On the rates of convergence of the finite element method

The rate of convergence of the finite element method is a function of the strategy by which the number of degrees-of-freedom are increased. Alternative stragegies are examined in the light of recent theoretical results and computational experience.     

Keywords in communications technology

New communications products are often described by their manufacturers using a variety of confusing keywords, such as teletex, videotex, network integration etc. The manufacturers do not, however, explain the relationships between these terms, or the concepts that they share. The paper discusses these keywords with respect to the ISO reference model for open systems interconnection, and their relative positions within this structure. It discusses, in detail; transmission, switching, internetworking, network integration, local area networks and integrated service digital networks. Keywords relating to applications such as office automation and text processing are more clearly interrelated, and future end systems are proposed.     

Integrated ambient ozone evaluation by passive samplers and clover biomonitoring mini-stations

An ozone monitoring network was set up using passive samplers and biological mini-stations of two clones of white clover (Trifolium repens L. cv. Regal), NC-R (O(3)-resistant) and NC-S (O(3)-sensitive). This paper reports on a pilot study performed in the period June-October 1999 in the Rome municipal area by using five biomonitoring mini-stations and ozone passive samplers with a new nitrite based design. This combined methodology can be used to obtain information on the biological implications of the injury due to tropospheric ozone. The two techniques can integrate data for the short-medium period and can be placed in different urban and rural sites, proving to be a very useful tool for ozone concentration mapping.     

Assessment of the cost and accuracy of the generalized FEM

In this paper, we address the cost versus accuracy capabilities for the generalized FEM (GFEM) which was developed in (Comput. Methods Appl. Mech. Eng. 2003; 192 :3109–3161, Int. J. Numer. Meth. Engng 2004; 60 :1639–1672, Ph.D. Thesis, Texas A&M University, College Station, TX, August 2003 (Advisor: T. Strouboulis)), and also the construction of two‐sided a posteriori error estimates, which can be used to assess the achieved accuracy at all levels of the method. Copyright © 2006 John Wiley & Sons, Ltd.     

Ultra‐precision Surface Finishing by Ion Beam Techniques

Ion beam etching based ultra precision surface finishing is a versatile technology with a high degree of predictability due to the high stability of state of the art ion sources and the acquired knowledge of the physics of beam surface interaction. The independent control of the ion energy and the ion current density over wide ranges and the possible additional use of chemical reactive species in combination with physical sputter removal allow solving tasks in a wide variety of applications. The paper summarizes the present status of more than 20 years of development of ion beam finishing technology in IOM. It gives an overview on the equipment and the components developed for production purposes and on the ion beam technologies developed to achieve nanometer and sub‐nanometer depth accuracies over the entire spectrum of spatial surface wavelength from the full aperture size down to the microroughness level of only micrometer lateral feature size. Results of the finishing of high‐end optical surfaces shown demonstrate the outstanding performances of the techniques with topography and roughness control on the atomic scale.     

Microwave dewaxing applied to the investment casting process

Autoclave processing is commonly used nowadays for dewaxing in the investment casting process. However, since the use of microwave is steadily growing in industrial processes and the wax interacts with the electromagnetic energy of the microwaves, the present work studies the possibility of carrying out dewaxing via microwave. The wax (mineral wax, vegetable resin, low molecular-weight polymer and anti-oxidant) used in this work was prepared by melting in an oven equipped with a mineral oil bath. The chemical and structural stability of the wax were monitored throughout 12 simulated dewaxing cycles, via various analyses, namely, volumetric expansion, hardness, Fourier transform infrared spectroscopy, ultraviolet–visible spectrophotometry, differential scanning calorimetry and viscosity. The results showed that microwave dewaxing is viable, significantly decreasing the incorporation of dirt and water, which is inevitable in the autoclave dewaxing process.     

The dissolution of activated titanium slag in dilute sulfuric acid

Finely ground titanium slag (–400 mesh) dissolves slowly in dilute H₂SO₄ (2–10 mol/L) in the temperature range 70–110°C, but attrition ground slag dissolves much faster under similar conditions. The process is strongly dependent on the speed of agitation in the region 345–1035 rpm, and has an activation energy of 28 kJ/mole TiO₂, thus suggesting that the dissolution is controlled by diffusion through the boundary layer.