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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.
71

Energy-aware encryption mechanism for m-commerce devices

Hamad, F. M. January 2010 (has links)
With the wide spread of mobile phones, PDAs, and Smartphones, M-Commerce has become a major application domain for mobile devices, unlike conventional wired networks, mobile devices allow the user to conduct online transactions regardless of the time and the place as long as there is mobile network coverage. However, online transactions require adequate level of security to insure the confidentiality, the integrity, and the availability of the user’s information. Security measures consume a considerable amount of energy and require more time in processing. The aim of this thesis is to optimise the energy and the resources consumption of mobile phones when applying variant symmetric and asymmetric schemes. This aim can be achieved through developing A System State Security Management Framework, SSSM, which will implement encryption schemes, symmetric and asymmetric, and will provide different options to enable the user to choose the type of encryption, the key size, and number of rounds of computation to optimise the energy consumption level of the mobile phone. This thesis compares the power and the resources consumed by the most commonly used encryption algorithms such as CAST, IDEA, Triple-DES, RSA, and AlGamal. This comparison helps to draw the advantages and disadvantages of each algorithm scheme used in reference to the security level it provides and the power it consumes. Implementing this mechanism will enhance the performance of mobile phones by increasing the security levelsprovided by the encryption schemes and utilising the limited power and resources efficiency. Therefore, confidentiality will be presented in mobile phones and variant encryption schemes, symmetric and asymmetric, and changeable key sizes and rounds, will ensure the authenticity of both senders and recipients depending on their needs as well as resources available. This research makes contributions in two major areas; the first area consists of the novel Energy Aware Encryption polices generated by this work, the second area of contribution is the energy measurements and experimental results which validate the approach presented in the research.
72

Cottage mobile phones in China

Cai, Guangning January 2010 (has links)
No description available.
73

A Modular, Behaviour-Based Hierarchical Controller For Mobile Manipulators

Gong, Kelvin January 2013 (has links)
A mobile manipulator is a robotic system consisting of a robotic manipulator mounted onto a mobile base. This greatly extends the workspace of the robotic manipulator and allows it to perform more tasks. However, combining both systems increases the complexity of the control task as well as introducing additional controller tasks such as coordination of motion, where executing the task can involve using both the mobile base and manipulator, and cooperation of task, where many tasks can be executed at once. In this thesis a controller for a mobile manipulator is developed from smaller, simple controller blocks, allowing the controller to be flexible, easy to understand, and straightforward to implement using well-known embedded software implementation approaches. A behaviour-based approach was used to build the individual controllers, and a hierarchical structure was used to organise the individual controllers to provide cooperation between them and coordinated motion. The task assigned to the controller was to reach a series of waypoints in a large workspace, while satisfying performance metrics of manipulability and tip-over sta- bility. The operation of the controller was tested in simulation using 100 randomly generated scenarios consisting of five randomly generated waypoints in each. Using default thresholds for manipulability and tip-over stability, the controller was success- fully able to complete all scenarios. Further simulations were then performed testing the effects of varying the thresholds of the performance metrics to explore the tradeoffs involved in different parameter choices. The controller was successful in a majority of these scenarios, with only a few failing due to extreme threshold choices. The reasons for these failures, and the corresponding lessons for robot designers are discussed. Finally, to demonstrate the modularity of the controller, an obstacle avoidance con- troller was added and simulation results showed the controller was capable of avoiding obstacles while still performing the same tasks that were used in previous tests. Successful simulation results of the controller across a range of performance metrics shows that the combination of a behaviour based and hierarchical approach to mobile manipulator control is not only capable of producing a functional controller, but also one that is more modular and easier to understand than the monolithic controllers developed by other researchers.
74

Design of a MAVT and analysis of test results

Gill, David Alan January 1998 (has links)
No description available.
75

Optimisation techniques for combining code modulation with equalisation for fading channels

Gomez, Jose Ismael Soto January 1997 (has links)
No description available.
76

Automatic frequency tuning control of microstrip patch antennas

Rostbakken, Olaf January 1997 (has links)
No description available.
77

An investigation of multi-format high speed wireless communications using a hybrid software : hardware packet based simulator

Horseman, Tony Roland January 2000 (has links)
No description available.
78

Development and applications of site-specific microcell comunications channel modelling using ray tracing

Anderson, Harry R. January 1994 (has links)
No description available.
79

A rapid response multilevel differential modem for narrowband mobile fading channels

Castle, Robert John January 1993 (has links)
No description available.
80

Linearisation of radio frequency power amplifiers using the Cartesian feedback technique

Boloorian, Majid January 1995 (has links)
No description available.

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