A Privacy Conscious Bluetooth Infrastructure for Location Aware Computing

We present a low cost and easily deployed infrastructure for location aware computing that is built using standard Bluetooth® technologies and personal computers. Mobile devices are able to determine their location to room-level granularity with existing bluetooth technology, and to even greater resolution with the use of the recently adopted bluetooth 1.2 specification, all while maintaining complete anonymity. Various techniques for improving the speed and resolution of the system are described, along with their tradeoffs in privacy. The system is trivial to implement on a large scale – our network covering 5,000 square meters was deployed by a single student over the course of a few days at a cost of less than US$1,000.Singapore-MIT Alliance (SMA

Modeling Information Flow in Face-to-Face Meetings while Protecting Privacy

Social networks have been used to understand how information flows through an organization as well as identifying individuals that appear to have control over this information flow. Such individuals are identified as being central nodes in a graph representation of the social network and have high "betweenness" values. Rather than looking at graphs derived from email, on-line forums, or telephone connections, we consider sequences of bipartite graphs that represent face-to-face meetings between individuals, and define a new metric to identify the information elite individuals. We show that, in our simulations, individuals that attend many meetings with many different people do not always have high betweenness values, even though they seem to be the ones that control the information flow.Singapore-MIT Alliance (SMA

Using Open Stack for an Open Cloud Exchange(OCX)

We are developing a new public cloud, the Massachusetts Open Cloud (MOC) based on the model of an Open Cloud eXchange (OCX). We discuss in this paper the vision of an OCX and how we intend to realize it using the OpenStack open-source cloud platform in the MOC. A limited form of an OCX can be achieved today by layering new services on top of OpenStack. We have performed an analysis of OpenStack to determine the changes needed in order to fully realize the OCX model. We describe these proposed changes, which although significant and requiring broad community involvement will provide functionality of value to both existing single-provider clouds as well as future multi-provider ones

A Dynamically Partitionable Compressed Cache

The effective size of an L2 cache can be increased by using a dictionary-based compression scheme. Naive application of this idea performs poorly since the data values in a cache greatly vary in their “compressibility.” The novelty of this paper is a scheme that dynamically partitions the cache into sections of different compressibilities. While compression is often researched in the context of a large stream, in this work it is applied repeatedly on smaller cache-line sized blocks so as to preserve the random access requirement of a cache. When a cache-line is brought into the L2 cache or the cache-line is to be modified, the line is compressed using a dynamic, LZW dictionary. Depending on the compression, it is placed into the relevant partition. The partitioning is dynamic in that the ratio of space allocated to compressed and uncompressed varies depending on the actual performance, Certain SPEC-2000 benchmarks using a compressed L2 cache show an 80reduction in L2 miss-rate when compared to using an uncompressed L2 cache of the same area, taking into account all area overhead associated with the compression circuitry. For other SPEC-2000 benchmarks, the compressed cache performs as well as a traditional cache that is 4.3 times as large as the compressed cache in terms of hit rate, The adaptivity ensures that, in terms of miss rates, the compressed cache never performs worse than a traditional cache.Singapore-MIT Alliance (SMA

Relaxing Routing Table to Alleviate Dynamism in P2P Systems

In dynamic P2P networks, nodes join and depart from the system frequently, which partially damages the predefined P2P structure, and impairs the system performance such as basic lookup functionality. Therefore stabilization process has to be done to restore the logical topology. This paper presents an approach to relax the requirement on routing tables to provide provably better stability than fixed structured P2P systems. We propose a relaxed Chord that keeps the O(logN) number of hops for greedy lookup, but it requires less stabilization overhead. It allows a tradeoff between lookup efficiency and structure flexibility without adding any overhead to the system. In the relaxed routing structure, each routing entry ("finger") of the node is allowed to vary within a set of values. Each node only needs to keep a certain number of fingers that point to nodes in its anchor set. This relaxation reduces the burden of state management of the node. The relaxed routing scheme provides an alternative structure other than randomized P2P and deterministic P2P, by relaxing on finger selection. It provides good flexibility and therefore extends the system functioning time.Singapore-MIT Alliance (SMA

New methods and results for quantification of lightning-aircraft electrodynamics

The NASA F-106 collected data on the rates of change of electromagnetic parameters on the aircraft surface during over 700 direct lightning strikes while penetrating thunderstorms at altitudes from 15,000 t0 40,000 ft (4,570 to 12,190 m). These in situ measurements provided the basis for the first statistical quantification of the lightning electromagnetic threat to aircraft appropriate for determining indirect lightning effects on aircraft. These data are used to update previous lightning criteria and standards developed over the years from ground-based measurements. The proposed standards will be the first which reflect actual aircraft responses measured at flight altitudes. Nonparametric maximum likelihood estimates of the distribution of the peak electromagnetic rates of change for consideration in the new standards are obtained based on peak recorder data for multiple-strike flights. The linear and nonlinear modeling techniques developed provide means to interpret and understand the direct-strike electromagnetic data acquired on the F-106. The reasonable results obtained with the models, compared with measured responses, provide increased confidence that the models may be credibly applied to other aircraft

NASA Specialized Center of Research and Training (NSCORT) in Gravitational Biology

The mission of our NSCORT is to investigate the effects of gravity and other environmental factors on biological function at the cellular and molecular level. The research efforts, training opportunities, and scientific exchange will promote the expansion of a scientific peer group well-educated in space-related biological issues. This will stimulate the interest of the larger scientific community and insure the continuing development of rigorous flight investigations in Gravitational Biology

commanimation: Creating and managing animations via speech

A speech controlled animation system is both a useful application program as well as a laboratory in which to investigate context aware applications as well as controlling errors. The user need not have prior knowledge or experience in animation and is yet able to create interesting and meaningful animation naturally and fluently. The system can be used in a number of applications ranging from PowerPoint presentations to simulations to children’s storytelling tools.Singapore-MIT Alliance (SMA

Ubiquitous Memory Introspection (Preliminary Manuscript)

Modern memory systems play a critical role in the performance ofapplications, but a detailed understanding of the application behaviorin the memory system is not trivial to attain. It requires timeconsuming simulations of the memory hierarchy using long traces, andoften using detailed modeling. It is increasingly possible to accesshardware performance counters to measure events in the memory system,but the measurements remain coarse grained, better suited forperformance summaries than providing instruction level feedback. Theavailability of a low cost, online, and accurate methodology forderiving fine-grained memory behavior profiles can prove extremelyuseful for runtime analysis and optimization of programs.This paper presents a new methodology for Ubiquitous MemoryIntrospection (UMI). It is an online and lightweight mini-simulationmethodology that focuses on simulating short memory access tracesrecorded from frequently executed code regions. The simulations arefast and can provide profiling results at varying granularities, downto that of a single instruction or address. UMI naturally complementsruntime optimizations techniques and enables new opportunities formemory specific optimizations.In this paper, we present a prototype implementation of a runtimesystem implementing UMI. The prototype is readily deployed oncommodity processors, requires no user intervention, and can operatewith stripped binaries and legacy software. The prototype operateswith an average runtime overhead of 20% but this slowdown is only 6%slower than a state of the art binary instrumentation tool. We used32 benchmarks, including the full suite of SPEC2000 benchmarks, forour evaluation. We show that the mini-simulation results accuratelyreflect the cache performance of two existing memory systems, anIntel Pentium~4 and an AMD Athlon MP (K7) processor. We alsodemonstrate that low level profiling information from the onlinesimulation can serve to identify high-miss rate load instructions with a77% rate of accuracy compared to full offline simulations thatrequired days to complete. The online profiling results are used atruntime to implement a simple software prefetching strategy thatachieves a speedup greater than 60% in the best case