Exploring tradeoffs in pleiotropy and redundancy using evolutionary computing

Evolutionary computation algorithms are increasingly being used to solve optimization problems as they have many advantages over traditional optimization algorithms. In this paper we use evolutionary computation to study the trade-off between pleiotropy and redundancy in a client-server based network. Pleiotropy is a term used to describe components that perform multiple tasks, while redundancy refers to multiple components performing one same task. Pleiotropy reduces cost but lacks robustness, while redundancy increases network reliability but is more costly, as together, pleiotropy and redundancy build flexibility and robustness into systems. Therefore it is desirable to have a network that contains a balance between pleiotropy and redundancy. We explore how factors such as link failure probability, repair rates, and the size of the network influence the design choices that we explore using genetic algorithms.Comment: 10 pages, 6 figure

Wireless Sensor Network Security: Approaches to Detecting and Avoiding Wormhole Attacks

This paper explores Wireless Sensor Networks (WSNs) and the related security issues and complications arising from a specific type of security breach, the wormhole attack. Wormhole attacks against WSNs are classified as passive, external laptop-class threats. Because malicious wormhole attacks are increasing, these attacks pose a serious security threat and increase the costs to maintain a Wireless Sensor Network. Research into preventing wormhole attacks yields two distinct model approach types: Administrator-Viewpoint models and User-Viewpoint models. While the modalities vary, the four Administrator-Viewpoint models reviewed were designed in the early 2000s and suggest defending against wormhole attacks through the use of expensive hardware, packet leashes, or topology visualization systems. On the other hand, the four proposed User-Viewpoint models have become the current theoretical models of choice.  While existing as simulation approaches to defend against wormhole attacks, the User-Viewpoint models use internally calculated routing algorithms to suggest routes to avoid or evade, not defend against, established wormhole routes. This paper confirms the efficacies of the User-Viewpoint models in the lab simulations are viewed as the most promising cost-effective, future security solutions to wormhole attacks

Perseverance

undergraduat

StormSense: A Blueprint for Coastal Flood Forecast Information & Automated Alert Messaging Systems

Increased availability of low-cost water level sensors communicating through the Internet of Things (IoT) has expanded the horizons of publicly-ingestible data streams available to modern smart cities. StormSense is an IoT-enabled inundation forecasting research initiative and an active participant in the Global City Teams Challenge seeking to enhance flood preparedness in the smart cities of Hampton Roads, VA for flooding resulting from storm surge, rain, and tides. In this study, we present the a blueprint and series of applicable protocols through the use of the new StormSense water level sensors to help establish a regional resilience monitoring network. In furtherance of this effort, the Virginia Commonwealth Center for Recurrent Flooding Resiliency\u27s Tidewatch tidal forecast system is being used as a starting point to integrate the extant (NOAA) and new (USGS and StormSense) water level sensors throughout the region, and demonstrate replicability of the solution across the cities of Newport News, Norfolk, and Virginia Beach within Hampton Roads, VA. StormSense\u27s network employs a mix of ultrasonic sonar and radar remote sensing technologies to record water levels and develop autonomous alert messaging systems through the use of three separate cloud environments. One to manage the water level monitoring sensors and alert messaging, one to run the model and interface with the post-processed results, and one to geospatially present the flood results

Reaction rate predictions of dislocation–precipitate interactions with atomistic simulation

The high strength of many modern engineering alloys can be attributed to the presence of precipitates in the microstructure, which inhibit dislocation motion. Thus, a key step in the quest to comprehensively understand and predict the mechanical behavior of engineering alloys is to develop a sound understanding of dislocation–-precipitate interactions. With many features of the dislocation–precipitate interaction being governed by atomic scale processes, atomistic modeling is a valuable tool for improving our understanding. Under this motivation, we will summarize our recent efforts to predict the rate at which a dislocation overcomes a precipitate using atomistic modeling. Specifically, we will focus on the goal of making predictions at timescales and temperatures comparable to typical experiments. Using direct MD simulation as a standard, we first examine the utility of Transition State and Transition Path theories for this problem, using the Finite Temperature String and Transition Interface Sampling (TIS) methods. We find that the TIS approach is the only method that can produce similar predictions to those of direct MD simulations, for the simple reaction coordinate that we have used

Facilitators and Barriers to Prescribing PreExposure Prophylaxis (PrEP) for the Prevention of HIV

Background: What is PrEP and who gets it? PrEP is the use of medication by individuals to prevent HIV contraction, approved in 2012 after demonstrating safety and efficacy in the iPrEx study and Partners PrEP2 trials. HIV infection risk is 92% lower in patients using PrEP. Truvada®, a combination of tenofovir and emtricitabine taken orally daily, is the only approved PrEP regimen and is intended to compliment other prevention strategies such as condoms. HIV negative-individuals at risk for exposure to HIV have been identified as men who have sex with men (MSM), IV drug users, heterosexuals who have unprotected sex with partners of unknown HIV status, and those in serodiscordant relationships. Barriers to PrEP Implementation PrEP is effective when patients adhere; however, both the medical community and some high-risk populations have been slow to adopt it as an HIV prevention strategy. Surveys have shown clinicians perceived barriers to PrEP such as adverse side effects, viral drug resistance, increased high-risk behavior, cost, and training. HIV in Vermont New diagnoses of HIV among Vermont residents has remained relatively stable over the last twenty years. Vermont CARES, a non-profit, offers free and anonymous HIV tests and in-person risk-reduction counseling. Clients are increasingly asking about PrEP as a prevention strategy, but the response from the medical community is difficult to ascertain.https://scholarworks.uvm.edu/comphp_gallery/1235/thumbnail.jp

Di-Isocyanate Crosslinked Aerogels with 1, 6-Bis (Trimethoxysilyl) Hexane Incorporated in Silica Backbone

Silica aerogels are desirable materials for many applications that take advantage of their light weight and low thermal conductivity. Addition of a conformal polymer coating which bonds with the amine decorated surface of the silica network improves the strength of the aerogels by as much as 200 times. Even with vast improvement in strength they still tend to undergo brittle failure due to the rigid silica backbone. We hope to increase the flexibility and elastic recovery of the silica based aerogel by altering the silica back-bone by incorporation of more flexible hexane links. To this end, we investigated the use of 1,6-bis(trimethoxysilyl)hexane (BTMSH), a polysilsesquioxane precursor3, as an additional co-reactant to prepare silica gels which were subsequently cross-linked with di-isocyanate. Previously, this approach of adding flexibility by BTMSH incorporation was demonstrated with styrene cross-linked aerogels. In our study, we varied silane concentration, mol % of silicon from BTMSH and di-isocyanate concentration by weight percent to attempt to optimize both the flexibility and the strength of the aerogels

StormSense: A New Integrated Network of IoT Water Level Sensors in the Smart Cities of Hampton Roads, VA

Propagation of cost-effective water level sensors powered through the Internet of Things (IoT) has expanded the available offerings of ingestible data streams at the disposal of modern smart cities. StormSense is an IoT-enabled inundation forecasting research initiative and an active participant in the Global City Teams Challenge, seeking to enhance flood preparedness in the smart cities of Hampton Roads, VA, for flooding resulting from storm surge, rain, and tides. In this study, we present the results of the new StormSense water level sensors to help establish the “regional resilience monitoring network” noted as a key recommendation from the Intergovernmental Pilot Project. To accomplish this, the Commonwealth Center for Recurrent Flooding Resiliency’s Tidewatch tidal forecast system is being used as a starting point to integrate the extant (NOAA) and new (United States Geological Survey [USGS] and StormSense) water level sensors throughout the region and demonstrate replicability of the solution across the cities of Newport News, Norfolk, and Virginia Beach within Hampton Roads, VA. StormSense’s network employed a mix of ultrasonic and radar remote sensing technologies to record water levels during 2017 Hurricanes Jose and Maria. These data were used to validate the inundation predictions of a street level hydrodynamic model (5-m resolution), whereas the water levels from the sensors and the model were concomitantly validated by a temporary water level sensor deployed by the USGS in the Hague and crowd-sourced GPS maximum flooding extent observations from the sea level rise app, developed in Norfolk, VA

Autonomous three-dimensional formation flight for a swarm of unmanned aerial vehicles

This paper investigates the development of a new guidance algorithm for a formation of unmanned aerial vehicles. Using the new approach of bifurcating potential fields, it is shown that a formation of unmanned aerial vehicles can be successfully controlled such that verifiable autonomous patterns are achieved, with a simple parameter switch allowing for transitions between patterns. The key contribution that this paper presents is in the development of a new bounded bifurcating potential field that avoids saturating the vehicle actuators, which is essential for real or safety-critical applications. To demonstrate this, a guidance and control method is developed, based on a six-degreeof-freedom linearized aircraft model, showing that, in simulation, three-dimensional formation flight for a swarm of unmanned aerial vehicles can be achieved