From Artifacts to Aggregations: Modeling Scientific Life Cycles on the Semantic Web

In the process of scientific research, many information objects are generated, all of which may remain valuable indefinitely. However, artifacts such as instrument data and associated calibration information may have little value in isolation; their meaning is derived from their relationships to each other. Individual artifacts are best represented as components of a life cycle that is specific to a scientific research domain or project. Current cataloging practices do not describe objects at a sufficient level of granularity nor do they offer the globally persistent identifiers necessary to discover and manage scholarly products with World Wide Web standards. The Open Archives Initiative's Object Reuse and Exchange data model (OAI-ORE) meets these requirements. We demonstrate a conceptual implementation of OAI-ORE to represent the scientific life cycles of embedded networked sensor applications in seismology and environmental sciences. By establishing relationships between publications, data, and contextual research information, we illustrate how to obtain a richer and more realistic view of scientific practices. That view can facilitate new forms of scientific research and learning. Our analysis is framed by studies of scientific practices in a large, multi-disciplinary, multi-university science and engineering research center, the Center for Embedded Networked Sensing (CENS).Comment: 28 pages. To appear in the Journal of the American Society for Information Science and Technology (JASIST

Security for Rural Public Computing

Current research on securing public computing infrastructure like Internet kiosks has focused on the use of smartphones to establish trust in a computing platform or to offload the processing of sensitive information, and the use of new cryptosystems such as Hierarchical Identity-based Encryption (HIBE) to protect kiosk user data. Challenges posed by rural kiosks, specifically (a) the absence of specialized hardware features such as Trusted Platform Modules (TPMs) or a modifiable BIOS in older recycled PCs, (b) the potential use of periodically disconnected links between kiosks and the Internet, (c) the absence of a production-ready implementation of HIBE and (d) the limited availability of smartphones in most developing regions make these approaches difficult, if not impossible, to implement in a rural public computing scenario. In this thesis, I present a practical, unobtrusive and easy-to-use security architecture for rural public computing that uses a combination of physical and cryptographic mechanisms to protect user data, public computing infrastructure and handheld devices that access this infrastructure. Key contributions of this work include (a) a detailed threat analysis of such systems with a particular focus on rural Internet kiosks and handheld devices, (b) a security architecture for rural public computing infrastructure that does not require any specialized hardware, (c) an application-independent and backward-compatible security API for securely sending and receiving data between these systems and the Internet that can operate over delay tolerant links, (d) an implementation of my scheme for rural Internet kiosks and (e) a performance evaluation of this implementation to demonstrate its feasibility

Resource Efficient Urban Delay/disruptive Tolerant Networks

Ph.DDOCTOR OF PHILOSOPH

Viivesietoisten verkkojen nykytila ja tulevaisuuden haasteet

Delay and disruption tolerant networks (DTNs) are computer networks where round trip delays and error rates are high and disconnections frequent. Examples of these extreme networks are space communications, sensor networks, connecting rural villages to the Internet and even interconnecting commodity portable wireless devices and mobile phones. Basic elements of delay tolerant networks are a store-and-forward message transfer resembling traditional mail delivery, an opportunistic and intermittent routing, and an extensible cross-region resource naming service. Individual nodes of the network take an active part in routing the traffic and provide in-network data storage for application data that flows through the network. Application architecture for delay tolerant networks differs also from those used in traditional networks. It has become feasible to design applications that are network-aware and opportunistic, taking an advantage of different network connection speeds and capabilities. This might change some of the basic paradigms of network application design. DTN protocols will also support in designing applications which depend on processes to be persistent over reboots and power failures. DTN protocols could also be applicable to traditional networks in cases where high tolerance to delays or errors would be desired. It is apparent that challenged networks also challenge the traditional strictly layered model of network application design. This thesis provides an extensive introduction to delay tolerant networking concepts and applications. Most attention is given to challenging problems of routing and application architecture. Finally, future prospects of DTN applications and implementations are envisioned through recent research results and an interview with an active researcher of DTN networks.Viive- ja häiriösietoiset verkot (Delay/Disruption Tolerant Networks, DTN) ovat tietoliikenneverkkoja, joissa siirtoviiveet ja virhetiheydet ovat suuria sekä yhteyskatkot tavallisia. DTN-verkoissa toimivat sovellukset ovat mukautuneet yhteyskatkoihin sekä päästä päähän -yhteyden puuttumiseen. Näille sovelluksille riittää, että viesti toimitetaan perille esimerkiksi tiettyyn aikaan mennessä. DTN-verkkojen virheiden sietokyky perustuu viestien siirtämiseen verkossa yksi solmuväli kerrallaan ja viestien tallettamiseen verkkosolmuissa haihtumattomalle tallennusvälineelle. Näin verkon viestinvälitys voi toimia pitkistäkin yhteyskatkoista ja solmujen uudelleenkäynnistyksistä huolimatta. Viivesietoisten verkkojen sovelluksia ovat esimerkiksi yhteydet avaruusluotaimiin toisilla planeetoilla tai viestinvälitys seuduilla, joilla ei ole tarjolla kiinteää tietoliikenneinfrastruktuuria. Muita sovellusalueita ovat pelastus- ja sotilasyhteydet, sensoriverkot sekä liikkuvien käyttäjien ja ajoneuvojen verkot. Tässä tutkielmassa esitellään viivesietoisten verkkojen arkkitehtuurin perusratkaisuja sekä joitakin sovellusalueita. Erityisesti käsitellään reititystä sekä sen resurssinkulutuksen pienentämiseen kehitettyjä ratkaisuja. Lisäksi tutkielmassa esitellään viivesietoisten verkkojen ja niiden sovellusalueiden tulevaisuudennäkymiä sekä alan uusimpien tutkimustulosten että aktiivitutkijan haastattelun avulla

Disruption Tolerant Shell

Wireless network technology is being applied to a wide range of scientific and engineering problems and across a wide dynamic range of spatial scales. When node placement is constrained by the application (e.g, coupled to sensor placement needs), and can not rely on pre-existing infrastructure (e.g., cellular infrastructure or power-lines), such systems may experience erratic link qualities and intermittent node disconnection. These characteristics, combined with unpredictable environmental conditions, make it difficult to rely upon traditional end to end connections for regular high bandwidth data acquisition and for system management and configuration. We have implemented and deployed such a "challenged network" system of 50 nodes for use by seismologists along a part of the Mesoamerican Subduction Experiment (MASE) broadband seismic array, stretching 500 KM from Acapulco to Tampico through Mexico city. In addition to supporting Delay Tolerant data transfer of relatively high bandwidth seismic data, our system includes a reliable asynchronous remote shell interface (referred to as Disruption Tolerant Shell, DTS) to accomplish the management on these types of system. We present the implementation of this solution and its evaluation on a 13 node portion of the MASE network

Disruption Tolerant Shell

Wireless network technology is being applied to a wide range of scientific and engineering problems and across a wide dynamic range of spatial scales. When node placement is constrained by the application (e.g, coupled to sensor placement needs), and can not rely on pre-existing infrastructure (e.g., cellular infrastructure or power-lines), such systems may experience erratic link qualities and intermittent node disconnection. These characteristics, combined with unpredictable environmental conditions, make it difficult to rely upon traditional end to end connections for regular high bandwidth data acquisition and for system management and configuration. We have implemented and deployed such a “challenged network ” system of 50 nodes for use by seismologists along a part of the Mesoamerican Subduction Experiment (MASE) broadband seismic array, stretching 500 KM from Acapulco to Tampico through Mexico city. In addition to supporting Delay Tolerant data transfer of relatively high bandwidth seismic data, our system includes a reliable asynchronous remote shell interface (referred to as Disruption Tolerant Shell, DTS) to accomplish the management on these types of system. We present the implementation of this solution and its evaluation on a 13 node portion of the MASE network

Latest Scientific and Technological Results From The Mexico Experiment

We have examined seismic data and wireless network characteristics from 100 broadband stations installed from Acapulco to Tampico in Mexico over a period of 1.5 years (2005-2007). The instruments were part of the MASE (Middle America Subduction Experiment) which has the objective to build a geodynamical model of the subduction process beneath the Middle America Trench. The stations had a 5-6 km spacing and were connected wirelessly with each other providing a unique data set. It allows examination of various aspects in tomography, shear wave splitting, wave travel times as well as extensive analysis of the wireless network used for data delivery. Tomographic and SKS splitting studies in this area show the presence of a 50-80 km thick flat slab under the western part of the array, and a steeply dipping slab beneath its center to a depth of ~550km and ~375 km inland.The research in wireless area displays no correlation between SNR and throughput and a rough correlation between the throughput and the distance for the majority of the links. Various network tuning techniques were applied to further investigate the properties of the communication hardware and data transmission. A new disruption tolerant shell (DTS) was tested that provides duplex communication with the network and handles breaks in the RF communication by temporarily storing data and transmitting when a conection has been restored

Latest Scientific and Technological Results From The Mexico Experiment

We have examined seismic data and wireless network characteristics from 100 broadband stations installed from Acapulco to Tampico in Mexico over a period of 1.5 years (2005-2007). The instruments were part of the MASE (Middle America Subduction Experiment) which has the objective to build a geodynamical model of the subduction process beneath the Middle America Trench. The stations had a 5-6 km spacing and were connected wirelessly with each other providing a unique data set. It allows examination of various aspects in tomography, shear wave splitting, wave travel times as well as extensive analysis of the wireless network used for data delivery. Tomographic and SKS splitting studies in this area show the presence of a 50-80 km thick flat slab under the western part of the array, and a steeply dipping slab beneath its center to a depth of ~550km and ~375 km inland.The research in wireless area displays no correlation between SNR and throughput and a rough correlation between the throughput and the distance for the majority of the links. Various network tuning techniques were applied to further investigate the properties of the communication hardware and data transmission. A new disruption tolerant shell (DTS) was tested that provides duplex communication with the network and handles breaks in the RF communication by temporarily storing data and transmitting when a conection has been restored