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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Návrh jeřábu pro obecné použití, pro manipulaci na palubě plavidla / Design of General Service Crane, used for manipulation on the deck of the vessel

Dlužanský, Tomáš January 2011 (has links)
This master's thesis makes a brief comparison of design variants of cranes for general use on the deck of a vessel. Further, this thesis deals with a design of a crane with a telescopic jib and a single knuckle. An important part of the crane’s design is its kinematic solution, which was modified in the design phase. The last step of a simplified analytical calculation of the jib for design steel construction is given. This preliminary calculation is the starting point for a FEM model and for the following FEM analysis. A stress control is made according to the Lloyd's Register of Shipping agency’s standard for lifting appliances in marine environment and also according to the recommendations of Huisman company. A part of the proposed solution is a selection of main components of the crane. The master’s thesis contains a summary of some operational and other information which characterize possibilities of the crane’s use. This thesis also includes source materials for drawing documentation.
2

Binding Interactions of (R)- and (S)-hydroxypropyl-CoM Dehydrogenases and the Zinc Knuckle Proteins Air1 and Air2

Bakelar, Jeremy W. 01 May 2015 (has links)
This work is focused on understanding protein function by describing how paralogous proteins with overlapping and distinct functions interact with their substrates and with other proteins. Two model systems are the subject of this research: (1) the stereospecific dehydrogenases R- and S-HPCDH, and (2) the zinc knuckle proteins Air1 and Air2. R- and S-HPCDH are homologous enzymes that are central to the metabolism of propylene and epoxide in the soil bacterium Xanthobacter autotrophicus. The bacterium produces R- and S-HPCDH simultaneously to facilitate transformation of R- and S-enantiomers of epoxypropane to a common achiral product 2-ketopropyl-CoM (2-KPC). Both R- and S-HPCDH are highly stereospecific for their respective substrates as each enzyme displays less than 0.5% activity with the opposite substrate isomer. Presented here are substrate-bound x-ray crystal structures of S-HPCDH. Comparisons to the previously reported product-bound structure of R-HPCDH reveal structural differences that provide each enzyme with a distinct substrate binding pocket. These structures demonstrate how chiral discrimination by R- and S-HPCDH results from alternative binding of the distal end of substrates within each substrate binding pocket, providing a structural basis for stereospecificity displayed by R- and S-HPCDH. Air1 and Air2 are homologous eukaryotic proteins that individually function within a trimeric protein complex called TRAMP. In the nucleus, TRAMP participates in RNA surveillance, processing, and turnover by stimulating the 3’-5’ exonucleolytic degradation of targeted RNAs by the nuclear exosome. Previous studies have indicated that within TRAMP Air1 and Air2 provide crucial protein-protein interactions that link the individual subunits of the complex. However, the mechanistic details of these protein-protein interactions are poorly understood. The work in this dissertation has characterized a previously unknown binding interface between Air2 and another TRAMP component, the helicase Mtr4. This interaction may explain how helicase activity is modulated in TRAMP. In addition to TRAMP protein interactions, preliminary studies have identified a small region of Air1 that is required for modulating the activity of a protein that is not found in TRAMP, the methyltransferase Hmt1. Collectively, these studies provide important characterization of Air1 and Air2 protein-binding interactions, and establish a foundation for future research efforts aimed at exploring Air protein function.
3

Knuckle-Walking Signal in the Manual Phalanges and Metacarpals of the Great Apes (Pan and Gorilla)

Matarazzo, Stacey Ann 01 May 2013 (has links)
The "Knuckle-walking Hominin Hypothesis" postulates that there was a knuckle-walking phase during the transition from quadrupedalism to bipedalism. To address this question, previous research has focused on the search for a "signal" within the wrist, and metacarpals of extant knuckle walkers that can be used to infer this locomotor pattern in extinct hominins. To date, the examined features have not yielded a clear, non-contested signal. I explore the Knuckle-walking Hominin Hypothesis in two ways: 1. by examining the hand postures and the manual pressure application of Pan and Gorilla during knuckle walking to determine whether there are species specific differences and 2. by examining the internal and external morphology of the manual phalanges in an attempt to isolate a clear "knuckle-walking signal". Chimpanzees are more variable in their preferred contact digits, and use both hand positions with equal frequency ("palm-in" - palm facing toward the body and "palm-back" - palm facing posteriorly). In contrast, gorillas consistently make contact with all four digits 2-5, maintain a pronated arm, and use the palm-back hand position. In both taxa, hand position affects which digit acts as the final touch-off element and therefore receives maximum pressure in a given step, and digit 5 receives significantly less pressure than the other rays. Gorillas are, in effect, practicing a refined subset of the variety of knuckle-walking postures used by the more arboreal chimpanzees. A clear knuckle-walking signal is seen in both the external and internal morphology of the phalanges. Chimpanzees and gorillas have the same middle phalangeal curvature profile with the greatest curvature found in digit 5 (5 > 2 > 3 > 4), the element that receives the least amount of pressure. This phalangeal curvature profile is a feature not shared with any of the included taxa practicing different modes of locomotion. They also have similar Indices of Relative Curvature (IRC-middle phalangeal curvature/proximal phalangeal curvature) for digits 2-5 that clearly delineate them with "flatter" middle phalanges and more curved proximal phalanges (IRCs = ~0.85), from quadrupeds with more curved middle than proximal phalanges (IRCs > 1), and suspensory primates with higher and more equal curvature values for both elements (IRCs = ~1). This ability to differentiate between locomotor groups holds if the IRCs are composed of elements from different rays of the same manus and from elements of different individuals. Within the trabecular bone structure, knuckle walkers are differentiated from quadrupeds and suspsensory primates in 3 locations: the metacarpal head, and the proximal ends of the middle and proximal phalanges. In particular, the metacarpal head shows distinct differences between the groups: knuckle walkers have a palmar-dorsal alignment of trabeculae and disc-like shape, suspensory taxa have a proximodistal alignment and rod-like shape and quadrupeds have a proximodistal alignment and disc-like shape. The ability to differentiate between locomotor categories using isolated zones increases the applicability of these signals to a fragmentary and limited fossil record. The morphological similarities, specifically the shared curvature profile, and the similar knuckle-walking kinematics employed by chimpanzees and gorillas point to a shared origin of knuckle walking.
4

Řešení technologie obrábění kulových čepů v podmínkách firmy TRW / Solution of technology of cutting knuckle bolt in conditions of company TRW

Tichánek, Martin January 2008 (has links)
The Thesis deals with the increase in efficiency of the cutting process. The current state analysis of the knuckle bolt cutting. The choice of the alter-natives of the cutting tips and the iron chip former. The evaluation of the iron chip forming. The change of the path of the finishing cutting tip. Time loss when cutting bolts.
5

Kinematic Control of Redundant Knuckle Booms with Automatic Path Following Functions

Löfgren, Björn January 2009 (has links)
To stay competitive internationally, the Swedish forestry sector must increase its productivity by 2 to 3% annually. There are a variety of ways in which productivity can be increased. One option is to develop remote-controlled or unmanned machines, thus reducing the need for operator intervention. Another option—and one that could be achieved sooner than full automation—would be to make some functions semi-automatic. Semi-automatic operation of the knuckle boom and felling head in particular would create “mini-breaks” for the operators, thereby reducing mental and physiological stress. It would also reduce training time and increase the productivity of a large proportion of operators. The objective of this thesis work has been to develop and evaluate algorithms for simplified boom control on forest machines. Algorithms for so called boom tip control, as well as automatic boom functions have been introduced. The algorithms solve the inverse kinematics of kinematically redundant knuckle booms while maximizing lifting capacity. The boom tip control was evaluated – first by means of a kinematic simulation and then in a dynamic forest machine simulator. The results show that boom tip control is an easier system to learn in comparison to conventional control, leading to savings in production due to shorter learning times and operators being able to reach full production sooner. Boom tip control also creates less mental strain than conventional control, which in the long run will reduce mental stress on operators of forest machines. The maximum lifting capacity algorithm was then developed further to enable TCP path-tracking, which was also implemented and evaluated in the simulator. An evaluation of the fidelity of the dynamic forest machine simulator was performed to ensure validity of the results achieved with the simplified boom control. The results from the study show that there is good fidelity between the forest machine simulator and a real forest machine, and that the results from simulations are reliable. It is also concluded that the simulator was a useful research tool for the studies performed in the context of this thesis work. The thesis had two overall objectives. The first was to provide the industry and forestry sector with usable and verified ideas and results in the area of automation. This has been accomplished with the implementation of a simplified boom control and semi-automation on a forwarder in a recently started joint venture between a hydraulic manufacturer, a forest machine manufacturer and a forest enterprise. The second objective was to strengthen the research and development links between the forestry sector and technical university research. This has been accomplished through the thesis work itself and by a number of courses, projects and Masters theses over the last three years. About 150 students in total have been studying forest machine technology in one way or the other. / QC 20100729
6

Knuckle-Walking Signatures in Hominoid Scapulae

Kreierhoff, Jennifer Lynn 24 April 2014 (has links)
No description available.

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