A new decentralized implicit adaptive regulator for large-scale systems described by discrete-time state-space mathematical models

In this paper, we treat the problem of decentralized implicit adaptive regulation for large-scale stochastic systems composed into a set of interconnected systems that are described by discrete-time state-space mathematical models with unknown parameters. The key idea in the decentralized regulation method is to design local regulator using only local information such that the state of each interconnected system is regulated to a certain constant reference signal. The main contribution is the proposition of a decentralized implicit adaptive regulator based on state-feedback strategy that can be applied to stochastic interconnected systems with unknown parameters. Furthermore, the practical implementation of the proposed decentralized implicit adaptive regulator can be made easily (low-cost implementation of the electronic components, short computation of the decentralized control law, etc.). A theorem is established and proved which gives sufficient stability conditions of the resulting closed-loop interconnected systems by using the Lyapunov method. An example of numerical simulation is treated to test the performance of the proposed decentralized implicit adaptive regulator.     

Tensile and water vapour properties of calcium‐crosslinked alginate‐cashew tree gum films

In this study, sodium alginate films were blended with cashew tree gum (CTG) and immersed in CaCl₂ solution. The influence of CTG concentration and immersion time in CaCl₂ on tensile properties, water vapour permeability and water solubility (WS) of alginate films was evaluated. Glycerol‐plasticized alginate/CTG films were cast on glass plates, which were then immersed in a 2% CaCl₂ solution to crosslink alginate. CTG concentration in the film solution and immersion time in CaCl₂ bath were varied according to a central composite design. Tensile strength, Young′s modulus, WS and water vapour barrier of the films were favoured by higher immersion times in CaCl₂ and lower CTG concentrations. The negative CTG effects on such properties have been attributed to competition between the polysaccharides for interactions with calcium ions, reducing crosslinking density and loosening the film structure. On the other hand, this loosening effect resulted in higher film flexibility at higher CTG concentrations.     

Assessment of the levels of chlorinated pesticides in breast milk in Kuwait

Breast milk samples, randomly collected from 32 Kuwaiti donors were analysed for chlorinated pesticides. DDE residues ranged from 127 to 3333 micrograms/kg, averaging, 833 micrograms/kg, expressed on a fat weight basis. DDT levels ranged from 0.6 to 67 micrograms/kg fat and averaged 12.4 micrograms/kg, fat. High DDE/DDT ratios were found, which indicated that the exposure to DDT, in most cases, happened quite some time ago. In addition many of the samples also contained isomers of HCH, heptachlor-epoxide, aldrin, dieldrin and endrin. Residue levels of non-DDT pesticides were generally low. Overall levels of DDT-pesticides in Kuwaiti milk samples were lower than levels reported from other Middle Eastern countries, although methodologies may not be directly comparable.     

Influence of processing on composition and antinutritional factors of chickpea protein concentrates produced by isoelectric precipitation and ultrafiltration

The effect of chickpea processing (i.e. defatting, isoelectric precipitation vs ultrafiltration/diafiltration) on the composition, protein recovery and antinutritional factors of protein concentrates was studied for two varieties (Mylese and Xena). Defatting did not affect significantly the content of antinutritional factors in the flours. However, production of concentrates from defatted flours by isoelectric precipitation resulted in higher phosphorous and phenolic contents compared to the concentrates produced by the same process using the full fat flours as starting material, while trypsin inhibitor content was not affected. When processed by ultrafiltration/diafiltration, protein concentrates produced from defatted flour showed a slightly lower trypsin inhibitor content than the ones produced from full fat flours in most cases, while the inverse was true for the phosphorous content, and for the phenolic content; this effect was a function of chickpea variety. Overall, UF pH 9/DF pH 6 resulted in concentrates with the lowest phosphorous content, while isoelectric precipitation and UF pH 9/DF pH 9 resulted in concentrates with lower phenolic content compared to the ones produced by UF pH 9/DF pH 6; for both processes the trypsin inhibitor content of the concentrates remained high.Industrial relevanceChickpea production is one of the major agricultural sectors of significant importance to Canada. Although chickpeas are grown in Canada for export, very little is exported in the value-added or processed form. Development of new extraction technologies and value-added products such as the ones presented in this paper is of interest for Canada since it would have a significant impact on the growth of the industry domestically, thus, creating opportunities to strengthen rural development in Canada. Successful implementation of these technologies would make interested Canadian companies viable competitors in the global plant protein production industry and would put Canada in a good position to enjoy a large share of this market both locally and internationally.More specifically, we are the first research group to compare the use of isoelectric precipitation and ultrafiltration/diafiltration for the production of chickpea protein concentrates from full fat and defatted flours of Kabuli and Desi chickpea variety, and to quantify the effect of these processes on the composition and on the antinutritional factors (i.e. phytic acid, total phenolics and trypsin inhibitors) of the resulting concentrates. Overall, it was observed that isoelectric precipitation was effective to an extent in producing concentrates with low phosphorous and phenolic contents. UF pH 9/DF pH 9 was also effective to an extent in producing concentrates with low phenolic content, while UF pH 9/DF pH 6 was more efficient in producing concentrates with low phosphorous content. High-quality chickpea protein concentrates with improved nutritional properties and good functional properties could beneficially be combined with other protein sources, such as soy protein, or be used in the formulation of foods, such as meat analogues, dairy, and bakery products.     

Improvement of electrical arc furnace operation with an appropriate model

Electrical arc furnaces are commonly employed in industry to produce molten steel by melting iron and scrap steel. Furnace control is a necessary operation for production optimization. The principal parameters to be controlled are: maximum productivity requirements, minimum power off time, good power quality and safety. The aim of this study is to achieve all these objectives. Hence, because of the stochastic and dynamic behaviour of the arc during the melting process, a proposed model is checked with measurements at an industrial electrical arc furnace. How electrodes position and transformer taps can affect X and R arc function are discussed in detail. This new operating strategy has been determined taking into account Flicker, melting stages and electrode positions. It is shown that optimum efficiency can be reached by the integration of the proposed model in regulation loop.     

Composition and antimicrobial activity of essential oils of Cinnamosma fragrans

Essential oil samples of Cinnamosma fragrans from two regions in Madagascar, Tsaramandroso (38 samples) and Mariarano (30 samples), were analysed by GC/MS. Fifty-seven components were identified, accounting from 88.3% to 99.4% of the oils’ composition. The major components were linalool (72.5 ± 23.3%) in Tsaramandroso and 1,8-cineole (47.3 ± 10.2%) in Mariarano.     

Low-index surface investigation of KAlH4: Theoretical attempt to study the surface effect on the hydrogen storage properties

Different preparations of complex hydrides lead to different hydrogen uptake and release. Besides, Potassium Aluminum hydride is a structure with different re/dehydrogenation properties than the rest of alanates. Given these considerations, we investigated nine stable cleavages on the (100), (010), (001), (111), and (101)KAlH₄ surfaces. The results reveal that, while the (010) surface energy is much higher, all the other surfaces are approximately in the same range of energy. Some of these surfaces would be placed on top of the nanocrystallites and the different decomposition pathways may be originated from the different characteristics of these surfaces, which is one of the central issues of the present study. Our results are in accordance with experimental data indicating that long hours milling of alanates just creates fresh surfaces and the structures remain unchanged. Due to the surface effect, huge changes in electronic and geometric characteristics occur. The band gaps are narrowed up to 2eV, which alongside with massive changes in chemical bonds, lead to an improved dehydrogenation relative to the bulk.     

Photostability,thermal and mechanical properties of poly(vinyl chloride)/novel acrylate terpolymer blend

Methyl methacrylate/2‐hydroxyethyl methacrylate/maleic anhydride terpolymer with various compositions was synthesized, characterized and investigated as a photostabilizer for rigid polyvinyl chloride (PVC). The chemical structure of the terpolymer MMA/HEMA/MA, was confirmed by ultraviolet–visible and FTIR, spectroscopy. The molecular weights of the terpolymer were determined by applying gel permeation chromatography. The stabilizing efficiency of the terpolymer was evaluated by the determination of the weight loss of PVC/terpolymer blends after various irradiation times. The content of the formed gel as well as the intrinsic viscosity of the soluble fraction of the photodegraded polymer were also determined. The efficiency was also evaluated by measuring the extent of the discoloration of the photodegraded polymer. Thermal gravimetric analysis of the terpolymer and PVC/terpolymer blend were measured. Moreover, physicomechanical properties of photodegraded stabilized PVC samples were as well measured. The results revealed that the photostabilizing efficiency as well as thermal stability increased in the presence of the terpolymer as blended with PVC and by the increase of maleic anhydride ratio in the terpolymer. The photostabilizing efficiencies were compared with the industrially known UV absorber 2‐hydroxy‐4‐(octyloxy) phenylbenzophenone. J. VINYL ADDIT. TECHNOL., 25:E55–E62, 2019. © 2018 Society of Plastics Engineers     

Urinary 2-ethyl-3-oxohexanoic acid as major metabolite of orally administered 2-ethylhexanoic acid in human

Human metabolism of 2-ethylhexanoic acid (2-EHA), which is a known metabolite of important phthalates, was investigated using 2-EHA-contaminated food. The results of our studies reveal that the major catabolic pathway of 2-EHA in human is beta-oxidation. The dominant final urinary metabolite was identified and quantified as 3-oxo-2-ethylhexanoic acid (3-oxo-2-EHA), but only after immediate methylation of the extract from urine and prior to GC-MS analysis. Former studies without the precaution of immediate methylation had found 4-heptanone as the major metabolite, which is obviously an artifact arising from the decarboxylation of 3-oxo-2-EHA.     

A spatial kinetic model for simulating VVER-1000 start-up transient

An accurate prediction of reactor core behavior in transients depends on how much it could be possible to exactly determine the thermal feedbacks of the core elements such as fuel, clad and coolant. In short time transients, results of these feedbacks directly affect the reactor power and determine the reactor response. Such transients are commonly happened during the start-up process which makes it necessary to carefully evaluate the detail of process. Hence this research evaluates a short time transient occurring during the start up of VVER-1000 reactor. The reactor power was tracked using the point kinetic equations from HZP state (100 W) to 612 kW. Final power (612 kW) was achieved by withdrawing control rods and resultant excess reactivity was set into dynamic equations to calculate the reactor power. Since reactivity is the most important part in the point kinetic equations, using a Lumped Parameter (LP) approximation, energy balance equations were solved in different zones of the core. After determining temperature and total reactivity related to feedbacks in each time step, the exact value of reactivity is obtained and is inserted into point kinetic equations. In reactor core each zone has a specific temperature and its corresponding thermal feedback. To decrease the effects of point kinetic approximations, these partial feedbacks in different zones are superposed to show an accurate model of reactor core dynamics. In this manner the reactor point kinetic can be extended to the whole reactor core which means “Reactor spatial kinetic”. All required group constants in calculations are prepared using the WIMS code. In addition CITATION code was used to calculate the flux, power distribution and core reactivity inside the core. To update the last change in group constants and resultant reactivity in point kinetic equations, these neutronic codes were coupled with a developed dynamic program. This study is applied on a typical VVER-1000 reactor core to show the reactor response in short time transients caused during start-up procedure.