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Full-Text Articles in Computer Sciences
Simulating Mobile Ad Hoc Networks: A Quantitative Evaluation Of Common Manet Simulation Models, Calvin Newport
Simulating Mobile Ad Hoc Networks: A Quantitative Evaluation Of Common Manet Simulation Models, Calvin Newport
Dartmouth College Undergraduate Theses
Because it is difficult and costly to conduct real-world mobile ad hoc network experiments, researchers commonly rely on computer simulation to evaluate their routing protocols. However, simulation is far from perfect. A growing number of studies indicate that simulated results can be dramatically affected by several sensitive simulation parameters. It is also commonly noted that most simulation models make simplifying assumptions about radio behavior. This situation casts doubt on the reliability and applicability of many ad hoc network simulation results. In this study, we begin with a large outdoor routing experiment testing the performance of four popular ad hoc algorithms …
Ppl: A Packet Processing Language, Eric G. Krupski
Ppl: A Packet Processing Language, Eric G. Krupski
Dartmouth College Undergraduate Theses
Any computing device or system that uses the internet needs to analyze and identify the contents of network packets. Code that does this is often written in C, but reading, identifying, and manipulating network packets in C requires writing tricky and tedious code. Previous work has offered specification languages for describing the format of network packets, which would allow packet type identification without the hassles of doing this task in C. For example, McCann and Chandra's Packet Types [3] system allows the programmer to define arbitrary packet types and generates C unctions which match given data against a specified packet …
Mobile Agents Simulation With Dassf, Nikita E. Dubrovsky
Mobile Agents Simulation With Dassf, Nikita E. Dubrovsky
Dartmouth College Undergraduate Theses
Mobile agents are programs that can migrate from machine to machine in a network of computers and have complete control over their movement. Since the performance space of mobile agents has not been characterized fully, assessing the effectiveness of using mobile agents over a traditional client/server approach currently requires implementing an agent system and running time-consuming experiments. This report presents a simple mobile-agent simulation that can provide quick information on the performance and scalability of a generic information retrieval (IR) mobile-agent system under different network configurations. The simulation is built using the DaSSF and DaSSFNet frameworks, resulting in high performance …
Scheduling Pipelined, Multi-Threaded Programs In Linux, Brunn W. Roysden
Scheduling Pipelined, Multi-Threaded Programs In Linux, Brunn W. Roysden
Dartmouth College Undergraduate Theses
A process causes latency when it performs I/O or communication. Pipelined processes mitigate latency by concurrently executing multiple threads--- sequences of operations--- and overlapping computation, communication, and I/O. When more than one thread is ready to run, the scheduler determines which thread in fact runs. This paper presents techniques for scheduling pipelines, with the following three findings. First, using Linux kernel version 2.6 and the NPTL threads package, we observe a 3-6% performance improvement over kernel version 2.4 and the LinuxThreads package. Second, we test techniques that both take advantage of prior knowledge about whether a program is I/O-bound or …
Efficient Wait-Free Implementation Of Atomic Multi-Word Buffer, Rachel B. Ringel
Efficient Wait-Free Implementation Of Atomic Multi-Word Buffer, Rachel B. Ringel
Dartmouth College Undergraduate Theses
This thesis proposes algorithms for implementing a atomic multi-word buffer, which can be accessed concurrently by multiple readers and a single writer, from the hardware-supported shared memory. The algorithms are required to be wait-free: each process reads or writes the multi-word buffer in a bounded number of its own steps, regardless of whether other processes are fast, slow or have crashed. Our first algorithm is built from multi-writer, multi-reader variables whereas the second algorithm is built from single-writer, multi-reader variables. For either algorithm, the worst-case running time of a read or a write operation on the m-word buffer is O(m). …
Testing The Greenpass Wireless Security System, Kimberly S. Powell
Testing The Greenpass Wireless Security System, Kimberly S. Powell
Dartmouth College Undergraduate Theses
Greenpass, developed by Nick Goffee, Sung Hoon Kim, Meiyuan Zhao and John Marchesini under the supervision of Sean Smith and Punch Taylor, is a wireless security solution that implements SPKI/SDSI delegation on top of X.509 keypairs within the EAP-TLS authentication protocol. This system aims to model the decentralized way that authorization flows in real-world enterprise settings and provide a seamless solution that allows for easy access to all resources in the network by both registered users and authorized guests. These goals are achieved through the deployment of a delegation tool, which allows an active entity associated to the organization's network …
A Secure Network Node Approach To The Policy Decision Point In Distributed Access Control, Geoffrey H. Stowe
A Secure Network Node Approach To The Policy Decision Point In Distributed Access Control, Geoffrey H. Stowe
Dartmouth College Undergraduate Theses
To date, the vast majority of access control research and development has been on gathering, managing, and exchanging information about users. But an equally important component which has yet to be fully developed is the Policy Decision Point - the system that decides whether an access request should be granted given certain attributes of the requestor. This paper describes the research and implementation of a new PDP system for an undergraduate honors project. This PDP system employs three unique features which differentiate it from existing technology: collaboration capabilities, trusted management, and interoperability with other access control systems. Security considerations and …
Synchronizing Keyframe Facial Animation To Multiple Text-To-Speech Engines And Natural Voice With Fast Response Time, William H. Pechter
Synchronizing Keyframe Facial Animation To Multiple Text-To-Speech Engines And Natural Voice With Fast Response Time, William H. Pechter
Dartmouth College Undergraduate Theses
This thesis aims to create an automated lip-synchronization system for real-time applications. Specifically, the system is required to be fast, consist of a limited number of keyframes with small memory requirements, and create fluid and believable animations that synchronize with text-to-speech engines as well as raw voice data. The algorithms utilize traditional keyframe animation and a novel method of keyframe selection. Additionally, phoneme-to-keyframe mapping, synchronization, and simple blending rules are employed. The algorithms provide blending between keyframe images, borrow information from neighboring phonemes, accentuate phonemes b, p and m, differentiate between keyframes for phonemes with allophonic variations, and provide prosodromic …
Enhancing Expressiveness Of Speech Through Animated Avatars For Instant Messaging And Mobile Phones, Joseph E. Pechter
Enhancing Expressiveness Of Speech Through Animated Avatars For Instant Messaging And Mobile Phones, Joseph E. Pechter
Dartmouth College Undergraduate Theses
This thesis aims to create a chat program that allows users to communicate via an animated avatar that provides believable lip-synchronization and expressive emotion. Currently many avatars do not attempt to do lip-synchronization. Those that do are not well synchronized and have little or no emotional expression. Most avatars with lip synch use realistic looking 3D models or stylized rendering of complex models. This work utilizes images rendered in a cartoon style and lip-synchronization rules based on traditional animation. The cartoon style, as opposed to a more realistic look, makes the mouth motion more believable and the characters more appealing. …
Access Control In A Distributed Decentralized Network: An Xml Approach To Network Security Using Xacml And Saml, Paul J. Mazzuca
Access Control In A Distributed Decentralized Network: An Xml Approach To Network Security Using Xacml And Saml, Paul J. Mazzuca
Dartmouth College Undergraduate Theses
The development of eXtensible Distributed Access Control (XDAC) systems is influenced by the transference of data access and storage from the local computer to the network. In this distributed system, access control is determined by independent components which transmit requests and decisions over a network, utilizing XML signing capabilities found in the Security Assertion Markup Language (SAML). All resources in the XDAC system are protected by the first component, a Policy Enforcement Point (PEP), which acts as the main divider between the requesting entity and the requested resource. The PEP grants access to a resource only if the second component, …