Bruelheide H.,Martin Luther University of Halle Wittenberg |
Vonlanthen B.,Martin Luther University of Halle Wittenberg |
Jandt U.,Martin Luther University of Halle Wittenberg |
Thomas F.M.,University of Trier |
And 5 more authors.
Applied Vegetation Science | Year: 2010
Questions: Do the vegetation-specific patterns in the forelands of river oases of the Taklamakan Desert provide clues to the degree to which a vegetation type depends on unsaturated soil moisture, brought about by extensive floodings, or phreatic water? Location: Foreland of the Qira oasis on the southern rim of the Taklamakan Desert, Xinjiang Uygur Autonomous Region, China. Methods: A vegetation map was prepared using a SPOT satellite image and ground truthing. Measurements of soil water contents were obtained from a flooding experiment and transformed into water potentials. Sum excedance values were calculated as the percentage of days on which different thresholds of soil water potentials were transgressed. Groundwater depth was mapped by drilling 30 groundwater holes and extrapolating the distances to the whole study area. Results: The vegetation was characterized by only six dominant or codominant species: Alhagi sparsifolia, Karelinia caspia, Populus euphratica, Tamarix ramosissima, Calligonum caput-medusae and Phragmites australis. The vegetation patterns encountered lacked any linear features typical of phreatophytes, thus not allowing direct conclusions on the type of the sustaining water sources. Soil water potentials never transgressed a threshold of pF 5 (- 10 MPa) in horizons above the capillary fringe during periods without inundation, thus representing water not accessible for plants. Depth to the groundwater ranged between 2.3 and 17.5 m among plots and varied between 1.7 and 8.0m within a plot owing to dune relief. The seven main vegetation types showed distinct niches of groundwater depths, corresponding to the observed concentric arrangement of vegetation types around the oasis. Conclusions: Inundation by flooding and unsaturated soil moisture are irrelevant for the foreland vegetation water supply. Although distances to the groundwater table can reach about 20 m, which is exceptionally large for phreatophytes, groundwater is the only water source for all vegetation types in the oasis foreland. In consequence, successful maintenance of oasis foreland vegetation will crucially depend on providing non-declining ground water tables. © 2009 International Association for Vegetation Science.
Casale G.,Imperial College London |
Ardagna D.,Polytechnic of Milan |
Artac M.,XLAB |
Barbier F.,Netfective |
And 12 more authors.
Proceedings - 7th International Workshop on Modeling in Software Engineering, MiSE 2015 | Year: 2015
Model-driven engineering (MDE) often features quality assurance (QA) techniques to help developers creating software that meets reliability, efficiency, and safety requirements. In this paper, we consider the question of how quality-aware MDE should support data-intensive software systems. This is a difficult challenge, since existing models and QA techniques largely ignore properties of data such as volumes, velocities, or data location. Furthermore, QA requires the ability to characterize the behavior of technologies such as Hadoop/MapReduce, NoSQL, and stream-based processing, which are poorly understood from a modeling standpoint. To foster a community response to these challenges, we present the research agenda of DICE, a quality-aware MDE methodology for data-intensive cloud applications. DICE aims at developing a quality engineering tool chain offering simulation, verification, and architectural optimization for Big Data applications. We overview some key challenges involved in developing these tools and the underpinning models. © 2015 IEEE.
Bacon L.,University of Greenwich |
Cesta A.,National Research Council Italy |
Coraci L.,National Research Council Italy |
Cortellessa G.,National Research Council Italy |
And 4 more authors.
Frontiers in Artificial Intelligence and Applications | Year: 2012
This short paper introduces a novel use of timeline-based planning as the core element of a dynamic training environment for crisis managers called PANDORA. A trainer is provided with a combination of planning and execution functions that allow him/her to maintain and adapt a "lesson plan" as the basis for the interaction between the trainer and a class of trainees. The training session is based on the concept of Scenario, that is a set of events and alternatives deployed on a timeline-based system, that shapes an abstract plan proposed to trainees. Throughout a training session a continuous planning, execution, re-planning loop takes place, based around trainer observation of trainees and self-reporting by trainees, which provides analysis of both their behavioral and psychological changes. These, combined with the trainee decisions about what actions to take to manage the crisis, are used to maintain an updated model of each user. In addition the trainer has the ability to directly intervene in a training session to, for example, interject new scenario events. The training session is therefore managed through a combination of automated analysis of trainee behaviour and decisions, coupled with trainer input and direction. © 2012 The Author(s).
Casola V.,University of Naples Federico II |
De Benedictis A.,University of Naples Federico II |
Modic J.,XLAB |
Rak M.,The Second University of Naples |
Villano U.,University of Sannio
Proceedings - 25th IEEE International Conference on Enabling Technologies: Infrastructure for Collaborative Enterprises, WETICE 2016 | Year: 2016
In the cloud computing context, Service Level Agreements (SLAs) are contracts between Cloud Service Providers (CSPs) and Cloud Service Customers (CSCs), stating the guaranteed quality level of the services offered by CSPs. Existing cloud SLAs focus only on few service terms, completely ignoring all security related aspects. They are often reported in a way that is hardly understandable for customers. Moreover, they offer guarantees uniform for all offered services and all customers, regardless of particular service characteristics or customers specific needs. This paper presents a framework that enables the adoption of a per-service SLA model, by supporting the automatic implementation of cloud Security SLAs tailored to the needs of each customer for specific service instances. In particular, the process and the software architecture for per-service SLA implementation are shown. A case study application demonstrates the feasibility and effectiveness of the proposed solution. © 2016 IEEE.
Randic M.,Slovenian National Institute of Chemistry |
Orel R.,XLAB |
Balaban A.T.,Texas A&M University at Galveston
Match | Year: 2013
We explore the possibility of using selective invariants of a novel distance matrix DMAX of graphs to discriminate between graphs. The DMAX matrix contains information only on dominant distances of a graph, which are defined as those entries in a distance matrix that are the largest in any row or a column. For a test we selected a set of the smallest trees having the same Balaban index J (six pairs of trees on n = 12 vertices). The Balaban index J is one of the early topological indices which has shown considerable power of discrimination between similar graphs. We have examined ordered sequences of row sums and a new topological index j, the DMAX analog to Balaban index J as invariants to be tested for their discrimination power. This novel topological index j discriminated all 12 graphs having the same index J. However, neither J nor j can discriminate the pairs of acyclic graphs constructed by Slater, which are the smallest graphs (having 18 vertices) having the same distance degree sequence. In the search for alternative conceptually and structurally simple invariants we found that the ordered sequence of row sums of terminal matrices T and TMAX do differentiate the two Slater graphs, which have identical DMAX. We discuss the loss of information associated with DMAX and end with a brief introduction of the concept of matrix projection, which is illustrated on terminal matrices of Slater graphs.
Orel R.,XLAB |
Randic M.,Slovenian National Institute of Chemistry
Journal of Mathematical Chemistry | Year: 2012
In contrast to the standard construction of Voronoi regions, in which the boundaries between different regions are at equal distance from the given points, we consider the construction of modified Voronoi regions obtained by giving greater weights to spots reported to have higher abundance. Specifically we are interested in applying this approach to 2-D proteomics maps and their numerical characterization. As will be seen, the boundaries of the weighted Voronoi regions are sensitive to the relative abundances of the protein spots and thus the abundances of protein spots, the z component of the (x, y, z) triplet, are automatically incorporated in the numerical analysis of the adjacency matrix, rather than used to augment the adjacency matrix as non-zero diagonal matrix elements. The outlined approach is general and it may be of interest for numerical analyses of other maps that are defined by triplets (x, y, z) as input information. © 2012 Springer Science+Business Media, LLC.
Pierre G.,VU University Amsterdam |
El Helw I.,VU University Amsterdam |
Stratan C.,VU University Amsterdam |
Oprescu A.,VU University Amsterdam |
And 5 more authors.
Proceedings of the Workshop on Posters and Demos Track, PDT'11 - 12th International Middleware Conference, Middleware'11 | Year: 2011
Most Cloud applications are re-enactments of traditional enterprise applications such as Web applications, content delivery and e-commerce . The advantages of the Cloud are well-known: access to a near-infinite number of resources, ability to adjust an application's capacity on demand, pay-as-you-go pricing model. However, Cloud application developers need to pay attention to new topics: building custom VM images, making applications elastic and scalable, controlling performance, fault-tolerance, etc. © 2011 ACM.
Sanders R.,Sintef |
Brataas G.,Sintef |
Cecowski M.,XLAB |
Haslum K.,Sintef |
And 3 more authors.
Procedia Computer Science | Year: 2015
This paper describes CloudStore, an open source application that lends itself to analyzing key characteristics of Cloud computing platforms. Based on an earlier standard from transaction processing, it represents a simplified version of a typical e-commerce application - an electronic book store. We detail how a deployment on a popular public cloud offering can be instrumented to gain insight into system characteristics such as capacity, scalability, elasticity and efficiency.