Recovering metals from hydrometallurgical residues

Experimental results and a method for recovering Cu, Zn, Cd, and Co from a solid hydrometallurgical residue are presented. A series of leaching, oxidation, and solvent extraction stages are the keys to the process.     

A Numerical Study on Large-Time Asymptotics of the Lifshitz–Slyozov System

We numerically investigate the long time behavior of solutions of the Lifshitz–Slyozov system. We propose a numerical scheme in which the numerical dissipation is controlled in such a way that the results for large time are meaningful. In this respect, we find the long time behavior to crucially depend on the distribution of largest aggregates present in the solution. This fact proved, in some particular cases in (23), was difficult to obtain with previous numerical schemes in the engineering literature leading to wrong statements. We propose a numerical scheme in which we can observe and quantify the equilibration rates towards the right asymptotic profile. Moreover, this system appears to be a very interesting test problem for any anti dissipative scheme for conservation laws.     

A Framework for the Automation of LTE Physical Layer Tests

This study proposes an uncooperative-multi-cell-multiple-input–multiple-output system to increase the throughput of an ill-conditioned wireless MIMO downlink system. The proposed algorithm suppresses the inter-cell interference at each mobile station using a set of adaptive receive beamformers, but handles the intra-cell interference at each base station using a Tomlinson Harashima precoder. Using the singular vectors of channel matrices, the receive beamformers can be designed based on a linear-constrained-minimum-variance criterion. On the other hand, to obtain high enough degree of freedoms for cancelling the intra-cell interference at each base station, the precoder is applied to the re-assembled downlink virtual channel formed by the simplified channel state information. Using the proposed interference suppression techniques, a multi-cell downlink system with multiple uncooperative base stations can be decomposed into a set of parallel subchannels. The resulting system has better performance in channel capacity than conventional MIMO systems. Computer simulations support the validity of the proposed approach.     

Active primary mirror support for the 2.1-m telescope at the San Pedro Mártir Observatory

We have designed and installed a new set of actuators for the suspension of the primary mirror of the 2.1-m telescope at San Pedro Mártir. This active optics system has allowed us to correct low-order aberrations identified by several wave-front analysis techniques.     

Velocity Regulation in Pmsms Using Standard Field Oriented Control Plus Adaptation

In this paper we present a control scheme for permanent magnet synchronous motors which is proven to be stable and globally convergent to the constant desired velocity. Our controller only differs from standard field oriented control by some simple adaptive terms and performance achieved by both controllers is almost identical. Thus, the main contribution of the present paper is to introduce a formal stability proof which is the closest, to date, to explaining why standard field oriented control of permanent magnet synchronous motors works well in practice providing explicit tuning guidelines. We stress that a global stability proof for standard field oriented control of permanent magnet synchronous motors has not existed until now, which makes the importance of our contribution remarkable.     

Solid-state synthesis of LnOCl/Ln2O3 (Ln = Eu,Nd) by using chitosan and PS-co-P4VP as polymeric supports

A series of lanthanide materials of type LnOCl or Ln_2 O_3(Ln = Eu, Nd) were successfully prepared via a convenient and straightforward two-step procedure. Firstly, and by using chitosan and PS-co-P4 VP as polymeric supports, macromolecular complexes of type chitosan ·LnCl_3 and PS-co-P4 VP·LnCl3 were prepared. These macro molecular complexes were treated in solid state at 800 ℃ under air, leading to the corresponding LnOCl or Ln_2 O_3 materials(Ln = Eu, Nd) with moderate to good yields. The nature of the asprepared lanthanide materials(LnOCl and/or Ln_2 O_3) is strongly influenced by the polymeric template(i.e.,chitosan or PS-co-P4 VP), the lanthanide salt precursor, and the polymer/lanthanide molar ratio. Thus, when chitosan · EuCl_3 and PS-co-P4 VP·EuCl_3 are used as macromolecular precursors, a mixture of crystalline phases of both EuOCl and Eu_2 O_3 are obtained. However, when chitosan· NdCl_3 and PS-co-P4 VP· NdCl_3 are used, a sole pure crystalline phase of NdOCl is obtained. The nano structured lanthanide materials were characterized by means of XRD(X-ray diffraction of powder), SEM, EDS, TEM, and HRTEM. The luminescent spectra of the asprepared EuOCI/Eu_2 O_3 mixture materials show an emission pattern whose intensity is strongly influenced by the nature of the polymeric precursor, as well as on the metal/polymer molar ratios.     

Comparing effects of α‐ vs. β‐chitosan coating and emulsion coatings on egg quality during room temperature storage

Effects of α‐ and β‐chitosan (CH), soybean oil (SO) and their emulsions (CH:SO = 2:3) as coating materials on selected internal quality and sensory properties of eggs were evaluated during 5 weeks storage at 25 °C. After 3 weeks of storage, α‐ and β‐CH‐coated eggs changed to B grade, while SO‐ and emulsion‐coated eggs preserved grade A quality. Weight loss of eggs coated with SO and CH:SO emulsions was <2.0% vs. 5.3–5.8% for noncoated and CH‐coated eggs after 5 weeks of storage. β‐CH (0.9%) maintained lower weight loss of eggs than α‐CH (1.2%) only at 1‐week storage. Albumen pH of eggs coated with SO and CH:SO emulsions decreased progressively throughout storage. Eggs coated with β‐CH:SO emulsion and SO were significantly glossier than noncoated eggs. Consumers indicated positive purchase intent (69.17–76.67%) for all coated eggs. Overall, α‐CH:SO and β‐CH:SO emulsions extended egg shelf life by at least 3 weeks during room temperature storage.     

Effect of different compatibilizers on environmentally friendly composites from poly(lactic acid) and diatomaceous earth

Environmentally friendly composites from poly(lactic acid) (PLA) and diatomaceous earth (DE) were successfully manufactured by extrusion, followed by injection moulding. DE was used as a filler; several compatibilizer/coupling agents, namely (3‐glycidyloxypropyl)trimethoxysilane, epoxy styrene acrylic oligomer and maleinized linseed oil, were used to improve polymer–filler interactions. Mechanical characterization was carried out by standard tensile, impact and hardness tests while morphological characterization of the fractured surfaces was conducted by field emission scanning electron microscopy. The effect of DE was evaluated by differential scanning calorimetry and dynamic mechanical thermal behaviour. The results show that the addition of DE provides an improved tensile modulus and induces more brittle composites due to stress concentration phenomena. The addition of compatibilizers in PLA‐DE positively contributes to improve ductile properties, thus leading to high environmental efficiency materials with balanced mechanical properties. Specifically, the compatibility improvement between the PLA and DE was good with maleinized linseed oil and contributed to improving the impact strength, which is a key factor in PLA‐based composites due to the intrinsic brittleness of neat PLA. © 2019 Society of Chemical Industry     

Projects with sequential iteration: Models and complexity

Many New Product Development (NPD) projects are inherently complex, making effective management of the tasks, resources, and teams necessary to bring new products to market problematic. Frequently, managers of NPD projects are overwhelmed by complicating factors such as stochastic task times, ill-defined specifications, complex interrelationships between tasks, and information dependencies. Recently, an alternative project management tool called the Design Structure Matrix (DSM) that explicitly takes into account the iterative nature of NPD projects has been proposed. In this paper, we first introduce a mixed-integer linear programming formulation for the numerical DSM. Then, we analyze the numerical DSM and establish the complexity of this class of problems. Finally, numerical analysis of the DSM problem and heuristic approaches is presented that shows that relatively good solutions can be easily obtained, thereby offering managers an efficient alternative solution approach to the original DSM problem.     

应对高级嵌入式处理器系统调试挑战

FPGA最大的优点在于其灵活性，可激发设计人员创造出无数不同的设计。然而，设计调试通常最后才加以考虑——如果还加以考虑的话，因此调试器通常要适应系统的要求。