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Articles 271 - 300 of 1103

Full-Text Articles in Computer Sciences

Detection And Monitoring Of Repetitions Using An Mhealth-Enabled Resistance Band, Curtis L. Peterson, Emily V. Wechsler, Ryan J. Halter, George G. Boateng, Patrick O. Proctor, David F. Kotz, Summer B. Cook, John A. Batsis Sep 2018

Detection And Monitoring Of Repetitions Using An Mhealth-Enabled Resistance Band, Curtis L. Peterson, Emily V. Wechsler, Ryan J. Halter, George G. Boateng, Patrick O. Proctor, David F. Kotz, Summer B. Cook, John A. Batsis

Dartmouth Scholarship

Sarcopenia is defined as an age-related loss of muscle mass and strength which impairs physical function leading to disability and frailty. Resistance exercises are effective treatments for sarcopenia and are critical in mitigating weight-loss induced sarcopenia in older adults attempting to lose weight. Yet, adherence to home-based regimens, which is a cornerstone to lifestyle therapies, is poor and cannot be ascertained by clinicians as no objective methods exist to determine patient compliance outside of a supervised setting. Our group developed a Bluetooth connected resistance band that tests the ability to detect exercise repetitions. We recruited 6 patients aged 65 years …

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Battery-Free Eye Tracker On Glasses, Tianxing Li, Xia Zhou Aug 2018

Battery-Free Eye Tracker On Glasses, Tianxing Li, Xia Zhou

Computer Science Technical Reports

This paper presents a battery-free wearable eye tracker that achieves sub-millimeter tracking accuracy at high tracking rates. It tracks both the 2D position and diameter of pupil based on pupil's light absorption property. With a few near-infrared (NIR) lights and photodiodes around the eye, NIR lights sequentially illuminate the eye from various directions while photodiodes sense spatial patterns of reflected light, which are used to infer pupil's position and diameter on the fly via a lightweight inference algorithm. The system also exploits characteristics of different eye movement stages and adjusts its sensing and computation accordingly for further energy savings. A …

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Application Memory Isolation On Ultra-Low-Power Mcus, Taylor Hardin, Ryan Scott, Patrick Proctor, Josiah Hester, Jacob Sorber, David Kotz Jul 2018

Application Memory Isolation On Ultra-Low-Power Mcus, Taylor Hardin, Ryan Scott, Patrick Proctor, Josiah Hester, Jacob Sorber, David Kotz

Dartmouth Scholarship

The proliferation of applications that handle sensitive user data on wearable platforms generates a critical need for embedded systems that offer strong security without sacrificing flexibility and long battery life. To secure sensitive information, such as health data, ultra-low-power wearables must isolate applications from each other and protect the underlying system from errant or malicious application code. These platforms typically use microcontrollers that lack sophisticated Memory Management Units (MMU). Some include a Memory Protection Unit (MPU), but current MPUs are inadequate to the task, leading platform developers to software-based memory-protection solutions. In this paper, we present our memory isolation technique, …

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Contact Prediction Is Hardest For The Most Informative Contacts, But Improves With The Incorporation Of Contact Potentials, Jack Holland, Qinxin Pan, Gevorg Grigoryan Jun 2018

Contact Prediction Is Hardest For The Most Informative Contacts, But Improves With The Incorporation Of Contact Potentials, Jack Holland, Qinxin Pan, Gevorg Grigoryan

Dartmouth Scholarship

Co-evolution between pairs of residues in a multiple sequence alignment (MSA) of homologous proteins has long been proposed as an indicator of structural contacts. Recently, several methods, such as direct-coupling analysis (DCA) and MetaPSICOV, have been shown to achieve impressive rates of contact prediction by taking advantage of considerable sequence data. In this paper, we show that prediction success rates are highly sensitive to the structural definition of a contact, with more permissive definitions (i.e., those classifying more pairs as true contacts) naturally leading to higher positive predictive rates, but at the expense of the amount of structural information contributed …

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Robotic Laundry Folding, Evan Honnold Jun 2018

Robotic Laundry Folding, Evan Honnold

Dartmouth College Undergraduate Theses

We designed and implemented laundry-folding strategies for a six-jointed robotic arm. Our two main contributions are a "bar-folding" method for folding shirts that have already been unwrinkled and positioned on a table, and a planner for generating new sequences of folds that this method can use. Our "bar-folding" method is quick, accurate, and simple compared to other folding methods, and our fold planner provides an automated alternative to the pre-programmed fold sequences used in other research.

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Securing, Standardizing, And Simplifying Electronic Health Record Audit Logs Through Permissioned Blockchain Technology, Jessie Anderson Jun 2018

Securing, Standardizing, And Simplifying Electronic Health Record Audit Logs Through Permissioned Blockchain Technology, Jessie Anderson

Dartmouth College Undergraduate Theses

Audit logs perform critical functions in electronic health record (EHR) systems. They provide a chronological record of all operations performed in an EHR, allowing health care organizations to track EHR usage, hold system users accountable for their interactions with patient records, detect anomalous and potentially malicious behavior in the system, protect patient privacy, and develop insight into workflows and interactions among system users. However, several problems exist with the way that current state-of-the-art EHR technology handles audit data. Specifically, current systems complicate the collection and analysis of audit logs because they lack an interoperable audit log structure, spread audit log …

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Balancing Patient Control And Practical Access Policy For Electronic Health Records Via Blockchain Technology, Elena Horton Jun 2018

Balancing Patient Control And Practical Access Policy For Electronic Health Records Via Blockchain Technology, Elena Horton

Dartmouth College Undergraduate Theses

Electronic health records (EHRs) have revolutionized the health information technology domain, as patient data can be easily stored and accessed within and among medical institutions. However, in working towards nationwide patient engagement and interoperability goals, recent literature adopts a very patient-centric model---patients own their universal, holistic medical records and control exactly who can access their health data. I contend that this approach is largely impractical for healthcare workflows, where many separate providers require access to health records for care delivery. My work investigates the potential of a blockchain network to balance patient control and provider accessibility with a two-fold approach. …

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The Next Generation Of Empress: A Metadata Management System For Accelerated Scientific Discovery At Exascale, Margaret R. Lawson Jun 2018

The Next Generation Of Empress: A Metadata Management System For Accelerated Scientific Discovery At Exascale, Margaret R. Lawson

Dartmouth College Undergraduate Theses

Scientific data sets have grown rapidly in recent years, outpacing the growth in memory and network bandwidths. This I/O bottleneck has made it increasingly difficult for scientists to read and search outputted datasets in an attempt to find features of interest. In this paper, we will present the next generation of EMPRESS, a scalable metadata management service that offers the following solution: users can "tag" features of interest and search these tags without having to read in the associated datasets. EMPRESS provides, in essence, a digital scientific notebook where scientists can write down observations and highlight interesting results, and an …

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Navigating Virtual Reality Using Only Your Gazes And Mind, Christopher J. Kymn Jun 2018

Navigating Virtual Reality Using Only Your Gazes And Mind, Christopher J. Kymn

Dartmouth College Undergraduate Theses

We present a novel brain-computer interface that allows users to control virtual reality using only their brain waves and eye gazes. The interface allows users to control multiple objects with two dimensions of control. The system is portable, non-invasive, and runs on commercial-grade hardware. It thus provides a high-transmission and user-adaptive interface for users to engage in virtual reality. In addition, we present a training procedure that allows the user to increase control over the brain-computer interface by engaging with the program in an intuitive manner. We explain this procedure and demonstrate its effectiveness in formulating more readily interpreted commands.

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Thinking Inside The Box: Converting Encapsulated Postscript To Scalable Vector Graphics, Trevor L. Davis Jun 2018

Thinking Inside The Box: Converting Encapsulated Postscript To Scalable Vector Graphics, Trevor L. Davis

Dartmouth College Undergraduate Theses

Following the deprecation of the MacDraw graphics application, no extant application arose as a suitable substitute. A team of of Dartmouth undergraduates that included myself set out to rectify this by creating DartDraw, a graphics app that mimics MacDraw along with a few improvements. This was our combined effort over the past year. My role was to convert the Scalable Vector Graphics (SVG) used within the application to an exportable Encapsulated PostScript File. This process relied on an in-depth understanding of both the PostScript language and the React-Redux framework. Computing the bounding boxes of figures proved to be the largest …

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Time-Space Tradeoffs For The Memory Game, Yining Chen, Amit Chakrabarti Jun 2018

Time-Space Tradeoffs For The Memory Game, Yining Chen, Amit Chakrabarti

Computer Science Technical Reports

A single-player game of Memory is played with n distinct pairs of cards, with the cards in each pair bearing identical pictures. The cards are laid face-down. A move consists of revealing two cards, chosen adaptively. If these cards match, i.e., they bear the same picture, they are removed from play; otherwise, they are turned back to face down. The object of the game is to clear all cards while minimizing the number of moves. Past works have thoroughly studied the expected number of moves required, assuming optimal play by a player has that has perfect memory. In this work, …

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Workshop On Emerging Technology And Data Analytics For Behavioral Health, David Kotz, Sarah E. Lord, A. James O'Malley, Luke Stark, Lisa Marsch Jun 2018

Workshop On Emerging Technology And Data Analytics For Behavioral Health, David Kotz, Sarah E. Lord, A. James O'Malley, Luke Stark, Lisa Marsch

Dartmouth Scholarship

Wearable and portable digital devices can support self-monitoring for patients with chronic medical conditions, individuals seeking to reduce stress, and people seeking to modify health-related behaviors such as substance use or overeating. The resulting data may be used directly by a consumer, or shared with a clinician for treatment, a caregiver for assistance, or a health coach for support. The data can also be used by researchers to develop and evaluate just-in-time interventions that leverage mobile technology to help individuals manage their symptoms and behavior in real time and as needed. Such wearable systems have huge potential for promoting delivery …

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Reflections On Building Dartdraw: A React + Redux Vector-Based Graphics Editor, Elisabeth G. Pillsbury May 2018

Reflections On Building Dartdraw: A React + Redux Vector-Based Graphics Editor, Elisabeth G. Pillsbury

Dartmouth College Undergraduate Theses

In this paper, I discuss some of the design challenges I encountered while contributing to DartDraw, a React-Redux drawing application modeled after MacDraw. The features I worked on include: zoom, pan, grid, ruler, and arrowheads.

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Overlaying Virtual Scale Models On Real Environments Without The Use Of Peripherals, George Hito May 2018

Overlaying Virtual Scale Models On Real Environments Without The Use Of Peripherals, George Hito

Dartmouth College Undergraduate Theses

The Architecture, Engineering, and Construction (AEC) industries have become increasingly reliant on detailed 3D modeling software and visualization tools. In the past few years, the arrival of effective and relatively cheap virtual reality has transformed the workflows of people in these professions. Augmented reality (AR) is poised to have a similar if not greater effect. For that to occur, the transition into using this technology must be seamless and straightforward. In particular, a clear bridge should be made between Computer Aided Design (CAD) models and their corresponding real-world environments. Using Unity and Microsoft's Hololens, I developed a method of automatically …

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Ipv6 Security Issues In Linux And Freebsd Kernels: A 20-Year Retrospective, Jack R. Cardwell May 2018

Ipv6 Security Issues In Linux And Freebsd Kernels: A 20-Year Retrospective, Jack R. Cardwell

Dartmouth College Undergraduate Theses

Although IPv6 was introduced in 1998, its adoption didn't begin to take off until 2012. Furthermore, its vulnerabilities haven't received as much attention as those of IPv4. As such, there is potential to exploit these vulnerabilities. With the amount of IPv6 traffic rapidly increasing, these exploits present real-world consequences. This paper aims to re-evaluate the security of IPv6 stack implementations in FreeBSD and Linux kernels, specifically FreeBSD 11.1 and Ubuntu Linux 4.13. It contributes to the literature in three ways. We first reproduce ten vulnerabilities from existing research to determine whether known bugs have been patched. Then, we examine two, …

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Co-Training Of Audio And Video Representations From Self-Supervised Temporal Synchronization, Bruno Korbar May 2018

Co-Training Of Audio And Video Representations From Self-Supervised Temporal Synchronization, Bruno Korbar

Dartmouth College Undergraduate Theses

There is a natural correlation between the visual and auditive elements of a video. In this work, we use this correlation in order to learn strong and general features via cross-modal self-supervision with carefully chosen neural network architectures and calibrated curriculum learning. We suggest that this type of training is an effective way of pretraining models for further pursuits in video understanding, as they achieve on average 14.8% improvement over models trained from scratch. Furthermore, we demonstrate that these general features can be used for audio classification and perform on par with state-of-the-art results. Lastly, our work shows that using …

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Afterimage: Collecting And Replaying Geospatial Memory, Hyun Ji Seong May 2018

Afterimage: Collecting And Replaying Geospatial Memory, Hyun Ji Seong

Dartmouth College Master’s Theses

AfterImage is an interactive wall consisted of light detecting units controlled by microprocessors. Each light-sensing unit determines user proximity through the intensity of the shadow being cast, turning these shadows into bright snapshots portrayed through built-in LED lights. AfterImage extends the concept of memory to a space and location by imitating two unique characteristics of human memory: a lingering afterimage effect for intense stimuli, and a flashback of events that happened in the past. To create a more organic representation of flashbacks, a native data structure was explored. Through the collection and reproduction of geospatial memory, AfterImage attempts to change …

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Dartdraw: The Design And Implementation Of Global State Management, User Interaction Management, And Text In A React-Redux Drawing Application, Collin M. Mckinney May 2018

Dartdraw: The Design And Implementation Of Global State Management, User Interaction Management, And Text In A React-Redux Drawing Application, Collin M. Mckinney

Dartmouth College Undergraduate Theses

This paper outlines the design and implementation of DartDraw, a drawing application which closely emulates the user interface of the original MacDraw application and supports the importing of MacDraw files.

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Full And Dense Cyclic Gray Codes In Mixed Radices, Devina Kumar May 2018

Full And Dense Cyclic Gray Codes In Mixed Radices, Devina Kumar

Dartmouth College Undergraduate Theses

The Gray code is a sequence of n consecutive binary numbers arranged so that adjacent numbers in the sequence differ in a single digit and that each number appears in the sequence exactly once. A Gray code is considered cyclic if the first and last numbers in the sequence differ in only one digit position, and those digits have a difference of exactly 1. In this thesis, numbers in a Gray-code sequence may be modular cyclic, meaning that in radix r, two consecutive numbers may vary in a digit with values 0 and r-1. This thesis focuses on methods to …

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Development Of A ‘Smart’ Resistance Exercise Band To Assess Strength, Emily V. Wechsler, John A. Batsis, David F. Kotz, Ryan J. Halter May 2018

Development Of A ‘Smart’ Resistance Exercise Band To Assess Strength, Emily V. Wechsler, John A. Batsis, David F. Kotz, Ryan J. Halter

Wetterhahn Science Symposium Posters 2018

No abstract provided.

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Customizing Indoor Wireless Coverage Via 3d-Fabricated Reflectors, Xi Xiong May 2018

Customizing Indoor Wireless Coverage Via 3d-Fabricated Reflectors, Xi Xiong

Dartmouth College Master’s Theses

Judicious control of indoor wireless coverage is crucial in built environments. It enhances signal reception, reduces harmful interference, and raises the barrier for malicious attackers. Existing methods are either costly, vulnerable to attacks, or hard to configure. We present a low-cost, secure, and easy-to-configure approach that uses an easily-accessible, 3D-fabricated reflector to customize wireless coverage. With input on coarse-grained environment setting and preferred coverage (e.g., areas with signals to be strengthened or weakened), the system computes an optimized reflector shape tailored to the given environment. The user simply 3D prints the reflector and places it around a Wi-Fi access point …

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Secure Short-Range Communications, Timothy J. Pierson May 2018

Secure Short-Range Communications, Timothy J. Pierson

Dartmouth College Ph.D Dissertations

Analysts predict billions of everyday objects will soon become ``smart’' after designers add wireless communication capabilities. Collectively known as the Internet of Things (IoT), these newly communication-enabled devices are envisioned to collect and share data among themselves, with new devices entering and exiting a particular environment frequently. People and the devices they wear or carry may soon encounter dozens, possibly hundreds, of devices each day. Many of these devices will be encountered for the first time. Additionally, some of the information the devices share may have privacy or security implications. Furthermore, many of these devices will have limited or non-existent …

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Complex Neural Networks For Audio, Andy M. Sarroff May 2018

Complex Neural Networks For Audio, Andy M. Sarroff

Dartmouth College Ph.D Dissertations

Audio is represented in two mathematically equivalent ways: the real-valued time domain (i.e., waveform) and the complex-valued frequency domain (i.e., spectrum). There are advantages to the frequency-domain representation, e.g., the human auditory system is known to process sound in the frequency-domain. Furthermore, linear time-invariant systems are convolved with sources in the time-domain, whereas they may be factorized in the frequency-domain. Neural networks have become rather useful when applied to audio tasks such as machine listening and audio synthesis, which are related by their dependencies on high quality acoustic models. They ideally encapsulate fine-scale temporal structure, such as that encoded in …

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A Radiative Transfer Framework For Non-Exponential Media, Benedikt Bitterli, Srinath Ravichandran, Thomas Müller, Magnus Wrenninge, Jan Novák, Steve Marschner, Wojciech Jarosz Apr 2018

A Radiative Transfer Framework For Non-Exponential Media, Benedikt Bitterli, Srinath Ravichandran, Thomas Müller, Magnus Wrenninge, Jan Novák, Steve Marschner, Wojciech Jarosz

Computer Science Technical Reports

We develop a new theory of volumetric light transport for media with non-exponential free-flight distributions. Recent insights from atmospheric sciences and neutron transport demonstrate that such distributions arise in the presence of correlated scatterers, which are naturally produced by processes such as cloud condensation and fractal-pattern formation. Our theory accommodates correlations by disentangling the concepts of the free-flight distribution and transmittance, which are equivalent when scatterers are statistically independent, but become distinct when correlations are present. Our theory results in a generalized path integral which allows us to handle non-exponential media using the full range of Monte Carlo rendering algorithms …

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Investigating Contextual Cues As Indicators For Ema Delivery, Varun Mishra, Byron Lowens, Sarah Lord, Kelly Caine, David Kotz Apr 2018

Investigating Contextual Cues As Indicators For Ema Delivery, Varun Mishra, Byron Lowens, Sarah Lord, Kelly Caine, David Kotz

Computer Science Technical Reports

In this work, we attempt to determine whether the contextual information of a participant can be used to predict whether the participant will respond to a particular Ecological Momentary Assessment (EMA) prompt. We use a publicly available dataset for our work, and find that by using basic contextual features about the participant's activity, conversation status, audio, and location, we can predict whether an EMA prompt triggered at a particular time will be answered with a precision of 0.647, which is significantly higher than a baseline precision of 0.410. Using this knowledge, the researchers conducting field studies can efficiently schedule EMA …

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Types For The Chain Of Trust: No (Loader) Write Left Behind, Rebecca Shapiro Apr 2018

Types For The Chain Of Trust: No (Loader) Write Left Behind, Rebecca Shapiro

Dartmouth College Ph.D Dissertations

The software chain of trust starts with a chain of loaders. Software is just as reliant on the sequence of loaders that ultimately setup its runtime environment as it is on the libraries with which it shares its address space and offloads tasks onto. Loaders, and especially bootloaders, act as the keystone of trust, and yet their formal security properties -- which should be a part of any solid bootloader design -- are both underappreciated and not well understood. This is especially problematic given the increasing adoption of loader-based code signing and execution enforcement mechanisms. My thesis digs deeply into …

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Nocloud: Experimenting With Network Disconnection By Design, Reza Rawassizadeh, Timothy Pierson, Ronald Peterson, David Kotz Mar 2018

Nocloud: Experimenting With Network Disconnection By Design, Reza Rawassizadeh, Timothy Pierson, Ronald Peterson, David Kotz

Dartmouth Scholarship

Application developers often advocate uploading data to the cloud for analysis or storage, primarily due to concerns about the limited computational capability of ubiquitous devices. Today, however, many such devices can still effectively operate and execute complex algorithms without reliance on the cloud. The authors recommend prioritizing on-device analysis over uploading the data to another host, and if on-device analysis is not possible, favoring local network services over a cloud service.

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Stem Outreach Activity With Fitbit Wearable Devices, Joseph Carrigan, David Kotz, Aviel Rubin Feb 2018

Stem Outreach Activity With Fitbit Wearable Devices, Joseph Carrigan, David Kotz, Aviel Rubin

Computer Science Technical Reports

This document provides a toolkit for an STEM outreach activity based on Fitbit wearable fitness devices. The activity is targeted toward high-school students. This document provides guidance preparing for and executing the activity and measuring outcomes. This document contains templates that can be used as is or altered to suit your specific needs.

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A Jpeg Corner Artifact From Directed Rounding Of Dct Coefficients, Shruti Agarwal, Hany Farid Feb 2018

A Jpeg Corner Artifact From Directed Rounding Of Dct Coefficients, Shruti Agarwal, Hany Farid

Computer Science Technical Reports

JPEG compression introduces a number of well known artifacts including blocking and ringing. We describe a lesser known or understood artifact consisting of a slightly darker or lighter pixel in the corner of 8 x 8 pixel blocks. This artifact is introduced by the directed rounding of DCT coefficients. In particular, we show that DCT coefficients that are uniformly rounded down or up (but not to the nearest neighbor) give rise to this artifact. An analysis of thousands of different camera models reveals that this artifact is present in approximately 61% of cameras. We also propose a simple filtering technique …

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The Accuracy, Fairness, And Limits Of Predicting Recidivism, Julie Dressel, Hany Farid Jan 2018

The Accuracy, Fairness, And Limits Of Predicting Recidivism, Julie Dressel, Hany Farid

Dartmouth Scholarship

Algorithms for predicting recidivism are commonly used to assess a criminal defendant’s likelihood of committing a crime. These predictions are used in pretrial, parole, and sentencing decisions. Proponents of these systems argue that big data and advanced machine learning make these analyses more accurate and less biased than humans. We show, however, that the widely used commercial risk assessment software COMPAS is no more accurate or fair than predictions made by people with little or no criminal justice expertise. We further show that a simple linear predictor provided with only two features is nearly equivalent to COMPAS with its 137 …

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