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Dartmouth College

Dartmouth College Undergraduate Theses

2005

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Full-Text Articles in Physical Sciences and Mathematics

Managing Access Control In Virtual Private Networks, Twum Djin Jun 2005

Managing Access Control In Virtual Private Networks, Twum Djin

Dartmouth College Undergraduate Theses

Virtual Private Network technology allows remote network users to benefit from resources on a private network as if their host machines actually resided on the network. However, each resource on a network may also have its own access control policies, which may be completely unrelated to network access. Thus users� access to a network (even by VPN technology) does not guarantee their access to the sought resources. With the introduction of more complicated access privileges, such as delegated access, it is conceivable for a scenario to arise where a user can access a network remotely (because of direct permissions from …


Lower Bounds On The Communication Complexity Of Shifting, Marco D. Adelfio Jun 2005

Lower Bounds On The Communication Complexity Of Shifting, Marco D. Adelfio

Dartmouth College Undergraduate Theses

We study the communication complexity of the SHIFT (equivalently, SUM-INDEX) function in a 3-party simultaneous message model. Alice and Bob share an n-bit string x and Alice holds an index i and Bob an index j. They must send messages to a referee who knows only n, i and j, enabling him to determine x[(i+j) mod n]. Surprisingly, it is possible to achieve nontrivial savings even with such a strong restriction: Bob can now make do with only ceil(n/2) bits. Here we show that this bound is completely tight, for all n. This is an exact lower bound, with no …


A Toy Rock Climbing Robot, Matthew P. Bell May 2005

A Toy Rock Climbing Robot, Matthew P. Bell

Dartmouth College Undergraduate Theses

The goal of this thesis was to build a simple toy rock climbing robot, and to explore problems related to grasping, path planning, and robot control. The robot is capable of climbing a wall of pegs either under manual control through a host system and an infrared interface, or on the basis of a set of pre-recorded keyframes. In addition, the robot can climb certain peg configurations using a cyclic gait. The robot climbs in an open-loop mode without sensor feedback. All communications are sent through the IR connection, and the tether to the robot consists only of two power …