Oat–buckwheat breads – technological quality, staling and sensory properties

peer reviewedThe technological and sensory properties and the staling of breads made from oat flour (OF) and buckwheat flour (BF) were analysed. Significant differences in protein and ash content were found in the experimental breads due to significant differences in the composition of the BF and OF used. As the proportion of BF in the recipe increased, a deterioration in the technological properties of the dough and bread as well as an increase in the crumb hardness were observed. The presence of OF in the recipe increased the bread volume, significantly enhanced the lightness of the crust and crumb and improved the overall sensory quality. The OF used in the recipe decreased the starch retrogradation enthalpy value, which is strongly related to a delay in bread staling. The proposed bakery products can be attractive to consumers who are looking for new food products

Multi-objective turbomachinery optimization using a gradient-enhanced multi-layer perceptron

Response surface models (RSMs) have found widespread use to reduce the overall computational cost of turbomachinery blading design optimization. Recent developments have seen the successful use of gradient information alongside sampled response values in building accurate response surfaces. This paper describes the use of gradients to enhance the performance of the RSM provided by a multi-layer perceptron. Gradient information is included in the perceptron by modifying the error function such that the perceptron is trained to fit the gradients as well as the response values. As a consequence, the back-propagation scheme that assists the training is also changed. The paper formulates the gradient-enhanced multi-layer perceptron using algebraic notation, with an emphasis on the ease of use and efficiency of computer code implementation. To illustrate the benefit of using gradient information, the enhanced neural network model is used in a multi-objective transonic fan blade optimization exercise of engineering relevance. Copyright © 2008 John Wiley and Sons, Ltd

A three-dimensional hybrid finite element/spectral analysis of noise radiation from turbofan inlets

This paper describes a new three-dimensional (3D) analysis of tonal noise radiated from non-axisymmetric turbofan inlets. The novelty of the method is in combining a standard finite element discretisation of the acoustic field in the axial and radial coordinates with a Fourier spectral representation in the circumferential direction. The boundary conditions at the farfield, fan face and acoustic liners are treated using the same spectral representation. The resulting set of discrete acoustic equations are solved employing the well-established BICGSTAB or QMR iterative algorithms and a very effective specialised preconditioner based on the axisymmetric mean geometry and flow field. Numerical examples demonstrate the suitability of the new method to engine configurations with realistic 3D features, such as relatively large degrees of asymmetry and spliced acoustic liners. The examples also illustrate the two advantages of the new method over a traditional 3D finite element approach. The new method requires a significantly smaller number of unknowns as relatively few circumferential Fourier modes in the spectral solution ensure an accurate field representation. Also, due to the effective preconditioner, the spectral linear solver benefits from stable iterations at a high rate of convergence. © 2006 Elsevier Ltd. All rights reserved

Turbomachinery design optimization using automatic differentiated adjoint code

The last decade has established the adjoint method as an effective way in Computational Fluid Dynamics of calculating the gradients of an objective functional in a large dimensional design space. This paper addresses the concerns that code developers face when creating a discrete adjoint computer program for design optimization, starting from a nonlinear flow solver and using Automatic Differentiation. Adjoint code development benefits greatly from using Automatic Differentiation but at its current state of maturity, this technology is best applied selectively rather than on entire codes. The paper discusses the practical aspects of using Automatic Differentiation on a large industrial turbomachinery flow solver with the objective of deriving efficient adjoint code. The use of the adjoint gradients is illustrated in an optimization exercise using gradient based methods on the NASA Rotor 37 public testcase

Adjoint calculation of sensitivities of turbomachinery objective functions

An overview is presented of the steady and harmonic adjoint methods for turbomachinery design using the discrete approach in which the discretized nonlinear Euler/Navier-Stokes equations are linearized and the resulting matrix is then transposed. Steady adjoint solvers give the linear sensitivity of steady-state functionals such as mass flow and average exit flow angle to arbitrary changes in the geometry of the blades, and this linear sensitivity information can then be used as part of a nonlinear optimization procedure. The harmonic adjoint method is based on a single frequency of unsteadiness and allows one to determine the generalized force acting on the blades due to arbitrary incoming time-periodic gusts. When the forcing is due to the wakes of the upstream blades, the adjoint approach can be used to tailor the shape of the incoming wakes to reduce greatly the level of forced vibration they induce. The presented suite of test cases includes the inlet guide vane and the rotor of a high-pressure turbine

Aeroacoustic analysis using a hybrid finite element method

This paper describes a novel three-dimensional analysis of tone noise radiated from turbofan inlets. This analysis combines a standard finite element (FE) discretization of the acoustic field in the axial and radial coordinates with a Fourier spectral representation in the circumferential direction. The boundary conditions at the farfield, fan duct, and acoustic liners are treated using the same spectral representation. The resulting equations are solved iteratively using an axisymmetric approximation of the inlet geometry to form all effective preconditioner. The analysis method is far less expensive than a conventional three-dimensional FE method because relatively few circumferential Fourier modes need to be retained for an accurate field representation

Algorithm developments for discrete adjoint methods

A number of algorithm developments are presented for adjoint methods using the "discrete" approach in which the discretization of the nonlinear equations is linearized and the resulting matrix is then transposed. With a new iterative procedure for solving the adjoint equations, exact numerical equivalence is maintained between the linear and adjoint discretizations. The incorporation of strong boundary conditions within the discrete approach is discussed, and difficulties associated with the use of linear perturbation and adjoint methods for applications with strong shocks are also examined

Parallel Simulation for Parameter Estimation of Optical Tissue Properties.

Several important laser-based medical treatments rest on the crucial knowledge of the response of tissues to laser penetration. Optical properties are often localised and are measured using optically active fluorescent microspheres injected into the tissue. However, the measurement process combines the tissue properties with the optical characteristics of the measuring device which in turn requires numerically intensive mathematical simulations for extracting the tissue properties from the data. In this paper, we focus on exploiting the algorithmic parallelism in the biocomputational simulation, in order to achieve significant runtime reductions. The entire simulation accounts for over 30,000 spatial points and is too computationally demanding to run in a serial fashion. We discuss our strategies of parallelisation at different levels of granularity and we present our results on two different parallel platforms. We also emphasise the importance of retaining a high level of code abstraction in the application to benefit both agile coding and interdisciplinary collaboration between research groups. © 2010 Springer-Verlag