A new test for cleaning efficiency assessment of cleaners for hard surfaces

A new test was developed to assess the efficiency of no-wiping hard-surface cleaning. The test allows cleaner comparisons according to their ability to remove greasy soils. The chosen approach minimizes the mechanical forces applied while cleaning so that the interactions between a detergent solution and the soil to be removed can be characterized. For this, immersion cleaning was chosen, with coated stainless steel as substrate and pigmented oils as the model soil. Several parameters were studied in defined ranges using the Experimental Design method and systematic comparisons. The test shows high reliability on degreasing assessments and is there-fore especially suited to optimization of nonionic surfactant mixes. The originality of the test lies in the possibility of keeping a visual trace of the cleaned substrate appearance by imprinting it on a piece of paper. The validation of the test leads to corroboration of several practical observations. Temperature and agitation play a major role in cleaning efficiency. Detergent solution concentration is a more relevant parameter than pH. Sodium carbonate is shown to have a higher buffering effect than pentahydrated sodium metasilicate. The test is easy to set up, highly sensitive, and can be adapted to solve the problems encountered by formulators of detergent cleaners, such as screening the best ethoxylated fatty alcohol mix for better degreasing properties.     

Scattering from several test-objects computed by 3-D hybrid IE/PDEmethods

The electromagnetic scattering from composite anisotropic dielectric and conducting structures is modeled by hybrid partial differential equation-integral equation formulations. We emphasize the role of edge elements for both the partial differential equation and the integral equation discretization and for the coupling of the two. Numerical results from the various formulations are presented and measurements are compared in order to obtain test cases for the development and validation of numerical methods     

Iterative solution of a 3-D scattering problem from arbitraryshaped multidielectric and multiconducting bodies

We present an iterative algorithm used for the computation of the scattering from arbitrary shaped bodies made of dielectric and conducting material. The harmonic problem is discretized by a hybrid boundary integral method/finite element method. To solve the discretized linear system, a modified version of a minimal residual algorithm has been developed for complex matrices. It takes into account the Lagrange multiplier constraint in a special way. This modified version also allows the linear system to be solved for many right-hand sides in an efficient manner     

Scattering from 3-D cavities with a plug and play numerical schemecombining IE, PDE, and modal techniques

In this paper, we present a multidomain and multi-method coupling scheme called FACTOPO, based on generalized scattering matrix computations on three-dimensional (3-D) subdomains. The global target Ω is split in N_V subdomains (V_i)(i=1, N_V), separated by N_I fictitious surfaces (Γ _j)(j=1,N_I). We use a modal representation of the tangent fields on the interfaces. In each domain, the generalized scattering matrix S_i is computed with different methods such as the 3-D finite-element method (FEM) or the electric field integral equation (EFIE). This coupling scheme leads to an important reduction in computational resources, especially for cavities with one dimension much larger than the other two. The advantages of this formulation for parametric studies is illustrated by two cases: computing the RCS of an air-intake terminated with a flat PEC or a fan (CHANNEL) and of an antenna structure coupled to an electronic feed with a varying parameter (DENEB). Numerical as well as experimental results are presented     

Computation of the scattering from inhomogeneous objects with adiscrete rotational symmetry and a nonsymmetric part

Using a specific solver for circulant matrices can reduce the cost of computing the scattering from a discrete rotational symmetric object by up to several orders of magnitude. A solver is developed for symmetric objects with a nonsymmetrical part (such as an antenna on a body of revolution). This solver has been implemented in a finite-element code based upon a hybrid formulation. The hybrid formulation combines integral equations and partial differential equations; it can handle inhomogeneous anisotropic objects of arbitrary shape. Results on inhomogeneous objects with defects are shown. The solver can also be used to perform a parametric study of the defects