A catalytic platinum–ruthenium–polyaniline electrode for methanol oxidation

Polyaniline films prepared on Au wires were employed as substrates to deposit Pt and/or Ru using a potential-programmed perturbation. Different compositions of Pt and Ru ions in acid electrolyte were employed to decorate the electrodes. The atomic percentages of Pt and Ru on Pani were determined by EDAX and particle size and distribution by SEM. The catalytic activity was tested for adsorbed CO and CH₃OH electrooxidation. Nanoparticles of Pt–Ru with different Pt–Ru contents were obtained and characterized for each reaction.     

Dielectric properties of alternative refrigerants

This paper gives an overview of our research, from experimental measurements of the relative permittivity on new and alternative refrigerants, to theoretical interpretation of the data and density functional and density functional self-consistent reaction field calculations for a series of HFC molecules. Experimental measurements were obtained as a function of temperature and pressure for Class B refrigerants-HCFC-123, HCFC-142b, HCFC-141b, Class A refrigerants-HFC-32, HFC-134a, HFC-152a, HFC-143a, HFC-227ea, HFC-245fa, HFC-365mfc and some mixtures of them: HFC-125/143a/134a (R-404A), HFC-32/125/134a (R-407C), HFC-125/143a (R-507), HFC-32/125 (R-410A). Density functional and density functional self-consistent reaction field calculations were performed for CHF2CF3 (HFC-125), CH2FCF3 (HFC-134a), CH3CF3 (HFC-143a), CH2F2 (HFC-32), and CHF2CH3 (HFC-152a). A particular emphasis has been given to the calculation of dimerisation energies, rotational potentials, polarisabilities and dipole moments.     

Fuzzy repertory table: a method for acquiring knowledge about input variables to machine learning algorithm

In this paper, we develop a technique for acquiring the finite set of attributes or variables which the expert uses in a classification problem for characterising and discriminating a set of elements. This set will constitute the schema of a training data set to which an inductive learning algorithm will be applied. The technique developed uses ideas taken from psychology, in particular from Kelly's Personal Construct Theory. While we agree that Kelly's repertory grid technique is an efficient way to do this, it has several disadvantages which we shall try to solve by using a fuzzy repertory table. With the suggested technique, we aim to obtain the set of attributes and values which the expert can use to "measure" the object type (class) on the classification problem in some way. We will also acquire some general rules to identify the expert's evident knowledge; these rules will comprise concepts belonging to their conceptual structure.     

A pulp mill benchmark problem for control: application of plantwide control design

A heuristic for design of plantwide control strategies is introduced and applied to the millwide control of a previously presented pulp mill benchmark. Two control strategies (decentralized control and unit-based model predictive control) are compared according to their capacity to reduce the total error and maximize the operating profits. The control strategies are studied through closed-loop simulations of the process including several disturbances and setpoint changes in the digester, oxygen reactor, bleach plant, recausticizing plant and lime kiln.     

Comments on the Force on Pinned Vortices in Superconductors

The question of the nature of the force, usually referred to as the “Lorentz force” experienced by vortices in superconductors has arosen new attention in the last years. This paper contains some observations that may help understand the nature of this force, at least for stationary, pinned vortices. One observation is that the force is not proportional to the electromagnetic coupling constant, i.e. the electric charge. This points to the importance of kinematical analysis in discussing it. A second observation refers to the fact that in the London limit, kinetic energy dominates over magnetic energy in the formation energy of a vortex. We give an exact derivation of the force using the London model. We indicate that in the Ginzburg–Landau theory the same result obtains. Our derivation shows also the origin of additional forces experienced by the vortex near the sample surface.     

Autonomous indoor ultrasonic positioning system based on a low-cost conditioning circuit

This work presents a low cost 3-D location system based on ultrasonics and implemented with low-cost FPGAs. The mobile nodes of the system use distance estimation to several anchor points in order to trilaterate their positions with an accuracy of few centimeters. The ultrasonic transducers are handled with an ad hoc conditioning circuit based on instrumental amplifiers which provides high amplification keeping low noise. The proposed system is autonomous so there is no need of an external PC or other devices. A prototype of the system has been attached to a mobile robot to check the viability of the location system in a real scenario.     

Extraction of high added value biological compounds from sardine,sardine-type fish and mackerel canning residues — A review

Different valuable compounds, which can be employed in medicine or in other industries (i.e. food, agrochemical, pharmaceutical) can be recovered from by-products and waste from the fish canning industries. They include lipids, proteins, bio-polymers, minerals, amino acids and enzymes; they can be extracted from wastewaters and/or from solid residues (head, viscera, skin, tails and flesh) generated along the canning process, through the filleting, cooking, salting or smoking stages.In this review, the opportunities for the extraction and the valorisation of bioactive compounds from sardine, sardine-type fish and mackerel canning residues are examined and discussed. These are amongst the most consumed fishes in the Mediterranean area; moreover, canning is one of the most important and common methods of preservation. The large quantities of by-products generated have great potentials for the extraction of biologically desirable high added value compounds.     

Broadband Microwave Measurements of Overdoped Y0.9Ca0.1Ba2Cu3O7−δ Films Using Corbino Geometry

The surface impedance of Y_0.9Ca_0.1Ba₂Cu₃O_7?δ thin films was measured using the Corbino spectroscopy method. This special geometry, in which the sample dimensions are well defined by a ring pattern, is ideal for broadband high frequency reflection measurements. Using the complex reflected signal, S ₁₁, measured by a vector network analyzer, one can find the surface impedance of the thin film, from which the complex conductivity can be deduced. In the current work we present the three-standard approach for calibration of the Corbino method and demonstrate the benefits of this approach in measuring superconducting Y_0.9Ca_0.1Ba₂Cu₃O_7?δ thin films up to 20 GHz and down to 6 K. For the data analysis the well-known generalized two-fluid model was implemented, taking into account a film thickness which is much smaller than the normal state skin depth and superconducting penetration depth.     

Detection of Channel Variations to Improve Channel Estimation Methods

In current digital communication systems, channel information is typically acquired by supervised approaches that use pilot symbols included in the transmit frames. Given that pilot symbols do not convey user data, they penalize throughput spectral efficiency, and transmit energy consumption of the system. Unsupervised channel estimation algorithms could be used to mitigate the aforementioned drawbacks although they present higher computational complexity than that offered by supervised ones. This paper proposes a simple decision method suitable for slowly varying channels to determine whether the channel has suffered a significant variation, which requires to estimate the matrix of the recently changed channel. Otherwise, a previous estimate is used to recover the transmitted symbols. The main advantage of this method is that the decision criterion is only based on information acquired during the time frame synchronization, which is carried out at the receiver. We show that the proposed criterion provides a considerable improvement of computational complexity for both supervised and unsupervised methods, without incurring in a penalization in terms of symbol error ratio. Specifically, we consider systems that make use of the popular Alamouti code. Performance evaluation is accomplished by means of simulated channels as well as making use of indoor wireless channels measured using a testbed.     

Hybrid film of chemically modified graphene and vapor-phase-polymerized PEDOT for electronic nose applications

A hybrid of graphene and conducting polymer holds great potential as the active materials for high performance chemical sensor application. In this work, a thin hybrid film of reduced graphene oxide (RG-O) and poly(3,4-ethylenedioxythiophene) (PEDOT) was fabricated by means of vapor phase polymerization and explored as active material for chemical sensors. The chemical sensors based on hybrid film of RG-O and PEDOT are capable of detecting electrical signals caused by the absorption of trace levels of different analyte vapors with high sensitivity, selectivity and fast response.