A study on time schemes for DRBEM analysis of elastic impact wave

 The precise integration and differential quadrature methods are two new unconditionally stable numerical schemes to approximate time derivative with more than the second order accuracy. Recent studies showed that compared with the Houbolt and Newmark methods, they produced more accurate solutions with large time step for the problems where response is primarily dominated by low and intermediate frequency modes. This paper aims to investigate these time schemes in the context of the dual reciprocity BEM (DRBEM) formulation of various shock-excited scalar elastic wave problems, where high modes have important affect on traction response. The Houbolt method was widely recommended in many literatures for such DRBEM dynamic formulations. However, this study found that the damped Newmark algorithm was the most efficient and accurate for impact traction analysis in conjunction with the DRBEM. The precise integration and differential quadrature methods are shown inapplicable for such shock-excited problems due to the absence of numerical damping. On the other hand, we also found that to achieve the same order of accuracy, the differential quadrature method required much less computing effort than the precise integration method due to the use of the Bartels–Stewart algorithm solving the resulting Lyapunov matrix analogization equation. Received 6 November 2000     

The ponding problem on elastic membranes: an analog equation solution

 In this paper, the nonlinear response of elastic membranes with arbitrary shape under partial and full ponding loads has been analyzed. Large deflections are considered, which result from nonlinear kinematic relations. The problem is formulated in terms of the displacements components and the three coupled nonlinear governing equations are solved using the analog equation method (AEM). The membrane may be prestressed either by prescribed boundary displacements or tractions. Using the concept of the analog equation the three coupled nonlinear equations are replaced by three uncoupled Poisson's equations with fictitious sources under the same boundary conditions. Subsequently, the fictitious sources are established using a procedure based on the BEM and the displacement components as well as the stress resultants at any point of the membrane are evaluated from their integral representations. In addition to the geometrical nonlinearity, the ponding problem is itself nonlinear, because the ponding load depends on the deflection surface that it produces. Iterative schemes are developed which converge to the equilibrium state of the membrane under the ponding loads. Several membranes are analyzed which illustrate the method and demonstrate its efficiency and accuracy. The method has all the advantages of the pure BEM, since the discretization and integration is limited only to the boundary. Received 28 July 2001     

CD Moisture Profile Disturbances in Tissue Production - Their Origins and possible Control

The origins of poor CD (cross machine) moisture profiles In tissue production are discussed generally. CD line force distribution at the first and second presser roll has a significant influence on the CD moisture profile. The crowning of cylinder and presser rolls compensates for the deformation of the Yankee cylinder shell (due to nip load, internal steam pressure and hood operating conditions) and of the presser rolls but only for any one given operating condition. However, during operation the parameters often have to be varied. in a sensitivity analysis the resulting CD line force deviations were calculated and typical figures are given here to demonstrate the relative effect. The shape of the resulting line load curves are drawn and from these the typical shape of the resulting CD moisture- profile can be derived. Means for possible control such as controllable presser rolls, sectionally adjustable hoods and steam boxes as well as eddy current and infra-red -heating are discussed and evaluated.     

Electroplating of nickel-cadmium alloys from alkaline solutions

The electroplating of Ni-Cd alloy coatings was carried out from alkaline baths (pH 10). For comparison, electroplating of the parent metals, Ni and Cd, was performed individually under the same conditions. The cathodic current efficiency for codeposition was high and decreased with increasing current density. The codeposition process is an anomalous type of plating with Cd being the preferentially deposited metal. The Ni content in the deposits increased with increasing current density. This increase in Ni content improves the corrosion resistance and microhardness of the deposits. X-ray diffraction analysis showed that the deposits consist of a mixture of Ni, β, γ, γ¹ phases.     

Procedure employed in SSTF USSR for calculating the earth's rotational parameters

Translated from Izmeritel'naya Tekhnika, No. 4, pp. 38–39, April, 1989.     

Flying solo and solar to Mars

This paper describes the work done by the Autonomous Systems Lab of Ecole Polytechnique Federale de Lausanne (EPFL) on the global design of an unmanned solar airplane that can fly continuously over days and night. Part of the Sky-Sailor Project, a first prototype was designed and demonstrated to have very good flight characteristics. The prototype achieved an autonomous flight of five hours with its energy only from the sun. A lightweight control and navigation system was also designed for the aircraft.     

Amplification of c-myc proto-oncogene in primary tumors, metastases and blood leukocytes of patients with ovarian cancer

The structure of DNA sequences homologous to the viral myc oncogene from ovarian tumours, intact tissues and the same patients peripheral blood leukocytes has been studied. The Southern blot analysis of malignant tumour DNA reveals amplification of c-myc protooncogene of 3 from 11 patients. Metastases DNAs of two from those patients also contain multiple copies of c-myc. No myc gene amplification has been detected in 6 examined benign ovarian tumours. The presence of extra copies of myc-related sequences has been shown in two from three DNA samples from peripheral blood leukocytes of patients with ovarian cancer.