Asymmetric Coefficients Research Articles

Estimating the functional relationships for quality function deployment under uncertainties

Product planning is one of four important processes in new product development (NPD) using quality function deployment (QFD), which is a widely used customer-driven approach. In our opinion, the first problem to be solved is how to incorporate both qualitative and quantitative information regarding relationships between customer requirements (CRs) and engineering characteristics (ECs) as well as those among ECs into the problem formulation. Owing to the typical vagueness or imprecision of functional relationships in a product, product planning is becoming more difficult, particularly in a fuzzy environment. In this paper, an asymmetric fuzzy linear regression approach is proposed to estimate the functional relationships for product planning based on QFD. Firstly, by integrating the least-squares regression into fuzzy linear regression, a pair of hybrid linear programming models with asymmetric triangular fuzzy coefficients are developed to estimate the functional relationships for product planning under uncertainties. Secondly, using the basic concept of fuzzy regression, asymmetric triangular fuzzy coefficients are extended to asymmetric trapezoidal fuzzy coefficients, and another pair of hybrid linear programming models with asymmetric trapezoidal fuzzy coefficients is proposed. The main advantage of these hybrid-programming models is to integrate both the property of central tendency in least squares and the possibilistic property in fuzzy regression. Next, the illustrated example shows that trapezoidal fuzzy number coefficients have more flexibility to handle a wider variety of systematic uncertainties and ambiguities that cannot be modeled efficiently using triangular number fuzzy coefficients. Both asymmetric triangular and trapezoidal fuzzy number coefficients can be applicable to a much wider variety of design problems where uncertain, qualitative, and fuzzy relationships are involved than when symmetric triangular fuzzy numbers are used. Finally, future research direction is also discussed.

Lipid characterization of seed oils from high‐palmitic, low‐palmitoleic, and very high‐stearic acid sunflower lines

Information obtained in recent years regarding the enzymes involved in FA synthesis can now be applied to develop novel sunflower lines by incorporating enzymes with specific characteristics into lines with a defined background. We have generated three highly saturated mutant lines in this way and characterized their FA content. The new high-palmitic, low-palmitoleic lines CAS-18 and CAS-25, the latter on a high-oleic background, have been selected from the high-stearic mutant CAS-3 by introducing a deficient stearic acid desaturase in a high-palmitic background from the previously developed mutant lines CAS-5 and CAS-12, respectively. As such, the desaturation of palmitic acid and the synthesis of palmitoleic acid and its derivatives (asclepic and palmitolinoleic acids) were reduced in these high-palmitic lines, increasing the stearic acid content. Likewise, introducing a FA thioesterase from a high-palmitic line (e.g., CAS-5) into the high-stearic CAS-3 increased the stearic acid content from 27 to 32% in the new high-stearic line CAS-31. As previously described in high-palmitic lines, high growth temperatures did not reduce the linoleic acid content of the oil. Furthermore, the FA composition of TAG, DAG, and phospholipids was modified in these lines. Besides a high degree of saturation, the TAG from these new vegetable oils have a low content of saturated FA in the sn-2 position. The alpha asymmetric coefficient obtained also indicates that the saturated FA are asymmetrically distributed within the TAG molecules. Indeed, the disaturated TAG content rose from 31.8 to 48.2%. These values of disaturated TAG are the highest to date in a temperate oilseed.

Experimental study of mass transfer limited reaction—Part I: Use of fibre optic spectrometry to infer asymmetric mass transfer coefficients

Mass transfer coefficients, often quantified using empirical correlations in chemical engineering, are useful in predicting the final concentration of the reactants [(Fogler 1992). In: Amundson (Ed.)., Element of Chemical Reaction Engineering, International Series in the Physical and Chemical Engineering, Princeton-Hall]. In the present work, we propose an inverse methodology to estimate mass transfer coefficients from the experimentally measured concentrations of the reactants. The potential of the inverse methodology is that asymmetric mass transfer coefficients of all the premixed reactants can be inferred, which has not been reported so far in literature. In general, only the slowest transfer coefficient estimate has been feasible before. We first review the potential reactions satisfying the required criteria and then discuss multi-component spectrum analysis to decipher the concentrations of the reactants from the absorbance spectrum of the reaction mixture using the principle of additivity. We show that linear additivity does not hold if there is any interaction between the reacting species. In that case, we use a non-linear calibration for the concentrations of the reactants. The mass transfer coefficients inferred using the inverse methodology are validated by solving the forward problem and could be potentially used to study transport limited characteristics of heterogeneous reactions.

THE BOUNDS ON LORENTZ AND CPT VIOLATING PARAMETERS IN THE HIGGS SECTOR

In this talk, I discuss possible bounds on the Lorentz and CPT violating parameters in the Higgs sector of the so called minimal Standard-Model Extension (SME). The main motivation to this study is coming from the fact that unlike the parameters in the fermion and gauge sector, there are no published bounds on the parameters in the Higgs sector. From the one-loop contributions to the photon propagator the bounds on the CPT-even asymmetric coefficients are obtained and the cμν coefficients in the fermion sector determine the bound on the CPT-even symmetric coefficients. The CPT-odd coefficient is bounded from the non-zero vacuum expectation value of the Z-boson.

Three-dimensional plasma field reconstruction with multiobjective optimization emission spectral tomography.

A novel emission spectral tomography algorithm based on multiobjective optimization is proposed. Its reconstruction results for asymmetrical emission coefficient fields are studied with computer simulation. The results show that this algorithm provides a significant improvement in reconstruction precision and convergence over traditional algorithms and is suitable for real-time reconstruction of an emission-coefficient field with incomplete data. In an experiment of the argon-arc plasma diagnosis, we adopted this algorithm and the spectrum relative-intensity method to obtain the three-dimensional distributions of temperature, ionization coefficient, and electron (ion) and atom densities.

Lorentz and CPT violation in the Higgs sector

Colladay and Kostelecky have proposed a framework for studying Lorentz and CPT violation in a natural extension of the Standard Model. Although numerous bounds exist on the Lorentz and CPT violating parameters in the gauge boson and fermion sectors, there are no published bounds on the parameters in the Higgs sector. We determine these bounds. The bounds on the CPT-even asymmetric coefficients arise from the one-loop contributions to the photon propagator, those from the CPT-even symmetric coefficients arise from the equivalent c_{\mu\nu} coefficients in the fermion sector, and those from the CPT-odd coefficient arise from bounds on the vacuum expectation value of the Z-boson.

Self-adaptive reconstruction algorithm for emission spectral volume tomography

A novel self-adaptive volume reconstruction technique (SVRT) based on multiobjective optimization is proposed. Its reconstruction results for asymmetrical 3-D single-peak cosine emission coefficient fields are studied with the numerical simulation of a computer. The results show that this algorithm has faster convergences and higher reconstruction precision, and can reconstruct asymmetrical single-peak cosine emission coefficient fields perfectly with only two views. (The average error is 0.18% with no noise data.) In the experiment of argon-arc plasma diagnosis, the 3-D reconstructions of temperature and ionization coefficient fields are fulfilled with this algorithm combined with the spectrum relative-intensity method.

Emission spectral tomography algorithm based on multi-objective optimization and its application in plasma diagnosis

A multiobjectiveoptimizationbased emission spectral tomography alg or ithm(EST) is proposed. Its reconstruction results for asymmetrical emission coefficient field are studied by numerical simulation with compute r. The results show that this algorithm has faster convergences and higher recon struction precision than that of traditional algorithms and is suitable for real time reconstruction of emission coefficient field with incomplete data. In the experiment of argonarc plasma diagnosis, the threedimensional reconstructio ns of temperature and atomic (ionic) density fields are accomplished with this a lgorithm and the spectrum relativeintensity method.

Scattering of image-potential-state electrons by steps on Cu(001)

Scanning tunneling spectroscopy (STS) reveals a distinct asymmetry in the scattering properties of an isolated step for the n=1 image-potential state on Cu(001). The elastic scattering probability for an electron traveling downstairs is determined from the strength of density oscillations in front of a step edge and is found to be approximately two times higher than for the opposite upstairs direction. A one-dimensional scattering model is extended to the case of asymmetric transmission and reflection coefficients. The calculations using the asymmetry measured by STS explain the dispersion and the decay rate of the n=1 band on Cu(119) measured by two-photon photoemission. In particular, the asymmetry of the decay rate can be described quantitatively with a minimum of adjustable parameters. While the results can also be transferred successfully to the Cu(1115) surface, the limit of applicability is reached for Cu(117) with a step separation of 3.5 nearest-neighbor distances.

Visualization of two-phase flow through microgrooved tubes for understanding enhanced heat transfer

Though widely used, questions remain as to the mechanisms by which micro-fin or microgrooved tubes enhance heat transfer performance. In this work, new experimental liquid film thickness profiles in adiabatic, air–water flow through clear tubes with 20 microgrooves at three different helix angles are presented. These results correlate well with the asymmetrical temperature measurements and heat transfer coefficients seen by previous investigators. Important observations include increased wall wetting for a given flow condition, decreasing influence of the grooves with increasing gas velocity, and a rotational redistribution of the liquid film by helical grooves, though without indication of a swirling behavior.

Nearly irreversible, fast heterogeneous reactions in premixed flow

When heterogeneous chemical reaction is sufficiently fast, transport of reactants becomes limiting. In a fixed bed reactor, macroscopic concentration gradients cannot be eliminated as a factor limiting the rate of reaction, possibility coupling to the mesoscopic mass transfer of reactants to the surface of the catalyst as limiting, if the reaction does not occur inside a porous support. A theory for strictly irreversible binary reaction is developed that shows the possibility of regimes of kinetic asymmetry in which a crossover point occurs internally in the reactor, demarking a region of high supersaturation in which the surface is effectively depleted of one reagent, followed by a region of rapidly decaying supersaturation, where the surface is effectively depleted of the other reagent. The parametric dependence of this crossover point is given in terms of a transcendental equation which depends on operating parameters (superficial velocity and inlet concentrations) and ratios of transport properties of the reagents. These solutions are corroborated by full nonlinear numerical computations of the boundary value problem, for the case when asymmetric mass transfer coefficients admit the possibility that the mode of operation switches from relative surface depletion of one reactant to depletion of the other in a binary reaction. It is shown that X indicates the region of greatest molecular efficiency in the reactor, and if operating parameters are so chosen such that X is large, high conversion is achieved in the precrossover region. The modified Thiele modulus analysis of the numerical solutions identifies the crossover point and the region of greatest product formation.

Fast binary reactions in a heterogeneous catalytic batch reactor

When heterogeneous chemical reaction is sufficiently fast, transport of reactants becomes limiting. In a well stirred, batch reactor, macroscopic concentration gradients can be eliminated as a factor limiting the rate of reaction, leaving only the mesoscopic mass transfer of reactants to the surface of the catalyst as limiting, if the reaction does not occur inside a porous support. Here, a transformation of the governing equations for the time-dependence of bulk and surface concentrations results in second order ODE in time and a single nonlinear constraint with boundary values at the initial and infinite times for two auxiliary variables termed modified Thiele moduli. This system of two equations—one differential, one algebraic—and two unknowns is an exact consequence of the governing equations (three ODEs and three algebraic constraints). The power of this formulation is demonstrated by analytic solutions for irreversible and nearly irreversible theories. These solutions are corroborated by full nonlinear numerical computations of the boundary value problem, for the case when asymmetric mass transfer coefficients admit the possibility that the mode of operation switches from relative surface depletion of one reactant to depletion of the other in a binary reaction. The modified Thiele modulus formulation reveals the time scale for the switch over, as well as giving a reliable prediction for the time scale for 99% conversion based on the switch time identified from the irreversible theory.

Contribution of convection, diffusion and migration to electrolyte transport through nanofiltration membranes

Transport mechanisms through nanofiltration membranes are investigated in terms of contribution of convection, diffusion and migration to electrolyte transport. A Donnan steric pore model, based on the application of the extended Nernst–Planck equation and the assumption of a Donnan equilibrium at both membrane–solution interfaces, is used. The study is focused on the transport of symmetrical electrolytes (with symmetric or asymmetric diffusion coefficients). The influence of effective membrane charge density, permeate volume flux, pore radius and effective membrane thickness to porosity ratio on the contribution of the different transport mechanisms is investigated. Convection appears to be the dominant mechanism involved in electrolyte transport at low membrane charge and/or high permeate volume flux and effective membrane thickness to porosity ratio. Transport is mainly governed by diffusion when the membrane is strongly charged, particularly at low permeate volume flux and effective membrane thickness to porosity ratio. Electromigration is likely to be the dominant mechanism involved in electrolyte transport only if the diffusion coefficient of coions is greater than that of counterions.

Persistence and flow reliability in simple food webs

Twenty-five model food webs can be designed from five points (species) and five links (trophic interactions), if they contain a single top-predator (i.e. sink webs). According to a simple topological approach, we presented elsewhere a reliability theoretical analysis of this set of food web graphs. The question addressed here is how network flow reliability is related to the dynamical behavior and stability of these ‘model communities’. We simulated the behavior of these webs and calculated their persistence, according to four models: (1) with symmetrical interaction coefficients between species; (2) with asymmetrical interaction coefficients and lower death rates for predators; and (3) with absolutely and (4) relatively perturbed, formerly persistent parameter sets of the asymmetrical model. We used both Lotka–Volterra (LV) and Holling II-type equations (with switching effect). Thus, we had eight persistence values for each web. Persistence (a dynamical property) and flow reliability (a structural property) were analyzed. We found that (1) reliable flow pattern is associated with high persistence in the Holling models, while the LV models predict no consistent correlations; (2) in asymmetrical situations, persistence is always much higher (in both LV and Holling models); and (3) the predictions of Holling models (versus LV models) are much less sensitive to local perturbations. Based on these results, we conclude that (1) reliable network flows can contribute to persistence only if switching is possible; (2) asymmetrical interactions increase persistence, independently of the switching effect but it indicates persistence in Holling II model; (3) switching makes the relationship much more predictable between structure and dynamics. Thus, the network design is less useful predictor of persistence without switching effect but well can ensure dynamical stability under the conditions of the Holling II model. We have presented how various dynamical models predict different behavior of modelled communities characterized by the same structure and complexity. Complementing dynamical with structural analysis may further increase our understanding of persistence in food webs.

Adjoint Design Sensitivity Analysis of Molecular Gas Film Lubrication Sliders

This paper proposes an analytical design sensitivity analysis (DSA) to topological parameters of MGL (molecular gas film lubrication) sliders by introducing an adjoint variable method. For the analysis of slider air bearings, we used the spatial discretization of the generalized lubrication equation based on a control volume formulation. The residual functions for inverse analysis of the slider are considered as the equality constraint functions. The slider rail heights of all grid cells are chosen as design variables since they are the topological parameters determining air bearing surface (ABS). Then, a complicated adjoint variable equation is formulated to directly handle the highly nonlinear asymmetric coefficient matrix and vector in the discrete system equations of slider air bearings. An alternating direction implicit (ADI) scheme is utilized to efficiently solve large-scale problem in special band storage. The simulation results of DSA are directly compared with those of finite-difference approximation (FDA) to show the effectiveness and accuracy of the proposed approach. The overall sensitivity distribution over the ABS is reported, and clearly shows to which section of the ABS the special attention should be given during the manufacturing process. It is demonstrated that the proposed method can reduce more than 99 percent of the CPU time in comparison with FDA, even though both methods give the same results.

LEARNING TO FORECAST PRICE

We study learning in an individual choice price forecasting task in which subjects must learn coefficients of two independent variables in stationary linear stochastic processes. The 99 subjects each forecast in 480 trials with feedback. Learning is tracked by fitting individual forecasts to the independent variables. Results: (1) Learning is fairly consistent with respect to objective values, but with slight tendency toward overresponse. (2) Learning is noticeably slower than the Marcet‐Sargent ideal. Two striking treatment effects are tendencies toward (3) overresponse with high background noise and (4) underresponse with asymmetric coefficients.

Topological design sensitivity on the air bearing surface of head slider

In this study, a topological design sensitivity of the air bearing surface (ABS) is suggested by using an adjoint variable method. The discrete form of the generalized lubrication equation based on a control volume formulation is used as a compatible condition. A residual function of the slider is considered as an equality constraint function, which represents the slider in equilibrium. The slider thickness parameters at all grid cells are chosen as design variables since they are the topological parameters determining the ABS shape. Then, a complicated adjoint variable equation is formulated to directly handle the highly nonlinear and asymmetric coefficient matrix and vector in the discrete system equation of air-lubricated slider bearings. An alternating direction implicit (ADI) scheme is utilized for the numerical calculation. This is an efficient iterative solver to solve large-scale problem in special band storage. Then, a computer program is developed and applied to a slider model of a sophisticated shape. The simulation results of design sensitivity analysis (DSA) are directly compared with those of FDM at the randomly selected grid cells to show the effectiveness of the proposed approach. The overall distribution of DSA results are reported, clearly showing the region on the ABS where special attention should be given during the manufacturing process.

Azimuthal asymmetry of J / ψ suppression in non-central heavy-ion collisions

The azimuthal asymmetry of J / ψ suppression in non-central heavy-ion collisions is studied within a dynamic model of J / ψ suppression in a deconfined partonic medium. Within this model, J / ψ suppression in heavy-ion collisions is caused mainly by the initial state nuclear absorption and dissociation via gluon- J / ψ scattering in deconfined partonic medium. Only the second mechanism gives arise to azimuthal asymmetry of the final J / ψ production. We demonstrate that if there is an onset of suppression by quark–gluon plasma (QGP) in the NA50 data, it must be accompanied by the non-vanishing azimuthal asymmetry. Using the same critical density above which the QGP effect enters, we predict the azimuthal asymmetric coefficient v 2 as well as the survival probability for J / ψ at the RHIC energy.

A Boundary Value Problem for an Elliptic Equation with Asymmetric Coefficients in a Nonschlicht Domain

We propose some minimum principle for the quadratic energy functional of an elliptic boundary value problem describing a transport process with asymmetric tensor coefficients in a nonschlicht domain. We prove the existence and uniqueness of a weak solution in the energy space. The energy norm equals the entropy production rate.

Far-Infrared Spectra, Conformational Stability, Barriers to Internal Rotation, Ab Initio Calculations, r0 Structural Parameters, and Vibrational Assignment of Ethyl Methyl Ether

The far-infrared spectra (350–35 cm−1) of gaseous ethyl methyl ether-d 0 and ethyl methyl-d 3-ether have been recorded at a resolution of 0.10 cm−1. For the d 0 species, the fundamental asymmetric torsion of the more stable trans conformer (two methyl moieties are trans to one another) has been observed at 115.40 cm−1 with four upper state transitions falling to lower frequency, whereas, for the gauche form, it has been observed at 93.56 cm−1 with two excited states falling to lower frequency. the corresponding series for the d 3 species start from 106.00 and 87.10 cm−1, respectively. From these data, the asymmetric torsional potential coefficients for the d 0 species have been determined to be: V 1 = 572 ± 30; V 2 = 85 ± 8; V 3 = 619 ± 30; V 4 = 175 ± 18, and V 6 = −28 ± 3 cm−1. The trans to gauche and gauche to gauche barriers were calculated to be 958 cm−1 (11.5 kJ/mol) and 631 cm−1 (7.55 kJ/mol), respectively, with an energy difference of 550 ± 6 cm−1 (6.58 ± 0.07 kJ/mol). Utilizing three conformer pairs, variable temperature studies (−105 to −150°C) of the infrared spectra of the d 0 sample dissolved in liquid krypton gave an enthalpy difference of 547 ± 28 cm−1 (6.54 ± 0.33 kJ/mol) with the trans conformer the more stable rotamer. It is estimated that there is only 4% of the gauche conformer present at ambient temperatures. The structural parameters, conformational stabilities, barriers to internal rotation, and fundamental vibrational frequencies, which have been determined experimentally, are compared to those obtained from ab initio gradient predictions from RHF/6-31G* and with full electron correlation at the MP2 level with three different basis sets. The adjusted r 0 structural parameters have been obtained for the trans conformer from combined ab initio MP2/6-311+G** predictions and previously reported microwave rotational constants. The reported distances should be accurate to 0.003 A and the angles to 0.5°. These results are compared to the corresponding quantities obtained for some similar molecules.