Plasma Discharge Initiation of Explosives in Rock Blasting Application： A Case Study

A plasma discharge initiation system for the explosive volumetric combustion charge was designed, investigated and developed for practical application. Laboratory scale experiments were carried out before conducting the large scale field tests. The resultant explosions gave rise to less noise, insignificant seismic vibrations and good specific explosive consumption for rock blasting. Importantly, the technique was found to be safe and environmentally friendly.     

Features-based castability evaluation

A features-driven knowledge-based approach to the quantitative assessment of castings for ease of manufacture is presented. Geometric features such as undercuts, holes, sharp corners and hot spots are recognized from a solid model of the casting and analysed by a number of dimensionless criteria functions. The criteria have been developed through a detailed study of design heuristics used by practising engineers and are written as functions of geometric attributes of component and tool features. This is useful for identifying problem features in a casting at an early stage and for objective comparison of two or more design solutions for manufacturability. The proposed approach lends itself to computer implementation for automating the design of castings in a concurrent engineering environment.     

Globally asymptotically stable ‘PD+’ controller for robot manipulators

We describe a globally stable tracking controller for robot manipulators. The controller is an extension of Takegaki and Arimoto's position controller to the tracking case where a theorem of Matrosov is used to prove its stability. An attractive feature of this controller is its resemblance to the computed torque controller with the inertia matrix outside the position and velocity feedback loops. Thus, our controller is decomposed into an inner PD loop and an outer dynamic compensation loop. This structure allows the simple PD computations to be run at a higher speed than the dynamic compensation loop in digital implementations.     

ADIABATIC SORPTION OF BULK SINGLE ADSORBATE FROM AN INERT GAS-EFFECT OF GAS-SOLID MASS AND HEAT TRANSFER COEFFICIENTS

The effects of the gas-solid mass and heat transfer coefficients on the dynamics of adiabatic adsorption of a single adsorbate exhibiting Type I behavior were analyzed by numerically solving the conservation equations for a column. It was assumed that the adsorbate obeyed Langmuir equilibra and the local mass transfer rate could be described by the linear driving force model. The properties of the front zones were found to be controlled by mass transfer, while those of the rear zones were primarily determined by heat transfer. The separation between the two zones might vanish under certain conditions resulting in overlap of the two zones. The front zones were found to be constant pattern. The rear zones can be constant or proportionate pattern depending on the equilibrium properties and the feed condition of the adsorbate.     

ADAPTIVE SOLVER FOR THE p-VERSION OF FINITE ELEMENT METHOD

An adaptive solver for large-scale hierarchic finite element systems has been developed. A decision-making methodology aimed at selecting an optimal solution strategy on the basis of estimated conditioning, sparsity and memory requirements for a given problem has been devised. Numerical experiments have been conducted on selected shell and 3-D problems in the range of 1000–100 000 degrees of freedom. © 1997 by John Wiley & Sons, Ltd.     

Analytical simulation of rib-web forging

The friction calibration curves were generalized using ALPID simulations of ring compression tests and were used to establish the friction factor associated in the workpiece-tool interface. ALPID simulations were carried out for different rib-web sections. The metal flow characteristics were closely watched and load requirements for these processes were established. The distribution of effective strain and strain rate and stress were established.     

Luminescence performance of Eu<Superscript>3+</Superscript>-doped lead-free zinc phosphate glasses for red emission

In this study, the luminescence performance of zinc phosphate glasses containing Eu³⁺ ion with the chemical compositions (60–x)NH₄H₂PO₄-20ZnO-10BaF₂-10NaF–x Eu₂O₃ (where x = 0.2, 0.5, 1.0 and 1.5 mol%) has been studied. These glasses were characterized by several spectroscopic techniques at room temperature. All the glasses showed relatively broad fluorescence excitation and luminescence spectra. Luminescence spectra of these glasses exhibit characteristic emission of Eu³⁺ ion with an intense and most prominent red emission (614 nm), which is attributed to ⁵D₀ → ⁷F₂ transition. Judd-Ofelt (Ω₂, Ω₄) parameters have been evaluated from the luminescence intensity ratios of ⁵D₀ → ⁷F_J (where J = 2 and 4) to ⁵D₀ → ⁷F₁ transition. Using J-O parameters and excitation spectra, the radiative parameters are calculated for different Eu³⁺-doped glasses. Effect of γ-irradiation at fixed dose has been studied for all the Eu³⁺-doped glass matrices. The lifetimes of the excited level, ⁵D₀, have been measured experimentally through decay profiles. The colour chromaticity coordinates are calculated and represented in the chromaticity diagram for Eu³⁺-doped zinc phosphate glasses for all concentrations.