A Universal RAM Machine Resistant to Isolated Bursts of Faults

The most natural question of reliable computation, in every computation model and noise model,is whether given a certain level of noise, a machine of that model exists that canperform arbitrarily complex computations under noise of that level. This question has positive answers for circuits, cellular automata, and recently for Turing machines. Here, we raise the question of the existence of a random access machine that---with some moderate slowdown --- can simulate any other random access machine even if the simulator is subjected to constant size bursts of faults separated by a certain minimum number of steps from each other. We will analyze and spell out the problems and difficulties that need to be addressed in such construction

Context-Aware Intelligent Traffic Light Control through Secure Messaging

In this paper, we propose STCM, a context-aware secure traffic control model to manage competing traffic flows at a given intersection by using secure messages with real-time traffic information. The vehicle is modeled as a virtual sensor which reports the traffic state, such as its speed and location, to a traffic light controller through a secure and computationally lightweight protocol. During the reporting process, a vehicle’s identity and location are kept anonymous to any other vehicle in the system. At an intersection, the traffic light controller receives the messages with traffic information, verifies the identities of the vehicles, and dynamically implements and optimizes the traffic light phases in real-time. Moreover, the system is able to detect the presence of emergency vehicles (such as ambulances and fire fighting trucks) in the communication range and prioritize the intersection crossing of such vehicles to in order to minimize their waiting times. The simulation results demonstrate that the system significantly reduces the waiting time of the vehicles in both light and heavy traffic flows compared to the pretimed signal control and the adaptive Webster’s method. Simulation results also yield effective robustness against impersonating attacks from malicious vehicles. Document type: Articl

A fault-tolerant Turing machine

Thesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.The Turing machine is the most studied universal model of computation. This thesis studies the question if there is a Turing machine that can compute reliably even when violations of its transition function occur independently of each other with some small probability. In this thesis, we prove the existence of a Turing machine that - with a polynomial overhead - can simulate any other Turing machine, even when it is subject to faults of the above type, thereby answering the question that was open for 25 years