Ricardo Silva

Organic-Rich facies in the Sinemurian and Pliensbachian of the Lusitanian Basin, Portugal: Total organic carbon distribution and relation to transgressive-regressive facies cycles

The upper Sinemurian to Pliensbachian series of the Lusitanian Basin (Portugal) correspond to marly limestone sediments rich in benthic and nektonic macrofauna. This sedimentary record includes several intervals of organicrich facies, which are particularly well developed in the western sectors of the basin. They correspond to grey and dark marls locally showing strong lamination (black shale type) and are recognized as one of the most important potential oil source rocks. This study shows the vertical and lateral distribution of these organic-rich intervals, supported by over 550 total organic carbon (TOC) determinations. The results presented reveal two important intervals, with several black shale occurrences, in the Oxynotum(?)–Raricostatum (Polvoeira Member of Agua de Madeiros Formation) and at the top of the Ibex-upper part of Margaritatus zones (top of the Vale das Fontes Formation), showing in the distal (western) sectors up to 22% and 15% TOC, respectively. TOC values decrease progressively towards the proximal sectors, the youngest organic-rich interval being the most expressive at the basin scale. This lateral TOC distribution, the facies stacking patterns and the decrease observed in benthic macrofauna confirm that these intervals are related to 2nd-order transgressive phases. 2nd-order regressive phases, developed during the uppermost Raricostatum and Spinatum zones respectively, show lower TOC values. TOC distribution combined with other stratigraphic and sedimentological parameters enabled seven facies maps to be created for the time interval studied. At the regional scale, this study shows for the first time the good similarity between the upper Sinemurian-Pliensbachian sedimentary successions of the Lusitanian and Basque- Cantabrian basins.

The GINSENG system for wireless monitoring and control: Design and deployment experiences

Todays industrial facilities, such as oil refineries, chemical plants, and factories, rely on wired sensor systems to monitor and control the production processes. The deployment and maintenance of such cabled systems is expensive and inflexible. It is, therefore, desirable to replace or augment these systems using wireless technology, which requires us to overcome significant technical challenges. Process automation and control applications are mission-critical and require timely and reliable data delivery, which is difficult to provide in industrial environments with harsh radio environments. In this article, we present the GINSENG system which implements performance control to allow us to use wireless sensor networks for mission-critical applications in industrial environments. GINSENG is a complete system solution that comprises on-node system software, network protocols, and back-end systems with sophisticated data processing capability. GINSENG assumes that a deployment can be carefully planned. A TDMA-based MAC protocol, tailored to the deployment environment, is employed to provide reliable and timely data delivery. Performance debugging components are used to unintrusively monitor the system performance and identify problems as they occur. The article reports on a real-world deployment of GINSENG in an especially challenging environment of an operational oil refinery in Sines, Portugal. We provide experimental results from this deployment and share the experiences gained. These results demonstate the use of GINSENG for sensing and actuation and allow an assessment of its ability to operate within the required performance bounds. We also identify shortcomings that manifested during the evaluation phase, thus giving a useful perspective on the challenges that have to be overcome in these harsh application settings.

Mobility in Wireless Sensor Networks — Survey and Proposal

Abstract Targeting an increasing number of potential application domains, wireless sensor networks (WSN) have been the subject of intense research, in an attempt to optimize their performance while guaranteeing reliability in highly demanding scenarios. However, hardware constraints have limited their application, and real deployments have demonstrated that WSNs have difficulties in coping with complex communication tasks – such as mobility – in addition to application-related tasks. Mobility support in WSNs is crucial for a very high percentage of application scenarios and, most notably, for the Internet of Things. It is, thus, important to know the existing solutions for mobility in WSNs, identifying their main characteristics and limitations. With this in mind, we firstly present a survey of models for mobility support in WSNs. We then present the Network of Proxies (NoP) assisted mobility proposal, which relieves resource-constrained WSN nodes from the heavy procedures inherent to mobility management. The presented proposal was implemented and evaluated in a real platform, demonstrating not only its advantages over conventional solutions, but also its very good performance in the simultaneous handling of several mobile nodes, leading to high handoff success rate and low handoff time.

A proposal for proxy-based mobility in WSNs

Inability to meet the key requirement of efficient mobility support is becoming a major impairment of wireless sensor network (WSN). Many critical WSN applications need not only reliability, but also the ability to adequately cope with the movement of nodes between different sub-networks. Despite the work of IETFs 6lowPAN WG and work on the use of MIPv6 (and many of its variants) in WSNs, no practical mobility support solution exists for this type of networks. In this paper we start by assessing the use of MIPv6 in WSNs, considering soft and hard handoff, showing that, although feasible in small networks, MIPv6 complexity leads to long handoff time and high energy consumption. In order to solve these problems, we propose a proxy-based mobility approach which, by relieving resource-constrained sensor nodes from heavy mobility management tasks, drastically reduces time and energy expenditure during handoff. The evaluation of both MIPv6 and the proposed solution is done by implementation and simulation, with a varying number of nodes, sinks and mobility strategies.

Mobility in WSNs for critical applications

Recent critical application sectors of sensor networks like military, health care, and industry require the use of mobile sensor nodes, something that poses unique challenges in aspects like handoff delay, packet loss, and reliability. In this paper we propose a novel mobility model that handles those challenges effectively by providing on-time mobility detection and handoff triggering. In that way soft handoffs and controlled disconnections are assured. The proposed solution uses cross-layer information from the MAC and Network layers. Our solution was implemented and evaluated in an experimental testbed, in the context of the European FP7 GINSENG project.

Mobility solutions for wireless sensor and actuator networks with performance guarantees

Wireless sensor and actuator networks (WSANs) have been studied for about ten years now. However, a gap between research and real applications and implementations remains. The lack of an integrated solution, capable of providing the reliability levels of monitoring and actuation required by critical applications, have postponed the replacement and extension of the existing inflexible and expensive wired solutions with the low-cost, easy-to-deploy, and portable wireless options. In order to assist this transition this paper presents a new method for supporting mobility in WSANs specifically designed for time-critical scenarios. The method is being targeted for a critical application located in a real oil refinery, in which a WSAN has been implemented in the scope of a European research project.

A new approach for multi-sink environments in WSNs

Wireless Sensor Networks are low cost networks constituted by modest devices with limited resources, whose main function is monitoring. Based on the low price of these devices, it will be cheap to deploy a large amount of nodes to monitor a large area. However, to provide an efficient ad hoc network using these limited devices, new and optimized algorithms should be proposed. Most of the current work about WSNs are based on simulation studies and do not take in consideration engineering processes. This paper presents a Multi-Sink Node alternative to multi-hop solutions. The proposed solution also provides a new system for the discovery of devices and services over IPv6, allowing nodes to be automatically incorporated in the nearest WSN. This paper also presents a paradigm to efficiently provide mobility, granting a fast handover of nodes between different WSNs, without loosing the connection.

Characteristics of Channels of IEEE 802.15.4 Compliant Sensor Networks

Wireless sensor networks have been more and more deployed for monitoring and controlling real environments. However, because of sensor nodes’ limitations, their radios are more susceptible to noise and interference than in other wireless technologies. These are critical factors in the rigorous industrial environment, whose effects may not be the same on all channels of a sensor network. In this paper, we present some experimental studies about the characteristics of IEEE 802.15.4 channels in ISM band. We are particularly interested in the differences of implementing wireless sensor networks in academic and industrial environments. A common problem of wireless sensor network implementations is that most of them are purely academic or initially prepared in laboratory. Our study shows that it is very difficult to predict the quality and stability of the different channels in sensor networks, as the environment conditions greatly influence the network performance. Empirical approaches are suitable methods for choosing the appropriate channels to deploy WSNs in noisy environments. We conduct several tests in both laboratory and in a real world environment, particularly in an oil refinery as this is our case study in the context of the FP7 GINSENG project (Ginseng 2010).

Mobile multimedia in wireless sensor networks

One of the most referred and promising Wireless Sensor Network (WSN) applications is health monitoring. The small size and portability of nodes have made WSNs the perfect tool to easily monitor a persons health condition. In this type application, as well as in several other critical applications, reliability and mobility are paramount. In this paper we propose a method, based on WSNs and mobile intra-body sensors, to accurately detect the fertile period of women on time and other applications based on intra-vaginal temperature monitoring. In addition, our proposal also introduces the proposal of intra-body micro-cameras to monitor the womens cervix, capable to detect related pathologies. To efficiently support this mobile multimedia application, guaranteeing reliability in a continuous monitoring mode, we make use of a new WSN paradigm based on mobility proxies.

Facies and Carbon Isotope Chemostratigraphy of Lower Jurassic Carbonate Deposits, Lusitanian Basin (Portugal): Implications and Limitations to the Application in Sequence Stratigraphic Studies

Abstract The Lower Jurassic carbonate series of the Lusitanian Basin (Portugal), due to their remarkable exposure and high quality outcrops, are currently regarded as a pivotal point to the comprehension of the less-known offshore basins located along the Atlantic Margin. This study presents a detailed sedimentological and biostratigraphical framework and the carbon and oxygen isotopic record of one of the main organic-rich intervals of the Lusitanian Basin, the marly limestones with organic-rich facies member of the Vale das Fontes Formation (Pliensbachian). We report the occurrence of secular δ13C trend of the Lusitanian Basin concordant with the (second-order) Pliensbachian transgressive–regressive facies cycle. An overall increase in carbon isotopic record with transgression, reaching its maximum just above the maximum flooding interval and enhanced organic matter preservation is also observed. When compared with the defined third-order sequences, a transient δ13C increase during the onset of transgression is recognizable. Higher frequency variations in the carbon isotopic record can possibly be traced along the offshore studied sections and are interpreted to be the reflections of local controls which may eventually outpace the regional variation.