Electrochemical synthesis of poly(3′-alkyl-terthiophenes). Characterization and applications

A new series of polymers obtained from 3′-alkyl-terthiophene monomers have been electropolymerized aimed at using them as raw materials for the development of electronic devices, e.g., solar cell and organic light-emitting diodes, among others. The polymers were characterized by infrared and UV–Vis spectroscopy and cyclic voltammetry. Cyclic voltammetry results revealed that during polymerization both terthiophene system and substituent groups are oxidized, but these processes are reversible. The products were tested in solar cells and the maximum yield obtained was 0.01%.     

Design methodology for the frequency shift method of islanding prevention and analysis of its detection capability

Islanding protection is one of the most important sources of discrepancy in grid‐connected photovoltaic systems. Even when islanding is not very likely to happen, regulations demand the photovoltaic inverters to implement effective protection methods. Due to its several advantages, the frequency shift method of islanding prevention, commonly known as Sandia Frequency Shift, is one of the most important active methods. This method implements a positive feedback of the frequency that tends to move it outside the trip limits in case of islanding. The method shows a very high detection capability, which depends on both the values of the method parameters and the characteristics of the load that remains in the same power section after islanding. This paper develops a mathematical analysis of the Sandia Frequency Shift method and proposes a new methodology to design its parameters as a trade‐off between the detection capability, which is evaluated as a function of the load characteristics, and the distortion that the method could introduce in the grid as a consequence of transitory frequency disturbances. The ability of this methodology to design the method parameters and achieve the highest detection capability is satisfactorily proved by means of both simulation and experimental results on a commercial photovoltaic inverter that implements the method once its parameters have been designed with the proposed methodology. Copyright © 2005 John Wiley & Sons, Ltd.     

A Business-Oriented Management Framework for Mobile Communication Systems

The incremental efforts needed to manage low-level radio access network decisions from a business-perspective have received little attention so far. This paper considers the influence of business-level indicators on network management decisions related to low-level network control mechanisms. It provides a formal understanding of all involved aspects, the representation of the adjustable parameters, and the network control mechanisms that enable the reconfiguration of access network entities from a business perspective (i.e., users?? information, operator??s goals). The effectiveness of our approach is validated through a simulation environment that we developed on OPNET.     

Assessment of the anaerobic degradation of six active pharmaceutical ingredients

Research examined the anaerobic degradation of 17α-ethynylestradiol, acetaminophen, acetylsalicylic acid, ibuprofen, metoprolol tartrate, and progesterone by methanogenic bacteria. Using direct sample analysis and respirometric testing, anaerobic degradation was examined with (a) each compound as the sole organic carbon source and (b) each compound at a lower concentration (250 µg/L) and cellulose serving as the primary organic carbon source. The change in pharmaceutical concentration was determined following 7, 28, 56, and 112 days of anaerobic incubation at 37 °C. Only acetylsalicylic acid demonstrated significant degradation; the remaining compounds showed a mixture of degradation and abiotic removal mechanisms. Experimental results were compared with BIOWIN, an anaerobic degradation prediction model of the US Environmental Protection Agency. The BIOWIN model predicted anaerobic biodegradability of the compounds in the order: acetylsalicylic acid > metoprolol tartrate > ibuprofen > acetaminophen > 17α-ethinylestradiol > progesterone. This corresponded well with the experimental findings which found degradability in the order: acetylsalicylic acid > metoprolol tartrate > acetaminophen > ibuprofen.     

Experiment Dashboard for Monitoring Computing Activities of the LHC Virtual Organizations

The Large Hadron Collider (LHC) is preparing for data taking at the end of 2009. The Worldwide LHC Computing Grid (WLCG) provides data storage and computational resources for the high energy physics community. Operating the heterogeneous WLCG infrastructure, which integrates 140 computing centers in 33 countries all over the world, is a complicated task. Reliable monitoring is one of the crucial components of the WLCG for providing the functionality and performance that is required by the LHC experiments. The Experiment Dashboard system provides monitoring of the WLCG infrastructure from the perspective of the LHC experiments and covers the complete range of their computing activities. This work describes the architecture of the Experiment Dashboard system and its main monitoring applications and summarizes current experiences by the LHC experiments, in particular during service challenges performed on the WLCG over the last years.     

Metoprolol abatement from wastewaters by electrochemical oxidation with boron doped diamond anodes

BACKGROUND: Metoprolol is a beta‐blocker that can be found in urban wastewaters and which is not removed efficiently by conventional wastewater treatments. In this work, the removal of this pollutant by conductive diamond electrochemical oxidation (CDEO) is studied. RESULTS: CDEO is able to degrade Metoprolol tartrate down to the 10 ppb level (detection limit of the technique used) with a current charge requirement that increases with increase in the initial concentration of pollutant, although it is many times greater than the stoichiometric current charge required. CDEO also removed very efficiently the reaction intermediates. In terms of TOC the depletion follows a first‐order kinetic, but the kinetic constant of Metoprolol decreases with concentration. NaCl increases significantly Metoprolol degradation rate, but it barely affects the TOC removal rate. CONCLUSIONS: CDEO can be used to remove Metoprolol from wastewaters, independently of the initial concentration of compound. Several reaction intermediates are formed during the electrolyses although their concentrations are very low and negligible compared with that of Metoprolol. The removal rate (in terms of TOC) does not depend on the nature of the electrolyte used. The process is under mass transfer control for the complete range of concentrations studied. Copyright © 2011 Society of Chemical Industry     

A data mining approach to guide students through the enrollment process based on academic performance

Student academic performance at universities is crucial for education management systems. Many actions and decisions are made based on it, specifically the enrollment process. During enrollment, students have to decide which courses to sign up for. This research presents the rationale behind the design of a recommender system to support the enrollment process using the students?? academic performance record. To build this system, the CRISP-DM methodology was applied to data from students of the Computer Science Department at University of Lima, Perú. One of the main contributions of this work is the use of two synthetic attributes to improve the relevance of the recommendations made. The first attribute estimates the inherent difficulty of a given course. The second attribute, named potential, is a measure of the competence of a student for a given course based on the grades obtained in related courses. Data was mined using C4.5, KNN (K-nearest neighbor), Naïve Bayes, Bagging and Boosting, and a set of experiments was developed in order to determine the best algorithm for this application domain. Results indicate that Bagging is the best method regarding predictive accuracy. Based on these results, the ??Student Performance Recommender System?? (SPRS) was developed, including a learning engine. SPRS was tested with a sample group of 39 students during the enrollment process. Results showed that the system had a very good performance under real-life conditions.     

Unitarity plus causality implies localizability

We consider a graph with a single quantum system at each node. The entire compound system evolves in discrete time steps by iterating a global evolution U. We require that this global evolution U be unitary, in accordance with quantum theory, and that this global evolution U be causal, in accordance with special relativity. By causal we mean that information can only ever be transmitted at a bounded speed, the speed bound being quite naturally that of one edge of the underlying graph per iteration of U. We show that under these conditions the operator U can be implemented locally; i.e. it can be put into the form of a quantum circuit made up with more elementary operators — each acting solely upon neighboring nodes. We take quantum cellular automata as an example application of this representation theorem: this analysis bridges the gap between the axiomatic and the constructive approaches to defining QCA.