To see the other types of publications on this topic, follow the link: Derricks.
Dissertations / Theses on the topic 'Derricks'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Derricks.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Sorensen, Khalid Lief. "A Combined Feedback and Command Shaping Controller for Improving Positioning and Reducing Cable Sway in Cranes." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6853.
Full textAbstract:
Bridge and gantry cranes are crucially important elements in the industrial complex; they are used in many areas such as shipping, building construction, steel mills, and nuclear facilities, just to name a few.
These types of systems tend to be highly flexible in nature, generally responding to commanded motion with oscillations of the payload and hook. The response of these systems to external disturbances, such as wind, is also oscillatory in nature. Often, the oscillations of the hook and payload have undesirable consequences. For instance, precise manipulation of payloads is difficult when cable sway is present. Oscillation of the hook can also present a safety hazard. For these reasons, the ability to successfully negate these detrimental dynamics can result in improved positioning, quicker settling time, and improved safety.
This thesis addresses the dynamic properties of bridge and gantry cranes in an effort to develop a control scheme that enables strides to be made in these areas of positioning, efficiency, and safety.
The fundamental advancement arising from this thesis is the development of a control scheme that enables precise positioning of the payload while motion and disturbance-induced oscillations are eliminated. A command generation technique uniquely suited for reducing oscillation in low-frequency flexible systems is examined and utilized in the control. The control scheme is implemented on a 10-ton bridge crane for validation purposes.
2
Vaughan, Joshua Eric. "Dynamics and control of mobile cranes." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24736.
Full textAbstract:
Thesis (Ph.D.)--Mechanical Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: William Singhose; Committee Member: John-Paul Clarke; Committee Member: Kok-Meng Lee; Committee Member: Patricio Vela; Committee Member: Rhett Mayor.
3
Peng, Chen Chih. "Interfaces and control systems for intuitive crane control." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31782.
Full textAbstract:
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010.<br>Committee Chair: Singhose, William; Committee Member: Sadegh, Nader; Committee Member: Ueda, Jun. Part of the SMARTech Electronic Thesis and Dissertation Collection.
4
Ramesh, Periyakulam S. "Experimental design and results of 2D dynamic damping of payload motion for cranes." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-07102009-040346/.
Full text
5
Manning, Raymond Charles. "Improving the control of two-mode flexible systems with input shaping." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22566.
Full text
6
Shang, Jin. "Solution techniques for a crane sequencing problem." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4539.
Full textAbstract:
Thesis (Ph. D.)--West Virginia University, 2006.<br>Title from document title page. Document formatted into pages; contains viii, 99 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 93-99).
7
張大任 and Tai-yam Cheung. "Evolutionary design of fuzzy-logic controllers for overhead cranes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31243010.
Full text
8
Cheung, Tai-yam. "Evolutionary design of fuzzy-logic controllers for overhead cranes /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23636543.
Full text
9
Ruddy, Thomas A. "Anti-sway control of a construction crane modeled as a two-dimensional pendulum." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12302008-063756/.
Full text
10
Rauch, Andreas. "Stability analysis of mobile boom cranes." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26535.
Full textAbstract:
Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: William Singhose; Committee Member: Nader Sadegh; Committee Member: Wayne J. Book. Part of the SMARTech Electronic Thesis and Dissertation Collection.
11
Chui, Yun Chuen. "Coordinated scheduling with two automatic stacking cranes in a container block /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?IELM%202009%20CHUI.
Full text
12
Hernandez, Eileen Cynthia. "Dynamic characterization and analysis of aerial lifts." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45944.
Full textAbstract:
Aerial lifts are used to elevate people and material to high heights. There are many different types of aerial lifts which have vastly different dynamics characteristics. Thus, a new categorization for aerial lifts was created and organizes them by their kinematics. Many accidents occur while using aerial lifts. Hazards of aerial lifts and current solutions to those hazards were reviewed to understand the causes of the accidents. Some major accidents are due to the complex dynamics and flexibility of aerial lifts, such as oscillations and tip-overs. Oscillations of full-size aerial lifts were experimentally tested to determine frequencies in different configurations. Machine-motion induced oscillations of an articulating aerial lift were simulated and analyzed for both non-overcenter and overcenter configurations. Input shaping was used to achieve reduction in machine-motion induced oscillations. Tip-over stability margin was used to simulate and analyze the stability of both non-overcenter and overcenter configurations. The effect of increased platform mass on tip-over stability margin was also analyzed. The results in this thesis are a categorization of aerial lifts including their hazards and methods of reducing those hazards, an experimental verification of the dynamic response of full-size aerial lifts, a fully dynamic tip-over prediction model of double-boom articulating aerial lift by applying flexibility in the joints and realistic velocity profiles, and a detailed study of the dynamics of a double-boom articulating aerial lift.
13
Huey, John. "Dynamics and vibration control of large area manipulators." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/16469.
Full text
14
Wang, Lei. "Quay crane scheduling at container terminals : reducing the maximum tardiness of vessel departures /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?IEEM%202003%20WANGL.
Full textAbstract:
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.<br>Includes bibliographical references (leaves 40-42). Also available in electronic version. Access restricted to campus users.
15
Ak, Aykagan. "Berth and quay crane scheduling problems, models and solution methods /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26652.
Full textAbstract:
Thesis (Ph.D)--Industrial and Systems Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: Erera, Alan L.; Committee Member: Ergun, Ozlem; Committee Member: Savelsbergh, Martin; Committee Member: Tetali, Prasad; Committee Member: White III, Chelsea C.. Part of the SMARTech Electronic Thesis and Dissertation Collection.
16
Maleki, Ehsan A. "Dynamics and control of a small-scale mobile boom crane." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37166.
Full textAbstract:
Boom cranes are one of the most dynamically complicated types of cranes because they possess rotational joints as opposed to the linear tracks of bridge and gantry cranes. In addition, if the boom crane is placed on a mobile base, additional complexity is added to the system. However, mobile boom cranes have huge potential benefits as they can be quickly transported from one location to another. Furthermore, if they utilize their mobile base during lifting operations, then they can have an extremely large workspace. All cranes share the same limiting weakness; the payload oscillates when the crane moves. A command-generation approach is taken to control the payload oscillation. Input shaping is one such command-generation technique that modifies the original reference command by convolving it with a series of impulses. The shaped command produced by the convolution can then move the crane without inducing payload oscillation. Input shaping can accommodate parameter uncertainties, nonlinearities, multiple modes of vibration, and has been shown to be compatible with human operators. This thesis focuses on three aspects of mobile boom cranes: 1) dynamic analysis, 2) input-shaping control, and 3) experimental testing. A majority of the thesis focuses on analyzing and describing the complicated dynamics of mobile boom cranes. Then, various input-shaping controllers are designed and tested, including two-mode shapers for double-pendulum dynamics. In order to experimentally verify the simulation results, a small-scale mobile boom crane has been constructed. The details of the mobile boom crane and its important features are presented and discussed. Details of the software used to control the crane are also presented. Then, several different experimental protocols are introduced and the results presented. In addition, a set of operator performance studies that analyze human operators maneuvering the mobile boom crane through an obstacle course is presented.
17
Tsang, Wan-sze, and 曾韻詩. "Genetic algorithm for scheduling yard cranes in port container terminals." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29544609.
Full text
18
Fujioka, Daichi. "Tip-over stability analysis for mobile boom cranes with single- and double-pendulum payloads." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37162.
Full textAbstract:
This thesis investigated a tip-over stability of mobile boom cranes with swinging payloads. Base and crane motion presents a tip-over problem. Attaching complex payloads further complicates the problem. They study began with a single-pendulum payload to analyze a tip-over stability characteristics under different conditions. A simple tip-over prediction model was developed with a goal of limiting a computational cost to a minimum. The stability was characterized by a tip-over stability margin method. The crane's tip-over stability was also represented by the maximum possible payload it can carry throughout the workspace. In a static stability analysis, mobile boom crane was assumed to be stationary, thus with no payload swing. The study provided basic understanding on the relationship between tip-over stability and boom configuration. In a pseudo-dynamic stability analysis, the method incorporated payload swing into the analysis by adding estimated maximum payload swing due to motions. To estimate the angles, differential equations of motions of payload swings were derived. The thesis extended the study to a double-pendulum payload. The maximum swing angles estimated in the single-pendulum case were directly applied to the double-pendulum case. To validate the analytical methods, a full dynamic multi-body simulation model of a mobile boom crane was developed. The predictions from the previous analysis were verified by the simulation results. The prediction model and the analytical methods in the thesis provide a significant tool for practical application of tip-over stability analysis on mobile boom cranes. The experimental results increase the confidence of the study's accuracy.
19
Wen, Charlie Hsiao Kuang. "Heuristic approaches for crane scheduling in ship building." Master's thesis, Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-07012008-141639.
Full text
20
Lawrence, Jason William. "Crane Oscillation Control: Nonlinear Elements and Educational Improvements." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-07072006-175615/.
Full textAbstract:
Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2007.<br>William Singhose, Committee Chair ; Steven Danyluk, Committee Member ; Donna Llewellyn, Committee Member ; Nader Sadegh, Committee Member ; Neil Singer, Committee Member.
21
Danielson, Jon David. "Mobile boom cranes and advanced input shaping control." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24651.
Full text
22
Jacobs, Laura Diane. "Shake table experiments for the determination of the seismic response of jumbo container cranes." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37200.
Full textAbstract:
Container cranes represent one of the most critical components of ports worldwide. Despite their importance to port operations, the seismic behavior of cranes has been largely ignored. Since the 1960s, industry experts have recommended allowing cranes to uplift, believing that it would limit the amount of seismic loading. However, modern cranes have become larger and more stable, and the industry experts are now questioning the seismic performance of modern jumbo cranes.
The main goal of this research was to experimentally investigate the seismic behavior of container cranes from the general elastic behavior through collapse, including non-linear behavior such as buckling and cross section yielding, utilizing the 6 degree-of-freedom shake tables at the University at Buffalo. The testing was divided into two phases. The first phase of testing was conducted on a 1/20th scale model. The second phase of testing was conducted on a 1/10th scale model, which was designed such that no inelastic action would develop prior to uplift (as is the common design practice). In support of the experiments, finite element models were created to determine what simplifications could be made to the structure to aid in testing. The data collected from the testing has been used to validate finite element models, to give a better understanding of the behavior of container cranes under seismic excitations, validate fragility models, and to develop recommendations and guidelines for the design and testing of container cranes.
23
Maleki, Ehsan A. "Control of human-operated machinery with flexible dynamics." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50305.
Full textAbstract:
Heavy-lifting machines such as cranes are widely used at ports, construction sites, and manufacturing plants in a variety of material-transporting applications. However, cranes possess inherent flexible dynamics that make fast and precise operation challenging. Most cranes are driven by human operators, which adds another element of complexity. The goal of this thesis is to develop controllers that allow human operators to easily and efficiently control machines with flexible dynamics. To improve the ease of human operation of these machines, various control structures are developed and their effectiveness in aiding the operator are evaluated. Cranes are commonly used to swing wrecking balls that demolish unwanted structures. To aid the operator in such tasks, swing-amplifying controllers are designed and their performance are evaluated through simulations and experiments with real operators. To make maneuvering of these machines in material-transporting operations easier, input-shaping control is used to reduce oscillation induced by operator commands. In the presence of external disturbances, input shaping is combined with a low-authority feedback controller to eliminate unwanted oscillations, while maintaining the human operator as the primary controller of the machine. The performance and robustness of the proposed controllers are thoroughly examined via numerical simulations and a series of experiments and operator studies on a small-scale mobile boom crane and a two-ton dual-hoist bridge crane.
24
Peng, Chen-Chih. "Methods for improving crane performance and ease of use." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50343.
Full textAbstract:
Cranes are widely used in material-handling and transportation applications, e.g. in shipyards, construction sites, and warehouses. As they are critical to the economic vitality of modern-day industries, improving crane performance and ease of use are important contributors to industrial productivity, low production costs, and workplace safety.
In a typical crane operation, a payload is lifted, moved to its destination, and then lowered into place. This dissertation aims to improve crane performance and reduce task difficulty for the human operator in the movements mentioned above, namely: 1) Moving payloads laterally in the horizontal plane, 2) Lifting payloads off the ground, and 3) Lowering or laying down payloads on the ground.
The design of a novel and intuitive human-machine control interface is the focus for improving operations that involve moving payloads laterally. The interface allows operators to drive a crane by simply moving a hand-held device through the desired path. The position of the device, which is tracked by sensors, is used to generate command signals to drive the crane. This command is then input-shaped such that payload oscillations are greatly reduced, making it much easier for the operator to drive the crane. Several facets of this crane control method are examined, such as control structure and stability, usability contexts, modes of operation, and quantitative measures (by means of human operator studies) of performance improvements over standard crane control interfaces.
Lifting up a payload can be difficult for the operator, if the hoist is not properly centered above the payload. In these potentially dangerous and costly ``off-centered" lifts, the payload may slide on the ground and/or oscillate in the air after it is hoisted. Newtonian and Coulomb friction models that focus on the stiction-sliding-separation contact dynamics are derived and experimentally verified to study off-centered lifts. Then, with the goal of aiding operators during lift operations, simple but practical, self-centering solutions are proposed and implemented.
Laying down or lowering a payload to the ground can also be challenging for operators in certain situations. For example, laying down a long, slender payload from a vertical orientation in the air, to a horizontal position on a flat surface. If the operator does not properly coordinate the motions of the crane in the vertical and horizontal directions simultaneously, then the potential hazards that may occur during these operations include: 1) slipping of the pivot about which the payload rotates, leading to sudden and dangerous payload movements; and 2) excessive hoist cable angles that lead to ``side-pull" problems. Newtonian and Coulomb friction models are derived to describe this lay-down scenario. The forces and motions experienced by the payload are then used to determine the motion trajectories that the crane and payload should follow to execute a successful lay-down maneuver.
Finally, a special chapter is included to address the oscillation control of systems that have on-off nonlinear actuators, such as cranes powered by relay-controlled circuits. Due to their simplicity, ruggedness, and long service life, this type of crane can be commonly found in older factories or in applications where precise motion control is not a strict requirement. However, controlling payload oscillations on this type of crane is challenging for two reasons: 1) Relays that can only be turned on or off allow for only limited control over the crane velocity; and 2) These cranes typically have nonlinear asymmetrical acceleration and deceleration properties. Methods are derived for determining the relay switch-times that move single-pendulum and double-pendulum payloads with low residual oscillations.
25
Pizarro, David Victor. "Pulse rate, pulse pattern, and onset distance effects on subject braking responses while using an auditory collision warning signal." Thesis, Virginia Tech, 1994. http://hdl.handle.net/10919/40655.
Full text
26
Kosbab, Benjamin David. "Seismic performance evaluation of port container cranes allowed to uplift." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33921.
Full textAbstract:
The seismic behavior of port container cranes has been largely ignored-by owners, operators, engineers, and code officials alike. This is despite their importance to daily port operations, where historical evidence suggests that port operational downtime following a seismic event can have a crippling effect on the affected local, regional, and national economies. Because the replacement time in the event of crane collapse can be a year or more, crane collapse has the potential to be the "critical path" for post-disaster port recovery. Since the 1960's, crane designers allowed and encouraged an uplift response from container cranes, assuming that this uplift would provide a "safety valve" for seismic loading; i.e. the structural response at the onset of uplift was assumed to be the maximum structural response. However, cranes have grown much larger and more stable such that the port industry is now beginning to question the seismic performance of their modern jumbo container cranes.
This research takes a step back, and reconsiders the effect that uplift response has on the seismic demand of portal-frame structures such as container cranes. A theoretical estimation is derived which accounts for the uplift behavior, and finds that the "safety valve" design assumption can be unconservative. The resulting portal uplift theory is verified with complex finite element models and experimental shake-table testing of a scaled example container crane. Using the verified models, fragility curves and downtime estimates are developed which characterize the risk of crane damage and operational downtime for three representative container cranes subjected to a range of earthquakes. This research demonstrates that container cranes designed using previous and current standards can significantly contribute to port seismic vulnerability. Lastly, performance-based design recommendations are provided which encourage the comparison of demand and capacity in terms of the critical portal deformation, using the derived portal uplift theory to estimate seismic deformation demand.
27
Sorensen, Khalid Lief. "Operational Performance Enhancement of Human Operated Flexible Systems." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24773.
Full textAbstract:
Recent decades have been witness to explosive leaps in manufacturing productivity. Advances in communication technology, computing speed, control theory, and sensing technology have been significant contributors toward the increased productivity and efficiency that industry has exhibited. The continued growth of technological equipment and engineering knowledge challenges engineers to fully utilize these advancements in more sophisticated and useful automation systems.
One such application involves enhancing bridge and gantry crane operation. These systems are used throughout the globe, and are critical aspects of industrial productivity. Consequently, improving the operational effectiveness of cranes can be extremely valuable.
Effective control of cranes can be largely attributed to two distinct, but related aspects crane manipulation: 1) the expertise of operators, which are responsible for issuing commands to the structures, and 2) the dynamic properties of cranes, which influence how the structures respond to issued commands. Accordingly, the operational efficiency of cranes can be influenced by changing both the way that operators issue commands to cranes, and also how the crane responds to issued commands.
This thesis is concerned with dynamic control theory of flexible machines, and human/machine interaction, especially as these areas relate to industrial crane control. In the area of dynamic control, this thesis investigates control strategies that are specifically suited for use on systems that possess common actuator nonlinearities, like saturation, rate limiting, dead-zone, backlash, and finite-state actuation. In the area of human/machine interaction, this thesis investigates the effects of different crane interface devices on the operational efficiency of cranes.
28
Schmidt, Aubrey-Derrick Verfasser], and Sahin [Akademischer Betreuer] [Albayrak. "Detection of Smartphone Malware / Aubrey-Derrick Schmidt. Betreuer: Sahin Albayrak." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2011. http://d-nb.info/1014946328/34.
Full text
29
Mashau, Thinandavha Derrick. "Towards a strategy for poverty alleviation in Mashau / Thinandavha Derrick Mashau." Thesis, North-West University, 2006. http://hdl.handle.net/10394/949.
Full textAbstract:
The main aim of this study is to investigate the poverty situation and outline a
strategy for poverty alleviation in the rural area of Mashau. Mashau is one of the
villages in the Limpopo province of South Africa and it forms part of the 70% of the
country's most poor people who are in the rural areas. Chapter 1 of this study
presupposed by way of a central theoretical argument that community based job
creation projects that ensure the participation of all stakeholders, community
members, government, traditional leaders, non-government and faith-based
organizations and business people, can be a useful poverty alleviation strategy in
general and also in Mashau. This should be implemented in line with the human
centred approach. Each of the four objectives (1.3) comes under scrutiny in
Chapters 2-5 respectively.
The quest to investigate and assess the poverty situation at Mashau and to come up
with a relevant strategy required a broader understanding of the economic and
demographic context of the entire Republic of South Africa. That is why Chapter 2
of this study mainly focused on identifying the core variables that are used to measure
levels of poverty in South Africa, whilst Chapter 3 focused on current strategic
initiatives for poverty alleviation on the part of the government.
Chapter 4 paid attention to the scale, manifestations and causes of poverty in
Mashau. It became clear that the majority of people in Mashau are unemployed, lack
the basics of life and are unable to access services. They depend mainly on
government social grants and natural resources (small-scale farming) for subsistence.
Although South African policies and frameworks for poverty alleviation are among
the best in the world, they have failed the country's people regarding implementation.
Mashau village is one of many examples of this neglect. The government has
succeeded in building a small number of RDP houses and providing other services at
a very low pace. But further than that, the Mashau people cannot experience and
enjoy the beauty of South African economic policies and strategies for poverty
alleviation.
Chapter 5 suggests a relevant strategy for poverty alleviation at Mashau. The strategy
proposed affirms the central theoretical argument outlined in Chapter 1. It may be
concluded that the suggested strategy can only succeed if the implementation plan or
program is put in place together with monitoring and evaluating systems.<br>Thesis (M. Development and Management)--North-West University, Potchefstroom Campus, 2006.
30
Pokharel, Rajib. "Structural Optimization of Offset Derrick Structure and Channel Endplate Connections Study." Thesis, University of Louisiana at Lafayette, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10002396.
Full textAbstract:
<p> This study is intended to focus on the optimization of offset derrick structures and to present a novel connection details for derrick structures. The overall goal of this study is to improve performance, ease fabrication, and reduce material and labor costs associated with derrick structures, and study the performances of Double Channel Endplate and Single Channel Endplate Connections using Finite Element Method (FEM) analysis. </p><p> Optimization of derrick structure is carried out by modeling different bracing systems with different parameters of design, for example, vertical panel height, bracing type, buckling restraint, and member orientation to come to optimum result in terms of structural weight, lateral stiffness, and number of joints. Eccentric bracing system, 2X-bracing system, X-bracing system, and K-bracing system are studied and comparisons are made among structures with similar vertical panel height to come to efficient geometry of that category. A Double Channel and Single Channel Endplate connection are developed and modeled to see the stress distribution, moments, and rotation capacities. Finally, behavioral plots (moment-rotation) are modeled to rate the performance of connections. </p><p> Structures with relatively shorter force path, uniform internal force distribution, and small internal forces are found to respond well and they are stiff, economical, and elegant as well. For 2X-bracing system, efficiency of offset derrick structure to resist the load is found to decrease for both small and large vertical panel height and optimum height was found in between. For this study, the optimum height was 20 ft. for 2X-bracing system. Thickness, and overlapping length of channel plate is found important for in-plane capacity of connection while stiffeners are more important for out-of-plane capacity. Connection is found to have higher in-plane bending stiffness than for out-of-plane. </p>
31
Mehta, Urmish R. "Optimal control of a high speed overhead crane including hoisting." Ohio : Ohio University, 1992. http://www.ohiolink.edu/etd/view.cgi?ohiou1172863064.
Full text
32
Hecker, Achim. "Übergänge Metaphysikkritik auf den Spuren Heideggers und Derridas /." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963843885.
Full text
33
Gasslander, Åke. "Att uttrycka det otänkbara : Jacques Derridas farmakon som argument." Thesis, Uppsala universitet, Litteraturvetenskapliga institutionen, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-385268.
Full textAbstract:
I den här uppsatsen ämnar jag att undersöka retoriken i ordet farmakon så som det behandlats av Jacques Derrida. Genom en nära läsning av Derridas texter identifieras farmakon först som ett ogripbart koncept och sedan som en typ av paradox. Funktionen av denna paradox beskrivs först ur en derrideansk kontext och senare i en mer klassisk retorisk sådan. I den här uppsatsen visas farmakon fungera som något som låter oss inse tänkandets gränser, samtidigt som vi ges en förklaring på vad som utgör dessa gränser. Farmakon visas också förlänas en större retorisk effekt på grund av Derridas dubbla läsning, medan retoriken i farmakon visas vara beroende av ett kunskapssökande hos publiken.
34
Debnath, Rakhi. "Revisiting the tale of Jacques Derridas deconstruction: critical study." Thesis, University of North Bengal, 2019. http://ir.nbu.ac.in/handle/123456789/3649.
Full text
35
Nolan, Derrick. "Implementing a competing limit increase challenger strategy to a retail - banking segment / Derrick Nolan." Thesis, North-West University, 2008. http://hdl.handle.net/10394/2859.
Full textAbstract:
Today, many financial institutions extending credit rely on automated credit scorecard decision engines to drive credit strategies that are used to allocate (application scoring) and manage (behavioural scoring) credit limits. The accuracy and predictive power of these models are meticulously monitored, to ensure that they deliver the required separation between good (non-delinquent) accounts and bad (delinquent) accounts.
The strategies associated to the scores (champion strategies) produced using the scorecards, are monitored on a quarterly basis (minimum), ensuring that the limit allocated to a customer, with its associated risk, is still providing the lender with the best returns on their appetite for risk. The strategy monitoring opportunity should be used to identify possible clusters of customers that are not producing the optimal returns for the lender. The identified existing strategy (champion) that does not return the desired output is challenged with an alternative strategy that may or may not result in better results. These clusters should have a relatively low credit risk ranking, be credit hungry, and have the capacity to service the debt. This research project focuses on the management of (behavioural) strategies that manage the ongoing limit increases provided to current account holders. Utilising a combination of the behavioural scores and credit turnover, an optimal recommended or confidential limit is calculated for the customer. Once the new limits are calculated, a sample is randomly selected from the cluster of customers and tested in the operational environment. With the implementation of the challenger, strategy should ensure that the intended change on the customer's limit is well received by the customers. Measures that can be used are risk, response, retention, and revenue. The champion and challenger strategies are monitored over a period until a victor (if there is one) can be identified. It is expected that the challenger strategy should have a minimal impact on the customers affected by the experiment and that the bank should not experience greater credit risk from the increased limits. The profit from the challenger should increase the interest revenue earned from the increased limit. Once it has been established through monitoring whether the champion or the challenger strategy has won, the winning strategy is rolled-out to the rest of the customers from the champion population.<br>Thesis (Ph.D. (Operational Research))--North-West University, Vaal Triangle Campus, 2009.
36
Potter, James Jackson. "Input-shaped manual control of helicopters with suspended loads." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50342.
Full textAbstract:
A helicopter can be used to transport a load hanging from a suspension cable. This technique is frequently used in construction, firefighting, and disaster relief operations, among other applications. Unfortunately, the suspended load swings, which makes load positioning difficult and can degrade control of the helicopter. This dissertation investigates the use of input shaping (a command-filtering technique for reducing vibration) to mitigate the load swing problem. The investigation is conducted using two different, but complementary, approaches. One approach studies manual tracking tasks, where a human attempts to make a cursor follow an unpredictably moving target. The second approach studies horizontal repositioning maneuvers on small-scale helicopter systems, including a novel testbed that limits the helicopter and suspended load to move in a vertical plane. Both approaches are used to study how input shaping affects control of a flexible element (the suspended load) and a driven base (the helicopter). In manual tracking experiments, conventional input shapers somewhat degraded control of the driven base but greatly improved control of the flexible element. New input shapers were designed to improve load control without negatively affecting base control. A method for adjusting the vibration-limiting aggressiveness of any input shaper between unshaped and fully shaped was also developed. Next, horizontal repositioning maneuvers were performed on the helicopter testbed using a human-pilot-like feedback controller from the literature, with parameter values scaled to match the fast dynamics of the model helicopter. It was found that some input shapers reduced settling time and peak load swing when applied to Attitude Command or Translational Rate Command response types. When the load was used as a position reference instead of the helicopter, the system was unstable without input shaping, and adding input shaping to a Translational Rate Command was able to stabilize the load-positioning system. These results show the potential to improve the safety and efficiency of helicopter suspended load operations.
37
Peter, Martin G., Abiy Yenesew, Hannington Twinomuhwezi, et al. "Antiplasmodial and larvicidal flavonoids from Derris trifoliata." Universität Potsdam, 2009. http://opus.kobv.de/ubp/texte_eingeschraenkt_verlag/2010/4461/.
Full textAbstract:
From the dichloromethane-methanol (1:1) extract of the seed pods of Derris trifoliata, a new flavanone derivative (S)-lupinifolin 4´-methyl ether was isolated. In addition, the known flavonoids lupinifolin and rotenone were identified. The structures were determined on the basis of spectroscopic evidence. Lupinfolin showed moderate in vitro antiplasmodial activity against the D6 (chloroquine-sensitive) and W2 (chloroquineresistant)
strains of Plasmodium falciparum. The different parts of this plant showed larvicidal activities against Aedes aegypti and rotenoids were identified as the active principles.
38
Haaf, Derrick [Verfasser]. "Einfluss des Umrichterbetriebs auf das akustische Verhalten im Gesamtsystem Asynchronmotor-Getriebe / vorgelegt von Derrick Haaf." Aachen : Mainz, 2004. http://d-nb.info/972713174/34.
Full text
39
Stallworth, Stefeni A. "A theoretical framework and application of Derrick Bell's interest-convergence principle an urban public community school /." Cincinnati, Ohio : University of Cincinnati, 2008. http://rave.ohiolink.edu/etdc//view?acc_num=ucin1211568841.
Full textAbstract:
Thesis (Ph.D.)--University of Cincinnati, 2008.<br>Advisors: Leo Krzywkowski (Committee Chair), Roger Collins PhD (Committee Chair), Mark Gooden PhD (Committee Chair), Patricia O'Reilly PhD (Committee Co-Chair). Title from electronic thesis title page (viewed June 1, 2010). Keywords: Interest-Convergence; Critical Race Theory; Urban Education Reform; Community School; Urban Public Community School Parents. Includes abstract. Includes bibliographical references.
40
Stallworth, Stefeni A. "A Theoretical Framework and Application of Derrick Bell’s Interest-Convergence Principle: An Urban Public Community School." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1211568841.
Full text
41
Högberg, Amelia. "Tilltro och kritik inom rätten : en läsning av Jacques Derridas Lagens kraft." Thesis, Södertörns högskola, Filosofi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-33704.
Full textAbstract:
The aim of this essay is to show how the relationship between credit and critique is important for Jacques Derrida’s deconstruction of law. I will start from Force of Law, in which law, as well as justice, is deconstructed by Derrida. My purpose is further to show how the two concepts, credit and critique, are intertwined in the discourse of law and thereby crucial for Derrida’s deconstruction. As Derrida always states, the rational projects need to have a master concept, which the project revolves around, and this master concept needs at least one other subordinate concept to contrast itself against. In this context, I argue that critique can be that master concept. I base this argument upon the fact that critique in its ancient Greek sense, krinein, can be translated into the verb ‘to separate’, ‘to decide’ or ‘to judge’, which shows that there is an obvious link to the task of a judge. This puts critique in center of the discourse of law. Credit on the other hand is not rational, which makes it opposed to critique, but it is still important for law. It is a typical subordinated concept that just appears in the discourse without any further explanation but is present by its implicit importance to the discourse. I argue that credit is the subordinate concept that is needed for the concept of critique to be a master concept. Both concepts are important for the foundation of law, and this is why I believe that Derrida in the end states the importance to take responsibility for the law. In other words, one must take responsibility for both founding aspects of credit and critique when deconstructing the law.
42
Mashau, Thinandavha Derrick. "Hugo du Plessis' contribution to the reformed Churches' struggle for a relevant mission and missiology / Thinandavha Derrick Mashau." Thesis, North-West University, 2004. http://hdl.handle.net/10394/417.
Full textAbstract:
It was the aim of this research to investigate Hugo du Plessis' contribution to the
GKSA' struggle for a relevant mission and missiology. It became apparent in the
course of the research that Du Plessis contributed in a meaningful way towards the
Reformed paradigm for a relevant mission and missiology. In the Dopper churches.
Hugo had a great reputation, which is fully justified. He was the first Dopper
missionary who stayed in a mission field for a considerable period and who, as a
result, could show a church that endured after years. Many people admired him as
"our missionary, the expert on mission and on the language and cultural anthropology
of the black peoples".
Mission-minded Doppers were not critical of him at all. On the other hand, in those
years mission and intensive contact with black people on a spiritual level were still
relative novelties to the average Dopper mind. There were those who did not trust any
missionary, because they suspected him of undermining "their Apartheid policy".
Between these two extremes, there was a majority who were neither enthusiastic nor
hostile towards mission. This picture only changed radically when Dr Jan Schutte
succeeded in bringing Prof J H Bavinck to Potchefstroom for a year.
Knowing how much suspicion he might create, Hugo was very careful not to offend
the Afrikaners. One should understand this attitude, since suspicion against him of
being a "liberalist" might slow down the flow of funds for mission and eventually
force him to leave the mission field. At that time the very fact that one was a
missionary was sufficient to mark one as "eccentric" in some circles. So if one finds
traces of racism and support of "Apartheid" in the life and works of du Plessis, one
should keep in mind that he was a child of his times, even though he was ahead of
most of his compatriots in his views. The very fact that he and his wife were willing
to endure the hardships of a mission field at that time speaks of his dedication.
However, it seems he was a far greater success as a theologian than as a missionary.<br>Thesis (Ph.D. (Missiology))--North-West University, Potchefstroom Campus, 2004.
43
Morel, Sylvie. "Etude phytochimique et évaluation biologique de Derris ferruginea Benth. (Fabaceae)." Phd thesis, Université d'Angers, 2011. http://tel.archives-ouvertes.fr/tel-00671071.
Full textAbstract:
Les plantes du genre Derris (Fabaceae) sont connues pour contenir des flavonoïdes, en particulier des isoflavonoïdes dont des roténoïdes. Derris ferruginea (Benth.), liane originaire d'Asie, est utilisée traditionnellement comme insecticide, poison de pêche et dans la lutte contre les ectoparasites. L'étude phytochimique d'extraits de tiges et de feuilles de Derris ferruginea a permis d'isoler et de caractériser 14 composés essentiellement de type flavanones et isoflavonoïdes. Ces composés comportent pour la plupart des prénylations. Une évaluation biologique étendue à la fois des extraits et de certains composés a été réalisée. Pour deux composés, des méthodes d'obtention alternatives ont été utilisées. La chromatographie de partage centrifuge a permis d'obtenir en quantité plus importante la cajaflavanone qui s'avère posséder des propriétés intéressantes du point de vue biologique (effet anti-inflammatoire sur cellules microgliales, inhibiteur de la formation des produits terminaux de glycation par un mécanisme non-antioxydatif, effet proangiogénique ex vivo). La synthèse d'un composé original a été entreprise et a permis de valider sa structure. Enfin, le composé majoritaire des feuilles a fait l'objet d'une étude préliminaire sur un modèle d'étude de l'activité insecticide : les DUM neurones de Periplaneta americana. Cette technique électrophysiologique a permis d'appréhender le mécanisme d'action de ce composé.
44
Corrêa, Raquel da Silva. "Toxicidade de extratos de timbós (Derris spp.) sobre Tetranychus desertorum (Acari: Tetranychidae) em folhas de pimentão." Universidade Federal do Amazonas, 2011. http://tede.ufam.edu.br/handle/tede/3135.
Full textAbstract:
Made available in DSpace on 2015-04-20T12:31:53Z (GMT). No. of bitstreams: 1
Raquel da Silva Correa.pdf: 2133386 bytes, checksum: 50c647396bc7dfa86c0445d6a28b0b4e (MD5)
Previous issue date: 2011-05-12<br>Fundação de Amparo à Pesquisa do Estado do Amazonas<br>The pepper is a vegetable of great importance socioeconomic in Brazil. Is among the ten most vegetables grown in country. Like most crops, many arthropods pests are associated with that culture, including some species of mites such as Tetranychus desertorum, reported infesting crops in Manaus. In most cases the mites are controlled by chemicals, which although effective can lead to problems both human health and the environment. In that sense, this work aimed to study the toxicity of extracts of Derris rariflora Benth. and Derris floribunda Benth. on T. desertorum leaf Pepper, aiming to offer products safer, cheaper and with less environmental impact. Plants were collected in natural areas, washed, dried and ground. Were then diluted in water distilled ethanol and acetone at concentrations of 0.5, 1, 10, 20 and 30%, resulting in aqueous extract, ethanol and acetone, these extracts were analyzed by High Performance Liquid Chromatography Efficiency. For bioassays, discs of pepper leaves were treated with extracts by dipping each disk and then received eight female mites. The commercial rotenone (98%) was also tested on the mites in concentrations of 0.1, 0.5 and 1%. It was found that rotenone is not present in aqueous extracts of the species. The extracts acetone and ethanol was found a rotenone content of 4.5 and 4% for D. floribunda and 4,3 e 5% for D. rariflora, not among them. The species D. rariflora was more toxic to the mite when compared to D. floribunda. Among the extracts, the ethanol was the most toxic followed by and aqueous acetone. The concentrations of 20 and 30% caused more mortality rates. The lowest LC50 was observed for the extract ethanolic D. rariflora. Rotenone commercial was not toxic to T. desertorum. However, except the aqueous extract of acetone and D. floribunda, which failed to achieve 50% mortality, the others were promising for control of T. desertorum on pepper leaves<br>O pimentão é uma hortaliça de grande importância socioeconômica no Brasil. Está entre as dez hortaliças mais cultivadas no país. Assim como a maioria das plantas cultivadas, muitos artrópodes pragas estão associados a essa cultura, entre eles algumas espécies de ácaros, como Tetranychus desertorum, relatado infestando plantios no município de Manaus. Na maioria das vezes os ácaros são controlados por produtos químicos, que apesar de eficientes podem acarretar problemas tanto a saúde humana quanto ao meio ambiente. Nesse sentido, o presente trabalho teve como objetivo estudar a toxicidade dos extratos de Derris rariflora Benth. e Derris floribunda Benth. sobre T. desertorum em folha de pimentão, visando à oferta de produtos mais seguros, menos onerosos e de menor impacto ambiental. As plantas foram coletadas em áreas naturais, lavadas, desidratadas e moídas. Em seguida, foram diluídas em água destilada, álcool etílico e acetona, nas concentrações de 0,5, 1, 10, 20 e 30%, resultando no extrato aquoso, etanólico e acetônico, esses extratos foram analisados por Cromatografia Líquida de Alta Eficiência. Para os bioensaios, discos de folhas de pimentão foram tratados com os extratos por meio de imersão e em seguida cada disco recebeu 8 ácaros fêmeas. A rotenona comercial (98%) também foi testadas sobre os ácaros, nas concentrações de 0,1, 0,5 e 1%. Foi verificado que a rotenona não está presente nos extratos aquosos das espécies estudadas. Nos extratos acetônico e etanólico foi verificado um teor de rotenona de 4,5 e 4% para D. floribunda e 4,3 e 5% para D. rariflora, não diferindo entre si. A espécie D. rariflora foi mais tóxica para o ácaro quando comparada a D. floribunda. Entre os extratos, o etanólico foi o mais tóxico seguido do aquoso e acetônico. As concentrações de 20 e 30% causaram maior percentual de mortalidade. A menor CL50 foi observada para o extrato etanólico de D. rariflora. A rotenona comercial não foi tóxica para T. desertorum. Contudo, com exceção ao extrato aquoso e acetônico de D. floribunda, que não atingiram 50% de mortalidade, os demais foram promissores para o controle de T. desertorum em folhas de pimentão
45
Weber, Christine. "Philosophien der Differenz zwischen Sprache und Schrift : Affinität und Divergenz im Denken Lyotards und Derridas /." Essen : Die Blaue Eule, 2009. http://d-nb.info/993691625/04.
Full text
46
Weber, Christine. "Philosophien der Differenz zwischen Sprache und Schrift Affinität und Divergenz im Denken Lyotards und Derridas." Essen Verl. Die Blaue Eule, 2008. http://d-nb.info/993691625/04.
Full text
47
Steinnes, Jenny. "Den andre skoleporten : Om institusjonalisering av den pedagogiske handling, et møte med Jacques Derridas språkkritiske perspektiver." Doctoral thesis, Norwegian University of Science and Technology, Department of Education, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1804.
Full textAbstract:
<p>Den grunnleggende problemstillingen i avhandlingen dreier rundt forståelser av språk og begreper der et institusjonaliseringsprinsipp blir forsøkt identifisert og problematisert ut fra Jacques Derridas språkkritiske perspektiver. Begreper som er spesielt behandlet og som er satt i forhold til institusjonaliseringsprinsippet er: sannhetsbegrepet, rettferdighet, demokrati, utvikling/transformasjon, territorium/sted/différance og opprinnelse/forutsetning.</p><p>I avhandlingen blir det konkludert med at en slik problematisering ikke leder fram til at institusjonaliseringsprinsippet blir presentert som et unngåelig prinsipp, som negativt eller mindre ønskelig. Det blir i stedet påpekt at kulturell virksomhet per definisjon vil måtte foregå som, og forholde seg til, dette prinsippet, men at det er et prinsipp som bør få ny oppmerksomhet i lys av en poststrukturalistisk språkkritikk. Rommet mellom strukturene, av Derrida gitt navnet différance ut fra prinsippet om det ureduserbart ulike, som “the threshold”, eller som en paradoksal Annen Port, både innenfor og mellom det institusjonaliserte, vil måtte få oppmerksomhet. Avhandlingen forsøker å vise at dette er spesielt relevante og aktuelle problemstillinger for pedagogikk som fagfelt, både som praksis og som akademisk disiplinfag.</p>
48
Curry, Tommy J. "Cast Upon The Shadows: Essays Toward The Culturalogic Turn In Critical Race Theory." OpenSIUC, 2009. https://opensiuc.lib.siu.edu/dissertations/59.
Full textAbstract:
Unlike many Black-specific disciplines in the academy (Black psychology, Black history, etc), Black philosophy never completely forged a unique conceptual framework separate from American and Continental intellectual traditions. Instead the field has continued to define its validity by the extent that Black authors extend the thought of white philosophers towards race. This epistemic convergence, or the extent to which Black theory converges with established white philosophical traditions, and hence white racial sensibilities, continues to misguide many of the current philosophical systems of Africana thought. Because this practice is so dominate, it has made current scholarship in African American and Africana thought derelict, in the sense that all investigations into Blackness are normatively, hence ideologically driven, and not culturally relevant to the actual lives of Africana people. Because whites are able to connect their work in traditional philosophy to studies of race under the misnomer of "critical race theory," these white associations with Black philosophy have given the illusion that integration and multicultural exchanges in Africana philosophy contribute to the restructuring of the discipline of philosophy and psychical changes in whites. Unfortunately this is merely wishful thinking that fails to consider the empirical research that confirms the undeniable failure of integration. This inability by Blacks to accept and explore racism without the illusion of racial coexistence in America makes current approaches to Black philosophy irrelevant to the present day struggles that Blacks find themselves burdened by in the American context. This dissertation however argues that the acceptance of the racial realist perspective, which accepts the permanence of racism, allows Blacks to "conceptually disengage" the triumphalism of the integrationist myth and explore the world without the illusion of anthropological parity. This lacuna in the European narration of liberal democracy's vision of equality spurs the culturalogical turn in Critical Race Theory, and introduces the philosophical insights of Derrick Bell and Paul Robeson as guiding voices towards the silencing of the idealist trends in contemporary studies of racism.
49
Lawson, Ata Martin. "Etude phytochimique d'une Fabacée tropicale, Lonchocarpus nicou : évaluation biologique préliminaire." Limoges, 2006. https://aurore.unilim.fr/theses/nxfile/default/81766147-569e-4f9d-a925-1b4c6ddcbcee/blobholder:0/2006LIMO300B.pdf.
Full textAbstract:
Cette thèse s’inscrit dans le cadre de la thématique de l'EA 4021 "Biomolécules et Thérapies Antitumorales". Elle vise essentiellement la recherche de molécules naturelles d’origine végétale, dotées d’une activité antitumorale. Lonchocarpus nicou (Aublet) D. C. Est une liane tropicale de la famille des Fabacées, longtemps utilisée pour ses propriétés insecticide, acaricide et piscicide, attribuées généralement à des roténoïdes prénylés (roténone essentiellement). Ces roténoïdes dérivent biogénétiquement des isoflavonoïdes connus depuis longtemps pour leur activité estrogénique. Cela explique le choix de cette plante qui n’a pas fait l’objet d’une étude phytochimique complète, contrairement à d’autres espèces du même genre. En effet, une dizaine de composés seulement sont jusqu'alors connus de L. Nicou. Nos travaux effectués concernent l'étude des extraits peu polaires (benzénique et hexanique) de la racine de cette plante. Ils sont développés et détaillés, après une description botanique de l'espèce et une présentation générale des molécules rencontrées dans le genre Lonchocarpus, puis dans l'espèce nicou. Cette étude phytochimique conduit à l'isolement et à la détermination structurale de trente huit molécules (dont trois sont à l'état de traces), grâce à l'utilisation de diverses techniques chromatographiques (CC, MPLC, CCM centrifuge, HPLC) et spectroscopiques (UV, RMN et SM). Ces résultats montrent une composition polyphénolique originale et diversifiée, caractérisée par quatre groupes de métabolites : chalcone (un composé), benzoquinone (un composé), isoflavonoïde (trente cinq composés) et un dérivé d'acide para coumarique (un composé). Outre la roténone, la déguéline et leurs deux dérivés 12ab-hydroxylés, qui s'accumulent préférentiellement dans la racine de cette plante, on distingue au niveau des autres phytocontituants mineurs treize composés naturels nouveaux et sept autres cités pour la première fois dans le genre. Ces quatre composés majeurs ont été testés par la suite, sur les récepteurs aux estrogènes, sur l'aromatase ainsi que sur deux lignées cellulaires cancéreuses : érythroleucémique humaine (cellules HEL), ostéosarcome humain (cellules 1547), en vue d'évaluer leur activité antiproliférative et cytotoxique. Les résultats obtenus sont satisfaisants (IC50 de l'ordre du nanomolaire) et ouvrent de nombreuses perspectives de recherche<br>According to the topic of our research team EA 4021 "Biomolécules et Thérapies Antitumorales", phytochemical study of Lonchocarpus nicou (Aublet) D. C. Was conducted in order to isolate natural molecules with antitumor or anticancer activity. Lonchocarpus nicou (Aublet) D. C. Is a tropical liana of the Fabaceae family used for a long time for its insecticidal, acaricidal and piscicidal activities assigned to prenylated rotenoids (rotenone essentially). Rotenoids derived biogenetically from isoflavonoids known a long time ago for their estrogenic activity. That explains the choice of this plant which was not completely studied in contrary to those species of Lonchocarpus genus. Indeed, about ten compounds only were reported in previous study of this plant. After botanical description and presentation of previous phytochemical studies about Lonchocarpus genus and nicou specie, the least polar extracts (bezenic and hexanic) studied in this work was developed. Their investigation led to the isolation and structural elucidation of thirty eight molecules (in which three ultra-minor compounds) by using various chromatographicals (CC, MPLC, CCM centrifuge, HPLC) and spectroscopics (UV, RMN and SM) techniques. This showed an original and diversified polyphenolic composition characterized by four groups of metabolites: chalcone (one compound), benzoquinone (one compound), isoflavonoid (thirty five compounds), and a para coumaric acid derivative (one compound). Besides rotenone, deguelin and their 12ab-hydroxylated derivatives, which constituted the major components of the root of Lonchocarpus nicou, thirteen new metabolites were found in the other minor phytochemicals as well as seven other never cited before in Lonchocarpus genus. Preliminary bioassays were further conducted on the four main isolated components by evaluating their effect on estrogens receptors and on aromatase enzyme. Their antiproliferative activity and cytotoxic effect on HEL (Human Erythroleukemia) cells and 1547 cells (osteosarcoma) have been also investigated. The latter biological study gave interesting results (IC50 about nanomolar) that might be explored by a solid scientific project
50
LÔBO, Lívia Trindade. "Investigação de metabólitos secundários de folhas de Derris urucu (Killip et Smith) Macbr. com atividades biológicas." Universidade Federal do Pará, 2009. http://repositorio.ufpa.br/jspui/handle/2011/4049.
Full textAbstract:
Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2013-07-01T22:18:33Z
No. of bitstreams: 2
license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5)
Tese_InvestigacaoMetabolitosSecundarios.pdf: 33546833 bytes, checksum: 8b53915fe9f8903b2e2ed7ec75293d2f (MD5)<br>Approved for entry into archive by Irvana Coutinho(irvana@ufpa.br) on 2013-07-02T12:42:44Z (GMT) No. of bitstreams: 2
license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5)
Tese_InvestigacaoMetabolitosSecundarios.pdf: 33546833 bytes, checksum: 8b53915fe9f8903b2e2ed7ec75293d2f (MD5)<br>Made available in DSpace on 2013-07-02T12:42:44Z (GMT). No. of bitstreams: 2
license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5)
Tese_InvestigacaoMetabolitosSecundarios.pdf: 33546833 bytes, checksum: 8b53915fe9f8903b2e2ed7ec75293d2f (MD5)
Previous issue date: 2009<br>CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Derris urucu, pertencente à família Leguminosae/Fabaceae, é conhecida popularmente como
“timbó”. As raízes desta espécie são utilizadas comumente como pesticidas e veneno para
peixe. Do gênero Derris foram relatados muitos estudos fitoquímicos, sendo as raízes a parte
mais estudada das plantas desse gênero. A denominação “timbó” é mais generalizada para as
espécies Derris urucu e Derris nicou que são as espécies que produzem, nas raízes,
substâncias da classe dos rotenóides como a rotenona e a deguelina, de onde deriva a
importância dessas plantas. Os extratos, bem como, as substâncias isoladas deste gênero são
responsáveis por um vasto conjunto de atividades biológicas, principalmente a atividade
inseticida. Do extrato etanólico das folhas de D. urucu, doze substâncias foram isoladas e
purificadas por Cromatografia Líquida de Alta Eficiência: cinco estilbenos, seis
diidroflavonóis e uma flavanona. A identificação estrutural foi feita com base na análise
espectrométrica de massas, de RMN 1H e 13C e técnicas de RMN bidimensionais, além de
comparação com dados encontrados na literatura. O extrato etanólico das folhas de D. urucu
foi submetido a bioensaios para avaliação do seu potencial alelopático, tendo exibido
relevantes percentuais de inibição da germinação de sementes e do desenvolvimento de
plantas invasoras de pastagens. Com o objetivo de detectar as substâncias responsáveis pela
atividade alelopática, três estilbenos e três diidroflavonóis foram selecionados e submetidos a
bioensaios de inibição de germinação e de desenvolvimento da radícula e do hipocótilo de
plantas daninhas. Os ensaios alelopáticos foram realizados com as substâncias isoladas e com
a combinação delas, visando também avaliar o sinergismo entre elas, no entanto, as inibições
observadas foram de magnitudes muito baixas. Por outro lado, quando as substâncias foram
testadas em misturas observou-se um aumento significativo dos percentuais de inibição, por
isso essas substâncias em misturas, podem ser consideradas promissoras para futuros estudos,
envolvendo atividade alelopática. Foram realizados, também, bioensaios de atividade
antioxidante com oito substâncias, sendo três estilbenos e cinco diidroflavonóis frente ao
radical DPPH. Neste bioensaio, não foi observada uma atividade antioxidante relevante,
justificada pela presença de poucas hidroxilas fenólicas nas estruturas das substâncias
testadas.<br>Derris urucu, belonging to the family Leguminosae / Fabaceae, is popularly known as
“timbó”. The roots of this species are commonly used as pesticides and poison to fish. From
Derris genus many phytochemical studies have been reported, the roots being of the most
studied part from the plants of this genus. The name “timbó” is most general for the species
Derris urucu and Derris nicou, which are the species that produce, in their roots, rotenoids
such as rotenone and deguelin, from which derives the importance of these plants. The
extracts, and the substances isolated from this genus are responsible for a wide range of
biological activities, mainly the insecticidal activity. From the ethanolic extract of leaves of
D. urucu, twelve compounds were isolated and purified by High Performance Liquid
Chromatography: five stilbenes, six dihydroflavonols and one flavanone. The structural
identification was based on the mass, 1H and 13C NMR spectrometric analysis and two
dimensional NMR, beyond comparison with literature data . The ethanolic extract of leaves of
D. urucu was submitted to bioassays to avaluate the allelophatic potential, presenting relevant
percentage of inhibition of seed germination and development of weeds in pastures. Aiming
to detect the substances responsible for allelophatic activity, three stilbenes and three
dihydroflavonols were selected and submitted to bioassays of inhibition of germination and
development of the radicle and hypocotyl of weeds. The allelophatic tests were performed
with the substances isolated and with the combination of them, aiming to assess the synergism
between them, but the magnitude of inhibition observed was very low. By other side, when
the substances were tested in mixtures there was a significant increase in the percentage of
inhibition, so these substances in mixtures, can be considered promising for future studies
involving allelophatic activity. An other test was carried out with the isolated compounds.
Three stilbenes and five dihydroflavonols were evaluated for DPPH radical scavenging
activity (antioxidant activity). In this bioassay, was not observed a significant antioxidant
activity, justified by the analysis in the structures of the substances tested.