Networks within data centers, such as connections between servers and disk arrays, need lossless flow control allowing all packets to move quickly through the network to reach their destination. This paper proposes a new algorithm for congestion control to satisfy the needs of such networks and to answer the question: Is it possible to provide circuit-less reliability and flow control in an Ethernet network? TCP uses an end-to-end congestion control algorithm, which is based on end-to-end round trip time (RTT). Therefore its flow control and error detection/correction approach is dependent on end-to-end RTT. Other approaches utilize specialized data link layer networks such as InfiniBand and Fibre Channel to provide network reliability. The algorithm proposed in this thesis builds on the ubiquitous Ethernet protocol to provide reliability at the data link layer without the overhead and cost of the specialized networks or the delay induced by TCP’s end-to-end approach. This approach requires modifications to the Ethernet switches to implement a back pressure based flow control algorithm. This back pressure algorithm utilizes a modified version of the Random Early Detection (RED) algorithm to detect congestion. Our simulation results show that the algorithm can quickly recover from congestion and that the average latency of the network is close to the average latency when no congestion is present. With correct threshold and alpha values, buffer sizes in the network and on the source nodes can be kept small to allow little needed additional hardware to implement the system.

In this thesis we introduces the user interface design and forensic analysis tool for DIORAMA system. With an Android device, DIORAMA provides emergency personnel the ability to collect information in real time, track the resources and manage them. It allows the responders and commanders to mange multiple incidents simultaneously. This thesis also describes the implementations of commander app and responder app, as well as two different communication strategies used in DIORAMA. Several trials and simulated mass casualty incidents were conducted to test the functionalities and performance of DIORAMA system. All responders that participated in all trials were very satisfied with it. As a result, DIORAMA system significantly reduced the evacuation time by up to 43% when compared to paper based triage systems.

The processing of digital video has long been a significant computational task for modern x86 processors. With every video frame composed of one to three planes, each consisting of a two-dimensional array of pixel data, and a video clip comprising of thousands of such frames, the sheer volume of data is significant. With the introduction of new high definition video formats such as 4K or stereoscopic 3D, the volume of uncompressed frame data is growing ever larger. Modern CPUs offer performance enhancements for processing digital video through SIMD instructions such as SSE2 or AVX. However, even with these instruction sets, CPUs are limited by their inherently sequential design, and can only operate on a handful of bytes in parallel. Even processors with a multitude of cores only execute on an elementary level of parallelism. GPUs provide an alternative, massively parallel architecture. GPUs differ from CPUs by providing thousands of throughput-oriented cores, instead of a maximum of tens of generalized “good enough at everything” x86 cores. The GPU’s throughput-oriented cores are far more adept at handling large arrays of pixel data, as many video filtering operations can be performed independently. This computational independence allows for pixel processing to scale across hun- dreds or even thousands of device cores. This thesis explores the utilization of GPUs for video processing, and evaluates the advantages and caveats of porting the modern video filtering framework, Vapoursynth, over to running entirely on the GPU. Compute heavy GPU-enabled video processing results in up to a 108% speedup over an SSE2-optimized, multithreaded CPU implementation.

The web browser has become one of the most recognizable software applications on consumer desktops. Yet its utilization and capabilities are often misunderstood. Recent innovations in the web have evolved the Internet into a network of sophisticated applications that defy historical uses of the “browser”; a term that itself has become somewhat of a misnomer. This research studies the evolving set of user expectations for the browser as an application platform and challenges certain anachronistic features, specifically the “back” button, that are unnecessary and confusing given the new environment that browsers are used in. Because of this shift, implicit new user requirements arise around the browser’s user interface. The back button, like other elements in the browser have already demonstrated, should be de-emphasized in modern iterations of web browsers. The study is qualified by an analysis of user behavior within a popular, modern, web application. NOTE: This master's thesis has been removed at request of the author due to it containing experimentation data referencing a branded software application for which the author no longer has permission to share.

Secure Shell, a tool to securely access and run programs on a remote machine, is an important tool for both system administrators and developers alike. The technology landscape is becoming increasingly distributed and reliant on tools such as Secure Shell to protect information as a user works on a system remotely. While Secure Shell accounts for the abuses the security of older tools such as telnet overlook, it still has fundamental vulnerabilities which leak information about both the user and their activities through timing attacks. The OpenSSH client, the implementation included in all Linux, Mac, and Windows computers, sends each keystroke entered to the server as soon as it becomes available. As a result, an attacker can observe the network patterns to know when a user presses a key and draw conclusions based on that information such as what a user is typing or who they are. In this thesis, we demonstrate that such an attack allows a malicious observer to identify a user with a concerning level of accuracy without having direct access to either the client or server systems. Using machine learning classifiers, we identify individual users in a crowd based solely on the size and timing of packets traveling across the network. We find that our classifiers were able to identify users with 20\% accuracy using as little as one hour of network traffic. Two of them promise to scale well to the number of users.

Contemporary small office phone systems are specialized computers that connect a variety of phones within the office and to the local phone company. These systems use digital signaling processors (DSPs) to convert signals from analog to digital and vice-versa. Many different types of applications run on the DSPs and different businesses have varying application needs. Given the systems have limited amounts of DSP resources and growing numbers of applications for a phone system, an administrator needs a way to configure the uses of resources based on their individual business needs. This thesis provides an overview of a system for configuring resources on various types of DSP hardware some of which are removable and have differing tradeoffs between application uses. The system has to be able to change resource allocations while the phone system is running with minimal interruptions to calls. The configuration system needs to be designed to be flexible enough that new applications or DSP hardware could be supported without major changes to code. This thesis presents a system that uses a database-driven model along with algorithms that optimize configuration of DSP hardware given the administrator’s individual application needs.

This work further develops the way-finding model first proposed by Pearson and Kosicki (2017) which examines the flow of information in the digital age. Way-finding systems are online systems that help individuals find information—i.e. social media, search engines, email, etc. Using a grounded theory methodology, this new framework was explored in greater detail. Way-finding theory was created using the context of the elaboration likelihood model, gatekeeping theory, algorithmic gatekeepers, and the existence of the filter bubble phenomenon. This study establishes the three basic pillars of way-finding theory: the user’s mindset when accessing way-finding systems, the perception of how popular way-finding systems function, and the perception of the information personalization process—particularly regarding algorithmic gatekeepers and their roles in creating the filter bubble phenomenon. These pillars and the relationships that exist between each constitute way-finding theory.

The two-antenna problem in aeronautical mobile telemetry is created by the reception of two copies of the same RF waveform with different phases and time delays. Alamouti and Alamouti-like space time block codes can solve the two-antenna problem, but the decoder/detector needs to account for the different time delays between the signals received from the two transmit antennas. In this thesis, a comparison is made between the performance of Alamouti space-time block codes and time-reversed space-time block codes with 16-APSK to solve the two-antenna problem. The maximum likelihood decoder/detector for Alamouti-encoded 16-APSK is a sequence detector operating on a trellis with a large number of states. A practical state-reduction technique is presented. The results produce a trellis with 256 states and a small loss in bit error rate performance as long as the delay difference is not too big. The decoder/detector for the time-reversed space time block requires only waveform manipulations and channel matched filtering in the case where the two channels are simple delays. For the more general case of multipath propagation between the two transmit antennas and the receiver, the decoder/detector requires an equalizer; simulation results using a channel pair measured at a test range show that the decoder/detector is capable of achieving near AWGN performance with a modest equalizer.

Reliable wireless communication is essential for small systems of vehicles. However, for small-scale robotics projects where communication is not the primary goal, programmers frequently choose to use TCP with Wi-Fi because of their familiarity with the sockets API and the widespread availability of Wi-Fi hardware. However, neither of these technologies are suitable in their default configurations for highly mobile vehicles that experience frequent, extended disruptions. BRUNET (BRUNET Really Useful NETwork) provides a two-tier software solution that enhances the communication capabilities for Linux-based systems. An ad-hoc Wi-Fi network permits decentralized peer-to-peer and multi-hop connectivity without the need for dedicated network infrastructure. A background process adds disruption tolerance to specified TCP endpoints without any changes to existing software. This allows TCP connections to persist indefinitely over possibly multiple long network outages. Data sent by applications is automatically buffered and transmitted when network connectivity resumes.

[pt] Este é um projeto de pesquisa no campo da comunicação e política que coloca em questão as consequências da comunicação digital na atuação dos movimentos sociais no Brasil, a fim de averiguar de que maneira a comunicação digital transforma os projetos de reivindicação dos movimentos sociais na esfera pública democrática. O intuito é compreender especificamente de que forma as mídias digitais contribuíram para a transformação do repertório comunicacional dos movimentos sociais por meio de um estudo de caso que busca compreender, numa unidade teste, como pensar a organização, a operacionalização e a distribuição da comunicação dos movimentos. O presente trabalho seleciona o estudo de caso como proposta inicial de futuras pesquisas envolvendo a comunicação digital e os movimentos sociais no Brasil. / [en] This is a research project in the field of communication and politics that calls into question the consequences of digital communication in the performance of social movements in Brazil, in order to find out how digital communication transforms the projects of social movements in the public sphere. democratic. The aim is to specifically understand how digital media contributed to the transformation of the communicational repertoire of social movements through a case study that seeks to understand, in a test unit, how to think about the organization, operationalization and distribution of movement communication. The present work selects the case study as an initial proposal for future research involving digital communication and social movements in Brazil. It is intended to contribute to the debate on digital communication and its correlation with studies of social actions.