Combined hydrometallurgy—flotation scheme for Waelz clinker processing

Waelz clinker is a waste from Waelz furnace in the processing of lead-zinc cakes, which contains valuable metals such copper and silver. The main purpose of this experimental work is to investigate applying a combined hydrometallurgical-flotation scheme for Waelz clinker processing in order to recover copper and silver. Obtained results were unexpected and unique. It turned out that it is possible to recover 90% from copper, and silver only by coke flotation with nonionic collector after iron removal from clinker.     

The effect of the expander upon the two types of negative active mass structure in lead-acid batteries

The active mass of the negative plate in the lead-acid battery is organized in a skeleton (primary) and energetic (secondary) structure. With the aid of electrochemical measurements and SEM observations the effect of the expander upon these structures is investigated both during their formation and during the cycling of the cell under service conditions. It is established, that in the absence of an expander, an active mass with dendritic secondary structure is formed, which ensures a relatively low capacity of the plates. In active masses containing an expander no dendrites are formed. The expander enhances the formation of a secondary structure containing separate lead crystals deposited on the surface of the skeleton. The morphology and size of these crystals depend on the nature of the expander. Plates containing expander display a higher capacity and a longer life. The effect of the expander upon the primary structure is clearly revealed during the service life of the battery under deep charge-discharge cycling conditions. Plates with no expander show a contraction of the skeleton and the active mass becomes more compact. A reverse effect is observed in the presence of a highly efficient expander, the skeleton structure becomes more loose and the plates become thicker. This is evidence that the skeleton partially participates in the cycling process and that its branches are oxidized, being formed again later at a different site, thus changing the density of the skeleton structure. This process is affected by the expander. It is also established that the skeleton structure of the active mass is built either from compact, shapeless, interconnected crystals, or linked agglomerates of scale-form lead crystals.     

Forward Dynamics of Open-Loop Multibody Mechanisms Using an Efficient Recursive Algorithm Based on Canonical Momenta

A new method for establishing the equations of motion of multibodymechanisms based on canonical momenta is introduced in this paper.In absence of constraints, the proposed forward dynamicsformulation results in a Hamiltonian set of 2n first order ODEsin the generalized coordinates q and the canonical momenta p.These Hamiltonian equations are derived from a recursiveNewton–Euler formulation. As an example, it is shown how, in thecase of a serial structure with rotational joints, an O(n)formulation is obtained. The amount of arithmetical operations isconsiderably less than acceleration based O(n) formulations.     

Magnetic field sensor based on compensated silicon

The phenomenon of negative magnetoresistance in compensated silicon doped with manganese has been studied. The possibility of using this effect in magnetic field sensors is assessed.     

GRADIENT-DESCENT BASED UNIT-SELECTION OPTIMIZATION ALGORITHM USED FOR CORPUS-BASED TEXT-TO-SPEECH SYNTHESIS

This paper proposes a gradient-descent based unit selection optimization algorithm for the optimization of unit-cost function weights and for improving the overall performance of the unit-selection algorithm, as used in a corpus-based text-to-speech synthesis system. Complex multidimensional and fuzzy-logic based unit-cost functions are used in the presented unit-selection algorithm. The weights used by these unit-cost functions are usually defined by heuristics or by listening tests. This can be very laborious and time consuming, and does not necessarily result in an optimal performance of the unit-selection algorithm because of multidimensional unit-cost function space, within which different database candidates’ features are evaluated. Using heuristics or listening tests is also rather rigid, especially when working with several different databases or voices. It is especially difficult, within this scope, to set up those weights used in unit-cost functions in order to achieve overall optimal performance of the unit-selection algorithm. The proposed unit-selection optimization process consists of several steps. It is fully automatic, flexible, and fast enough to enable the development of a corpus-based text-to-speech (TTS) system that uses many different voices, without any heuristics or listening tests. This optimization process can also be helpful when evaluating the performances of unit-selection cost functions, and the performance of the unit-selection algorithm itself. The obtained results “suggest” those values that the unit-selection cost-function weights should have in order to obtain smoother transitions between selected unit candidates, after the unit-selection process. The obtained results also hint at the performance level that can be achieved with a given set of unit-cost function weights, and suggest what improvements can be gained when using those additional or changed unit-cost functions included within the unit-selection algorithm.     

Fast numerical upscaling of heat equation for fibrous materials

We are interested in numerical methods for computing the effective heat conductivities of fibrous insulation materials, such as glass or mineral wool, characterized by low solid volume fractions and high contrasts, i.e., high ratios between the thermal conductivities of the fibers and the surrounding air. We consider a fast numerical method for solving some auxiliary cell problems appearing in this upscaling procedure. The auxiliary problems are boundary value problems of the steady-state heat equation in a representative elementary volume occupied by fibers and air. We make a simplification by replacing these problems with appropriate boundary value problems in the domain occupied by the fibers only. Finally, the obtained problems are further simplified by taking advantage of the slender shape of the fibers and assuming that they form a network. A discretization on the graph defined by the fibers is presented and error estimates are provided. The resulting algorithm is discussed and the accuracy and the performance of the method are illusrated on a number of numerical experiments.     

Demonstration-based learning and control for automatic grasping

We present a method for automatic grasp generation based on object shape primitives in a Programming by Demonstration framework. The system first recognizes the grasp performed by a demonstrator as well as the object it is applied on and then generates a suitable grasping strategy on the robot. We start by presenting how to model and learn grasps and map them to robot hands. We continue by performing dynamic simulation of the grasp execution with a focus on grasping objects whose pose is not perfectly known.