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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.
171

Kamerový jeřáb / Kamera crane

Nádvorník, Jan January 2011 (has links)
This thesis deals with product design rotating camera crane with variable length telescopic arm. Proposed maximum arm length is 6 [m] with a maximum weight capacity of the camera 8 [kg]. The work deals with the various structural units associated mainly with the issue of the telescopic arm. In individual sections detail the construction of the camera head developed deformation and stress analysis of a telescopic jib.
172

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.
173

K problematice efektivního a spolehlivého navrhování nosné konstrukce jeřábových drah / To problems of effective and reliable design of crane girders

Kočařová, Jindřiška Unknown Date (has links)
Recently the most often used crane runway beams designed from rolled HEA sections as multispan beams is the topic of this doctoral thesis. It deals with the study of real stress in the cross section focused on local stress analysis in the web of cross section due to eccentricities of wheal load and on the problems of stress analysis above the middle support of multi-span beams. First, the outline of crane supporting structures, currently used methods of implementation and available stress analysis methods are summarized. Than two parametrical studies of crane runway beam design depending on statical determination of the beam, crane span, crane wheelbase and chosen quality of structural steel are presented. Following part of thesis contains the stress analysis of crane runway two-span beam in its continuous part above the middle support on implemented crane supporting structure. Experiment of crane runway two-span beams actions above the middle support are described in the last part of the thesis. Closing part of thesis summarizes results.
174

Posouzení traverzy mostového magnetového jeřábu 15t / Analysis of traverse of bridge magnet crane 15t

Bartušek, Filip January 2016 (has links)
The diploma thesis deals with some parts of bridge magnet crane with 15 tons of nominal lifting capacity. This crane is designed for operation in the steel mill for handling billets using magnets suspended on the traverse. This work is focused on design of hoisting and traverse mechanism of crane trolley, selection of individual components on the basis of relevant standards and calculations. Next part of this thesis is investigation magnet traverse in terms of its strength according to standard ČSN EN 13001.
175

Reduzierung der Spieldauer bei Brückenkranen mit überlagerten Bedienbereichen

Könze, Anke, Schulze, Frank January 2008 (has links)
Anhand eines Referenzmodells für ein automatisches Lager mit zwei Regalbediengeräten in einer Gasse wurde ein Algorithmus entwickelt, der für einen bekannten Auftragspool eine (Batch-) Optimierung und beim Einsatz von Mehrfachlastaufnahmemitteln zusätzlich eine Tourenoptimierung vornimmt. Die Spiele beider Geräte werden aufeinander abgestimmt, die Spielzeit wird minimiert. Es liegt ein Berechnungswerkzeug vor, mit dem die Spieldauer beim Einsatz von zwei Geräten und überlagerten Bedienbereichen ermittelt werden kann. Die Ergebnisse sind auf automatisierte Brückenkrane mit überlagerten Bedienbereichen übertragbar. Dazu wird ein Anwendungsbeispiel vorgestellt.
176

Laid eggs in vain got eaten by a crane? : Investigating habitat selection and activity by Common cranes to consider potential impact on other wetland bird species

Ingerström, Johnny January 2020 (has links)
Wetland species are declining and efforts are being made to protect wetlands and their biodiversity. In Europe, these efforts could be hampered by the recent rise in the Western European Common crane (Grus grus) population. Increasing anecdotal evidence has raised concerns that this population increase has led to an increase in crane predation on other bird species’ eggs and chicks. This study aims to investigate, weather cranes are a potential threat to other bird species by predating on eggs and chicks, and ultimately biodiversity. Proxies, like habitat selection and time devoted to foraging in wetlands, were used to investigate risk of crane predation. Habitat selection and time devotion were studied using location data derived from 13 GPS-tagged Common cranes during May and June in 2017 to 2019. Observational foraging data was collected in the protected wetland Kvismaren, Sweden in June 2019, including adult non-breeding cranes only. During daytime, the three habitats with highest mean relative probability of presence within a 95% confidence interval for cranes are open wetland (0.87, CI: 0.86-0.89), followed by inland water (0.60, CI: 0.56-0.63) and arable land (0.55, CI: 0.52-0.59). The proportion of time cranes spend in wetlands is 0.39 in May and 0.28 in June. Cranes spend a proportional majority of their time (0.69) on foraging behavior compared to other activities they perform in wetlands. Since every encounter with a chick or egg can end in predation and cranes spend most of their time foraging in wetlands a population increase in cranes could have severe impact on bird species. Future research should take into account crane diet, which categories of cranes (e.g., non-breeding versus breeding) are most likely to predate on eggs and chicks and the negative impact on bird populations in relation to crane numbers to fill in the major research gap in this field. Lastly, future studies should evaluate how an increasing crane population also could impact the abundances of other wetland species such as, rodents, amphibians, fish and invertebrates.
177

Stephen Crane's ironic vision

O'Bryant, Michael J. 01 January 1978 (has links)
Stephen crane's major irony in his art is produced by contrasting his characters' illusions with reality. In Maggie that reality is an environmental indifference that is very much like the deterministic environment of the Naturalistic Novelists. Maggie's perceptions and expectations contrast with this reality, seeming very ironic. In The Red Badge of Courage, "The Open Boat," and "The Blue Hotel,” each character's illusion is contrasted with a reality that is absolutely indifferent. It is in these works (as well as in his letters and poetry) that Crane affirms man's need to embrace those illusions which enable him to face reality. The contrast between illusion and reality still generates irony, yet, Crane accepts the irony as a fact of life in an ironic universe.
178

A Real-time Crane Service Scheduling Decision Support System (css-dss) For Construction Tower Cranes

Tork, Amir 01 January 2013 (has links)
The success of construction projects depends on proper use of construction equipment and machinery to a great extent. Thus, appropriate planning and control of the activities that rely on construction equipment could have significant effects on improving the efficiency of project operations. Cranes are the largest and most conspicuous construction equipment, widely used in typical construction sites. They play a major role in relocation of materials in horizontal and vertical directions on construction sites. Given the nature of activities relying on construction cranes in various stages of a project, cranes normally have control over the critical path of the project with the potential to create schedule bottlenecks and delaying the completion of the project. This dissertation intends to improve crane operations efficiency by developing a new framework for optimizing crane service sequence schedule. The crane service sequence problem is mathematically formulated as an NP-complete optimization problem based on the well-known Travel Salesman Problem (TSP) and is solved using different optimization techniques depending on the problem’s size and complexity. The proposed framework sets the basis for developing near-real time decision support tools for on-site optimization of crane operations sequence. To underline the value of the proposed crane sequence optimization methods, these methods are employed to solve several numerical examples. Results show that the proposed method can create a travel time saving of 28% on average in comparison with conventional scheduling methods such as First in First out (FIFO), Shortest Job First (SJF), and Earliest Deadline First (EDF).
179

Adaptation of Nontraditional Control Techniques to Nonlinear Micro and Macro Mechanical Systems

Daqaq, Mohammed F. 15 August 2006 (has links)
We investigate the implementation of nontraditional open-loop and closed-loop control techniques to systems at the micro and macro scales. At the macro level, we consider a quay-side container crane. It is known that the United States relies on ocean transportation for 95% of cargo tonnage that moves in and out of the country. Each year over six million loaded marine containers enter U.S. ports. Current growth predictions indicate that container cargo will quadruple in the next twenty years. To cope with this rapid growth, we develop a novel open-loop input-shaping control technique to mitigate payload oscillations on quay-side container cranes. The proposed approach is suitable for automated crane operations, does not require any alterations to the existing crane structure, uses the maximum crane capabilities, and is based on an accurate two-dimensional four-bar-mechanism model of a container crane. The shaped commands are based on a nonlinear approximation of the two-dimensional model frequency and, unlike traditional input-shaping techniques, our approach can account for large hoisting operations. For operator-in-the-loop crane operations, we develop a closed-loop nonlinear delayed-position feedback controller. Key features of this controller are that it: does not require major modifications to the existing crane structure, accounts for motion inversion delays, rejects external disturbances, and is superimposed on the crane operator commands. To validate the controllers, we construct a 1:10 scale model of a 65-ton quay-side container crane. The facility consists of a 7-meter track, 3.5-meter hoisting cables, a trolley, a traverse motor, two hoisting motors, and a 50-pound payload. Using this setup, we demonstrated the effectiveness of the controllers in mitigating payload oscillations in both of the open-loop and closed-loop modes of operation. At the micro level, we consider a micro optical device known as the torsional micromirror. This device has a tremendous number of industrial and consumer market applications including optical switching, light scanning, digital displays, etc. To analyze this device, we develop a comprehensive model of an electrically actuated torsional mirror. Using a Galerkin expansion, we develop a reduced-order model of the mirror and verify it against experimental data. We investigate the accuracy of representing the mirror using a two-degrees-of-freedom lumped-mass model. We conclude that, under normal operating conditions, the statics and dynamics of the mirror can be accurately represented by the simplified lumped-mass system. We utilize the lumped-mass model to study and analyze the nonlinear dynamics of torsional micromirrors subjected to combined DC and resonant AC excitations. The analysis is aimed at enhancing the performance of micromirrors used for scanning applications by providing better insight into the effects of system parameters on the microscanner's optimal design and performance. Examining the characteristics of the mirror response, we found that, for a certain DC voltage range, a two-to-one internal resonance might be activated between the first two modes. Due to this internal resonance, the mirror exhibits complex dynamic behavior. This behavior results in undesirable vibrations that can be detrimental to the scanner performance. Torsional micromirrors are currently being implemented to provide all-optical switching in fiber optic networks. Traditional switching techniques are based on converting the optical signal into electrical signal and back into optical signal before it can be switched into another fiber. This reduces the rate of data transfer substantially. To realize fast all-optical switching, we enhance the transient dynamic characteristics and performance of torsional micromirrors by developing a novel technique for preshaping the voltage commands applied to activate the mirror. This new approach is the first to effectively account for inherent nonlinearities, damping effects, and the energy of the significant higher modes. Using this technique, we are able to realize very fast switching operations with minimal settling time and almost zero overshoot. / Ph. D.
180

The American Village: as Revealed in the Autobiographical Fiction of E.W. Howe, Stephen Crane, and Clarence S. Darrow

Markey, Mary M. January 1961 (has links)
No description available.

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