LP-based disaggregation approaches to solving the open pit mining production scheduling problem with block processing selectivity

Given a discretisation of an orebody as a block model, the open pit mining production scheduling problem (OPMPSP) consists of finding the sequence in which the blocks should be removed from the pit, over the lifetime of the mine, such that the net present value (NPV) of the operation is maximised. In practice, due to the large number of blocks and precedence constraints linking them, blocks are typically aggregated to form larger scheduling units. We aim to solve the OPMPSP, formulated as a mixed integer programme (MIP), so that aggregates are used to schedule the mining process, while individual blocks are used for processing decisions. We propose an iterative disaggregation method that refines the aggregates (with respect to processing) up to the point where the refined aggregates defined for processing produce the same optimal solution for the linear programming (LP) relaxation of the MIP as the optimal solution of the LP relaxation with individual block processing. We propose several strategies of creating refined aggregates for the MIP processing, using duality results and exploiting the problem structure. These refined aggregates allow the solution of very large problems in reasonable time with very high solution quality in terms of NPV.     

Scheduling of hard real-time multi-phase multi-thread (MPMT) periodic tasks

In this paper we study the scheduling of parallel and real-time recurrent tasks on multiprocessor platforms. Firstly, we propose a new parallel task model which allows recurrent tasks to be composed of several phases, each one composed of several threads. Each thread requires a single processor for execution and can be scheduled simultaneously. We then propose an algorithm to transpose popular Fork-Join task model to our MPMT task model. Secondly, we define several kinds of real-time schedulers that can be applied to our parallel task model. We distinguish between two scheduling classes: Hierarchical schedulers and Global Thread schedulers. We present and prove correct an exact schedulability test for each class. Lastly, we also evaluate the performance of our scheduling paradigm in comparison with Gang scheduling by means of simulations. In this work we extend the work of Lupu and Goossens in Scheduling of hard real-time multi-thread periodic tasks (Real-Time and Network Systems, 2011) which considers mono-phase multi-thread task model. We extend their previous results to a Multi-Phase Multi-Thread task model.     

Cr-doped II–VI materials for lasers and nonlinear optics

The paper reviews material, spectroscopic, laser and nonlinear optical properties of wide-band Cr²⁺-doped II–VI materials. The strong revival of research interest in these materials is explained by the announcement of the extremely efficient (up to >70% slope efficiency) laser operation at room-temperature. With up to 11 W of average output power, one can achieve super broad tunability (up to 1100 nm between 2 and 3.1 μm) in narrow-line continuous-wave operation and 4 ps pulses at 400 mW in mode-locked regime. Directly diode-pumping and lasers based on ceramic active media have been demonstrated, allowing development of cost-efficient compact tunable and mode-locked lasers, with a possibility to generate few-optical cycle pulses. In this wavelength range the Cr²⁺-doped lasers proved to be viable competitors to the conventional semiconductor lasers or more complex laser systems, based on frequency conversion techniques in such applications as medicine, trace gas monitoring, remote sensing, spectroscopy, metrology, optical radars, optical communications, and all-optical switching. In contrast to conventional dielectric laser materials the Cr²⁺-doped II–VI compounds combine properties of semiconductors with that of the traditionally used dielectric active media. The semiconductor nature determines strong nonlinear optical response of these materials, giving rise to charge transport and photorefractive-like phenomena, harmonic generation and parametric processes, and self-focusing effects of various origins. This calls for a considerable modification of the mode-locking techniques and reconsideration of the existing theories, which should finally enable generation of few-optical cycle pulses directly from the laser oscillator in the mid-infrared. In this connection a number of important new aspects are being discussed, such as contribution of cascaded second-order nonlinearity and Raman processes to the third-order nonlinearity, its dispersion and anisotropy, and others.     

VOC emission reduction and energy efficiency in the flexible packaging printing processes: analysis and implementation

Volatile organic compound (VOC) emissions into the atmosphere are among the primary environmental problems caused by flexible packaging printing plants. Since 1999, VOC emissions from the use of solvents in various technological processes have been limited by the volatile organic compounds solvents emissions directive, and by directive 2010/75/EU on industrial emissions since 2010. Thus, flexible packaging plants require processing technologies or other solutions to ensure compliance with these requirements. In this paper, combined VOC pollution prevention and treatment alternatives were suggested and were evaluated for their technical, environmental, and economic feasibility. A flexible plastic packaging company that produces over 1920 t/year of plastic packaging for the food industry was selected for detailed analysis. The material and energy flow analysis shows that VOC emissions from the main technological processes reached 112.2 kg/t of production, and a considerable amount of energy (up to 771.6 kWh/t of production) was used. Three integrated pollution prevention and control (IPPC) alternatives of the five analysed in this study were selected and implemented within the company to reduce its VOC emissions and energy consumption. The results indicate that after the implementation of the three suggested economically reasonable IPPC alternatives (replacement of solvent-based with water-based inks; modernisation of the ventilation and lighting system), the VOC emissions decreased to 8.4 kg/t (92.5%) and the total energy consumption for the production of 1 t of flexible packaging decreased to 605.6 kWh/t (21.5%). This study shows that IPPC methods not only significantly reduces VOC emissions from flexible packaging printing processes, but also saves energy and raw materials, and reduces costs.     

Bilateral Comparison of Spectral Irradiance Between NIM and VNIIOFI from 250 to 2500 nm

With the new spectral irradiance measurement facility based on blackbody BB3500M of National Institute of Metrology (NIM), a bilateral spectral irradiance comparison was carried out between NIM and VNIIOFI (All Russian Research Institute for Optical and Physical Measurements) in the spectral wavelength from 250 to 2500 nm for the period of January 2015 to June 2016. The temperature measurement of the high temperature blackbodies were traced to the Pt–C and Re–C fixed point blackbodies and checked against the WC–C fixed-point blackbody for the two institutes respectively. The consistency of the temperature at 3021 K is better than 70 mK. The comparison result shows that the average relative deviation of spectral irradiance at 44 designated wavelengths is 0.45%. The consistency is better than 0.9% except the maximum deviation 1.1% at the wavelength of 2000 nm. The spectral irradiance units measured by NIM and VNIIOFI in this comparison are in agreement within the combined standard uncertainties of the laboratories over the wavelength range compared.     

Orientation-controlled,low-temperature plasma growth and applications of h-BN nanosheets

Nano Research - Dimensionality and orientation of hexagonal boron nitride (h-BN) nanosheets are promising to create and control their unique properties for diverse applications. However,...     

Zeitoptimaler Mastaufbau einer mobilen Autobetonpumpe unter Nebenbedingungen

Mobile truck-mounted concrete pumps are designed to transport concrete over long distances efficiently and are therefore often deployed on construction sites. Currently, a worker manually controls the unfold procedure of these large scale manipulators using a sequential strategy because of the raising boom complexity and large safety margins. Due to the narrow space on construction sites, some trucks only allow the operator to use partial outrigger configurations. Hereby, to provide static stability the operator has to follow fixed and slow unfold sequences. The manual control and the fixed unfold sequences cause the unfold procedure currently to take approximately \(39\,\%\) of the whole start-up phase. This paper utilizes a model predictive control approach to realize an automated and time-optimal unfold procedure that satisfies constraints regarding self-collisions, static stability and oil volume flow restrictions. The model predictive controller is verified, and theoretical saving potentials regarding the unfold time are presented in an analysis consisting of simulated time-optimal unfold procedures for several goal configurations.     

A branch-and-bound algorithm for the cell formation problem

The Cell Formation Problem (CFP) is an important optimisation problem in manufacturing. It has been introduced in the Group Technology (GT) and its goal is to group machines and parts processed on them into production cells minimising the movement of parts to other cells for processing and maximising for each cell the loading of its machines with operations on its parts. We consider one of the computationally hardest formulations of this problem – the CFP with a variable number of cells and the grouping efficacy objective, which is a fractional function. The CFP literature contains many heuristic algorithms, but only a small number of exact approaches especially for this formulation. In the current paper, we present an exact branch-and-bound algorithm for the same hard CFP formulation. To linearise the fractional objective function, we apply the Dinkelbach approach. We have been able to solve 24 of the 35 instances from the well known GT benchmark. For the remaining 11 instances, the difference in the grouping efficacy with the best known solutions is less than 2.6%.     

A new universal approximation result for fuzzy systems,which reflects CNF DNF duality

There are two main fuzzy system methodologies for translating expert rules into a logical formula: In Mamdani's methodology, we get a DNF formula (disjunction of conjunctions), and in a methodology which uses logical implications, we get, in effect, a CNF formula (conjunction of disjunctions). For both methodologies, universal approximation results have been proven which produce, for each approximated function f(x), two different approximating relations R_DNF(x, y) and R_CNF(x, y). Since, in fuzzy logic, there is a known relation F_CNF(x) ≤ F_DNF(x) between CNF and DNF forms of a propositional formula F, it is reasonable to expect that we would be able to prove the existence of approximations for which a similar relation R_CNF(x, y) ≤ R_DNF(x, y) holds. Such existence is proved in our paper. © 2002 Wiley Periodicals, Inc.     

Flame retardancy afforded by polyaniline deposited on wood

Wood scantlings were coated with polyaniline (PANI) during the in situ polymerization of aniline with ammonium peroxydisulfate in an aqueous medium. The coating was made in hydrochloric or phosphoric acid solutions in both the absence and presence of stabilizers, poly(N‐vinylpyrrolidone) or colloidal silica. The PANI‐coated wood was placed in a flame or in a furnace operating at 400 or 600°C, and the decrease in the mass was determined. The wood coated with PANI was less reduced in its mass than uncoated samples and was converted to charcoal rather than to ashes. The deposition of related polymers, polypyrrole and poly(1,4‐phenylenediamine), provided similar protection against heat exposure. Fourier transform infrared and Raman spectra of the residues after the burning of PANI‐coated wood were compared. The soaking of wood in PANI colloids did not result in similar protection of wood against fire; the coating of the cellulose fibers with PANI during the polymerization was needed for the enhanced stability of wood at elevated temperatures. The concept of carbonization processes at the surface layer of PANI‐coated cellulose fibers leading to the formation of carbonaceous microtubes is offered to explain the improved stability of wood against flame and heat exposure. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 103: 24–30, 2007