Frequency identification of Hammerstein-Wiener systems with backlash input nonlinearity

International Journal of Control, Automation and Systems - The problem of system identification is addressed for Hammerstein-Wiener systems that involve memory operator of backlash type bordered by...     

New Cloud Consolidation Architecture for Electrical Energy Consumption Management

Cloud computing is taking more extensive space in the research field. Cloud architectures will need to worry about energy in its various forms, to be profitable, on the one hand, and comply with environmental constraints （energy consumption and CO2 emission） on the other hand. VM （virtual machines） consolidation （VMs in this document）, among other techniques, must take into account the consumption of electrical energy, for example, while providing a level of performance that meets the requirements of SLAs （service level agreements）. In our work, we focus on an architecture configuration to manage virtual machines in a data center, in order to optimize the consumption of energy, and meet SLAs＇s constraints at the same time, by grafting a tracing component of the multiple consolidation plans that leads to an optimal configuration to finally give the order of the migration machinery to a minimum number of servers switched on, knowing that VMs （virtual machines） that coexist in the same server, are at risk of congestion and interference.     

Fuzzy DIFACONN-miner: A novel approach for fuzzy rule extraction from neural networks

Artificial neural networks (ANNs) are mathematical models inspired from the biological nervous system. They have the ability of predicting, learning from experiences and generalizing from previous examples. An important drawback of ANNs is their very limited explanation capability, mainly due to the fact that knowledge embedded within ANNs is distributed over the activations and the connection weights. Therefore, one of the main challenges in the recent decades is to extract classification rules from ANNs. This paper presents a novel approach to extract fuzzy classification rules (FCR) from ANNs because of the fact that fuzzy rules are more interpretable and cope better with pervasive uncertainty and vagueness with respect to crisp rules. A soft computing based algorithm is developed to generate fuzzy rules based on a data mining tool (DIFACONN-miner), which was recently developed by the authors. Fuzzy DIFACONN-miner algorithm can extract fuzzy classification rules from datasets containing both categorical and continuous attributes. Experimental research on the benchmark datasets and comparisons with other fuzzy rule based classification (FRBC) algorithms has shown that the proposed algorithm yields high classification accuracies and comprehensible rule sets.     

Dense Output for Strong Stability Preserving Runge–Kutta Methods

We investigate dense output formulae (also known as continuous extensions) for strong stability preserving (SSP) Runge–Kutta methods. We require that the dense output formula also possess the SSP property, ideally under the same step-size restriction as the method itself. A general recipe for first-order SSP dense output formulae for SSP methods is given, and second-order dense output formulae for several optimal SSP methods are developed. It is shown that SSP dense output formulae of order three and higher do not exist, and that in any method possessing a second-order SSP dense output, the coefficient matrix A has a zero row.     

Machine loading in flexible manufacturing systems considering routeing flexibility

The key competitive strength of a manufacturing system lies in its flexibility, which represents the ability to respond effectively to changing circumstances. Flexible manufacturing systems (FMSs) react appropriately to change. The relevance of a particular type of flexibility depends upon the system and problem being considered. In this paper, the machine loading problem in a flexible manufacturing system is addressed. The loading problem is concerned with the allocation of part operations and required tools to the machines, so as to optimise some objective(s) subject to some technological constraints. Several objectives have been considered in the past such as maximisation of the utilisation of resources, minimisation of processing and tooling costs and maximisation of throughput rates. In such procedures, it is quite probable that a rigid loading schedule is obtained and in cases of machine breakdowns and tool failures alternate routeings are often not available. Therefore, in this paper, we develop a mathematical model which considers maximisation of the production routeings available for the parts and hence increases the routeing flexibility. The model is illustrated by examples.     

Chemical Composition and Antidiabetic Activity of Essential Oils Obtained from Two Spices (Syzygium aromaticum and Cuminum cyminum)

The current aim was to evaluate antidiabetic potential of Syzygium aromaticum and Cuminum cyminum essential oils and their emulsions by alpha amylase inhibition assay. Antidiabetic activity of C. cyminum and S. aromaticum was examined in dose dependent mode (1 to 100 µg/mL). The maximum antidiabetic activity for S. aromaticum and C. cyminum essential oils was noted at the highest dose (100 µg/mL). Five emulsions (essential oil + surfactant [tween 80] + co-surfactant [ethanol] + water) of different concentrations for S. aromaticum (A1 to A5) and C. cyminum (B1 to B5) essential oils were formulated. Among different emulsions, A5 of S. aromaticum and B5 of C. cyminum essential oil exhibited a maximum antidiabetic activity with 95.30 and 83.09% inhibition of α-amylase, respectively. Moreover, the analysis of essential oils showed that eugenol (18.7%) and α-pinene (18.8%) were the major components of S. aromaticum and C. cyminum essential oils, respectively.     

Effect of helium xenon as working fluid on centrifugal compressor of power conversion unit of closed Brayton cycle power plant

Closed Brayton cycle (CBC) having single-shaft, centrifugal type compressor is considered as an efficient energy-conversion option associated for gas-cooled reactor (GCR) heat source. In terrestrial power plants and space power systems noble gases are considered as an efficient working fluid for most of the GCR's and CBC engines. The effectiveness of various noble gases as working fluid in closed cycle power plants for the power conversion units is of imperative concern. Although pure helium is relatively difficult to compress nonetheless it is measured as the best coolants for closed Brayton cycle power plants due to its better transport properties. Due to compression properties, its use resulted in the requirement of more mass, bigger size, higher cost and relatively more dynamic problems of rotatory machines in energy conversion system. The mixture of xenon with helium up to a molecular weight of <40 g/mol resulted in an increase of the coefficient of heat transfer as well as the significant increase in the loading of the compressor. Therefore, performance analysis is conducted for a novel design of helium xenon centrifugal compressor. The performance analysis is conducted with different molecular weight mixtures of helium xenon using similarity criteria. It is concluded that the use of helium xenon 40 g/mol is the optimum choice for space applications and 15 g/mol for closed Brayton cycle terrestrial power plants.     

Biological activity of Boswellia serrata Roxb. oleo gum resin essential oil: effects of extraction by supercritical carbon dioxide and traditional methods

The findings of this study suggests that chemical composition, essential oil yield, antioxidant and antimicrobial activity of Boswellia serrata oleo gum resin essential oils extracted by hydro distillation, steam distillation and supercritical fluid carbon dioxide methods vary greatly from each other. The optimum essential oil yield was obtained using hydro distillation method (8.18 ± 0.15 %). The essential oils isolated through different extraction methods contained remarkable amounts of total phenolics and total flavonoids. Essential oil isolated through supercritical fluid carbon dioxide extraction exhibited better antioxidant activity with highest free radical scavenging potential (96.16 ± 1.57 %), inhibition of linoleic acid oxidation (94.18 ± 1.47 %) and hydrogen peroxide free radical scavenging potential (68.25 ± 1.02 %). Moreover, the antimicrobial activity of essential oils was performed through well diffusion, resazurin microtiter plate and micro dilution broth assay assays. The essential oil isolated through steam distillation method revealed highest antimicrobial activity with maximum inhibition zone (24.21 ± 0.34 to12.08 ± 0.30 mm) and least MIC values (35.18 ± 0.77 to 281.46 ± 7.03 µg/mL). The comparison of chemical composition of essential oils isolated at different extraction methods have shown that the concentration of α-thujene, camphene, β-pinene, myrcene, limonene, m-cymene and cis-verbenol was higher in steam distilled essential oil as compared to hydro and supercritical fluid carbon dioxide extracted essential oils. These compounds may be responsible for the higher antimicrobial activity of Boswellia serrata oleo gum resin steam distilled essential oil.     

Opportunities to change development pathways toward lower greenhouse gas emissions through energy efficiency

There is a multiplicity of development pathways in which low energy sector emissions are not necessarily associated with low economic growth. However, changes in development pathways can rarely be imposed from the top. On this basis, examples of energy efficiency opportunities to change development pathways toward lower emissions are presented in this paper. We review opportunities at the sectoral and macro level. The potential for action on nonclimate policies that influence energy use and emissions are presented. Examples are drawn from policies already adopted and implemented in the energy sector. The paper discusses relationships between energy efficiency policies and their synergies and tradeoffs with sustainable development and greenhouse gas emissions. It points to ways that energy efficiency could be mainstreamed into development choices.