A Novel Locality Algorithm and Peer-to-Peer Communication Infrastructure for Optimizing Network Performance in Smart Microgrids

[EN] Peer-to-Peer (P2P) overlay communications networks have emerged as a new paradigm for implementing distributed services in microgrids due to their potential benefits: they are robust, scalable, fault-tolerant, and they can route messages even with a large number of nodes which are frequently entering or leaving from the network. However, current P2P systems have been mainly developed for file sharing or cycle sharing applications where the processes of searching and managing resources are not optimized. Locality algorithms have gained a lot of attention due to their potential to provide an optimized path to groups with similar interests for routing messages in order to get better network performance. This paper develops a fully functional decentralized communication architecture with a new P2P locality algorithm and a specific protocol for monitoring and control of microgrids. Experimental results show that the proposed locality algorithm reduces the number of lookup messages and the lookup delay time. Moreover, the proposed communication architecture heavily depends of the lookup used algorithm as well as the placement of the communication layers within the architecture. Experimental results will show that the proposed techniques meet the network requirements of smart microgrids even with a large number of nodes on stream.This work is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) and the European Regional Development Fund (ERDF) under Grant ENE2015-64087-C2-2R. This work is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under BES-2013-064539.Marzal-Romeu, S.; González-Medina, R.; Salas-Puente, RA.; Figueres Amorós, E.; Garcerá, G. (2017). A Novel Locality Algorithm and Peer-to-Peer Communication Infrastructure for Optimizing Network Performance in Smart Microgrids. 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A framework for the dynamic management of Peer-to-Peer overlays

Peer-to-Peer (P2P) applications have been associated with inefficient operation, interference with other network services and large operational costs for network providers. This thesis presents a framework which can help ISPs address these issues by means of intelligent management of peer behaviour. The proposed approach involves limited control of P2P overlays without interfering with the fundamental characteristics of peer autonomy and decentralised operation. At the core of the management framework lays the Active Virtual Peer (AVP). Essentially intelligent peers operated by the network providers, the AVPs interact with the overlay from within, minimising redundant or inefficient traffic, enhancing overlay stability and facilitating the efficient and balanced use of available peer and network resources. They offer an “insider‟s” view of the overlay and permit the management of P2P functions in a compatible and non-intrusive manner. AVPs can support multiple P2P protocols and coordinate to perform functions collectively. To account for the multi-faceted nature of P2P applications and allow the incorporation of modern techniques and protocols as they appear, the framework is based on a modular architecture. Core modules for overlay control and transit traffic minimisation are presented. Towards the latter, a number of suitable P2P content caching strategies are proposed. Using a purpose-built P2P network simulator and small-scale experiments, it is demonstrated that the introduction of AVPs inside the network can significantly reduce inter-AS traffic, minimise costly multi-hop flows, increase overlay stability and load-balancing and offer improved peer transfer performance

Enabling Program Analysis Through Deterministic Replay and Optimistic Hybrid Analysis

As software continues to evolve, software systems increase in complexity. With software systems composed of many distinct but interacting components, today’s system programmers, users, and administrators find themselves requiring automated ways to find, understand, and handle system mis-behavior. Recent information breaches such as the Equifax breach of 2017, and the Heartbleed vulnerability of 2014 show the need to understand and debug prior states of computer systems. In this thesis I focus on enabling practical entire-system retroactive analysis, allowing programmers, users, and system administrators to diagnose and understand the impact of these devastating mishaps. I focus primarly on two techniques. First, I discuss a novel deterministic record and replay system which enables fast, practical recollection of entire systems of computer state. Second, I discuss optimistic hybrid analysis, a novel optimization method capable of dramatically accelerating retroactive program analysis. Record and replay systems greatly aid in solving a variety of problems, such as fault tolerance, forensic analysis, and information providence. These solutions, however, assume ubiquitous recording of any application which may have a problem. Current record and replay systems are forced to trade-off between disk space and replay speed. This trade-off has historically made it impractical to both record and replay large histories of system level computation. I present Arnold, a novel record and replay system which efficiently records years of computation on a commodity hard-drive, and can efficiently replay any recorded information. Arnold combines caching with a unique process-group granularity of recording to produce both small, and quickly recalled recordings. My experiments show that under a desktop workload, Arnold could store 4 years of computation on a commodity 4TB hard drive. Dynamic analysis is used to retroactively identify and address many forms of system mis-behaviors including: programming errors, data-races, private information leakage, and memory errors. Unfortunately, the runtime overhead of dynamic analysis has precluded its adoption in many instances. I present a new dynamic analysis methodology called optimistic hybrid analysis (OHA). OHA uses knowledge of the past to predict program behaviors in the future. These predictions, or likely invariants are speculatively assumed true by a static analysis. This creates a static analysis which can be far more accurate than its traditional counterpart. Once this predicated static analysis is created, it is speculatively used to optimize a final dynamic analysis, creating a far more efficient dynamic analysis than otherwise possible. I demonstrate the effectiveness of OHA by creating an optimistic hybrid backward slicer, OptSlice, and optimistic data-race detector OptFT. OptSlice and OptFT are just as accurate as their traditional hybrid counterparts, but run on average 8.3x and 1.6x faster respectively. In this thesis I demonstrate that Arnold’s ability to record and replay entire computer systems, combined with optimistic hybrid analysis’s ability to quickly analyze prior computation, enable a practical and useful entire system retroactive analysis that has been previously unrealized.PHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/144052/1/ddevec_1.pd

Robust health stream processing

2014 Fall.Includes bibliographical references.As the cost of personal health sensors decrease along with improvements in battery life and connectivity, it becomes more feasible to allow patients to leave full-time care environments sooner. Such devices could lead to greater independence for the elderly, as well as for others who would normally require full-time care. It would also allow surgery patients to spend less time in the hospital, both pre- and post-operation, as all data could be gathered via remote sensors in the patients home. While sensor technology is rapidly approaching the point where this is a feasible option, we still lack in processing frameworks which would make such a leap not only feasible but safe. This work focuses on developing a framework which is robust to both failures of processing elements as well as interference from other computations processing health sensor data. We work with 3 disparate data streams and accompanying computations: electroencephalogram (EEG) data gathered for a brain-computer interface (BCI) application, electrocardiogram (ECG) data gathered for arrhythmia detection, and thorax data gathered from monitoring patient sleep status

ssIoTa: A system software framework for the internet of things

Sensors are widely deployed in our environment, and their number is increasing rapidly. In the near future, billions of devices will all be connected to each other, creating an Internet of Things. Furthermore, computational intelligence is needed to make applications involving these devices truly exciting. In IoT, however, the vast amounts of data will not be statically prepared for batch processing, but rather continually produced and streamed live to data consumers and intelligent algorithms. We refer to applications that perform live analysis on live data streams, bringing intelligence to IoT, as the Analysis of Things. However, the Analysis of Things also comes with a new set of challenges. The data sources are not collected in a single, centralized location, but rather distributed widely across the environment. AoT applications need to be able to access (consume, produce, and share with each other) this data in a way that is natural considering its live streaming nature. The data transport mechanism must also allow easy access to sensors, actuators, and analysis results. Furthermore, analysis applications require computational resources on which to run. We claim that system support for AoT can reduce the complexity of developing and executing such applications. To address this, we make the following contributions: - A framework for systems support of Live Streaming Analysis in the Internet of Things, which we refer to as the Analysis of Things (AoT), including a set of requirements for system design - A system implementation that validates the framework by supporting Analysis of Things applications at a local scale, and a design for a federated system that supports AoT on a wide geographical scale - An empirical system evaluation that validates the system design and implementation, including simulation experiments across a wide-area distributed system We present five broad requirements for the Analysis of Things and discuss one set of specific system support features that can satisfy these requirements. We have implemented a system, called \textsubscript{SS}IoTa, that implements these features and supports AoT applications running on local resources. The programming model for the system allows applications to be specified simply as operator graphs, by connecting operator inputs to operator outputs and sensor streams. Operators are code components that run arbitrary continuous analysis algorithms on streaming data. By conforming to a provided interface, operators may be developed that can be composed into operator graphs and executed by the system. The system consists of an Execution Environment, in which a Resource Manager manages the available computational resources and the applications running on them, a Stream Registry, in which available data streams can be registered so that they may be discovered and used by applications, and an Operator Store, which serves as a repository for operator code so that components can be shared and reused. Experimental results for the system implementation validate its performance. Many applications are also widely distributed across a geographic area. To support such applications, \textsubscript{SS}IoTa must be able to run them on infrastructure resources that are also distributed widely. We have designed a system that does so by federating each of the three system components: Operator Store, Stream Registry, and Resource Manager. The Operator Store is distributed using a distributed hast table (DHT), however since temporal locality can be expected and data churn is low, caching may be employed to further improve performance. Since sensors exist at particular locations in physical space, queries on the Stream Registry will be based on location. We also introduce the concept of geographical locality. Therefore, range queries in two dimensions must be supported by the federated Stream Registry, while taking advantage of geographical locality for improved average-case performance. To accomplish these goals, we present a design sketch for SkipCAN, a modification of the SkipNet and Content Addressable Network DHTs. Finally, the fundamental issue in the federated Resource Manager is how to distributed the operators of multiple applications across the geographically distributed sites where computational resources can execute them. To address this, we introduce DistAl, a fully distributed algorithm that assigns operators to sites. DistAl also respects the system resource constraints and application preferences for performance and quality of results (QoR), using application-specific utility functions to allow applications to express their preferences. DistAl is validated by simulation results.Ph.D

Proceedings of the 7th Sound and Music Computing Conference

Proceedings of the SMC2010 - 7th Sound and Music Computing Conference, July 21st - July 24th 2010

Efficient Passive Clustering and Gateways selection MANETs

Passive clustering does not employ control packets to collect topological information in ad hoc networks. In our proposal, we avoid making frequent changes in cluster architecture due to repeated election and re-election of cluster heads and gateways. Our primary objective has been to make Passive Clustering more practical by employing optimal number of gateways and reduce the number of rebroadcast packets

The Association of Late-Life Depression, Cognitive Functioning, and Sleep Disorder in Aging

The continuing growth in the demographic of aging individuals in the United States creates concern for diseases of aging that are chronic, notably unipolar depressive disorders. The high rates of depression in the aging population are a concern because of the strong association between late-life depression and cognitive impairment. Poor cognitive functioning is a hallmark of aging related neurological disorders, the most prevalent being Alzheimer’s Disease (AD). Sleep disorder is a core symptom of depression, and is definitively associated with the development of mild cognitive impairment (MCI), the prodrome of AD. MCI is also characterized by similar types of sleep disturbance including sleep fragmentation, which consists of excessive awakenings during the night that leads to atypical suppression of night-time full awakenings and chronic sleep debt that impairs daytime attention and cognition as a consequence of poor sleep quality. The main hypothesis of this study is that current or historical depression in older adults will be associated with poor sleep quality and cognitive impairment. Participants (N=50) from 65-85 years were assessed to determine the impact of depression status on sleep disturbance and cognitive variables. Individuals endorsing current depression (n=9), history of diagnosed depression but no current depression (n=7), or no current depression (n=34) were tested for 7 nights using wrist actigraphy and self-report sleep diaries to assess various sleep parameters used to identify sleep disturbance. Memory consolidation was probed surrounding one night of sleep using a simple procedural memory task and one-month follow-up assessment was used to assess a variety of neurocognitive domains including immediate and delayed recall, visuospatial abilities, etc. Results from this study revealed that individuals with current depression showed poorer sleep quality (i.e. shorter sleep time, lower mean sleep efficiency, longer sleep latency, etc.) and self-reported more sleep disturbances and greater daytime dysfunction when compared with individuals with no current depression or depressive history (p’s \u3c .05). Results of impairment on cognitive tasks from participants with current depression or a history of diagnosed depression were not found. These results provide evidence of an association between sleep disturbance and late-life depression. Cognitive performance of depressed older adults warrant further exploration