Texte remanié de: Diss. Ph. D.--Department of history--Houston (Tex.)--Rice university, 1989. / Bibliogr. p. [247]-264. Index.

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.

The entry and exit side pinch roll unit of the reversing finishing mill of stainless hot strip rolling mill line bears heat effects during producing. Its transfer convection must be sufficient to maintain its function. According to the original pinch roll unit during producing, there are four questions as follows: (1) Strip marks are formed from the roll surface. (2) High temperature of roll surface cause burning phenomenon and lower the hardness of roll surface. (3) Cracks are formed on the roll surface. (4) There is a deflection of horizontal pipe of rocker arm. The improved pinch roll is called new pinch roll. The original pinch roll is called old pinch roll. First, temperature gradients of each location for the old pinch roll and the new pinch roll are calculated, and the reasons of the abnormal high temperature of roll surface are clarified. Second, for the places of the old and new pinch rolls which are the easiest to crack, its stresses of x-y and y-z directions are analyzed. Influence factors of thermal stress crack are clarified. It is proved that the thermal stress effects of the new pinch roll are less than the old pinch roll. Third, the relations of thermal deflection and heat convection for the original horizontal pipe of rocker arm and for the improved horizontal pipe are analyzed. Furthermore, according to the internal structure of the old and new pinch rolls, the flow resistance of circulating water cooling system for each place is considered. Finally, roll grinder is developed and designed to improve the quality of roll surface.

In the early design stages of a car body, a simplified model, which represents the constituent components of the car body by their performance characteristics, is used to optimize the overall car. The determined optimum performance characteristics of the components are used as performance targets to design these components. Since designers do not know the relation between the performance characteristics of the components and their dimensions and mass, this may lead to unreasonable performance targets for the components. Moreover, this process is inefficient because design engineers use empirical procedures to design the components that should meet these targets. To design the component more efficiently, design tools are needed to link the performance targets with the physical design variables of the components. General methodologies for developing two design tools for the design of car joints are presented. These tools can be viewed as translators since they translate the performance characteristics of the joint into its dimensions and vice-versa. The first tool, called translator A, quickly predicts the stiffness and the mass of a given joint. The second tool, called translator B, finds the dimensions and mass of the most efficient joint design that meets given stiffness requirements, packaging, manufacturing and styling constraints. Putting bulkheads in the joint structure is an efficient way to increase stiffness. This thesis investigates the effect of transverse bulkheads on the stiffness of an actual B-pillar to rocker joint. It also develops a translator A for the B-pillar to rocker joint with transverse bulkheads. The developed translator A can quickly predict the stiffness of the reinforced joint. Translator B uses optimization to find the most efficient, feasible joint design that meets given targets. Sequential Linear Programming (SLP) and the Modified Feasible Direction (MFD) method are used for optimization. Both Response Surface Polynomial (RSP) translator B and Neural Network (NN) translator B are developed and validated. Translator A is implemented in an MS-Excel program. Translator B is implemented in a MATHEMATICA program. The methodology for developing translator B is demonstrated on the B-pillar to rocker joint of an actual car. The convergence of the optimizer is checked by solving the optimization problem many times starting from different initial designs. The results from translator B are also checked against FEA results to ensure the feasibility of the optimum designs. By observing the optimum designs and by performing parametric studies for the effect of some important design variables on the joint mass we can establish guidelines for design of joints. / Master of Science

Bakgrund: Rullsulor används för att kompensera för ledstelhet, förbättra avveckling av steget, minska höga tryck plantart och minska böjningen vid tålederna.  Det finns dock få studier som undersöker om rullsulan verkligen minskar ledrörlighet i framfoten. Det saknas även information för betydelsen av rullsulans styvhet för böjmomentet av framfoten, vid avvecklingen av steget.   Metod: Fem friska kvinnor (n=5) gick med tre olika par skor, två par var modifierade med en likadan rullsula med olika styvheter och ett par utan rullsula. Fem upprepade mätningar för de tre olika skorna samlades in för alla deltagare. Det dorsala böjmomentet analyserades med sensorsulan (VebitoSCIENCE) som ersatte skons innersula.   Resultat: Det dorsala böjmomentet minskade för samtliga deltagare med en rullsula. Signifikant minskning av det dorsala böjmomentet vid MTP 1, för alla deltagare, när den styva rullsulan jämfördes med utan rullsula (94,4 – 20,1 Nmm) och mellan styv och flexibel rullsula för deltagare 1,2, 4 & 5 (68 – 22,2 Nmm).   Konklusion: Det dorsala böjmomentet minskade signifikant för MTP1 och MTP5 när en rullsula användes av friska kvinnor. Studien har också visat att en styv rullsula har en betydelse för att uppnå ett minskat dorsalt böjmoment vid MTP. / Background: Rocker soles are used to compensate for joint stiffness, reduce high plantar pressure and reduce the bending of the toe joints. Despite this, few studies have investigated if the rocker shoe really reduce the joint movement at the forefoot. There is also a lack of information regarding the importance of the rocker shoes stiffness for the bending moment of the forefoot, at the third rocker.   Method: Five healthy women (n=5) walked with three different pairs of shoes, two pairs were modified with the same rocker shape with different stiffness and one pair without a rocker. Five repeated measurements for the three different shoes were collected for all the participants. The dorsal bending moment was analyzed with a sensor sole (VebitoSCIENCE) that replaced the shoes insole.   Result: The dorsal bending moment was reduced for all participants with a rocker shoe. Significant reduction of the dorsal bending moment at MTP1, for all participants, when the stiff rocker was compared to the shoe without rocker (94,4 – 20,1 Nmm) and between the stiff and flexible rocker for participants 1,2,4 and 5 (68 -22,2 Nmm).   Conclusion: The dorsal bending moment was significantly reduced for MTP 1 and MTP 5 when a rocker shoe was used by healthy women, the study has also shown that the stiffness has an importance in order to achieve a reduction of the dorsal bending moment at MTP.

Measured and predicted static and dynamic characteristics are provided for a four-pad, rocker-pivot, tilting-pad journal bearing in the load-on-pad and load-between-pad orientations. The bearing has the following characteristics: 4 pads, .57 pad pivot offset, 0.6 L/D ratio, 60.33 mm (2.375in) pad axial length, 0.08255 mm (0.00325 in) radial clearance in the load-on-pad orientation, and 0.1189 mm (0.00468 in) radial clearance in the load-between-pad orientation. Tests were conducted on a floating test bearing design with unit loads ranging from 0 to 2903 kPa (421.1 psi) and speeds from 6.8 to 13.2 krpm. For all rotor speeds, hot-clearance measurements were taken to show the reduction in bearing clearance due to thermal expansion of the shaft and pads during testing. As the testing conditions get hotter, the rotor, pads, and bearing expand, decreasing radial bearing clearance. Hot-clearance measurements showed a 16-25% decrease in clearance compared to a clearance measurement at room temperature. For all test conditions, dynamic tests were performed over a range of excitation frequencies to obtain complex dynamic stiffness coefficients as a function of frequency. The direct real dynamic stiffness coefficients were then fitted with a quadratic function with respect to frequency. From the curve fit, the frequency dependence was captured by including a virtual-mass matrix [M] to produce a frequency independent [K][C][M] model. The direct dynamic stiffness coefficients for the load-on-pad orientation showed significant orthotropy, while the load-between-pad did not. The load-between-pad showed slight orthotropy as load increased. Experimental cross-coupled stiffness coefficients were measured in both load orientations, but were of the same sign and significantly less than direct stiffness coefficients. In both orientations the imaginary part of the measured dynamic stiffness increased linearly with increasing frequency, allowing for frequency independent direct damping coefficients. Rotordynamic coefficients presented were compared to predictions from two different Reynolds-based models. Both models showed the importance of taking into account pivot flexibility and different pad geometries (due to the reduction in bearing clearance during testing) in predicting rotordynamic coefficients. If either of these two inputs were incorrect, then predictions for the bearings impedance coefficients were very inaccurate. The main difference between prediction codes is that one of the codes incorporates pad flexibility in predicting the impedance coefficients for a tilting-pad journal bearing. To look at the effects that pad flexibility has on predicting the impedance coefficients, a series of predictions were created by changing the magnitude of the pad's bending stiffness. Increasing the bending stiffness used in predictions by a factor of 10 typically caused a 3-11% increase in predicted Kxx and Kyy, and a 10-24% increase in predicted Cxx and Cyy. In all cases, increasing the calculated bending stiffness from ten to a hundred times the calculated value caused slight if any change in Kxx, Kyy, Cxx, and Cyy. For a flexible pad an increase in bending stiffness can have a large effect on predictions; however, for a more rigid pad an increase in pad bending stiffness will have a much lesser effect. Results showed that the pad's structural bending stiffness can be an important factor in predicting impedance coefficients. Even though the pads tested in this thesis are extremely stiff, changes are still seen in predictions when the magnitude of the pad?s bending stiffness is increased, especially in Cxx, and Cyy. The code without pad flexibility predicted Kxx and Kyy much more accurately than the code with pad flexibility. The code with pad flexibility predicts Cxx more accurately, while the code without pad flexibility predicted Cyy more accurately. Regardless of prediction Code used, the Kxx and Kyy were over-predicted at low loads, but predicted more accurately as load increased. Cxx, and Cyy were modeled very well in the load-on-pad orientation, while slightly overpredicted in the load-between-pad orientation. For solid pads, like the ones tested here, both codes do a decent job at predicting impedance coefficients

This thesis is concerned with the specific genre of biographical literature - autobiographies of czech rock musicians. Since the terminology in the topic of the thesis is unclear, the author is first going to define it. Furthermore it asks the question of who really is a old-timer as well as who is a rocker. The material studied are texts in which the narrator recalls his past life and tries to reconstruct their path of life. The author seeks thematic and formal parallels in the chosen autobiographies. Using these the author intends to define the specifics of the rock autobiography genre in the Czech Republic. Key words: rock, autobiography, old-timer, rock musician, stereotype

This thesis describes a proposal for a rocker saw design. It addresses the general lack of current solutions, their description and it is drawing conclusions of these. The object of this thesis is to try to avoid potential problems which are being discussed in this thesis and therefore suggests solutions for enhancing the rocker saw, especially on the visual and ergonomic side.

This diploma thesis deals with investigation of dynamic straining valve OHV for four-valve head diesel engine Zetor 1505 – 90 kW. The calculation is performed analytically in mathematic software MathCad and MBS software ADAMS/Engine 2005. Also in this diploma thesis is from results obtained from MBS system perfomed stressed analysis valve_rocker arm gear divorce method final elements (MKP) in program ANSYS 10.

Diploma thesis deals with the design and stress analysis of the rocker suspension for an autocross car. The research describes some real cases of using suspension with pushrod and rocker in motorsport. Subsequently, the work deals with the design of the wheel bump/rebound limiting stops and bump/rebound measuring. The challenge is to design a component shape, size and select fit of a rocker with an emphasis on low weight whilst maintaining sufficient strength and rigidity. The design study include stress analysis which leads to optimize the final shape.