An alternative approach to electrochemistry

The concepts used conventionally in electrochemistry, single-ion chemical potential and electrostatic potential difference, are not obtainable from measurements in an inhomogeneous system. The use of nonoperational and mutually dependent forces in flux equations has impeded our understanding of electrochemical processes, and has led to wrong conclusions. The equation for entropy production is derived using only operationally defined quantities, chemical potentials of neutral components and the electric potential measured with reversible electrodes. The electric potential enters calculations as external electric work in the first law of thermodynamics. From entropy production, flux equations are obtained where the forces are operationally defined, measurable quantities. Three different problems from electrochemistry are discussed, the liquid junction potential, the Donnan potential, and energy coversion in mitochondria. The conventional method of calculations and the operational method are compared. The operational method permits more detailed calculations of emf, and an understanding of the process from a different approach.     

An approach based on tool mode control for surface roughness reduction in high-frequency vibration cutting

The presented research work, aimed at deeper understanding of vibrational process during high-frequency vibration cutting, is accomplished by treating cutting tool as an elastic structure which is characterized by several modes of natural vibrations. An approach for surface quality improvement is proposed in this paper by taking into account that quality of machined surface is related to the intensity of tool-tip (cutting edge) vibrations. It is based on the excitation of a particular higher vibration mode of a turning tool, which leads to the reduction of deleterious vibrations in the machine-tool-workpiece system through intensification of internal energy dissipation in the tool material. The combined application of numerical analysis with accurate finite element model as well as different experimental methods during investigation of the vibration turning process allowed to determine that the most favorable is the second flexural vibration mode of the tool in the direction of vertical cutting force component. This mode is excited by means of piezoelectric transducer vibrating in axial tool direction at the corresponding natural frequency, thereby enabling minimization of surface roughness and tool wear.     

An alternative approach to quantum phenomena

This paper outlines the qualitative foundations of a quasiclassical theory in which particles are pictured as spatially extended periodic excitations of a universal background field, interacting with each other via nonlinearity in the equations of motion for that field, and undergoing collapse to a much smaller volume if and when they are detected. The theory is based as far as possible directly on experiment, rather than on the existing quantum mechanical formalism, and it offers simple physical interpretations of such concepts as mass, 4-momentum, interaction, potentials, and quantization; it may lead directly to the standard equations of quantum theory, such as the multiparticle Schrödinger equation, without going through the conventional process of quantizing a classical theory. The theory also provides an alternative framework in which to discuss wave-particle duality and the quantum measurement problem; in particular, it is suggested that the unpredictability of quantum phenomena may arise from deterministic chaos in the behavior of the background field.     

Antisite defects in plastically-deformed GaAs: An alternative analysis

A revision is presented of the accepted view that the observed increease in electron paramagnetic resonance (EPR) with plastic deformation in GaAs is due to the generation of As antisite defects. It is proposed instead that only compensating deep acceptor defects are generated. The increase of the EPR signal from As antisites can then be attributed to the compensation of the neutral As antisites that were already present in the as-grown GaAs. The nonquenching extrinsic absorption can be attributed to the acceptors. The same analysis suggests that in the case of electron and neutron irradiation, both acceptors and As antisites are generated. These proposals succeed in eliminating some recently imposed complexities in the relationship between As antisites and EL2.     

An alternative approach for microlithography light source

A hybrid master oscillator–power amplifier (hybrid MOPA) scheme is proposed as a microlithography light source. The seed pulses are generated in the visible spectral range—where the necessary spectral purity is more easily achieved—and after frequency conversion are amplified in an excimer amplifier. The new concept enables us to decrease the bandwidth considerably, approaching the theoretical limit posed by the uncertainty relation. The feasibility of the new approach is demonstrated by a dye/excimer MOPA system, generating deep ultraviolet DUV (248-nm) pulses of 0.2-pm bandwidth.     

An alternative approach to heavy quark bags

We discuss a formulation of quark bags where the quark wave function depends only on the relative coordinate and the bag boundary is fixed with respect to the center of mass of the quark system. For technical reasons we have to restrict ourselves to a heavy quark-antiquark system in ans wave with spherical boundary. A phenomenological application to quarkonium states encourages further investigation of the approach.     

An alternative approach for the analysis of nonlinear vibrations of pipes conveying fluid

Based on a novel extended version of the Lagrange equations for systems containing non-material volumes, the nonlinear equations of motion for cantilever pipe systems conveying fluid are deduced. An alternative to existing methods utilizing Newtonian balance equations or Hamilton's principle is thus provided. The application of the extended Lagrange equations in combination with a Ritz method directly results in a set of nonlinear ordinary differential equations of motion, as opposed to the methods of derivation previously published, which result in partial differential equations. The pipe is modeled as a Euler elastica, where large deflections are considered without order-of-magnitude assumptions. For the equations of motion, a dimensional reduction with arbitrary order of approximation is introduced afterwards and compared with existing lower-order formulations from the literature. The effects of nonlinearities in the equations of motion are studied numerically. The numerical solutions of the extended Lagrange equations of the cantilever pipe system are compared with a second approach based on discrete masses and modeled in the framework of the multibody software HOTINT/MBS. Instability phenomena for an increasing number of discrete masses are presented and convergence towards the solution for pipes conveying fluid is shown.     

An alternative method to calculate surface states in crystals

An alternative method to calculate surface states in crystals is presented based on solving a one-dimensional problem in the direction perpendicular to the crystal surface and a nearly-free-electron (N.F.E.) model in the direction parallel to the surface. The potential is calculated making use of pseudopotential and a study of the structure factor. As an example we consider the case of the (111) surface orientation of Ge and Si, obtaining two bands of surface states separated 0.55 eV and 0.43 eV at the X and L points of the two-dimensional B.Z. This splitting is achieved without considering surface rearrangement.     

An alternative approach for deriving a positive P-representation

Using the technique of integration within an ordered product of operators and adopting similar procedures as for the theory for quantizing a gauge field, we derive the Drummond-Gardiner positive P-representation directly from the Glauber-Sudarshan P-representation. The analogy between the extra phase-space dimensions in the positive P-representation and the gauge transformation freedoms for gauge field quantization is pointed out.     

An alternative tuning approach to enhance NMR signals

By using spin-noise type measurement we show that the resonance frequency of the reception circuit of classical NMR spectrometers does not match the Larmor frequency even if, in emission, the electronic circuit is perfectly tuned at the Larmor frequency and matches the amplifier impedance. We also show that this spin-noise method can be used to ensure a match between the Larmor frequency and the reception circuit resonance frequency. In these conditions, (i) the radiation damping field is in perfect quadrature to the magnetization and (ii) the NMR signal level and potentially the signal-to-noise ratio, are enhanced. This choice induces a change of the probe resonance frequency by several hundreds of kHz for 500 or 700 MHz spectrometer. We show that the resulting mismatch condition for emission can be removed by adding other tuning and matching degrees of freedom located on the excitation line (or by symmetry on the reception line) decoupled to the probe resonance circuit by the crossed diodes.     

Spin-adapted vector method: An alternative to the conventional configuration interaction approach

A number of refinements have been incorporated in the vector method. The refinements include utilization of spin-adapted configurations, partitioning the steps in the calculation, and determining the connection of this spin-adapted vector method and standard configuration interaction techniques. To this end, the spin-adapted vector method can be used to generate an integral inverted formula tape commonly used by standard configuration interaction. Sample calculations on LiH are used to compare standard C1 and the spin-adapted vector method.     

An embedded sensitivity approach for diagnosing system-level vibration problems

In diagnosing a system-level vibration problem, the goals are to identify which component or components(s) are most responsible for the phenomenon and which changes to the system are most likely to mitigate the problem. The use of sensitivity analysis in diagnosing system-level vibration phenomena is examined in this work. It is shown that even if only a small subset of measured system input–output functions is available, an appropriate analytical parameterization of these functions leads to simple relationships between the measured data and the desired embedded sensitivity functions. These functions are then reformulated in terms of transmissibility functions with respect to a single input using a novel modal deflection chain technique in order to accommodate system-level operating response data in the absence of input measurements. The embedded sensitivity approach is used to examine two competing design modifications for reducing a structure-borne noise problem in an exhaust system. The sensitivity analysis shows that although both modifications mitigate the resonant vibration problem of interest, one of the modifications is more effective than the other because it introduces less overall change in the forced response characteristics at other frequencies.     

An alternative approach to canonical quantizationof the radiation damping

Inspired by some works on quantization of dissipative systems, in particular the ones treating the damped harmonic oscillator and by a paper due to Lukierski, we consider the dissipative system of a charge interacting with its own radiation, which is the origin of radiation damping. Using the indirect Lagrangian representation we obtained a Lagrangian formalism with a Chern-Simons-like term. A Hamiltonian analysis is also done in commutative and non-commutative scenarios, which leads to the quantization of the system. Received: 23 August 2005, Published online: 21 October 2005 PACS: 41.60.-m, 04.60.Ds     

An alternative approach to temporal laser-wing effects in saturated laser-induced fluorescence

Temporal laser-wing effects are associated with the unavoidable time characteristics of laser pulses. To remove their contribution in saturated laser-induced fluorescence, time sampling is commonly adopted. In the present work, an alternative approach is formulated. It is based on power measurements obtained from the whole fluorescence response. Numerical simulations with a four-level dynamical model are described to test the method against the traditional time-sampling procedure. A greater amount of measured signal and independence from the fast electronic sampler are the main advantages of the proposed method. PACS 32.50.+d; 42.62.Fi; 02.60.Cb     

Partial intensity approach for quantitative analysis of reflection-electron-energy-loss spectra

We have considered a formalism, known as partial intensity approach (PIA), previously developed to quantitatively analyze reflection electron energy loss (REEL) spectra [1,2]. The aim of the approach is, in particular, to recover the single scattering distribution of energy losses and to separate it into bulk and surface contributions, respectively referred to as the differential inverse inelastic mean free path (DIIMFP) and the differential surface excitation parameter (DSEP). As compared to [1] and [2], we have implemented a modified approach, and we have applied it to the specific geometry of the cylindrical mirror analyzer (CMA), used to acquire the REEL spectra shown here. Silicon, a material with well-defined surface and bulk plasmons, is taken as a case study to investigate the approach as a function of electron energy over the energy range typical of REELS, i.e. from 250 eV to 2 keV. Our goal is, on the one hand, to examine possible limits for the applicability of the approach and, on the other hand, to test a basic assumption of the PIA, namely that a unique DIIMFP and a unique DSEP account for REEL spectra, whatever the acquisition conditions (i.e. electron energy or angle of surface crossing) are. We find that a minimum energy exists below which the PIA cannot be applied and that the assumption of REEL spectra accounted for by unique DIIMFP and DSEP is indeed an approximation.     

An exact analytical approach to the free vibration analysis of rectangular plates with mixed boundary conditions

A comprehensive analytical technique is developed for the free vibration analysis of rectangular plates with discontinuities along the boundaries. For illustrative purposes a solution is obtained for plates with edges partially clamped and partially simply supported and plates with edges partially and partially simply supported. A vast array of first mode eigenvalues is provided for these families of plates. Solutions to the equations are obtained by exploiting a mathematical technique described by the author during an earlier publication. It is shown that eigenvalue matrices are easily generated for a wide range of plates with discontinuities in boundary conditions.     

Free vibration analysis for micro-structures used in MEMS considering surface effects

Based on state space method, a three-dimensional (3-D) approach is proposed to study the size-dependent dynamical properties of micro-structures considering surface effects. The structure is modeled as a laminate composed of a bulk bounded with upper and bottom surface layers, which are allowed to have different material properties from the bulk layer. On the basis of 3-D fundamental elasticity, the state equations, including the surface properties of the structure, can be established to analyze the size-dependent dynamic responses of the plate-like thin film structures used in MEMS. To show the feasibility of the proposed approach, a simply supported plate-like thin structure, including the surface layers, is considered. An algorithm strategy is proposed for the calculation of the state equations obtained to ensure that the numerical results can reveal the surface effects clearly even for extremely thin surface layers. Comparing with the two-dimensional plate theories based size-dependent models for the thin film structures in literature, the present 3-D approach is exact, which can provide benchmark results to assess the accuracy of various 2-D plate theories and numerical methods. Numerical tests prepared for the prediction of natural frequency are carried out to illustrate the surface effects. Some discussions and conclusions are presented based on the results of the numerical examples.     

Demagnetization factors of the general ellipsoid: An alternative to the Maxwell approach

A transparent, exhaustive, and self-contained method for the calculation of the demagnetization tensor of the uniformly magnetized ellipsoid is presented. The method is an alternative to the established Maxwell derivation and is based on a Fourier-space approach to the micromagnetics of magnetized bodies. The key to the success of the procedure lies in the convenient treatment of shape effects through the Fourier representation. The scaled form of the demagnetization factors which depends on two dimensionless aspect ratios is argued to be their natural integral representation. Amongst other advantages, it allows for the immediate implementation of symmetry arguments such that only one of the principal factors needs to be computed. The oblate and prolate ellipsoids of revolution are examined from the same general point of view. The demagnetization factors for these distinct types of spheroid are seen to be related by analytic continuation of well-known Gaussian hypergeometric functions.