A thermochemical approach to the gas-phase reduction of metal sulphates

The reduction of different metal sulphates by hydrogen occurs at different temperatures and can lead to a variety of products. It has been shown that the starting temperatures for the reduction of several sulphates are directly related to the magnitude of their (exothermic) heats of formation per equivalent. The thermochemical data also provide a basis for the interpretation of the relative thermal stabilities (under nitrogen atmosphere) of several metal sulphates. A consideration of the appropriate heat of formation values can also be useful in understanding the different reduction products obtained for different metal sulphates. Finally, the reduction behaviour of some binary metal sulphates is also consistent with the thermochemical data.     

A chromatographic approach for fluorescence reduction in liquid Raman analysis

In this study a chromatographic approach for fluorescence reduction in liquid Raman analysis has been evaluated. The idea behind the approach is to apply a chromatographic separation step prior to Raman analysis in order to separate fluorescing compounds from other components of interest, thus facilitating better quantitative and qualitative analysis of the latter components. A real-time liquid-core Raman waveguide detector designed for chromatographic applications was used in the study, thus providing real-time chemical pretreatment of liquid samples for Raman analysis. Twenty aqueous mixtures of additives frequently found in beverages were analyzed, and for comparative purposes the mixtures were also analyzed in the Raman waveguide detector without chromatographic separation and with a conventional immersion probe. Both qualitatively and quantitatively satisfying results were obtained using the chromatographic Raman approach, and the technique provided possibilities for quantitative and qualitative assessments superior to the two other instrumental setups. The technique may provide additional benefits through sensitivity enhancements, and the approach is simple, inexpensive, and easy to implement in the average applied Raman laboratory. The analysis of various chemical systems and factors such as system stability over time need further evaluation in order to confirm the general applicability of the approach.     

An approach to potential environmental impact reduction in chemical reaction processes

An approach to identify environmental impact reduction alternatives is presented for chemical reaction processes. The primary tools used in this approach are potential environmental impact (PEI) reaction scheme and PEI change due to reaction. A PEI reaction scheme can be used to visualize the transformation relationships among different types of PEI, and can be applied to aid in identifying the sources of environmental impacts and generating alternatives for reducing the impacts. PEI change due to reaction can be used to indicate the change in PEI when this reaction proceeds by one mole of reaction. With the aid of the PEI reaction scheme and the PEI change due to reaction as well as some heuristics, the chemicals and reactions responsible for the potential impacts in the various impact categories can be identified and environmental impact reduction alternatives for a reaction process can be derived. The environmental performance of each alternative is evaluated by doing a quantitative PEI balance. In the case study, the alternatives, which can reduce the output of PEI and the magnitudes of the fresh feeds as well as increase the selectivity of the product, are obtained by using the approach.     

A meta-heuristic cuckoo search and eigen permutation approach for model order reduction

In this paper, a new model order reduction technique is presented by combining the benefits of the meta-heuristic cuckoo search optimization and Eigen permutation methods for order reduction of higher order continuous-time systems. In the proposed approach, the numerator and the denominator polynomials of reduced order model are determined by Cuckoo search and Eigen permutation approaches, respectively. The proposed approach preserves the stability of the original system into the lower order model as the Eigen permutation retains the dominant pole with simultaneous cluster formation of the remaining real and complex poles. The effectiveness of the proposed method is validated by single-input single-output and multiple-inputs multiple-outputs numerical examples.     

Projection approach to complexity reduction in tomographic alignment of extremely large telescopes

We describe a complexity reduction approach intended to solve the tomographic alignment problem for the Thirty Meter Telescope by means of its alignment and phasing system (APS) with little loss of information. This approach is computationally efficient enough to perform detailed Monte-Carlo simulations of the APS on a standard PC. We present sample simulations to model error propagation through the system and to build a preliminary APS alignment error budget.     

Smart tailoring of molecular catalysts:Mounting approach to oxygen reduction reaction

Efficient electrocatalytic rupture of energy-rich molecules(H2 and O2)is a green approach for gener-ating clean energy for modern societies.In this context,porphyry-type molecular electrocatalysts act intelligently toward oxygen reduction reaction(ORR),a fundamental process in fuel cells,due to their redox-rich chemistry,which involves core metal ions and macrocyclic ligands.The concerned scientific community has tried many times to correlate the ORR intermediates with their formation kinetics and simplify the associated multi H+/e-stages during the ORR process,constructing several volcano plots be-tween catalytic Tafel data,turnover frequencies,and overpotentials for many electrocatalysts.Despite the fact that many review articles on molecular electrocatalysts for ORR have been published,understanding the strategic implications and molecular catalyst intelligence towards homogenous ORR has been poorly explored.This review examined the relationships between volcano plots of current vs.thermodynamic parameters and the Sabatier principle in order to explain the intelligence of molecular electrocatalysts and approaches for their creation,as well as the difficulties and potential prospects of molecular electro-catalysts.These facts distinguish this review from previously published articles and will pique the scien-tific community's interest in avoiding trial-and-error procedures for catalyst creation while also allowing for more exact evaluations of the molecular catalyst's performance.     

A pseudopotential approach to scattering

Scalar wave scattering is discussed using pseudopotentials. These are singular, wavefunction-dependent source terms subsuming the scattering properties of the object. The latter can be an impenetrable body or an inhomogeneity. In this approach, the boundary condition on the scatterer does not enter into computations explicitly, but the scattering amplitude in an unbounded medium appears in the Helmholtz equation. The pseudopotential gives the correct solution of the scattering problem outside the smallest sphere circumscribing the scatterer. If the scattering medium is spatially limited by a boundary (e.g., a waveguide or an enclosure), then the pseudopotentials decouple the scatterer boundary condition from that on the limiting surface. This simplifies the problem in that only the Green’s function for the limiting boundary needs to be considered. The formulation is entirely in terms of the free-space Green’s function, and hence is independent of any particular assumption or specific expression of the incident field. Numerical results are presented for a spherical inhomogeneity in a spherical Dirichlet enclosure. The pseudopotential formulation is anticipated to be useful in situations involving multiple scattering centers, and extraneous bounding surfaces.     

Application of the radon transform to detect small-targets in sea clutter

The authors present a novel and heuristic approach for the detection of low radar cross-section targets in high-resolution sea clutter. The proposed technique is based on the application of the Radon transform to range?time matrices formed by column-wise storage of consecutive range profiles. The objective of this paper is 2-fold: to analyse the effect of the transform on real high-resolution sea clutter and to describe a detection scheme based on the insight obtained. The proposed technique emulates the behaviour of traditional motion target detection algorithms without the need for reliable Doppler information. It also constitutes a powerful non-coherent integration strategy of the target?s energy along its specific path on the range?time plot. The performance of the detection technique has been tested against real high-resolution sea clutter data, acquired at the south coast of Spain with an in-house developed continuous wave linear frequency modulated millimetre-wave radar system. Monte Carlo simulations show a significant improvement over the conventional cell averaging constant false alarm rate schemes.     

Facile carbothermal reduction approach to hybrid platinum-carbon nanotubes composite for electrocatalytic oxidation of ethanol

We have provided an effective, environmentally benign approach for the synthesis of hybrid platinum-carbon nanotubes (Pt-CNTs) composite via a CNTs-guided carbothermal reduction. The materials were characterized by transmission electron microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results revealed that CNTs acted as both support and reducing agent, and therefore the Pt nanoparticles with an average particle size of 3.5 nm could uniformly disperse onto the surface of CNTs. Moreover, as-fabricated Pt-CNTs exhibited the enhanced electrocatalytic activity and stability for ethanol oxidation in both acidic and alkaline media, in comparison to that prepared by electrochemical deposition. This approach greatly enlarges the practical application areas of hybrid Pt-CNTs composite materials.     

A multidimensional approach to academic productivity

This study represents one of the first attempts to use empirical analysis to estimate academic productivity complex and proves the thesis that academic productivity is a function of multidimensional combination of the work of academic researchers: the scientific work, education, and external relationships. Given the complexity of academic productivity, it is necessary to clarify that it is divided into scientific productivity of the first type (scientific publications); scientific productivity of the second type (awards and academic positions); productivity in terms of external relationships (or external advice); and educational productivity. This objective of this paper is achieved through a sample survey (2,738 academics responded) conducted by Italian researchers from the PIR research project. The results obtained, however (as a case of estimates obtained using the results of a sample survey), are the result of a working reality that Italian academics are flooded by a myriad of activities that are not always consistent with the primary aims of the work of a researcher with an organisational and environmental well-being at the limit of iper productivity (or hyper productivity). The overall productivity (academic productivity) is significantly correlated with the four dimensions: average annual scientific productivity of the first type, average annual scientific productivity of the second type, the productivity external advice and, lastly, teaching productivity. The estimate of the sizes for the four indicators of productivity are the result of a literature search of the primary techniques used to assess productivity in academia. By comparing the most significant indicators, we managed to select all of the technical aspects missing in the Italian system of evaluation. This process allowed for us to add additional variables characterising the various aspects of productivity and prove the validity of our theory about the multidimensionality of academic productivity.     

A multiple-scales approach to crack-front waves

Perturbation of a steadily propagating crack with a straight edge is solved using the method of matched asymptotic expansions (MAE). This provides a simplified analysis in which the inner and outer solutions are governed by distinct mechanics. The inner solution contains the explicit perturbation and is governed by a quasi-static equation. The outer solution determines the radiation of energy away from the tip, and requires solving dynamic equations in the unperturbed configuration. The outer and inner expansions are matched via the small parameter ϵ = L/l defined by the disparate length scales: the crack perturbation length L and the outer length scale l associated with the loading. The method is illustrated for a scalar crack model and then applied to the elastodynamic mode I problem. The crack-front wave-dispersion relation is found by requiring that the energy release rate is unaltered under perturbation and dispersive properties of the crack-front wave speed are described for the first time. The example problems considered demonstrate the potential of MAE for moving-boundary-value problems with multiple scales.     

A new approach to bessel beams

Abstract

A new interpretation of the non-diffracting Bessel beams is given as a superposition of two fields described by Hankel functions. Within our picture, supported by the Sommerfeld radiation condition, we find that Bessel beams must be of finite transverse extension. Our approach also easily explains propagation characteristics of Bessel-Gauss beams and, in general, the propagation of amplitude modulated Bessel beams. Consequences are discussed and contrasted with the classic theory of Bessel beams.     

A new approach to production smoothing

Models for production smoothing generally assume that production can be adjusted to any desired level. However, there are industries where production must be carried out at given discrete levels, for example by the opening or closure of certain facilities or by the use of shift-working. The problem is to control the operation in a way that will minimize the cost of changes in the level of production. The method explored in this paper relies on inventory levels for control purposes to trigger a switch from one production level to another. Sample results from simulation runs are cited as examples.     

A new approach to Preisach diagrams

Magnetization processes are complex. A simple Preisach diagram can describe only the irreversible component of magnetization. An extended Preisach model is introduced, including a reversible magnetization component given by a Langevin function which describes low-field experimental hysteresis loops very well. A family of anhysteretic curves are shown that are dependent on the amplitude and form of the ac used to generate them and the turning points on theM-Hplane.     

A risk-based approach to land-use planning

The Seveso II-Directive requires that the objectives of preventing major accidents and limiting their consequences be taken into account by the Member States in their land-use policies and/or other relevant policies. This is to be achieved by ensuring adequate distances between industrial establishments and residential areas, areas of public use and areas of particular natural sensitivity or interest. A risk-based framework implemented in a computer program is presented which enables one to calculate adequate distances. The criterion used is a limit on the individual risk of death. The method is a simplified risk analysis which represents the plant, whose characteristics are normally unknown at the stage of land-use planning, by generic frequencies of release for process units and storage tanks. Their number depends on the size of the site to be allotted. The procedure is capable of addressing the siting of new establishments and, with due regard to the simplifications used, modifications to and new developments in the vicinity of existing establishments. Given the numerous assumptions, which have to be made, the framework represents a convention.