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Some Communication Complexity Results And Their Applications, Joshua E. Brody
Some Communication Complexity Results And Their Applications, Joshua E. Brody
Dartmouth College Ph.D Dissertations
Communication Complexity represents one of the premier techniques for proving lower bounds in theoretical computer science. Lower bounds on communication problems can be leveraged to prove lower bounds in several different areas. In this work, we study three different communication complexity problems. The lower bounds for these problems have applications in circuit complexity, wireless sensor networks, and streaming algorithms. First, we study the multiparty pointer jumping problem. We present the first nontrivial upper bound for this problem. We also provide a suite of strong lower bounds under several restricted classes of protocols. Next, we initiate the study of several non-monotone …
Out Of The Depths: Image Statistics Of Space, Water, And The Minuscule World, Nimit S. Dhulekar
Out Of The Depths: Image Statistics Of Space, Water, And The Minuscule World, Nimit S. Dhulekar
Dartmouth College Master’s Theses
In images of natural scenes, a consistent relationship exists between spectral power and spatial frequency. The power spectrum falls off with a form 1/f^p as spatial frequency f increases, with values of p approximately equal to 2. To quantify the extent to which this statistical characteristic is exhibited by other classes of images, we examined astronomical, underwater, and microscale images. It was found that this property holds for all three categories of images, although the value of p varies in the range 1.76 to 2.37. The second statistical characteristic computed was the angular spread of the power spectrum. This metric …
Numerical Methods For Fmri Data Analysis, Geethmala Sridaran
Numerical Methods For Fmri Data Analysis, Geethmala Sridaran
Dartmouth College Master’s Theses
Brain imaging data are increasingly analyzed via a range of machine-learning methods. In this thesis, we discuss three specific contributions to the field of neuroimaging analysis methods: 1. To apply a recently-developed technique for identifying and viewing similarity structure in neuroimaging data, in which candidate representational structures are ranked; 2. Provide side-by-side analyses of neuroimaging data by a typical non-hierarchical (SVM) versus hierarchical (Decision Tree) machine-learning classification methods; and 3. To develop a novel programming environment for PyMVPA, a current popular analysis toolbox, such that users will be able to type a small number of packaged commands to carry out …
Virtual Container Attestation: Customized Trusted Containers For On-Demand Computing., Katelin A. Bailey
Virtual Container Attestation: Customized Trusted Containers For On-Demand Computing., Katelin A. Bailey
Dartmouth College Undergraduate Theses
In today's computing environment, data is moving to central locations and most computers are merely used to access the data. Today is the era of cloud computing and distributed computing, where users have control over neither data nor computation. As this trend continues there is an increasing frequency of mutually distrustful parties being forced to interact and share resources with each other in potentially dangerous situations. Therefore, there is an urgent need for a means of creating trust between two entities, or at the very least providing some means of determining the trust level of a given machine. Current approaches …
Creating Large Disturbances In The Power Grid: Methods Of Attack After Cyber Infiltration, Loren D. Sands-Ramshaw
Creating Large Disturbances In The Power Grid: Methods Of Attack After Cyber Infiltration, Loren D. Sands-Ramshaw
Dartmouth College Undergraduate Theses
Researchers are pursuing methods of securing the cyber aspect of the U.S. power grid, one of the country's most critical infrastructures. An attacker who is able to infiltrate an Energy Management System (EMS) can instruct elements of the grid to function improperly or can skew the state information received by the control programs or operators. In addition, a cyber attack can combine multiple attacks and affect many physical locations at once. A study of the possible adverse effects an attack could generate can underline the urgency of improving grid security, contribute to a roadmap and priority list for security researchers, …
Block Sensitivity Versus Sensitivity, Karn Seth
Block Sensitivity Versus Sensitivity, Karn Seth
Dartmouth College Undergraduate Theses
Sensitivity and block sensitivity are useful and well-studied measures of computational complexity, but in spite of their similarities, the largest possible gap between them is still unknown. Rubinstein showed that this gap must be at least quadratic, and Kenyon and Kutin showed that it is at worst exponential, but many strongly suspect that the gap is indeed quadratic, or at worst polynomial. Our work shows that for a large class of functions, which includes Rubinstein's function, the quadratic gap between sensitivity and block sensitivity is the best we can possibly do.
Predictive Yasir: High Security With Lower Latency In Legacy Scada, Rouslan V. Solomakhin
Predictive Yasir: High Security With Lower Latency In Legacy Scada, Rouslan V. Solomakhin
Dartmouth College Master’s Theses
Message authentication with low latency is necessary to ensure secure operations in legacy industrial control networks, such as power grid networks. Previous authentication solutions by our lab and others looked at single messages and incurred noticeable latency. To reduce this latency, we develop Predictive YASIR, a bump-in-the-wire device that looks at broader patterns of messages. The device (1) predicts the incoming plaintext based on previous observations; (2) compresses, encrypts, and authenticates data online; and (3) pre-sends a part of ciphertext before receiving the whole plaintext. I demonstrate the performance properties of this approach by implementing it in the Scalable Simulation …
Optimization Algorithms For Site-Directed Protein Recombination Experiment Planning, Wei Zheng
Optimization Algorithms For Site-Directed Protein Recombination Experiment Planning, Wei Zheng
Dartmouth College Ph.D Dissertations
Site-directed protein recombination produces improved and novel protein variants by recombining sequence fragments from parent proteins. The resulting hybrids accumulate multiple mutations that have been evolutionarily accepted together. Subsequent screening or selection identifies hybrids with desirable characteristics. In order to increase the "hit rate" of good variants, this thesis develops experiment planning algorithms to optimize protein recombination experiments. First, to improve the frequency of generating novel hybrids, a metric is developed to assess the diversity among hybrids and parent proteins. Dynamic programming algorithms are then created to optimize the selection of breakpoint locations according to this metric. Second, the trade-off …
Graph Algorithms For Nmr Resonance Assignment And Cross-Link Experiment Planning, Fei Xiong
Graph Algorithms For Nmr Resonance Assignment And Cross-Link Experiment Planning, Fei Xiong
Dartmouth College Ph.D Dissertations
The study of three-dimensional protein structures produces insights into protein function at the molecular level. Graphs provide a natural representation of protein structures and associated experimental data, and enable the development of graph algorithms to analyze the structures and data. This thesis develops such graph representations and algorithms for two novel applications: structure-based NMR resonance assignment and disulfide cross-link experiment planning for protein fold determination. The first application seeks to identify correspondences between spectral peaks in NMR data and backbone atoms in a structure (from x-ray crystallography or homology modeling), by computing correspondences between a contact graph representing the structure …
The Curious Timekeeper: Creative Thesis In Interactive Sculpture, Kate I. Schnippering
The Curious Timekeeper: Creative Thesis In Interactive Sculpture, Kate I. Schnippering
Dartmouth College Undergraduate Theses
When we interact with computers, we have set expectations about our interactive experience, operating a mouse and keyboard to elicit predictable responses on a screen. Intersecting the world of Computing with Fine Art gains us potential to innovate outside these bounds by restricting the expected performance of a computer-- setting it to a particular purpose rather than allowing it to run anyone's software. To challenge standard human-computer interaction, this work set out to create an interesting and unusual interactive experience, fully integrated into a sculpture. The approach was to design a system to form a small environment, having many components …
Neurophone: Brain-Mobile Phone Interface Using A Wireless Eeg Headset, Matthew K. Mukerjee
Neurophone: Brain-Mobile Phone Interface Using A Wireless Eeg Headset, Matthew K. Mukerjee
Dartmouth College Undergraduate Theses
Neural signals are everywhere just like mobile phones. We propose to use neural signals to control mobile phones for hands-free, silent and effortless human-mobile interaction. Until recently, devices for detecting neural signals have been costly, bulky and fragile. We present the design, implementation and evaluation of the NeuroPhone system, which allows neural signals to drive mobile phone applications on the iPhone using cheap off-the-shelf wireless electroencephalography (EEG) headsets. We demonstrate a mind-controlled address book dialing app, which works on similar principles to P300-speller brain-computer interfaces: the phone flashes a sequence of photos of contacts from the address book and a …
Flexible Object Manipulation, Matthew P. Bell
Flexible Object Manipulation, Matthew P. Bell
Dartmouth College Ph.D Dissertations
Flexible objects are a challenge to manipulate. Their motions are hard to predict, and the high number of degrees of freedom makes sensing, control, and planning difficult. Additionally, they have more complex friction and contact issues than rigid bodies, and they may stretch and compress. In this thesis, I explore two major types of flexible materials: cloth and string. For rigid bodies, one of the most basic problems in manipulation is the development of immobilizing grasps. The same problem exists for flexible objects. I have shown that a simple polygonal piece of cloth can be fully immobilized by grasping all …