Adsorption of zinc by activated carbons prepared from solvent extracted olive pulp

Activated carbons have been prepared by a two-step physical activation with steam at different burn-off levels to study the porosity development and its effect in zinc adsorption from aqueous solutions. The main material used was the residual from the extraction with solvent of the kernel-oil [solvent extracted olive pulp (SEOP)]. Olive, apricot and peach stone have been also used as different precursors. The products were characterized by N2 at 77K adsorption, Hg porosimetry and iodine number determination. The influence of surface complexes and pH has been investigated in an attempt to elucidate the adsorption phenomena. The effect of different treatments [demineralization with H2SO4 and oxidation with (NH4)2S2O8] was also evaluated for the adsorption of zinc species.Both basic and acidic carbons, originated from SEOP, show remarkable adsorption ability at solution pH=7. Their adsorption ability mainly depends on the content and nature of functional surface groups, the ash content of the precursors and the pH of the solution. These activated carbons were proved to be efficient adsorbents for the removal of water pollutants and contaminants.     

A Listening Keyboard for Users with Motor Impairments—A Usability Study

Computer users with motor impairments find it difficult and, in many cases, impossible to access PC functionality through the physical keyboard-and-mouse interface. Studies show that even able-bodied users experience similar difficulties when interacting with mobile devices; this is due to the reduced size/usability of the input interfaces. Advances in speech recognition have made it possible to design speech interfaces for alphanumeric data entry and indirect manipulation (cursor control). Although several related commercial applications exist, such systems do not provide a complete solution for arbitrary keyboard and mouse access, such as the access needed for, say, typing, compiling, and executing a C++ program.We carried out a usability study to support the development of a speech user interface for arbitrary keyboard access and mouse control. The study showed that speech interaction with an ideal listening keyboard is better for users with motor impairments than handstick, in terms of task completion time (37% better), typing rate (74% better), and error rates (63% better). We believe that these results apply to both permanent and task-induced motor impairments. In particular, a follow-up experiment showed that handstick approximates conventional modes of alphanumeric input available on mobile devices (e.g., PDAs, cellular phones, and personal organizers). These modes of input include miniaturized keyboards, stylus soft keyboards, cellular phone numberpads, and handwriting recognition software. This result suggests that a listening keyboard would be an effective mode for alphanumeric input on future mobile devices.This study contributed to the development of SUITEKeys—a speech user interface for arbitrary keyboard and mouse access available for MS platforms as freeware.     

Information discovery across multiple streams

In this paper we address the issue of continuous keyword queries on multiple textual streams and explore techniques for extracting useful information from them. The paper represents, to our best knowledge, the first approach that performs keyword search on a multiplicity of textual streams. The scenario that we consider is quite intuitive; let’s assume that a research or financial analyst is searching for information on a topic, continuously polling data from multiple (and possibly heterogeneous) text streams, such as RSS feeds, blogs, etc. The topic of interest can be described with the aid of several keywords. Current filtering approaches would just identify single text streams containing some of the keywords. However, it would be more flexible and powerful to search across multiple streams, which may collectively answer the analyst’s question. We present such model that takes in consideration the continuous flow of text in streams and uses efficient pipelined algorithms such that results are output as soon as they are available. The proposed model is evaluated analytically and experimentally, where the Enron dataset and a variety of blog datasets are used for our experiments.     

Finding the K highest-ranked answers in a distributed network

In this paper, we present an algorithm for finding the k highest-ranked (or Top-k) answers in a distributed network. A Top-K query returns the subset of most relevant answers, in place of all answers, for two reasons: (i) to minimize the cost metric that is associated with the retrieval of all answers; and (ii) to improve the recall and the precision of the answer-set, such that the user is not overwhelmed with irrelevant results. Our study focuses on multi-hop distributed networks in which the data is accessible by traversing a network of nodes. Such a setting captures very well the computation framework of emerging Sensor Networks, Peer-to-Peer Networks and Vehicular Networks. We present the Threshold Join Algorithm (TJA), an efficient algorithm that utilizes a non-uniform threshold on the queried attribute in order to minimize the transfer of data when a query is executed. Additionally, TJA resolves queries in the network rather than in a centralized fashion which further minimizes the consumption of bandwidth and delay. We performed an extensive experimental evaluation of our algorithm using a real testbed of 75 workstations along with a trace-driven experimental methodology. Our results indicate that TJA requires an order of magnitude less communication than the state-of-the-art, scales well with respect to the parameter k and the network topology.     

An $\tilde{O}(m^{2}n)$ Algorithm for Minimum Cycle Basis of Graphs

We consider the problem of computing a minimum cycle basis of an undirected non-negative edge-weighted graph G with m edges and n vertices. In this problem, a {0,1} incidence vector is associated with each cycle and the vector space over generated by these vectors is the cycle space of G. A set of cycles is called a cycle basis of G if it forms a basis for its cycle space. A cycle basis where the sum of the weights of the cycles is minimum is called a minimum cycle basis of G. Minimum cycle basis are useful in a number of contexts, e.g. the analysis of electrical networks and structural engineering. The previous best algorithm for computing a minimum cycle basis has running time O(m ^ω n), where ω is the best exponent of matrix multiplication. It is presently known that ω<2.376. We exhibit an O(m ² n+mn ²log n) algorithm. When the edge weights are integers, we have an O(m ² n) algorithm. For unweighted graphs which are reasonably dense, our algorithm runs in O(m ^ω ) time. For any ε>0, we also design an 1+ε approximation algorithm. The running time of this algorithm is O((m ^ω /ε)log (W/ε)) for reasonably dense graphs, where W is the largest edge weight. A preliminary version of this paper appeared in Kavitha et al. (31st International Colloquium on Automata, Languages and Programming (ICALP), pp. 846–857, 2004). T. Kavitha and K.E. Paluch were in Max-Planck-Institut für Informatik, Saarbrücken, Germany, while this work was done.     

Optimised sensor selection for control and fault tolerance of electromagnetic suspension systems: A robust loop shaping approach

This paper presents a systematic design framework for selecting the sensors in an optimised manner, simultaneously satisfying a set of given complex system control requirements, i.e. optimum and robust performance as well as fault tolerant control for high integrity systems. It is worth noting that optimum sensor selection in control system design is often a non-trivial task. Among all candidate sensor sets, the algorithm explores and separately optimises system performance with all the feasible sensor sets in order to identify fallback options under single or multiple sensor faults. The proposed approach combines modern robust control design, fault tolerant control, multiobjective optimisation and Monte Carlo techniques. Without loss of generality, it's efficacy is tested on an electromagnetic suspension system via appropriate realistic simulations.     

Stress/strain state investigations for extreme points of thin wall cylindrical tanks

In all branches of industry, especially in power-engineering, thin wall steel structures are extensively used. Land vertical cylindrical tanks are examples of such structures. The manufacture and assembling of these structures are usually accompanied by deviations from an ideal cylindrical form. Therefore, the exact evaluation of real local imperfections and common deviations from the analytical model of the tank is very important for such potentially dangerous structures.The main objective of the presented investigations is to identify stress/strain state of the wall tank with local imperfections from the ideal cylindrical surface, taking into account the membrane theory of the shells by using the analytical method, natural experiment and the finite element method.Besides, across the tank wall at the sites of its rigidity variation, rigidity ribs and at places of the load’s significant change, total moment internal forces and stresses arise, which are defined by a solution of the problem of the beam on the elastic ground. The given investigation also suggests the solution of the above-mentioned problem not only for the case when the tank wall is considered as a (long) flexible shell but as a semi-rigid one, when the edge effect is distributed over the whole wall’s height.     

Partial purification and comparison of precipitation techniques of proteolytic enzymes from trout (Salmo gairdnerii) heads

Proteolytic enzymes have been detected and partially purified from trout (Salmo gairdnerii) heads, which were preserved at −20 °C. Proteolytic enzymes, either in crude extract or in partial purified samples, were stable for 15 days with an optimum temperature of 55 °C. Proteolytic activity was very high in either alkaline or acidic pH regions. A particular ratio of cold acetone to crude extract (1.25:1) was found to be best for the partial purification of proteases, with a 99% recovery, compared with the partial purifications achieved using different cold acetone ratios or ammonium sulphate. This recovery was also confirmed via measurement of the particles (particle size analyser) contained either in crude extract or in the precipitated samples. The existence of mainly Zn–serine and possibly some Zn-acidic proteases was observed.