An iterated local search heuristic for multi-capacity bin packing and machine reassignment problems

This paper proposes an efficient Multi-Start Iterated Local Search for Packing Problems (MS-ILS-PPs) metaheuristic for Multi-Capacity Bin Packing Problems (MCBPP) and Machine Reassignment Problems (MRP). The MCBPP is a generalization of the classical bin-packing problem in which the machine (bin) capacity and task (item) sizes are given by multiple (resource) dimensions. The MRP is a challenging and novel optimization problem, aimed at maximizing the usage of available machines by reallocating tasks/processes among those machines in a cost-efficient manner, while fulfilling several capacity, conflict, and dependency-related constraints. The proposed MS-ILS-PP approach relies on simple neighborhoods as well as problem-tailored shaking procedures. We perform computational experiments on MRP benchmark instances containing between 100 and 50,000 processes. Near-optimum multi-resource allocation and scheduling solutions are obtained while meeting specified processing-time requirements (on the order of minutes). In particular, for 9/28 instances with more than 1000 processes, the gap between the solution value and a lower bound measure is smaller than 0.1%. Our optimization method is also applied to solve classical benchmark instances for the MCBPP, yielding the best known solutions and optimum ones in most cases. In addition, several upper bounds for non-solved problems were improved.     

Comparison of two soft chemistry routes for the synthesis of mesoporous carbon/β-SiC nanocomposites

We compare the influence of using either molecular or colloidal precursors on the synthesis of a ceramic material containing SiC and porous carbon. Remarkably, the temperature of synthesis for crystalline SiC is independent of the route chosen. The excess carbon in the initial mixture is the source of the excess porous carbon that binds to the crystalline domains of SiC in the final products. Interestingly, increasing the initial area of surface contact between carbon and silicon in the ceramic precursor results in different porosities in the ‘meso’ range. Simultaneous control of the size and the relative amounts of Si and C in the precursors allows control to be exerted over the nature and texture of the final powders. A simple and general mechanism is herein proposed to explain the evolution of the surface area as a function of the volume fraction of residual carbon in the synthesised ceramic.     

SOLIDS TRANSPORTATION MODEL OF AN INDUSTRIAL ROTARY DRYER

A complete simulation model has been developed for an industrial rotary dryer to account for the heat and mass exchange between the solids and the gas. This simulator is mainly composed of three models: solids transportation model, furnace model, and gas model. The solids transportation model is the modified Cholette-Cloutier model It consists of a series of interactive reservoirs which are subdivided into an active and a dead compartments to account for the characteristic extended tail of the residence time distribution (RTD) curves observed in industrial dryers.

To expand the validity of the model, experiments have been performed in an industrial rotary dryer to obtain RTD curves under different mineral concentrate and gas flow rates. This paper describes these experiments and presents the variation of the average residence time and model parameters as function of solids and gas flow rates.     

A fast pipelined multi-mode DES architecture operating in IP representation

The Data Encryption Standard (DES) is a cipher that is still used in a broad range of applications, from smartcards, where it is often implemented as a tamper-resistant embedded co-processor, to PCs, where it is implemented in software (for instance, to compute crypt(3) on UNIX platforms). To the authors’ knowledge, implementations of DES published so far are based on the straightforward application of the NIST standard. This article describes an innovative architecture that features a speed increase for both hardware and software implementations, compared to the state of the art. For example, the proposed architecture, at constant size, is about twice as fast as the state of the art for 3DES-CBC. The first contribution of this article is an hardware architecture that minimizes the computation time overhead caused by key and message loading. The second contribution is an optimal chaining of computations, typically required when “operation modes” are used. The optimization is made possible by a novel computation paradigm, called “IP representation”.     

Toxicogenomic analysis of susceptibility to inhaled urban particulate matter in mice with chronic lung inflammation

Background  

Individuals with chronic lung disease are at increased risk of adverse health effects from airborne particulate matter. Characterization of underlying pollutant-phenotype interactions may require comprehensive strategies. Here, a toxicogenomic approach was used to investigate how inflammation modifies the pulmonary response to urban particulate matter.     

Investigation of optimal conditions for zinc electrowinning from aqueous sulfuric acid electrolytes

Results are reported of an experimental investigation of the effects of aqueous zinc(II) and sulfuric acid concentrations on current efficiencies and deposit morphologies of metallic zinc, aimed at designing a process for zinc recovery from solid industrial wastes by leaching and electrodeposition. Voltammetry and chronopotentiometry of additive-free solutions of zinc(II) sulfate and sulfuric acid were used to determine the zinc(II) reduction kinetics, prior to investigating the deposition in a Hull cell to observe the effects of the current density and the bath composition on current efficiencies and deposit morphologies. For a current density of 45 mA cm⁻², best performance was obtained with zinc(II) concentrations of the same order of magnitude as the H⁺ concentration; too acidic solutions resulted in lower current yields and pronounced 3-D growth of the deposit.