Electrochemical study of arsenate and water reduction on iron media used for arsenic removal from potable water

Zerovalent iron filings have been proposed as a filter medium for removing As(III) and As(V) compounds from potable water. The removal mechanism involves complex formation of arsenite and arsenate with the iron surface and with iron oxides produced from iron corrosion. There is conflicting evidence in the literature on whether As(V) can be reduced to As(III) by iron filter media. This research uses electrochemical methods to investigate the redox reactions that occur on the surface of zerovalent iron in arsenic solutions. The effect of arsenic on the corrosion rate of zerovalent iron was investigated by analysis of Tafel diagrams for iron wire electrodes in anaerobic solutions with As(V) concentrations between 100 and 20,000 microg/L. As(V) reduction in the absence of surface oxides was investigated by analysis of chronoamperometry profiles for iron wire electrodes in solutions with As(V) concentrations ranging from 10000 to 106 microg/L. The effect of pH on As(V) reduction was investigated by analyses of chronopotentiometry profiles for iron wire electrodes at pH values of 2, 6.5, and 11. For freely corroding iron, the presence of As(III) and As(V) decreased the iron corrosion rate by a factor of 5 as compared to that in a 3 mM CaSO4 blank electrolyte solution. The decrease in corrosion rate was independent of the arsenic concentration and was due to the blocking of cathodic sites for water reduction by arsenic compounds chemisorbed to the iron surface. The chronoamperometry and chronopotentiometry experiments showed that elevated pH and increased As(III) to As(V) ratios near the iron surface decreased the thermodynamic favorability for As(V) reduction. Therefore, reduction of As(V) occurred only at potentials that were significantly below the apparent equilibrium potentials based on bulk solution pH values and As(III) to As(V) ratios. The potentials required to reduce more than 1% of the As(V) to As(III) were below those that are obtainable in freely corroding iron media. This indicates that there will be minimal or no reduction of As(V) in iron media filters under conditions relevant to potable water treatment.     

Side-information-dependent correlation channel estimation in hash-based distributed video coding

In the context of low-cost video encoding, distributed video coding (DVC) has recently emerged as a potential candidate for uplink-oriented applications. This paper builds on a concept of correlation channel (CC) modeling, which expresses the correlation noise as being statistically dependent on the side information (SI). Compared with classical side-information-independent (SII) noise modeling adopted in current DVC solutions, it is theoretically proven that side-information-dependent (SID) modeling improves the Wyner-Ziv coding performance. Anchored in this finding, this paper proposes a novel algorithm for online estimation of the SID CC parameters based on already decoded information. The proposed algorithm enables bit-plane-by-bit-plane successive refinement of the channel estimation leading to progressively improved accuracy. Additionally, the proposed algorithm is included in a novel DVC architecture that employs a competitive hash-based motion estimation technique to generate high-quality SI at the decoder. Experimental results corroborate our theoretical gains and validate the accuracy of the channel estimation algorithm. The performance assessment of the proposed architecture shows remarkable and consistent coding gains over a germane group of state-of-the-art distributed and standard video codecs, even under strenuous conditions, i.e., large groups of pictures and highly irregular motion content.     

An ultra low die area 8-b ADC and its generic calibration logic

The 8-bit voltage mode subrange A/D converter described in this paper operates in a mid-input signal frequency range of up to 20 MHz and requires at least an order of magnitude lower die area (0.06 mm²) than other A/D converters with a similar resolution. Moreover, it dissipates only 4.5 mW power and is supported by a calibration logic that is general enough to be used by several other measurement and instrumentation applications that require a real time adjustment of the amplitude and the level of their differential signals. This voltage mode subrange A/D converter architecture is actually an asynchronous two-step A/D converter that is based on a novel integer division operation. The current mode implementation of such an integer divider has already been employed by the authors in an innovative low area/power binary tree A/D conversion architecture. The voltage mode implementation of the integer divider allows the realization of the higher speed and lower power/area subrange A/D converter that is presented in this article.     

Lightweight biometric detection system for human classification using pyroelectric infrared detectors

We use pyroelectric detectors that are differential in nature to detect motion in humans by their heat emissions. Coded Fresnel lens arrays create boundaries that help to localize humans in space as well as to classify the nature of their motion. We design and implement a low-cost biometric tracking system by using off-the-shelf components. We demonstrate two classification methods by using data gathered from sensor clusters of dual-element pyroelectric detectors with coded Fresnel lens arrays. We propose two algorithms for person identification, a more generalized spectral clustering method and a more rigorous example that uses principal component regression to perform a blind classification.     

The ramification problem in temporal databases: a solution implemented in SQL

In this paper we elaborate on the handling of the ramification problem in the setting of temporal databases. Starting with the observation that solutions from the literature on reasoning about action are inadequate for addressing the ramification problem, in our prior work (Papadakis and Plexousakis in Int. J. Artif. Intel., 12(3):315, 2003) we have presented a solution based on an extension of the situation calculus and the work of McCain and Turner. Also, we have dealt with the ramification problem in spatial databases (Papadakis and Christodoulou in Expert Syst. Appl. 37:1374, 2010). In this paper, we present a tool that connects the theoretical results to practical considerations, by producing the appropriate SQL commands in order to address the ramification problem. (A preliminary version of this work appears in Papadakis et al., 17th Inter Symposium on Methodologies for Intelligent Systems, pp. 381–388, 2008)     

Affective speech interface in serious games for supporting therapy of mental disorders

We describe a novel design, implementation and evaluation of a speech interface, as part of a platform for the development of serious games. The speech interface consists of the speech recognition component and the emotion recognition from speech component. The speech interface relies on a platform designed and implemented to support the development of serious games, which supports cognitive-based treatment of patients with mental disorders. The implementation of the speech interface is based on the Olympus/RavenClaw framework. This framework has been extended for the needs of the specific serious games and the respective application domain, by integrating new components, such as emotion recognition from speech. The evaluation of the speech interface utilized purposely collected domain-specific dataset. The speech recognition experiments show that emotional speech moderately affects the performance of the speech interface. Furthermore, the emotion detectors demonstrated satisfying performance for the emotion states of interest, Anger and Boredom, and contributed towards successful modelling of the patient’s emotion status. The performance achieved for speech recognition and for the detection of the emotional states of interest was satisfactory. Recent evaluation of the serious games showed that the patients started to show new coping styles with negative emotions in normal stress life situations.     

Enabling technologies for the ‘always best connected’ concept

‘Always Best Connected’ (ABC) is considered one of the main requirements for next generation networks. The ABC concept allows a person to have access to applications using the devices and network technologies that best suits his or her needs or profile at any time. Clearly, this requires the combination of a set of existing and new technologies, at all levels of the protocol stack, into one integrated system. In this paper, a considerable set of the technologies, that are expected to play a key role towards the ABC vision, are presented. Starting from a reference architecture, the paper describes the required enhancements at certain levels of a traditional protocol stack, as well as technologies for mobility and end‐to‐end Quality of Service (QoS) support. The paper concludes with a case study that reveals the advantages of the ABC concept. This article replaces a previously published version (Wireless Communications and Mobile Computing; 5 (2): 175‐191. [DOI: 10.1002/wcm.207]). Retraction notice DOI: 10.1002/wcm.426 . Copyright © 2006 John Wiley & Sons, Ltd.     

Date movement and control substrate for parallel adaptive applications

In this paper, we present the Data Movement and Control Substrate (DMCS), a library which implements low‐latency one‐sided communication primitives for use in parallel adaptive and irregular applications. DMCS is built on top of low‐level, vendor‐specific communication subsystems such as LAPI (Low‐level Application Programme Interface) for IBM SP machines, as well as on widely available message‐passing libraries like MPI for clusters of workstations and PCs. DMCS adds a small overhead to the communication operations provided by the lower communication system. In return, DMCS provides a flexible and easy to understand application program interface for one‐sided communication operations. Furthermore, DMCS is designed so that it can be easily ported and maintained by non‐experts. Copyright © 2002 John Wiley & Sons, Ltd.