New method for threshold voltage extraction of high-voltage MOSFETs based on gate-to-drain capacitance measurement

This letter reports on the extraction of the threshold voltage of laterally diffused MOS transistors. A clear analysis of the device physics is performed, highlighting the correlation between the change of the electron charge distribution along the channel and the device capacitance variations when the gate voltage is swept. Using numerical simulations, it is shown that the peak of the gate-to-drain capacitance is related to the transition of the surface from weak to moderate inversion in the intrinsic MOS transistor at the location of the maximum doping concentration, which corresponds to the threshold voltage of the device according to the MOS theory. Comparison between conventional I/sub D///spl radic/g/sub m/ extraction and the new proposed capacitance peak method is performed on both technology computer-aided design simulations and measurements in order to confirm the new experimental technique and related theory.     

Use of transportable test stations for measuring satellite coverage dependent parameters during IOT campaigns

The in-orbit tests of the satellite coverage dependent parameters require the rotation of the satellite around its pitch and roll axes in order to ‘bring’ the various coverage locations onto one fixed IOT station. Alternatively, several transportable test stations can be located at different sites in the coverage area in order to measure the satellite performances on site. Although the second technique does not provide enough measurement points to reconstruct the complete coverage of shaped beam antennas, it presents several advantages for which it is still used by EUTELSAT for the IOTs of its satellites in conjunction with measurements based on the satellite attitude movements. In particular, the transportable test stations are used to test the stability of satellite EIRP and IPFD at the edges of the coverage areas, where the performances are more sensitive to the pointing errors induced by thermal deformation or satellite attitude changes. This paper presents the common experience gained by EUTELSAT and ESA in testing the coverage dependent parameters of the first and second generation of EUTELSAT satellites. In particular, the paper deals with the use of the transportable test stations during the EUTELSAT II F1 to F3 acceptance tests and with the test campaigns performed at several sites in the eastern European countries. In the first case, the transportable test stations were used in conjunction with satellite rotations around the pitch axis in order to measure the coverage dependent parameters along several cuts parallel to the equatorial plane at different roll angles. In the second case, the transportable test stations were used to periodically repeat the EIRP measurements of many satellite channels over several hours in order to test the EIRP stability of the EUTELSAT II satellites. For both cases, the paper presents a synthesis of the most significant IOT results together with a comparison between these results and the values of the coverage dependent parameters predicted on the basis of the on-ground tests.     

A flexible,reliable, and adaptive timeslot‐based advance bandwidth‐reservation mechanism for media delivery services

Media‐centric networks deal with exchanging large media files between geographical distributed locations with strict deadlines. In such networks, resources need to be available at predetermined timeslots in the future and thus need to be reserved in advance, based on either flexible or fixed timeslot sizes. Reliability of the transfers is also important and can be attained by advance provisioning of redundant reservations. This, however, imposes additional costs, because redundant reservations are rarely in use, causing network resources to be wasted. Further adaptation and network utilization can be achieved at runtime by reutilizing unused reservations for transferring extra data as long as no failure has been detected. In this article, we design, implement, and evaluate a resilient advance bandwidth‐reservation approach based on flexible timeslots, in combination with a runtime adaptation approach. We take into account the specific characteristics of media transfers. Quality and complexity of the proposed approach have been extensively compared with that of a fixed timeslot algorithm. Our simulation results reveal that the highest admittance ratio and percentage of fully transferred requests in case of failures are almost always achieved by flexible timeslots, while the execution time of this approach is up to 17.5 times lower, compared with the approaches with fixed timeslot sizes.     

Influence of composition of MgAl2O4 supported NiCeO2ZrO2 catalysts on coke formation and catalyst stability for dry reforming of methane

Dry reforming of methane was studied over Ni catalysts supported on γAl₂O₃, CeO₂, ZrO₂ and MgAl₂O₄ (670 °C, 1.5 bar, 16–20 l CH₄ ml_catalyst⁻¹ h⁻¹). It is shown that MgAl₂O₄ supported Ni catalysts promoted with both CeO₂ and ZrO₂ are promising catalysts for dry reforming of methane with carbon dioxide. Within a certain composition range, the simultaneous promotion with CeO₂ and ZrO₂ has great influence on the amount of coke and the catalyst service time. XRD analyses indicate that formation of crystalline Ce_xZr_1−xO₂ mixed oxide phases occurs on double promotion. In particular, incorporation of low amounts of Zr in the CeO₂ fluorite structure provides stable dry reforming catalysis. As shown with TPR, promotion leads to a higher reduced state of Ni. SEM, XRD and TPR analyses demonstrate that highly dispersed, doubly promoted Ni catalysts with a strong metal-support interaction are essential for stable dry reforming and suppression of the formation of carbon filaments.     

High Resolution Crystal Structures of the Cerebratulus lacteus Mini-Hb in the Unligated and Carbomonoxy States

The nerve tissue mini-hemoglobin from Cerebratulus lacteus (CerHb) displays an essential globin fold hosting a protein matrix tunnel held to allow traffic of small ligands to and from the heme. CerHb heme pocket hosts the distal TyrB10/GlnE7 pair, normally linked to low rates of O(2) dissociation and ultra-high O(2) affinity. However, CerHb affinity for O(2) is similar to that of mammalian myoglobins, due to a dynamic equilibrium between high and low affinity states driven by the ability of ThrE11 to orient the TyrB10 OH group relative to the heme ligand. We present here the high resolution crystal structures of CerHb in the unligated and carbomonoxy states. Although CO binds to the heme with an orientation different from the O(2) ligand, the overall binding schemes for CO and O(2) are essentially the same, both ligands being stabilized through a network of hydrogen bonds based on TyrB10, GlnE7, and ThrE11. No dramatic protein structural changes are needed to support binding of the ligands, which can freely reach the heme distal site through the apolar tunnel. A lack of main conformational changes between the heme-unligated and -ligated states grants stability to the folded mini-Hb and is a prerequisite for fast ligand diffusion to/from the heme.     

A survey on question answering technology from an information retrieval perspective

This article provides a comprehensive and comparative overview of question answering technology. It presents the question answering task from an information retrieval perspective and emphasises the importance of retrieval models, i.e., representations of queries and information documents, and retrieval functions which are used for estimating the relevance between a query and an answer candidate. The survey suggests a general question answering architecture that steadily increases the complexity of the representation level of questions and information objects. On the one hand, natural language queries are reduced to keyword-based searches, on the other hand, knowledge bases are queried with structured or logical queries obtained from the natural language questions, and answers are obtained through reasoning. We discuss different levels of processing yielding bag-of-words-based and more complex representations integrating part-of-speech tags, classification of the expected answer type, semantic roles, discourse analysis, translation into a SQL-like language and logical representations.     

Exploitation of Social Media for Emergency Relief and Preparedness: Recent Research and Trends

Online Social Media, such as Twitter, Facebook and WhatsApp, are important sources of real-time information related to emergency events, including both natural calamities, man-made disasters, epidemics, and so on. There has been lot of recent work on designing information systems that would be useful for aiding post-disaster relief operations, as well as for pre-disaster preparedness. A special issue on “Exploitation of Social Media for Emergency Relief and Preparedness” was conducted for the journal Information Systems Frontiers. The objective of this special issue was to present a platform for dissemination of the empirical results of various technologies for extracting vital and actionable information from social media content in disaster situations. The papers included in this issue are expected to be the stepping stones for future explorations and technical innovations towards technologies meant for utilizing various online and offline information sources for enhancing pre-disaster preparedness and post-disaster relief operations.     

Highly discriminative statistical features for email classification

This paper reports on email classification and filtering, more specifically on spam versus ham and phishing versus spam classification, based on content features. We test the validity of several novel statistical feature extraction methods. The methods rely on dimensionality reduction in order to retain the most informative and discriminative features. We successfully test our methods under two schemas. The first one is a classic classification scenario using a 10-fold cross-validation technique for several corpora, including four ground truth standard corpora: Ling-Spam, SpamAssassin, PU1, and a subset of the TREC 2007 spam corpus, and one proprietary corpus. In the second schema, we test the anticipatory properties of our extracted features and classification models with two proprietary datasets, formed by phishing and spam emails sorted by date, and with the public TREC 2007 spam corpus. The contributions of our work are an exhaustive comparison of several feature selection and extraction methods in the frame of email classification on different benchmarking corpora, and the evidence that especially the technique of biased discriminant analysis offers better discriminative features for the classification, gives stable classification results notwithstanding the amount of features chosen, and robustly retains their discriminative value over time and data setups. These findings are especially useful in a commercial setting, where short profile rules are built based on a limited number of features for filtering emails.