Feed-in tariffs for promotion of energy storage technologies

Faster market integration of new energy technologies can be achieved by use of proper support mechanisms that will create favourable market conditions for such technologies. The best examples of support mechanisms presented in the last two decades have been the various schemes for the promotion of renewable energy sources (RES). In the EU, the most successful supporting schemes are feed-in tariffs which have significantly increased utilisation of renewable energy sources in Germany, Spain, Portugal, Denmark and many other EU countries. Despite the successful feed-in tariffs for RES promotion, in many cases RES penetration is limited by power system requirements linked to the intermittency of RES sources and technical capabilities of grids. These problems can be solved by implementation of energy storage technologies like reversible or pumped hydro, hydrogen, batteries or any other technology that can be used for balancing or dump load. In this paper, feed-in tariffs for various energy storage technologies are discussed along with a proposal for their application in more appropriate regions. After successful application on islands and outermost regions, energy storage tariffs should be also applied in mainland power systems. Increased use of energy storage could optimise existing assets on the market.     

Failure Analysis of Tool Steel-Based Compaction Punch Used in Powder Metallurgy

Powder metallurgy operations comprise the use of compaction dies and punches for transforming a mass of metallic powders into a porous block of aggregated particles with limited “green” strength. In this kind of application, dies and punches manufactured with tool steel are subjected to heavy loads to compress the metallic powders and form the block, which will be subjected to further consolidation operations such as sintering and/or some mechanical forming operation, such as forging or rolling. In general tool steels are high carbon and high alloyed steels designed for reaching high levels of mechanical strength, sufficient for his type of loading. However, defects on the surface of this material can lead to stress concentration, thus decreasing its fracture strength and eventually leading to failure. In this study, techniques such as optical and scanning electron microscopy are used to evaluate the possible causes of the failure of a compaction punch. The results indicated that machining grooves acted as stress concentrations which led to the premature fracture of the punch.     

Optimal selection of full scale tannery effluent treatment alternative using integrated AHP and GRA approach

The selection of optimal wastewater treatment alternative involves multiple objectives and/or criteria and hierarchy process. This study integrates analytical hierarchy process (AHP) and grey relation analysis (GRA) for optimal selection of full scale tannery effluent treatment plants. For this purpose, seven tanneries and their effluent treatment facilities are studied in detail in Southern India. The objective hierarchy criterion is considered based on three factors; economic, technical, and administrative, each of which again involves hierarchy of indices. A realistic treatment alternative selection is obtained since all the data used is on actual basis. The biggest advantage of this approach is that it provides the information regarding the scope for further improvement in existing treatment options. The study indicates that the AHP and grey relation analysis are powerful tools that can be used for implementation of appropriate wastewater treatment technology.     

Economic simulation of biodiesel production: SIMB-E tool

Recently biodiesel has been receiving increasing attention as an alternative fuel due to its environmental benefits. It is derived from renewable sources which are considered as strategic opportunities to favor environmental sustainability, to improve the population's quality of life and to promote the development of more efficient and equitable economic systems. Besides technical aspects, economics feasibility is also of great importance to access the biodiesel production viability. This paper traces the development of a software tool capable of performing economic analysis of different biodiesel plants considering the contemporary industry practices. The economic indexes considered during the analysis are the net present value (NVP), the Benefit–Costs Ratio (BCR), the Capital Return Time (CRT) and the Internal Rate of Return (IRR). Fixed capital costs, operating costs, depreciation, and auxiliary costs are also taken into account for the economic calculations.     

Virtual networks: isolation, performance, and trends

Currently, there is a strong effort of the research community in rethinking the Internet architecture to cope with its current limitations and support new requirements. Many researchers conclude that there is no one-size-fits-all solution for all of the user and network provider needs and thus advocate for a pluralist network architecture, which allows the coexistence of different protocol stacks running at the same time over the same physical substrate. In this paper, we investigate the advantages and limitations of the virtualization technologies for creating a pluralist environment for the Future Internet. We analyze two types of virtualization techniques, which provide multiple operating systems running on the same hardware, represented by Xen, or multiple network flows on the same switch, represented by OpenFlow. First, we define the functionalities needed by a Future Internet virtual network architecture and how Xen and OpenFlow provide them. We then analyze Xen and OpenFlow in terms of network programmability, processing, forwarding, control, and scalability. Finally, we carry out experiments with Xen and OpenFlow network prototypes, identifying the overhead incurred by each virtualization tool by comparing it with native Linux. Our experiments show that OpenFlow switch forwards packets as well as native Linux, achieving similar high forwarding rates. On the other hand, we observe that the high complexity involving Xen virtual machine packet forwarding limits the achievable packet rates. There is a clear trade-off between flexibility and performance, but we conclude that both Xen and OpenFlow are suitable platforms for network virtualization.     

Modeling and simulation of breakthrough curves during purification of two chitosanases from Metarhizium anisopliae using ion-exchange with expanded bed adsorption chromatography

A mathematical model was developed to predict breakthrough curves during purification of the two chitosanases from Metarhizium anisopliae by expanded bed adsorption, taking into account the axial dispersion of liquid and using Streamline DEAE and SP XL adsorbents, anion and cation exchange resins, respectively. All the experiments were performed without clarification (with cells) aiming at the reduction of unit operations in future projects of separation processes, thereby reducing capital and operating costs. Chitosanases are enzymes that hydrolyze the carbohydrate chitosan, resulting in oligosaccharides that have many remarkable biological activities, such as anti-cancer, anti-HIV and antioxidant activities. The two adsorbents had similar performance in relation to hydrodynamics and mass transfer. The results of the parametric sensitivity analysis agree with the literature, and the model was validated with an average high degree of fit (94.68%) between simulated and experimental data obtained in this work.     

Insight on the periodate oxidation of dextran and its structural vicissitudes

Periodate oxidized dextran has been widely studied in a broad range of biotechnological applications, regardless of this, usually little attention is paid to the oxidation extension consequences on the properties of the final modified dextran. Based on a bidimensional NMR analysis, we suggest that the two aldehydes groups, resulting from the periodate oxidation, are not fully reactive with N-nucleophiles, under certain pH conditions. The aldehyde group bonded to C₃ appeared to be the only prone to react. The other aldehyde might be arrested in more stable hemiacetal structures. The hemiacetals are also responsible for oxidized dextran crosslinking, interfering in simple processing steps, such as dissolution and solubility, as well as increasing the viscosity of the solutions. The molecular weight variation on the oxidized samples can be followed by dynamic mechanical thermal analysis in consequence of the variation of glass transition temperature with the molecular weight, which was corroborated by the onset temperature of the thermal degradation.     

Clays for polymeric nanocomposites

We discuss test methods and results for determining individual clay platelets shape, size, size distribution, elemental composition, and impurities. Commercial sodium salt varieties of natural, semisynthetic and synthetic clay (Cloisite®‐Na⁺, Somasif ME‐100, and Topy‐Na⁺, respectively) were analyzed. In this international collaboration, eight laboratories on three continents carried out the work within the VAMAS TWA‐33 activities. There are large differences between the three nanofillers as far as: (1) the platelet orthogonal dimensions, (2) chemical composition, and (3) contaminants (their diversity and quantity) are concerned. Elaborate purification of natural clays leaves behind 2–5 wt% of organic and mineral impurities, whose nature, shape, size, and chemistry depend on the clay origin. These contaminants affect nanocomposite performance, thus controlling their composition and quantity is essential. The article describes the developed methods, summarizes the preliminary results, discusses the encountered difficulties, and proposes methods for solving them. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Novel strategies for sparse regenerator placement in translucent optical networks

In this paper, we propose two strategies for sparse regenerator placement (RP) in translucent optical networks, named most used regenerator placement (MU-RP), and most simultaneous used regenerator placement (MSU-RP). Our proposals are compared to well known RP algorithms presented in literature for two different network topologies for different network loads, distribution of load along the networks and number of translucent nodes. MSU-RP presented remarkable results and outperformed all previous approaches in all cases, while MSU-RP obtained a slightly superior or similar performance when compared to previous approaches presented in the literature.