MobiStreams: A Reliable Distributed Stream Processing System for Mobile Devices

Multi-core phones are now pervasive. Yet, existing applications rely predominantly on a client-server computing paradigm, using phones only as thin clients, sending sensed information via the cellular network to servers for processing. This makes the cellular network the bottleneck, limiting overall application performance. In this paper, we propose Mobi Streams, a Distributed Stream Processing System (DSPS) that runs directly on smartphones. Mobi Streams can offload computing from remote servers to local phones and thus alleviate the pressure on the cellular network. Implementing DSPS on smartphones faces significant challenges: 1) multiple phones can readily fail simultaneously, and 2) the phones' ad-hoc WiFi network has low bandwidth. Mobi Streams tackles these challenges through two new techniques: 1) token-triggered check pointing, and 2) broadcast-based check pointing. Our evaluations driven by two real world applications deployed in the US and Singapore show that migrating from a server platform to a smartphone platform eliminates the cellular network bottleneck, leading to 0.78~42.6X throughput increase and 10%~94.8% latency decrease. Also, Mobi Streams' fault tolerance scheme increases throughput by 230% and reduces latency by 40% vs. prior state-of-the-art fault-tolerant DSPSs

RoadRunner: Infrastructure-less vehicular congestion control

RoadRunner is an in-vehicle app for traffic congestion control without costly roadside infrastructure, instead judiciously harnessing vehicle-to-vehicle communications, cellular connectivity, and onboard computation and sensing to enable large-scale traffic congestion control at higher penetration and finer granularity than previously possible. RoadRunner limits the number of vehicles in a congested region or road by requiring each to possess a token for entry. Tokens can circulate and be reused among multiple vehicles as vehicles move between regions. We built RoadRunner as an Android app utilizing LTE, 802.11p, and 802.11n radios, deployed it on 10 vehicles, and measured cellular access reductions of up to 84% and response time improvements of up to 80%. In a microscopic agent-based traffic simulator, RoadRunner achieved travel speed improvements of up to 7.7% over an industry-strength electronic road pricing system.Singapore-MIT Alliance for Research and TechnologyAmerican Society for Engineering Education. National Defense Science and Engineering Graduate Fellowshi

SignalGuru: Leveraging mobile phones for collaborative traffic signal schedule advisory

While traffic signals are necessary to safely control competing flows of traffic, they inevitably enforce a stop-and-go movement pattern that increases fuel consumption, reduces traffic flow and causes traffic jams. These side effects can be alleviated by providing drivers and their onboard computational devices (e.g., vehicle computer, smartphone) with information about the schedule of the traffic signals ahead. Based on when the signal ahead will turn green, drivers can then adjust speed so as to avoid coming to a complete halt. Such information is called Green Light Optimal Speed Advisory (GLOSA). Alternatively, the onboard computational device may suggest an efficient detour that will save the driver from stops and long waits at red lights ahead. This paper introduces and evaluates SignalGuru, a novel software service that relies solely on a collection of mobile phones to detect and predict the traffic signal schedule, enabling GLOSA and other novel applications. Our SignalGuru leverages windshield-mounted phones to opportunistically detect current traffic signals with their cameras, collaboratively communicate and learn traffic signal schedule patterns, and predict their future schedule. Results from two deployments of SignalGuru, using iPhones in cars in Cambridge (MA, USA) and Singapore, show that traffic signal schedules can be predicted accurately. On average, SignalGuru comes within 0.66s, for pre-timed traffic signals and within 2.45s, for traffic-adaptive traffic signals. Feeding SignalGuru's predicted traffic schedule to our GLOSA application, our vehicle fuel consumption measurements show savings of 20.3%, on average.National Science Foundation (U.S.). (Grant number CSR-EHS-0615175)Singapore-MIT Alliance for Research and Technology Center. Future Urban Mobilit

Enabling System-Level Modeling of Variation-Induced Faults in Networks-on-Chip

Process Variation (PV) is increasingly threatening the reliability of Networks-on-Chips. Thus, various resilient router designs have been recently proposed and evaluated. However, these evaluations assume random fault distributions, which result in 52%--81% inaccuracy. We propose an accurate circuit-level fault-modeling tool, which can be plugged into any system-level NoC simulator, quantify the system-level impact of PV-induced faults at runtime, pinpoint fault-prone router components that should be protected, and accurately evaluate alternative resilient multi-core designs.GigaScale Systems Research CenterFocus Center Research Program. Focus Center for Circuit & System Solutions. Semiconductor Research Corporation. Interconnect Focus Cente

Gene expression in early and progression phases of autosomal dominant polycystic kidney disease

<p>Abstract</p> <p>Background</p> <p>Little is known about the genes involved in the initial cyst formation and disease progression in autosomal dominant polycystic kidney disease (ADPKD); however, such knowledge is necessary to explore therapeutic avenues for this common inherited kidney disease.</p> <p>Findings</p> <p>To uncover the genetic determinants and molecular mechanisms of ADPKD, we analyzed 4-point time-series DNA microarrays from <it>Pkd1</it>^{<it>L</it>3/<it>L</it>3}mice to generate high resolution gene expression profiles at different stages of disease progression. We found different characteristic gene expression signatures in the kidneys of <it>Pkd1</it>^{<it>L</it>3/<it>L</it>3}mice compared to age-matched controls during the initial phase of the disease. By postnatal week 1, the <it>Pkd1</it>^{<it>L</it>3/<it>L</it>3}kidney already had a distinctive gene expression pattern different from the corresponding normal controls.</p> <p>Conclusion</p> <p>The genes differentially expressed, either induced or repressed, in ADPKD are important in immune defense, cell structure and motility, cellular proliferation, apoptosis and metabolic processes, and include members of three pathways (Wnt, Notch, and BMP) involved in morphogenetic signaling. Further analysis of the gene expression profiles from the early stage of cystogenesis to end stage disease identified a possible gene network involved in the pathogenesis of ADPKD.</p

Effects of temperature and irradiation damage on fracture around nanoindents

Indentation based fracture toughness measurements remain one of the fastest and most convenient ways of measuring fracture toughness and are widely used even though there are known inaccuracies with the methodologies used. In this work we use single crystal and monocrystalline silicon carbide to study the effects of temperature and irradiation damage on crack propagation and morphologies Please click Additional Files below to see the full abstract

High-temperature fracture test using chevron-notched tungsten microcantilevers

The combination of focused-ion beam (FIB) based sample preparation and nanoindentation allows fracture tests to be conducted at the micro-scale. Micro-fracture tests are of great interest to the nuclear materials community, as it allows direct measurements of fracture toughness within thin ion-irradiated layers and significantly reduces the volume of radioactive samples required as compared to working with neutron irradiated samples. The main drawback of existing micro-fracture tests is its limitation to brittle materials, as only linear-elastic fracture mechanics (LEFM) solutions have been developed so far. Tungsten-tantalum (W-Ta) alloy, is the primary candidate material for the plasma facing components of a future fusion reactor divertor, however is a semi-brittle material. LEFM solutions neglect any local plastic deformation that contribute to the blunting of the crack tip, therefore underestimate the true fracture toughness. Elastic-plastic fracture mechanics (EPFM) is necessarily to quantitatively analyse the complete fracture process, this greatly complicates both sample manufacture and experimental analysis. This research introduces a novel chevron-notch design to the W-Ta micro-cantilevers to promote stable crack growth which is a requisite for the EPFM approach. Cantilevers, manufactured using FIB machining, were loaded via a cyclic method, using a G200 Nanoindenter to monitor the stiffness in each cycle. By monitoring the decrease in stiffness of the cantilever through the cycles, crack length can be measured. Given detailed information of the crack length and the cantilever geometry, the complete fracture process of the semi-brittle W-Ta alloy can be quantitatively analysed. Initial results showed the fracture toughness of W-1%Ta alloy at room temperature is 2.7 MPa·m0.5, showing no significant R-curve behaviour before the onset of unstable fracture. This revealed no crack tip blunting occurred when tested at room temperature. This result is consistent with previous macro-scale fracture tests of W-1%Ta alloy at room temperature. The future goal is to extend this technique at elevated temperatures using our hot nanoindenter (up to 750 °C). This will provide quantitative analysis of the fracture process of W-Ta alloys at real reactor operating environment. By comparing micro- with macro-fracture toughness, this will also shed light on the feasibility of using micro-fracture tests to probe bulk fracture toughness