Added-mass magnitudes were below 32 kg for all test cases. No appreciable difference was measured in direct damping coefficients for both pivot offset. A bulk-flow Navier-Stokes CFD code provided rotordynamic coefficient predictions. The following stiffness and damping prediction trends were observed for both 50 and 60 percent offsets. The direct stiffness coefficients were modeled well at light loads and became increasingly over-predicted with increasing unit load. Stiffness orthotropy was measured at zero and light load conditions that was not predicted. Direct damping predictions in the loaded direction increased significantly with unit load while the experimental direct damping coefficients remained constant with load. The direct damping coefficients were reasonably modeled only at the highest test speed of 16 krpm. Experimental cross-coupled stiffness coefficients were larger than predicted for both offsets, but were of the same sign and considerably smaller than the direct coefficients.

Control of water erosion of soil at mine sites requires an ability to predict the effects of different management practices on soil loss. Using soil loss models such as the Revised Universal Soil Loss Equation (RUSLE) requires calibration of the model for materials and situations that are not defined in the model’s handbook or software. The outer slopes of bauxite residue disposal areas are potentially highly erodible surfaces, and a recent evaluation of previous rehabilitation practices at Worsley Alumina, Collie, Western Australia, identified areas on the bauxite residue disposal areas where vegetation establishment and management of long term soil loss could be improved. Field experiments commencing in April 2000 at Worsley Alumina’s bauxite refinery, Collie, and laboratory tilting flume experiments run at the University of Queensland, were designed to quantify the effectiveness of different surface treatments on reducing short-term soil loss, and to model long-term erosion risks. Crushed ferricrete caprock – rock-pitch – and different types of mulches, seed mixes and fertiliser rates were applied to the compacted clay batter slopes used to contain bauxite residue, with runoff, soil loss and vegetation establishment monitored periodically over 27 months. Laboratory tilting flume results were related to the field data using the soil erosion models MINErosion, the Modified Universal Soil Loss Equation (MUSLE) and RUSLE to predict event-based and annual soil loss for different treatments. Turbo-mulch, a blocky, coarse pine bark, was the most effective surface treatment for promoting vegetation establishment, reducing rill formation and reducing soil loss, a result supported in both the field and laboratory results. Turbo-mulch and vegetation did not reduce runoff, but resulted in decreased soil loss. This shows the importance of protecting soil from raindrop impact and of the soil holding capacity of vegetation. Increased seed and fertiliser rates did not significantly affect native plant numbers or foliage cover on topsoil without turbo-mulch. Rock-pitch was found to be resistant to erosion and mass movement along a rock-pitch/compacted clay interface. Field erosion measurements ranged from 0.87 t/ha/yr for turbo-mulched treatments to 7.41 t/ha/yr for a treatment with a different seed mix, lacking turbo-mulch and lacking underlying rock-pitch. RUSLE soil loss predictions based on soil properties and soil loss estimates from the MINErosion model ranged from 0.27 to 60.0 t/ha/yr. RUSLE predictions based on tilting flume data ranged from 0.14 to 81.1 t/ha/yr. RUSLE overpredicted soil loss for treatments without turbo-mulch, and underestimated soil loss for turbo-mulched treatments, necessitating calibration based on the unique materials trialed in this study. The relative soil loss measured in the field was best represented by RUSLE predictions based on tilting flume data rather than the MINErosion model. MINErosion did not adequately describe the effect of bulk density and infiltration on soil loss of compacted/consolidated materials. MUSLE and RUSLE are adequate models for the Western Australian conditions of this study, but further research is required to calibrate the C factor for turbo-mulched surfaces and calibrate the P factor for rock-pitch.

Title: Generalized injectivity and approximations Author: Serap S¸ahinkaya Department:Algebra Faculty of Mathematics and Physics, Charles University Supervisor: Prof. RNDr. Jan Trlifaj, DSc, Faculty of Mathematics and Physics, Charles University Abstract: Injective modules form a basic class studied in contemporary module theory. One of their generalizations, inspired by tilting theory, is the notion of a cotilting module. While tilting modules behave well with respect to localization, we show that colocalization is the correct approach when comparing the struc- ture of cotilting modules over commutative noetherian rings R with the structure of cotilting modules over their localizations Rm where m runs over the maximal spectrum of R. This is done in Chapter 2 of this Dissertation whose main results were published in the paper [33]. In Chapter 3, we investigate approximation properties of other classic generalizations of injective modules, the Ci- and quasi- injective modules, introduced by Harada et al. Suprisingly, we prove that these classes provide for approximations only in exceptional cases (when all Ci mod- ules are injective, or pure-injective). The Dissertation ends with a set of open problems. Keywords: Commutative noetherian ring, (co)tilting module, (generalized) injec- tive module. 1

Let $G$ be a reductive algebraic group over an algebraically closed field $k$ of characteristic $p > 0$. The indecomposable tilting modules $\{T(\lambda)\}$ for $G$, which are labeled by highest weight, form an important class of self-dual representations over $k$. In this thesis we investigate semisimple filtrations of minimal length (Loewy series) of tilting modules. We first demonstrate a criterion for determining when tilting modules for arbitrary quasi-hereditary algebras are rigid, i.e. have a unique Loewy series. Our criterion involves checking that $T(\lambda)$ does not have certain subquotients whose composition factors extend more than one layer in the radical or socle series. We apply this criterion to show that the restricted tilting modules for $SL_4$ are rigid when $p \geq 5$, something beyond the scope of previous work on this topic by Andersen and Kaneda. Even when $T(\lambda)$ is not rigid, in many cases it has a particularly structured Loewy series which we call a balanced semisimple filtration, whose semisimple subquotients or "layers" are symmetric about some middle layer. Balanced semisimple filtrations also suggest a remarkably straightforward algorithm for calculating tilting characters from the irreducible characters. Applying Lusztig's character formula for the simple modules, we show that the algorithm agrees with Soergel's character formula for the regular indecomposable tilting modules for quantum groups at roots of unity. We then show that these filtrations really do exist for these tilting modules. In the modular case, high weight tilting modules exhibit self-similarity in their characters at $p$-power scales. This is due to what we call higher-order linkage, an old character-theoretic result relating modular tilting characters and quantum tilting characters at $p$-power roots of unity. To better understand this behavior we describe an explicit categorification of higher-order linkage using the language of Soergel bimodules. Along the way we also develop the algebra and combinatorics of higher-order linkage at the de-categorified level. We hope that this will provide a foundation for a tilting character formula valid for all weights in the modular case when $p$ is sufficiently large.

The subjekt of this thesis is design of recumbent bicycle. Recumbent bicycle is designed as tricycle with partially open fairing. Main aim was to design a functional and timeless design using modern technologies. Recumbent tricycle was designed with the fairing and tilting mechanism to easily corner, with innovative solution of turning which makes easier to mount and dismount recumbent tricycle. The work was solved by design, technical and ergonomic side also includes other aspects of the design.

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This thesis presents a systematic study of human responses to different motions and strategies of car body tilt control regarding ride comfort, working/reading ability and motion sickness on high-speed tilting trains. Experiments with test subjects were performed in a tilting train on curved track as well as in a moving vehicle simulator. The study is multi-disciplinary, combining knowledge and methods from the fields of railway technology, human factors and vestibular science. The main experiment in a tilting train was performed with about 75 seated test subjects, mainly students from Linköping University, making three test runs. In total, these subjects participated in about 210 individual test rides, each with a duration of about 3 hours. Additional tests on comfort disturbances with pushbutton technique have been reported in the project. The simulator experiments used a total of about 75 subjects, making some 320 test rides each of about 30 minutes duration. Test motions consisted of combinations of horizontal (lateral) acceleration and roll acceleration, together with either roll or horizontal acceleration. Rate of change of horizontal acceleration (jerk) and roll velocity were of the same order of magnitude as in a tilting train environment, but horizontal acceleration alone was about half the magnitude. Horizontal and vertical vibrations from a tilting train were added to the test motions, and train seats and interior train noise were also introduced to create a "train feeling". Test designs and methodology have been developed during the course of the experiments. The test subjects answered questionnaires, four times per test run in the train experiment and each 5 minute in the simulator experiment. The investigated variables were: estimated average ride comfort, estimated ability to work or read, and occurrence of symptoms of motion sickness (dizziness, nausea and not feeling well). Lateral and vertical accelerations together with roll motions were monitored and recorded for later evaluation. Results from the train experiments show that the estimated average ride comfort was about 4 on a 5-degree scale, which indicates “good”. Results also show that a reduced tilt compensation of the lateral acceleration while curving together with a reduced tilt velocity of the car body reduce the provocation of motion sickness. However, a reduction in tilt compensation may produce an increased number of comfort disturbances due to lateral acceleration in the car body. Regression analysis shows that motion doses from roll acceleration may be used to predict the incidence of motion sickness. The simulator experiments show that the primary sources of provocation of nausea and motion sickness are the motion doses from roll and lateral acceleration in the horizontal plane. The study proposes a hypothesis and a model of provocation of motion sickness. It is shown that motion sickness has a time decay, or leakage. A model for this leakage is proposed. The determinative types of motion for provocation of nausea and motion sickness in tilting trains are identified and future tilting train and/or simulator experiments are proposed in order to further investigate their influence. / <p>NR 20140805</p>

We introduce the definition of 1-cotilting object in a Grothendieck category and investigate its relation to the analogue of the standard definition of 1-cotilting module. The 1-cotilting quasi-coherent sheaves on a Noetherian scheme are stud- ied in particular: using the classification of hereditary torsion pairs in the category of quasi-coherent sheaves on a Noetherian scheme X, to each hereditary torsion- free class F that is generating we assign a 1-cotilting quasi-coherent sheaf whose 1-cotilting class is F. This provides a family of pairwise non-equivalent 1-cotilting quasi-coherent sheaves which are parametrized by specialization closed subsets of X avoiding the set of associated points of a chosen generator of the category of quasi-coherent sheaves. In many cases (e.g. for separated schemes), this set of avoided points can be chosen as the set of associated points of the scheme. 1

There has been significant interest in BiFeO₃ over the past decade. This interest has focused on the magnetic and electrical properties, which in the long term may prove useful in device applications. This thesis focuses on the synthesis, electrical characterisation, and structural origin of the electrical properties of rare earth doped bismuth ferrite. Two systems have been studied: BiFeO₃ doped with lanthanum and neodymium (Bi₁₋ₓREₓFeO₃ RE= La, Nd). Specific examples have been highlighted focusing on a detailed structural analysis of a lanthanum doped bismuth ferrite, Bi₀.₅La₀.₅FeO₃, and a neodymium analogue, Bi₀.₇Nd₀.₃FeO₃. Both adopt an orthorhombic GdFeO₃-type structure (space group: Pnma) with G-type antiferromagnetism. Structural variations were investigated by Rietveld refinement of temperature dependent powder neutron diffraction using a combination of both conventional “bond angle/bond length” and symmetry-mode analysis. The latter was particularly useful as it allowed the effects of A-site displacements and octahedral tilts/distortions to be considered separately. This in-depth structural analysis was complemented with ac-immittance spectroscopy using the multi-formulism approach of combined impedance and modulus data to correlate structural changes with the bulk electrical properties. This approach was essential due to the complex nature of the electrical response with contributions from different electroactive regions. The structural variations occur due to a changing balance between magnetic properties and other bonding contributions in the respective systems. This results in changes in the magnitude of the octahedral tilts, and A-site displacements giving rise to phenomena such as negative thermal expansion and invariant lattice parameters i.e., the invar effect. More specifically, analysis of Bi₀.₅La₀.₅FeO₃ highlights a structural link between changes in the relative dielectric permittivity and changes in the FeO₆ octahedral tilt magnitudes, accompanied by a structural distortion of the octahedra with corresponding A-site displacement along the c-axis; this behaviour is unusual due to an increasing in-phase tilt mode with increasing temperature. The anomalous orthorhombic distortion is driven by magnetostriction at the onset of antiferromagnetic ordering resulting in an Invar effect along the magnetic c-axis and anisotropic displacement of the A-site Bi³⁺ and La³⁺ along the a-axis. This contrasts with the neodymium analogue Bi₀.₇Nd₀.₃FeO₃ in which a combination of increasing A-site displacements in the ac-plane and decrease in both in-phase and anti-phase tilts combine with superexchange giving rise to negative thermal expansion at low temperature. The A-site displacements correlate with the orthorhombic strain. By carefully changing the synthesis conditions, a significant change in bulk conductivity was observed for a number for Bi₁₋ₓLaₓFeO₃ compositions. A series of Bi₀.₆La0.₄FeO₃ samples are discussed, where changes in the second step of the synthesis result in significantly different bulk conductivities. This behaviour is also observed in other compositions e.g. Bi₀.₇₅La₀.₂₅FeO₃. Changes in the electrical behaviour as a function of temperature are discussed in terms of phase composition and concentration gradients of defects. Activation energies associated with the conduction process(es) in Bi₁₋ₓLaₓFeO₃ samples, regardless of composition, fall within one of two broad regimes, circa. 0.5 eV or 1.0 eV, associated with polaron hopping or migration of charge via oxygen vacancies, respectively. The use of symmetry-mode analysis, in combination with conventional crystallographic analysis and electrical analysis using multi-formulism approach, presents a new paradigm for investigation of structure-property relationships in rare earth doped BiFeO₃.

Narrow tilting vehicles offer an opportunity to tackle both traffic congestion and carbon emissions having a small footprint, low weight and small frontal area. Their narrow width requires that they tilt into corners in order to maintain stability; this may be achieved by means of an automated tilt control system. A three-wheeled tilting vehicle prototype, known as the Compact Low Emission Vehicle for uRban transport (CLEVER), was constructed at the University of Bath in 2006. The vehicle was equipped with a direct tilt control system in which a pair of hydraulic actuators applied a moment between the cabin and a non-tilting base. This tilt control system provided satisfactory steady state performance but limited transient stability. High tilt rate demands associated with rapid steering inputs would lead to large tilting moments being applied to the non-tilting rear engine module; this, combined with the engine module’s own propensity to roll out of the bend, could cause the inside wheel to lift and the vehicle to capsize. This thesis details the implementation of a Steering Direct Tilt Control (SDTC) system, whereby the front wheel steer angle is used to generate some of the tilting moment, on the prototype CLEVER Vehicle. Simulation and experimental results are presented which show a 40% reduction in load transfer across the rear axle during a transient ramp steer manoeuvre. The influence of the SDTC system, and associated steer angle alteration, on the vehicle trajectory is considered. A human driver is found to be capable of adapting their steer inputs such that they can follow their chosen path. Finally, a feed-forward control strategy is shown to reduce the load transfer across the rear axle by an additional 30% in transient situations, but only if the steer input signal is sufficiently free of noise.