A MACROSCOPIC MODEL FOR THE HEAT PROPAGATION IN THE MICROPERIODIC COMPOSITE SOLIDS

This article deals with the problem of heat propagation in periodic composites described by the Cattaneo-type constitutive law. The simplest model for the macroscopic behavior of these composites can be obtained using results of the well-known asymptotic homogenization theory. However, this model is not able to describe the phenomena related to higher order motions and higher propagation speeds that play an important role in wave propagation analysis. The aim of this contribution is to propose a more general macroscopic model for the heat propagation in periodic composites that can be used for the analysis of the aforementioned phenomena and is based on the tolerance averaging of equations with functional coefficients.     

Tunneling/shear force microscopy using piezoelectric tuning forks for characterization of topography and local electric surface properties

Characterization of novel nanoelectronic structures and materials requires advanced and high-resolution diagnostic methods. In this article new approach for high sensitivity measurements of electric surface properties using scanning probe microscopy is presented. In this procedure topography and tunneling current flowing between the metallic tip and the surface are observed simultaneously. In our design piezoelectric tuning fork equipped with metallic tip in shear force microscope is used.     

Effect of cultivar and fruit storage on basic composition of clear and cloudy pear juices

BackgroundPears due to low acidity are a suitable raw material for the production of multifruit nectars thus it is justified to determine the chemical composition and investigate the effect of cultivar and fruit maturity on juices quality.MethodsJuices from ‘Alexander Lucas’ and ‘Conference’ cultivars were produced after harvest and after 3 months of pears storage.ResultsAverage yield of clear juices was 76.4% for ‘Conference’ cultivar and 74.3% for ‘Alexander Lucas’. In the case of cloudy juices, the yield was lower by about 3%. Processing of ‘Conference’ cv. from stored fruit resulted in yield decrease compared to fruits after harvest; this was not in case of ‘Alexander Lucas’ in 2008, where juices produced from stored fruits were characterized by a higher yield compared to fresh fruit.Total solids content in clear juices was 125–135 g/L and 135–141 g/L for cloudy juices. ABTS^●+ and total phenolics analysis showed that cloudy juices were characterized by a higher antioxidant activity and phenolics content than the clear ones.ConclusionPear storage, on the contrary to apples, does not decrease their suitability for cloudy juice production. Cloudy juices as a rule have higher antioxidant activity than the clear ones.     

Subsurface Biological Activity Zone Detection Using Genetic Search Algorithms

Use of generic search algorithms for detection of subsurface biological activity zones (BAZ) is investigated through a series of hypothetical numerical biostimulation experiments. Continuous injection of dissolved oxygen and methane with periodically varying concentration stimulates the cometabolism of indigenous methanotropic bacteria. The observed breakthroughs of methane are used to deduce possible BAZ in the subsurface. The numerical experiments are implemented in a parallel computing environment to make possible the large number of simultaneous transport simulations required by the algorithm. Our results show that genetic algorithms are very efficient in locating multiple activity zones, provided the observed signals adequately sample the BAZ.     

Path Integration on a Quantum Computer

We study path integration on a quantum computer that performs quantum summation. We assume that the measure of path integration is Gaussian, with the eigenvalues of its covariance operator of order j^-k with k>1. For the Wiener measure occurring in many applications we have k=2. We want to compute an -approximation to path integrals whose integrands are at least Lipschitz. We prove: Path integration on a quantum computer is tractable. Path integration on a quantum computer can be solved roughly ^-1 times faster than on a classical computer using randomization, and exponentially faster than on a classical computer with a worst case assurance. The number of quantum queries needed to solve path integration is roughly the square root of the number of function values needed on a classical computer using randomization. More precisely, the number of quantum queries is at most 4.46 ^-1. Furthermore, a lower bound is obtained for the minimal number of quantum queries which shows that this bound cannot be significantly improved. The number of qubits is polynomial in ^-1. Furthermore, for the Wiener measure the degree is 2 for Lipschitz functions, and the degree is 1 for smoother integrands. PACS: 03.67.Lx; 31.15Kb; 31.15.-p; 02.70.-c     

Nonlinear Fly‐By‐Throttle H∞ Control Using Neural Networks

A neural network approach to gain scheduling H∞ controllers for propulsion controlled aircraft (PCA) systems is introduced. The PCA system is applied to backup control of aircraft experiencing control surface failure. The H∞ technology is applied to the problem of matching the crippled aircraft and the nominal model. Various H∞ controllers at various flight conditions are used to train radial basis function networks (RBFN), which can then be used as the nonlinear controller. Simulation on an L‐1011 under fly‐by‐throttle control demonstrates that the RBFN controller can stabilize the crippled airplane to obtain the desired model and possesses robustness against the engine delay.     

HBGC123D: a high-performance computer model of coupled hydrogeological and biogeochemical processes

Groundwater flow and transport models have been used to assist management of subsurface water resources and water quality. The needs of more efficient use of technical and financial resources have recently motivated the development of more effective remediation techniques and complex models of coupled hydrogeological and biogeochemical processes. We present a high-performance computer model of the coupled processes, HBGC123D. The model uses a hybrid Eulerian–Lagrangian finite element method to solve the solute transport equation and a Newton's method to solve the system of nonlinear, mixed kinetics and equilibrium reaction equations. Application of the model to a laboratory soil column with multispecies tracer injection suggests that one may use the model to derive important parameters of subsurface solute fate and transport. These parameters may be used for predictive purpose in similar field problems. To this end, we present a three-dimensional, hypothetical bioremediation simulation on an aquifer contaminated by CoNTA. The simulation suggests that, using oxygen alone to stimulate the biodegradation of the contaminant, one may reduce the waste to 40% in 10 years. Using a refined mesh of this three-dimensional model, we also conduct a performance study of HBGC123D on an array of SGI Origin 2000 distributed shared-memory processors. Both the computational kernels and the entire model show very good performance up to 32 processors. The CPU time is essentially reduced by 20-fold using 64 processors. This result suggests that HBGC123D may be a useful tool in assisting environmental restoration efforts such as waste site characterization and remediation.     

Corrected 2D-theories for composite plates

Summary The objective of the paper is to propose a simple method of formulation of 2D-theories for composite thin plates made of an arbitrary inhomogeneous linear-elastic material. The effect of inhomogeneity on the plate stiffness will be described by means of extra unknowns, called correctors, which have to satisfy a system of linear algebraic equations. The elimination of correctors can be performed in explicit form and leads to the formulas for effective stiffnesses of the plates under consideration.