This paper outlines the authors’ experimental research in rough-wall-bounded turbulent flows that has spanned the past 15 years. The results show that, in general, roughness effects are confined to the inner layer. In accordance with Townsend’s Reynolds number similarity hypothesis, the outer layer is insensitive to surface condition except in the role it plays in setting the length and velocit...

A negative permeability in a periodic array of pairs of thin silver strips is demonstrated experimentally for two distinct samples. The effect of the strip surface roughness on negative permeability is evaluated. The first sample, Sample A, is fabricated of thinner strips with a root mean square roughness of 7 nm, while Sample B is made of thicker strips with 3-nm roughness. The real part of pe...

We are examining surface characteristics of ultraviolet pulsed-laser micromachined structures in polymide as a function of the incident laser energy and the distance between subsequent laser spots in order to prepare surfaces for laser direct-write deposition of metals. Variations in the spot-to-spot translation distance provide an alternative means of average depth and roughness control when c...

We demonstrate an effective method for depositing smooth silver (Ag) films on SiO(2)/Si(100) substrates using a thin seed layer of evaporated germanium (Ge). The deposited Ag films exhibit smaller root-mean-square surface roughness, narrower peak-to-valley surface topological height distribution, smaller grain-size distribution, and smaller sheet resistance in comparison to those of Ag films di...

In this work, we report the transfer of graphene onto eight commercial microfiltration substrates having different pore sizes and surface characteristics. Monolayer graphene grown on copper by the chemical vapor deposition (CVD) process was transferred by the pressing method over the target substrates, followed by wet etching of copper to obtain monolayer graphene/polymer membranes. Scanning el...

Different optical characterization methods were applied to a series of microcrystalline silicon thin films, either as grown, textured, or subsequently polished, mirror-like. They reveal contributions of bulk and surface light scattering effects to the phenomenon of optical absorption enhancement. The enhanced light absorption in textured layers is mainly due to a longer optical path as a result...

We study the average separation between an elastic solid and a hard solid, with a nominally flat but randomly rough surface, as a function of the squeezing pressure. We present experimental results for a silicon rubber (PDMS) block with a flat surface squeezed against an asphalt road surface. The theory shows that an effective repulsive pressure acts between the surfaces of the form p∼exp(-u/u(...

According to vector scattering and scalar scattering theory, the relationship of BRDF (bidirectional reflectance distribution function) of light scattering from micro-rough surface with TIS (total integrated scattering) is analyzed. Roughness statistical characterization such as RMS (root mean square), PSD (power spectral density) function are deduced by TIS of polished surface. Based on the li...

The radar backscattering coefficient of three types of soil surfaces at observation angles (10°60°) have been calculated using integral equation model (IEM) for different values of root mean square (RMS) roughness heights and correlation lengths. The surfaces are represented by isotropic autocorrelation functions (exponential, 1.5 power and Gaussian). The dielectric constant (ε) of the soil, an...

response surface methodology (rsm) is a statistical method useful in the modeling and analysis of problems in which the response variable receives the influence of several independent variables, in order to determine which are the conditions under which should operate these variables to optimize a corrugated box production process. the purpose of this research is to create response surface mode...