Sentinel-1-based flood mapping: a fully automated processing chain

This article presents an automated Sentinel-1-based processing chain designed for flood detection and monitoring in near-real-time (NRT). Since no user intervention is required at any stage of the flood mapping procedure, the processing chain allows deriving time-critical disaster information in less than 45 min after a new data set is available on the Sentinel Data Hub of the European Space Agency (ESA). Due to the systematic acquisition strategy and high repetition rate of Sentinel-1, the processing chain can be set up as a web-based service that regularly informs users about the current flood conditions in a given area of interest. The thematic accuracy of the thematic processor has been assessed for two test sites of a flood situation at the border between Greece and Turkey with encouraging overall accuracies between 94.0% and 96.1% and Cohen’s kappa coefficients (κ) ranging from 0.879 to 0.910. The accuracy assessment, which was performed separately for the standard polarizations (VV/VH) of the interferometric wide swath (IW) mode of Sentinel-1, further indicates that under calm wind conditions, slightly higher thematic accuracies can be achieved by using VV instead of VH polarization data.     

Capacitance DNA bio-chips improved by new probe immobilization strategies

Label-free DNA detection plays a crucial role in developing point-of-care biochips. Capacitance detection is a promising technology for label-free detection. However, data published in literature often show evident time drift, large standard deviation, scattered data points, and poor reproducibility. To address these problems, mercapto-hexanol or similar alkanethiols are usually considered as blocking agents. The aim of the present paper is to investigate new blocking agents to further improve DNA probe surfaces. Data from AFM, SPR, florescence microscopy, and capacitance measurements are used to investigate new lipoate and ethylene-glycol molecules. The new surfaces offer further improvements in terms of diminished detection errors. Film structures are investigated at the nano-scale to justify the detection improvements in terms of probe surface quality. This study demonstrates the superiority of lipoate and ethylene-glycol molecules as blocking candidates when immobilizing molecular probes onto spot surfaces in label-free DNA biochip.     

Computational reflection and its application to platform verification

The complexity of modern hardware design has created the need for higher levels of abstraction, where system modeling is used to integrate modules into complex System-on-Chip (SoCs) platforms. SystemC, and its TLM (Transaction Level Modeling) extensions, have been used for this purpose mainly because of their fast prototyping and simulation features, which allow for early design space exploration. This paper proposes an approach to explore and interact with SystemC models by means of an introspection technique known as Computational Reflection. We use reflection to implement a white-box introspection mechanism called ReflexBox. We show that ReflexBox is a fast, non-intrusive technique that can be used to dynamically gather and inject stimuli into any SystemC module, without the need to use a proprietary SystemC implementation, change the SystemC library, instrument or even inspect the module source code. Our approach can be used to support many different verification tasks like platform debugging, performance evaluation and communication analysis. To show ReflexBox effectiveness we used it in three platforms case studies to address tasks like register inspection, performance analysis and signal replaying for testbench reuse. In all cases we assumed no source code availability and measured the impact on the overall platform performance.     

Diagnosis of learner dropout based on learning styles for online distance learning

The amount of data generated by computer systems in Online Distance Learning (ODL) contains rich information. One example of this information we define as the Learner Learning Trail (LLT), which is the sequence of interactions between the students and the virtual environment. Another example is the Learner Learning Style (LLS), which is associated with the student behavior and choices during the learning process. This information can be used to identify learner behavior and learning style. We perceived, after the study of related literature, that the research field of learner diagnosis for ODL does not apply the conjoint use of LLT and LLS. In this article, we propose a model capable of integrating data generated from the behavior of students in ODL with cognitive aspects of them, such as their Learning Styles, by crossing LLT with LLS. We also propose the CPAD method (Collect, Preprocessing, Analysis, Diagnosis), which is implemented by collecting the raw data regarding learning activities, preprocessing the data into structured time sequences, analyzing the sequences regarding the learning styles and using this analysis to diagnose the learner behavior. We selected the dropout to investigate, once the dropout rate in ODL is a real problem in universities around the world. In addition, the dropout is a student decision which can be associated with previous students behaviors. We performed a study with 202 learners to evaluate if learning styles are capable of explaining aspects of the student behavior. The results suggest that Sequential/Global learning style dimension is more capable of explaining the dropout than the other dimensions. Also, we performed four classification experiments to verify how the dimensions of Felder-Silverman Learning Style Model influence the learner diagnosis. We perceived that the Sequential/Global dimension could provide a higher accuracy average with lower variation independently of the diagnosis technique.     

Recursive partial realization for 2-D data arrays

In this paper an attempt is made to provide a proper formalization to the partial realization problem for discrete linear causal shift invariant 2-D systems. The approach falls into the class of 2-D Padé approximations; the results, however, are new, since the rational representation matches all the samples of a 2-D partial sequence. The realization algorithm, though characterized by a high complexity, exhibits a recursive structure and allows for a good computational economy.     

Platform designer: An approach for modeling multiprocessor platforms based on SystemC

This paper[3.5pc] presents the Platform Designer (PD) framework, a set of SystemC based tools that provide support for modeling, simulation and analysis of multiprocessor SoC platforms (MPSoC), at different abstraction levels. PD provides mechanisms for interconnection specification, process synchronization and communication, thus allowing the modeling of a complete platform, in a unified environment. To do that it uses an extension of the ArchC ADL and acsys, a tool that enables the automatic generation of a SystemC simulator of the platform. The main advantages of this approach are twofold. First, designers have more flexibility since they can integrate and configure different processors to the platform, using a single environment. Second, it enables a faster design space exploration, given that it automatically generates SystemC simulators of whole platforms at distinct abstraction levels. A number of platform variations can be tried out with minor design changes, thus reducing design time. Experimental results show the suitability of the platform simulator for design space exploration. Real applications (with medium complexity) run in the platform in few minutes. Combined with the facility to generate platforms with minor changes, this feature allows an improvement of the design space exploration.     

Design and implementation of a new scheduler for enhancing multi-rate fairness in IEEE 802.16

Without the definition of a mandatory scheduling algorithm for channel resource assignment, WiMAX is open to Quality of Service (QoS) enhancements by research groups and developers, at the aim of managing heterogeneous flows with different QoS requirements. Furthermore, besides performance enhancement, another key issue arises for QoS delivery: it is known as multi-rate fairness and it deals with efficient resource allocation for providing sufficient bandwidth to high rate flows, without penalizing low rate ones. In this paper, uplink scheduling algorithms are studied and an innovative solution is proposed to achieve performance enhancement, multi-rate fairness and improved QoS management. After an overview of the state of the art, two scheduling algorithms based on Deficit Round Robin are studied, implemented and tested in NS2 simulator. The schedulers are validated and compared through exhaustive simulations, showing the benefits coming from the adoption of the proposed scheduling mechanism.     

Evaluation of tritium diffusion through the Neutral Beam Injector calorimeter panel

The Neutral Beam Test Facility (NBTF) to be realized in Padoa will test the Neutral Beam Injection (NBI), one of the Heating and Current Drive Systems foreseen for ITER. The NBI is based on the acceleration of hydrogen or deuterium negative ions up to 1 MeV. This work has been aimed at assessing the tritium release from the NBTF in order to provide data for the safety analysis. In particular, the diffusion of the tritium through the neutral beam target material (the CuCrZr alloy calorimeter panels) has been assessed by using literature data of the diffusion coefficient. The tritium generated inside the calorimeter panels moves into both the vacuum and water side: the tritium diffusion flux has been evaluated during the beam-on (200 °C) and the beam-off (20 °C) phases of the NBTF experiments consisting of an interim campaign and a final test. The penetration depth of the tritium through the 2 mm thick CuCrZr alloy material has been also evaluated by using a Monte-Carlo code. As main result, the assessed diffusion flux of tritium during both the beam-on and the beam-off phases are modest. In fact, at the end of the interim campaign (100 days), about the 96% of the all generated tritium (626.5 MBq) exits the calorimeter while the residual tritium inventory (25 MBq) leaves the copper alloy with a diffusion time of about 1 month. At the end of the final test (14 days) about the 99% of the total generated tritium (1.023 × 10⁴ MBq) leaves the copper alloy and the remaining tritium inventory (152.2 MBq) is released by about 32 days. In both the interim campaign and the final test, more than the 99% of the total tritium is transferred into the vacuum side of the calorimeter panel while negligible tritium amounts enter the cooling water system thus showing a very low impact on the environment.     

Post Consumer Pet Depolymerization by Acid Hydrolysis

The reaction of post-consumer poly(ethylene terephthalate) with aqueous solutions of sulfuric acid 7.5 M was investigated in terms of temperature, time and particle size. The reaction extent reached 80% in four days at 100°C and 90% in 5 hours at 135°C. TPA obtained was purified and considered in the same level of quality of the commercial one after tests of elemental analysis, particle size and color. It was concluded that the hydrolysis occurred preferentially at the chain ends and superficially, having as controller mechanism the acid diffusion into the polymer structure. The shrinking-core model can explain the reaction kinetics.