Guaratinguetá - FEG - Faculdade de Engenharia e Ciências

URI Permanente para esta coleçãohttps://hdl.handle.net/11449/253825

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Oxygen defects, morphology, and surface chemistry of metal oxides: a deep insight through a joint experimental and theoretical perspective
(2022-01-01) Ciola Amoresi, Rafael Aparecido ; Coleto Junior, Ubirajara ; Simões, Alexandre Zirpoli ; Perazolli, Leinig Antonio ; Longo, Elson ; Andrés, Juan ; Universidade Estadual Paulista (UNESP) ; Universidade Federal do ABC (UFABC) ; Universidade Federal de São Carlos (UFSCar) ; Jaume I University - UJI
Comprehending the relationship between structure and function of materials is the main goal of materials science for the rational design of their enhanced performance. Despite being unavoidable, defects in materials are not considered an enemy of materials anymore, as some beneficial effects regarding their optimal properties, and consequently potential applications, have been observed. This suggests that the presence of defects is far from being completely understood. In this context, studying the basic interactions of defects in materials can provide a deeper comprehension of this conundrum. Thus, the consonance between the deviations of real materials and the ideal models are constant challenges to be addressed in solid-state science, which has for many decades demanded intense efforts from researchers regarding the control and exploitation of such imperfections. On the other hand, the morphology of materials is generally considered the key to modulate their functional properties. However, for semiconducting structures, morphology is as important as size and composition for the determination of the electronic structure. The exposed surfaces at the morphology are closely related to the physicochemical properties and distinct from the bulk of the material because they are constituted of undercoordinated atoms corresponding to oxygen vacancies and defects. The morphology control and manipulation at each exposed surface with a given surface energy provides a degree of freedom for harvesting and tailoring the functional properties of metal oxides, but this is usually a nontrivial task. Therefore, it is fundamental to understand how the local coordination of atoms at the exposed surfaces, that is, undercoordinated clusters of semiconductor metal oxides with oxygen vacancies, impacts the chemistry and physics of these semiconductors. Here, we investigate the relationship among oxygen defects, morphology, and surface chemistry of metal oxides using a combined experimental and theoretical strategy to unveil their peculiar technological applications as photoluminescent emission, photocatalysts, and antibacterial agents.
Thermodynamic Analysis of Hydrogen Production Processes
(2017-01-01) Braga, L. B. ; Tuna, C. E. ; De Araujo, F. H.M. ; Vane, L. F. ; Pedroso, D. T. ; Silveira, J. L. ; Universidade Estadual Paulista (UNESP)
In this chapter, thermodynamic studies are conducted for determining the energy efficiencies of each type of hydrogen production process. In the case of the steam reforming processes, a physicochemical analysis was previously conducted, which was based on the concepts of Gibbs free energy, equilibrium constant, and degree of advancement. In light of pressure and temperature conditions, the energy efficiency levels of such processes are determined. In the case of hydrogen production from renewable electrolytic processes, it was based on the electrolyzer’s efficiency and the average efficiencies of wind, photovoltaic, and hydroelectric power plants. In the case of algae, it was considered the energy contained in the hydrogen being produced and the energy consumption levels during the periods of growth, adaptation, and hydrogen production.
Hydrogen Production Processes
(2017-01-01) Braga, Lúcia Bollini ; Da Silva, Márcio Evaristo ; Colombaroli, Túlio Stefani ; Tuna, Celso Eduardo ; De Araujo, Fernando Henrique Mayworm ; Vane, Lucas Fachini ; Pedroso, Daniel Travieso ; Silveira, José Luz ; Universidade Estadual Paulista (UNESP)
This chapter discusses the state-of-the-art in terms of hydrogen production processes. At first, the steam reforming reactions of ethanol, biogas, and natural gas are introduced. A study on the catalysts being used in the selected reforming processes is also presented with their respective operating temperatures, feed molar ratio, and conversion rates of reagents. Afterwards, the electrolysis process and types of electrolyzers are presented with the renewable energy sources required for such, as well as the settings adopted for this type of hydrogen production processes. This chapter is concluded with the presentation of the biological hydrogen production process from green algae, with the description of the alga strain and methodology for determining the amount of hydrogen produced.
Ecological Efficiency of Some Hydrogen Production Processes
(2017-01-01) Braga, Lúcia Bollini ; Tuna, Celso Eduardo ; De Araujo, Fernando Henrique Mayworm ; Vane, Lucas Fachini ; Pedroso, Daniel Travieso ; Silveira, José Luz ; Universidade Estadual Paulista (UNESP)
As hydrogen production is not a clean process in its separation (from acid, methane, hydroxide, water, alcohol, etc.), there are energy requirements, thus resulting in pollutant emissions along its production process. The pollutant emissions associated with the studied processes are presented and the equivalent carbon dioxide [(CO2)e], pollutant indicator (П g) and ecological efficiency (ε) of hydrogen production processes are determined. Moreover, for the processes using renewable energy sources, such as in the case of ethanol, biogas and green algae, carbon credit incorporation is also presented so as to make ecological efficiency values yet to be determined more realistic.
Conclusions
(2017-01-01) Silveira, José Luz ; Universidade Estadual Paulista (UNESP)
Based on the results and data available in literature, it can be concluded that there is no optimal hydrogen production process from energy, ecological and economic points of view at the same time. What should better define the most appropriate process is the scenario that exists around the installation.
Economic Studies of Some Hydrogen Production Processes
(2017-01-01) Braga, Lúcia Bollini ; Tuna, Celso Eduardo ; Mayworm De Araujo, Fernando Henrique ; Vane, Lucas Fachini ; Pedroso, Daniel Travieso ; Silveira, José Luz ; Universidade Estadual Paulista (UNESP)
There are more than ten methods for an economic analysis of energetic systems. Each researcher chooses their own suitable methodology. In the case of hydrogen production processes, there is the need to use a method that permits a comparison of the cost of hydrogen production considering all the processes studied in the previous chapter. The economic feasibility study was based on the methodology developed by Silveira and Gomes (1999), which allows evaluating the attractiveness of a project through assessing the costs of investment, operation, and maintenance of the system, resulting in the selection of the best option. In this chapter, it is determined the cost of hydrogen production per kWh of electricity produced (US$/kWh) for each process, and a study drawing a comparison of their cost is thereof presented on the basis of inputs being used and levels of investment.
Sustainability Assessment of Hydrogen Production Techniques in Brazil: A Multi-criteria Analysis
(2017-01-01) Tapia, Luis Carlos Félix ; Vigouroux, Rolando Zanzi ; Silveira, José Luz ; Royal Institute of Technology (KTH) ; Universidade Estadual Paulista (UNESP)
Current global demands for energy resources along with the continuous global population growth have created a great deal of stress among natural environments and societies in fulfilling such a need without disrupting economic and social structures. Policy- and decision-making processes hold some of the most important keys to allow safe paths for societies towards energy security and to safeguard the environment. Brazil has played a leading role in renewable energy production and use during the last few decades, thus becoming one of the world’s leading producers of sugarcane-based ethanol, and adapted policies to support renewable energy generation and use. Although it is true that Brazil has historic experience in managing renewables development and their further integration into the consumer market, there is still a lot to be done in order to drive new technologies that could reduce emissions even further, thus increasing economic stability and social welfare.
Environmental Footprints of Hydrogen from Crops
(2022-01-01) Julio, Alisson Aparecido Vitoriano ; de Souza, Túlio Augusto Zucareli ; Rocha, Danilo Henrique Donato ; Rodriguez, Christian Jeremi Coronado ; Palacio, José Carlos Escobar ; Silveira, José Luz ; Federal University of Itajubá (UNIFEI) ; Universidade Federal do ABC (UFABC) ; Universidade Estadual Paulista (UNESP)
The environmental footprint of crops has become one of the main parameters for assessing the ecological impact of food production. However, with the development of renewable technologies for fuel and energy production from biomass-based feedstock, these environmental indicators were also extended to the energy sector. Among the fuels that are likely to soon increase its participation in the energy matrix, hydrogen must receive special attention due to its high energy content and carbon-free combustion. This fuel, however, remains dependent on fossil sources such as natural gas and oil-derived compounds, while production of the so-called “green hydrogen” remains a secondary option. Aiming to understand and quantify the potential decrease of environmental impact by moving toward more renewable hydrogen production pathways, several studies were carried out over the years in order to assess the real impact of this fuel’s production through land, water, energy, and other environmental indicators. In this sense, this chapter provides an up-to-date overview of the impact behind hydrogen production, including the three main options currently available: thermochemical processes, biological conversion, and electrolysis. Finally, the main findings allow a deep understanding of potential benefits to be achieved by making the hydrogen matrix more sustainable, while also presenting the main barriers that should be overcome in order for this goal to be achieved.
Identification and dynamical properties of asteroid families
(2015-01-01) Nesvorný, David ; Brož, Miroslav ; Carruba, Valerio ; Southwest Research Institute ; Charles University ; Universidade Estadual Paulista (UNESP)
Asteroids formed in a dynamically quiescent disk but their orbits became gravitationally stirred enough by Jupiter to lead to high-speed collisions. As a result, many dozen large asteroids have been disrupted by impacts over the age of the solar system, producing groups of fragments known as asteroid families. Here we explain how the asteroid families are identified, review their current inventory, and discuss how they can be used to get insights into long-term dynamics of main-belt asteroids. Electronic tables of the membership for 122 notable families are reported on the Planetary Data System node. See related chapters in this volume for the significance of asteroid families for studies of physics of large-scale collisions, collisional history of the main belt, source regions of the near-Earth asteroids, meteorites and dust particles, and space weathering.
Statistical approaches for the optimization of parameters for biotechnological production of xylitol
(2012-01-01) De Cassia Lacerda Brambilla, Rita ; Canettieri, Eliana Vieira ; Martinez, Ernesto Acosta ; Canilha, Larissa ; Solenzal, Ana Irene Napolez ; De Almeida E Silva, João Batista ; Universidade de São Paulo (USP) ; Universidade Estadual Paulista (UNESP)
Statistics is a fundamental tool in the analysis of any process data where there is variability. There are many ways to approach the problem of optimization and design of a process, which can be handled quickly using a number of statistical techniques. Statistical design of experiments is a mechanism of data collection appropriate to study the biotechnological process, like xylitol production. Several fermentation processes have been optimized using response surface methodology. However, one of the major problems to the researcher is identifying the independent variables that influence the study in order to explain the model which best represents the process. The upstream independent variables studied in the statistical design for fermentation processes are aeration rate, temperature, phosphate level, back pressure, carbon source, pH, power input, agitation rate, carbon/nitrogen ratio, nitrogen source and dissolved oxygen level. The statistical approach for biotechnological production of xylitol from lignocellulosic materials also could be helpful to optimize pretreatment of lignocellulosic biomass, conditioning of hemicellulosic hydrolysates and xylitol recovery from fermented hydrolysates. This chapter will provide an overview on the state of knowledge in these areas focus on statistical approaches.
Microalgal feedstock for bioenergy: Opportunities and challenges
(2014-01-01) Reis, Cristiano Eduardo Rodrigues ; De Souza Amaral, Mateus ; Loures, Carla Cristina Almeida ; Da Rós, Patrícia Caroline Molgero ; Hu, Bo ; Filho, Hélcio José Izário ; De Castro, Heizir Ferreira ; Gianesella, Sônia Maria Flores ; Silva, Messias Borges ; Universidade de São Paulo (USP) ; Universidade Estadual Paulista (UNESP)
The utilization of algal feedstock for bioenergy can be considered as one of the greatest challenges for biosystems engineering in the near future. Some species of microalgae show high potential for oil accumulation and further utilization of its biomass for biogas generation, pyrolysis, ethanol production, and even as fertilizer. Microalgae can utilize CO2 as carbon source and can also be grown on nonagricultural environments, such as wastewater facilities, industrial effluents, freshwater, and marine water habitats. The vast research field on microalgae engineering is due to the facts that it can be a source of energy and act as an air and water pollutants removal. There have been considerable advances in engineering its growth, in bioreactor designs, and on lipid accumulation due to chemical, biochemical, and genetic studies. Despite that, there are still some fundamental processing aspects that are considered challenges, either economical, ecological, or technical, such as biomass harvesting and the competition with the higher value products produced from algae, as proteins.
Green microalgae as substrate for producing Biofuels and chlorophyll in Biorefineries
(2018-01-01) Gonçalves, Bruna C. M. ; Silva, Messias B. ; Universidade de São Paulo (USP) ; Universidade Estadual Paulista (UNESP)
In order to develop sustainable technologies with reduced impacts in an attempt to repair previously caused damages to the environment, green alternatives have been the focus of several researches nowadays. Technological advances have enabled an effective use of natural sources to obtain clean energy, thus reducing emissions of gaseous pollutants into the environment. In this context, biofuels are promising alternatives for regulating climate change caused by an increase in the greenhouse effect, whose negative impact has been considerably perceived over the years. The use of microalgae as raw material to obtain biofuels has been proved promising. Due to the rich composition of carbohydrates, lipids and various proteins, biofuels and bioproducts can be obtained from microalgal cells, thereby contributing to bring down the final cost of products within the concept of biorefineries. Thus, this chapter aims to identify the process variables that interfere in microalgae cultivation to produce biofuels and pigments, and their impact on microalgal cell composition. Information on the most widely used culture media and the most studied species for obtaining biofuels by focusing on biohydrogen, biodiesel and bioethanol have been assessed. Furthermore, the process for obtaining these biofuels was illustrated in a simplified form in order to provide a general overview for readers.
Composite processed by RTM: Fatigue behavior
(2011-01-01) Cioffi, Maria ; Voorwald, Herman Jacobus Cornelis ; Shiino, Marcos Yutaka ; Rezende, Mirabel Cerqueira ; Universidade Estadual Paulista (UNESP) ; Praça Marechal Eduardo Gomes
Structural polymer composites have been widely applied in the aeronautical field. However, composite processing, which uses unlocked molds, should be avoided in view of the tight requirements in service and also due to the possibility of environmental contamination. To produce composite aeronautical structural components with low cost, the aircraft industry has shown interest in resin transfer molding process (RTM) as an adequate option to substitute for conventional process with the advantages of faster gel and cure times, besides the low percentage of voids and high fiber volume percentage, which are the essential parameters to design aircraft structures. Since the low viscosity resin is injected into the closed mold, in this process, the edge effect can promote incomplete wetting of the fiber reinforcement, dry spot formation and other defects in the final composite. Knowledge of material behavior is essential to design structures as aircraft landing gear, for example. Compared with isotropic materials, polymeric fibrous composites submitted to cyclic loading present a degradation phenomenon of mechanical properties as a consequence of residual stress redistribution into the structure. It was established that fatigue mechanisms associated to fibrous composites occur in four stages: nucleation of local damage, stable propagation of crack due to the cyclic load, local crack propagation which is dependent of fibers orientation, the matrix ductility and the interfacial adhesion and propagation of last loading cycle, which is analogous to the tensile test fail. Because of the many mechanisms involved during the degradation of the composites, scatter in fatigue is higher and special care need to be taken when approach the S-N curve. In this chapter, the review of data presented in the literature with focus in the fatigue behavior of polymeric composites reinforced with carbon fiber processed by RTM are compared with some experimental data obtained during three years of study. As a specific aim this chapter proposes a new methodology for fatigue behavior on composites, as this field lack of reliable predictive methods, and the main drawbacks of composites applied in aircraft structures.
Technological advancements in biohydrogen production and bagasse gasification process in the sugarcane industry with regard to Brazilian conditions
(2014-01-01) Silveira, Jose Luz ; Tuna, Celso Eduardo ; Pedroso, Daniel Travieso ; Da Silva, Marcio Evaristo ; Machin, Einara Blanco ; Braga, Lúcia Bollini ; Martinelli, Valdisley José ; Universidade Estadual Paulista (UNESP)
Global warming is caused mainly by the excessive use of fossil fuels (coal, oil, diesel, gasoline, etc.) that emit millions of tons of pollutants into the environment. Besides, the fact that these fossil fuels are nonrenewable resources promotes the research in cleaner energy sources. In this chapter are presented two different technologies that could be introduced in the sugarcane industry to generate electricity and other kinds of clean fuel (producer gas and hydrogen); the case of hydrogen production by ethanol steam reforming and biomass gasification, which appear like promising technologies for energy generation in the sugarcane industry. Currently, most hydrogen is obtained from natural gas through a process known as reforming. Other technologic alternatives that may improve the supply of energy to the sugarcane industry is the use of biomass gasifiers in association with cogeneration system utilizing combined cycles to produce simultaneously electricity and heat, a technology known as Biomass Integrated Gasification/Gas Turbine Combined Cycle (BIG/GTCC). Cogeneration, has been accepted by different industries and has gained great application in the sugarcane industry, where the thermic and electric demands are favorable to use this type of energy system. The main fuel used in the process is sugarcane bagasse which is a by-product of sugar and ethanol production processes; the obtained energy is used in the form of mechanical power, electric power, and saturated steam in the processes. The surplus electricity can be sold. Technical, economical, and ecological analyses were performed for introduction of hydrogen production and BIG/GTCC in the sugarcane industry, using bagasse as fuel, in order to identify the better scenarios for electricity and heat generation. The introduction of these technologies will engender innovations in the sugarcane industry and will promote the sector development and as main results will increase electricity production with an economic and ecologic sustainable approach.
Nanostructured Hydrogels
(2013-01-01) Montoro, Sérgio Roberto ; Medeiros, Simone de Fátima ; Alves, Gizelda Maria ; Universidade de São Paulo (USP) ; Universidade Estadual Paulista (UNESP)
Polymer systems can be developed into a variety of functional forms to meet industrial and scientific applications. In general, they are presented in four common physical forms: (1) linear free chains in solution, (2) covalently or physically cross-linked reversible gels, (3) micro and nanoparticles, and (4) chains adsorbed or in surface-grafted form. Hydrogels are polymeric particles consisting of water-soluble polymer chains, chemically or physically connected using, in general, a cross-linking agent. These materials do not dissolve in water but may swell considerably in aqueous medium, demonstrating an extraordinary ability (>20%) to absorb water into the reticulated structure. Such features make these materials promising tools in the biomedical field, especially as controlled drug release systems. This chapter describes recent progress in the development and applications of polymeric nanostructured hydrogels, mainly in the context of biomedical devices. Additionally, it reports the significant advances in synthesis and characterization strategies of these materials. Special attention is devoted to smart or stimuli-responsive bionanogels, which mimic the property of living systems responding to environmental changes such as pH, temperature, light, pressure, electric field, chemicals, or ionic strength, or a combination of different stimuli. Consequently, these bionanogels offer an efficient solution to various biomedical limitations in the field of drug administration. © 2014 Elsevier Inc. All rights reserved.
Review on natural fibers/HDPE composites: Effect of chemical modification on the mechanical and thermal properties
(2010-12-01) Mulinari, Daniella R. ; Cioffi, Maria Odila H. ; Voorwald, Herman J.C. ; Universidade Estadual Paulista (UNESP)
In the recent years, great attention has been dedicated to the exploitation of natural fibers as reinforcement for plastics, replacing fibers synthetic materials. Objectives are not just environmental concerns and consumer pressure but also a unique combination of high performance, great versatility and processing advantages at low cost. However, certain drawbacks such as incompatibility with a hydrophobic polymer matrix, the tendency to form aggregates during processing and poor resistance to moisture reduce greatly the potential of natural fibers to reinforce polymers. On the other hand, various treatments are being used to improve fibre-matrix compatibility. This process is considered critical as a development phase of these materials due to strong interfiber hydrogen bonding, which holds fibers together. Methods for surface modification can be physical or chemical according to superficial modification approach of the fibre. In this review, the main results presented in the literature are summarized, with specific attention on the properties in terms of physical and chemical structure of natural fibers, thermal and mechanical properties, processing performance and final properties of natural fibers reinforcing high density polyethylene matrix. The use of physical and chemical treatments for the improvement of fibers-matrix interaction was also considered. © 2010 by Nova Science Publishers, Inc. All rights reserved.
Thermoplastic and thermosetting composites with natural fibers
(2011-02-01) Mulinari, Daniella R. ; Saron, Clodoaldo ; Carvalho, Kelly C.C. ; Voorwald, Herman J.C. ; UNiFoa ; Universidade Estadual Paulista (UNESP)
Nowadays, great attention has been dedicated to the development of natural fiber reinforced composites. Natural fibers provide with interesting properties the final composite, especially those related to environment the protection such as their capacity to be recyclable, renewable raw material, and less abrasive and harmful behavior. Some advantages associated to the use of natural fibers as reinforcement in plastics are their non-abrasive nature, biodegradability, low energy consumption, low cost, low density and high specific properties. The specific mechanical properties of natural fibers are comparable to those of traditional reinforcements. However, certain drawbacks such as incompatibility with a hydrophobic polymer matrix, the tendency to form aggregates during processing and poor resistance to moisture greatly reduce the potential of natural fibers to be used as reinforcement in polymers. On the other hand, various treatments are being used to improve fiber-matrix compatibility. This process is considered critical as development phase of these materials due to strong interfiber hydrogen bonding, which holds the fibers together. Methods for surface modification can be physical or chemical according to superficial modification approach of the fiber. Others frequently used treatments are bleaching, acetylation and alkali treatment. In this chapter, the main results presented in the literature are summarized, focusing attention on the properties in terms of physical and chemical structure of natural fibers, thermal and mechanical properties, processing behavior and final properties of natural fibers with thermoplastics and thermosetting matrixes paying attention to the use of physical and chemical treatments for the improvement of fiber-matrix interaction. ©2011 Nova Science Publishers, Inc. All rights reserved.
Possible generalizations within braneworld scenarios: Torsion fields
(2012-03-01) da Silva, J.M. Hoff ; da Rocha, Roldão ; Universidade Estadual Paulista (UNESP) ; Universidade Federal do ABC (UFABC)
In this Chapter we introduce the aspects in which torsion can influence the formalismof braneworld scenarios in general, and also how it is possible to measure suchkind of effects, namely, for instance, the blackstring transverse area corrections andvariation of quasar luminosity due to those corrections. We analyze the projectedeffective Einstein equation in a 4-dimensional arbitrary manifold embedded in a 5-dimensional Riemann-Cartan manifold. The Israel-Darmois matching conditions areinvestigated, in the context where the torsion discontinuity is orthogonal to the brane.Unexpectedly, the presence of torsion terms in the connection does not modify suchconditionswhatsoever, despite of the modification in the extrinsic curvature and in theconnection. Then, by imposing the Z2-symmetry, the Einstein equation obtained viaGauss-Codazzi formalism is extended, in order to now encompass the torsion terms.We also show that the factors involving contorsion change drastically the effective Einsteinequation on the brane, as well as the effective cosmological constant. Also, wepresent gravitational aspects of braneworld models endowed with torsion terms bothin the bulk and on the brane. In order to investigate a conceivable and measurablegravitational effect, arising genuinely from bulk torsion terms, we analyze the variationin the black hole area by the presence of torsion. Furthermore, we extend the wellknown results about consistency conditions in a framework that incorporates branetorsion terms. It is shown, in a rough estimate, that the resulting effects are generallysuppressed by the internal space volume. This formalism providesmanageable models and their possible ramifications into some aspects of gravity in this context, and cognizablecorrections and physical effects as well. The torsion influences the braneworldscenario and we can check it by developing the bulk metric Taylor expansion aroundthe brane, which brings corrections in the blackstring transverse area. This generalizationis presented in order to better probe braneworld properties in a Riemann-Cartanframework, and it is also shown how the factors involving contorsion change the effectiveEinstein equation on the brane, the effective cosmological constant, and theirconsequence in a Taylor expansion of the bulk metric around the brane. © 2011 Nova Science Publishers, Inc. All rights reserved.
Nonvolatile memories
(2018-01-01) Rocha, Leandro S.R. ; Simões, Alexandre Z. ; Cortés, Johan A. ; Ramirez, Miguel A. ; Moura, Francisco ; Foschini, Cesar R. ; Tararam, Ronald ; Cilense, Mario ; Longo, Elson ; Paiva-Santos, Carlos O. ; Universidade Estadual Paulista (Unesp) ; Federal University of Itajubá (Unifei) ; CEITEC S.A Semiconductors ; Universidade Federal de São Carlos (UFSCar)
The need for faster, smaller, cheaper and energy-efficient electronic devices has been growing continuously in the last decade, with the conventional data storage technologies (i.e., static random access memory and dynamic random access memory), which have been so far fulfilled by CMOS-charge storage-based circuits, approaching their fundamental limits, due to the lesser progress of technology in comparison to logic. To overcome this challenge, increasingly high storage density memories has become one of the crucial approaches, aiming to improve storage capacity and reading/writing speed. A semiconductor memory is an indispensable component of all modern electronic devices, with all recognizable computing platforms, from hand-held devices to large supercomputer storage systems being used for storing data, temporarily or permanently. The ability of a material to store information is defined as a solid-state memory effect, which requires at least two switchable memory states that can be addressed by an externally controlled parameter. Based on storing data volatility, memories are basically classified into two categories, volatile and nonvolatile, with the former immediately losing the stored data after turning off the power, whereas the latter being capable of retaining the stored data for a longer period, even after the power is turned off. To optimize the performance-cost trade-off, hierarchical systems made from devices with varying speed, density, and cost have been adopted and the novel nonvolatile memory (NVM) concepts, such as ferroelectric random access memory, phase-change RAM, magnetic RAM, spin-transfer-torque RAM (STT-RAM), and resistive RAM (RRAM) are fulfilling the changing market trend requirements, from electronics to high performance computing, due to encouraging recent experimental demonstrations of high density, excellent scalability, low power consumption, endurance, and low cost. An RRAM is normally referred as those NVM technologies built on the resistance changing mechanisms, which can be varied by applying a voltage pulse, other than phase-change memory and STT-RAM. Data is stored by changing the resistance across a dielectric solid-state material in the RRAM cell, which presents two resistance states: a high-resistance state and a low-resistance state, being respectively defined as R ON and R OFF. Thus, the device can be used as a Boolean logic switch returning (0) when the resistance is R OFF and (1) when R ON.
Biohydrogen production and bagasse gasification process in the sugarcane industry
(2019-01-01) Paulino, Regina Franciélle Silva ; Silveira, José Luz ; Universidade Estadual Paulista (Unesp)
The steam reforming of ethanol and the gasification of sugarcane bagasse processes integrated with gas turbine combined cycle have been considered to produce biohydrogen and other bioelectricity forms. Biohydrogen obtained through alternative sources of energy, in this case sugarcane bagasse, may contribute to future demands for renewable energy and can replace fossil fuels. In order to investigate the technical viability of incorporating these processes, a thermodynamic analysis has been carried out using data about a typical Brazilian sugarcane industry. Furthermore, the economic viability of biohydrogen production processes has been investigated by comparing its cost with that of the steam reforming of hydrous and anhydrous ethanol. In addition, studies on the engineering economics of gasification processes that generate electricity were taken into account. Lastly, an ecological analysis has been carried out to determine the levels of pollutant emissions, equivalent carbon dioxide, pollutant indicators, and ecological efficiencies of the technological developments proposed. This chapter aims to introduce the incorporation of new technologies applied in the sugarcane industry. The steam reform of ethanol process is used to add a new product of high energy; biohydrogen. The gasification process is to improve the power supply of conventional plants and for the marketing of the production of surplus bioelectricity. To evaluate the viability of incorporating each process, technical, economic, and environmental engineering studies are carried out.

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