The solution algorithms for the multiprocessor scheduling with workspan criterion

In this paper, we consider multiprocessor scheduling problems, where each job (task) must be executed simultaneously by the specified number of processors, but the indices of the processors allotted to each job do not have to be contiguous (i.e., jobs can be fragmentable). Unlike other research in this domain, we analyse the problem under the workspan criterion, which is defined as the product of the maximum job completion time (makespan) and the number of used processors. Moreover, the job processing times can be described by non-increasing or non-decreasing functions dependent on the start times of jobs that model improvement (learning) or degradation (deteriorating), respectively. To solve the problems, we construct some polynomial time algorithms and analyse numerically their efficiency.     

Spectroscopic properties of Yb and Er ions in heavy metal glasses

Selected heavy metal glasses containing Yb³⁺ and Er³⁺ ions have been studied. Near-infrared luminescence spectra at 1.53 μm and up-conversion spectra of Er³⁺ ions were registered under excitation of Yb³⁺ ions by 975 nm diode laser line. The luminescence bands correspond to ⁴I_13/2-⁴I_15/2 (NIR), ⁴S_3/2-⁴I_15/2 (green) and ⁴F_9/2-⁴I_15/2 (red) transitions of Er³⁺, respectively. The optical transitions of rare earth ions have been examined as a function of glass host. The unusual large spectral linewidth nearly close to 110 nm for ⁴I_13/2-⁴I_15/2 transition of Er³⁺ ions in Yb-Er co-doped lead borate glass was obtained, whereas long-lived NIR luminescence at 1.53 μm was detected in lead germanate glass. The NIR luminescence and up-conversion phenomena strongly depend on stretching vibrations of glass host, which was confirmed by FT-IR spectroscopy.     

Enhanced and Long‐Lived Near‐Infrared Luminescence of Er3+ Ions in Lead Borate Glass‐Ceramics Containing PbWO4 Nanocrystals

Lead tungstate PbWO₄ nanocrystals in transparent lead borate glass‐ceramics containing Er³⁺ ions were fabricated. Luminescence spectra at about 1530 nm due to main ⁴I_13/2–⁴I_15/2 laser transition of Er³⁺ ions were examined for glass samples before and after heat treatment. Near‐infrared luminescence of Er³⁺ ions in glass‐ceramics is enhanced and long‐lived in comparison to precursor glasses. It suggests that the Er³⁺ ions are partially incorporated into PbWO₄ crystalline phase.     

Dyes based on the 6,7‐dichloro‐5,8‐quinolinedione skeleton as new type II photoinitiators for radical polymerisation

Several dyes based on the 6,7‐dichloro‐5,8‐quinolinedione skeleton have been synthesised and characterised by proton nuclear magnetic resonance spectroscopy and electron ionisation mass spectrometry. The spectroscopic and electrochemical properties of these dyes were investigated. Photoredox pairs consisting of the synthesised dyes and commercially available hydrogen donors (2‐mercaptobenzoxazole, 2‐mercaptobenzothiazole, 2‐mercaptobenzimidazole, and 2,5‐dimercapto‐1,3,4‐thiadiazole) were tested for use as effective initiator systems for radical polymerisation of trimethylolpropane triacrylate with visible light. The efficiencies of these initiator systems are discussed in terms of the free energy change for the electron transfer process from the dye to the hydrogen donor.     

Reaction sintering of dense gadolinium-iron garnet (GdIG) material

Two synthesis methods of gadolinium-iron garnet (GdIG) materials were described. The first one was a typical co-precipitation-calcination method (CP method). In the second one gadolinium-iron perovskite (GdIP, GdFeO3) and iron oxide (α-Fe2O3) were mixed in proper amounts for GdIG stoichiometry (RS method). DSC data for precursor powder mixtures obtained from both synthesis routes allowed to examine heat effects. In the case of the CP method, two crucial reactions were observed. The first one at ab. 767 °C was associated with the formation of GdIP phase, whereas the second one at ab. 1080 °C was attributed to GdIG formation. For the RS method, only formation of GdIG at 1122 °C was observed. Both powder mixtures were sintered at 1200, 1300, and 1400 °C for 2 h. For the CP method, the highest density was below 90 % even at 1400 °C whereas for the RS method the density of materials sintered at the same temperature exceeded 97 %.     

Storage of hydrogen,natural gas,and carbon dioxide – Geological and legal conditions

The analysis of geological and reservoir conditions of the underground storage of hydrogen, methane, and carbon dioxide, that are important when choosing rock formations for the storage of gas, was presented. Physico-chemical properties of the discussed gases, affecting underground storage, were taken into account. Aquifers, hydrocarbon reservoirs, and caverns leached in salt rocks were analyzed. Legal aspects of underground gas storage were indicated.The physico-chemical conditions of the gases considered (especially molecular mass, and dynamic viscosity) are important for the selection of geological structures for their storage. The reservoir tightness is one of the most important geological and reservoir conditions when taking the appropriate porosity and permeability of rocks building underground storage sites into account. Salt caverns should be mainly used for hydrogen storage due to the tightness of rock salt. Geochemical and microbiological interactions affecting the operation of the underground storage site and its tightness are especially important and should be taken into account. The size of the underground storage site, while not as crucial in the case of H₂ storage, is important for CO₂ storage. When it comes to reservoir conditions, the amount of cushion gas and storage efficiency are important. The legal status of gas storage sites is highly variable. While there are existing regulations regarding natural gas storage, CO₂ storage requires further legislation. In the case of H₂ storage legal regulations need to be developed based on the experience of storage of other gases. The potential competition from other entities focused on the use of underground space for gas storage should be taken into account.     

Screening and ranking framework for underground hydrogen storage site selection in Poland

This paper proposes the use of the Analytic Hierarchy Process (AHP) in order to select the potential underground hydrogen storage sites. The preliminary selection and evaluation of hydrogen storage sites may be considered as a multi-criteria decision-making process. The use of a decision model based on 5 (for aquifers) or 6 geological criteria (in the case of salt and hydrocarbon deposits) has been proposed. A ranking of salt structures, aquifers, and crude oil and natural gas reservoirs, previously identified as the potential hydrogen storage sites in Poland, has been presented. The obtained results have confirmed that the AHP-based approach can be useful for preliminary selection of potential underground hydrogen storage sites. The proposed method enables one to objectively choose the most satisfactory decision, from the point of view of the adopted decision-making criteria, regarding the choice of the best structure.     

Excess-methane dry and oxidative reforming on Ni-containing hydrotalcite-derived catalysts for biogas upgrading into synthesis gas

The activity of Ni-containing hydrotalcite-derived catalysts was assayed in the excess-methane dry reforming of different CH₄-CO₂ mixtures, aiming to simulate biogas upgrading to hydrogen and/or syngas. These catalysts yielded methane conversions quite far away from the thermodynamically predicted values, pointing to the inhibition of important methane consuming reactions, such as direct methane decomposition (DMD). Adding oxygen to the gas mixture (12.5%) results in increased methane conversions. Almost constant H₂/CO ratios, around 1.5, were measured at any temperature (600–850 °C). However, solid carbon formation was found to take place to a higher extent. The intrinsic properties of the hydrotalcite-derived catalysts tested results in favored reverse water gas shift reaction, leading to CO₂ and H₂ conversion.     

Silphium L. extracts – composition and protective effect on fatty acids content in sunflower oil subjected to heating and storage

The influence of ethanol and hexane extracts from leaves, inflorescences, and rhizomes of Silphium perfoliatum, Silphium trifoliatum, Silphium integrifolium on fatty acid content changes in sunflower oil subjected to heating and storage was studied in comparison to the synthetic antioxidant – butylated hydroxyanisole (BHA). A positive effect of extracts made of above-ground and underground organs of Silphium on the durable quantitative composition of fatty acids was proven. Tested extracts elevated the value of change inhibition with reference to linoleic acid to a level comparable with BHA, and sometimes, in appropriate systems, they were characterized by better values (for oil stored for 180 days at room temperature, the inhibition coefficient for linoleic acid changes reached 4.6% for 0.04% BHA, and 7.09% for hexane extract made of S. trifoliatum inflorescences, 400 μl/2 g; for oil heated for 120 h, the inhibition coefficient of linoleic acid changes amounted to 11.32% for 0.06% BHA, and 15.69% for hexane extract made of S. perfoliatum rhizomes, 600 μl/2 g). It was found that active substances groups such as phenolic acids, flavonoids and terpenes were present in tested extracts.