bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling the Process of Drying Biomass in a Fixed Bed
Authors: Yang Hai , Milota Michael R.
Published: December 2013

An alternative to a rotary dryer for biomass is a bed dryer. In this type of dryer, the wood particles are stationary, and the air passes upward through them. Compared with rotary dryers, bed dryers may be more economical to operate on a small scale. The present work investigated drying biomass in a fixed bed dryer.

The drying characteristics of wood biomass were measured using a thin-layer drying technique at inlet gas conditions of 50°C to 200°C and 0.3 to 0.9 m/s. The drying behavior was modeled using a one-parameter Newton model. The thin-layer model was then used in a deep bed model to predict drying times and moisture profiles in the bed. Drying times based on the model at depths up to 23 cm were within −22 to +12 percent, and typically within ±4 percent, of the experimental results.

A drying zone ranging from 0.13 to 0.18 m in depth moves up the bed as drying occurs. The biomass is wet above and dry below this zone, resulting in considerable variability in moisture content within the bed. The material in an industrial dryer would need to be mixed or a dryer would need to be designed with stages if a uniform moisture content among the particles was an important criterion.
Effect of Setting during Construction on Properties of Douglas-Fir Plywood and Oriented Strandboard Flooring
Authors: Meza Luis , Sinha Arijit , Morrell Jeffrey J.
Published: December 2013

The effects of rainfall exposure on panel integrity were investigated for oriented strandboard and plywood. Both panel materials experienced substantial increases in moisture content and thickness with limited rainfall exposure and these were coupled with decreases in flexural properties. The results showed that even short-term rainfall exposure was detrimental to the properties of both materials and emphasized the importance of protecting these materials during construction.
Línea de costa y sistemas de información geográfica: modelo de datos para la caracterización y cálculo de indicadores en la costa andaluza
Authors: Ojeda Zújar José , Díaz Cuevas María del Pilar , Prieto Campos Antonio , Álvarez Francoso José Ignacio
Published: December 2013

Presente en numerosas bases de datos geográficas y cartografía oficial, la línea de costa constituye un elemento fundamental en los procesos de análisis, gestión y planificación de la zona costera, si bien su levantamiento a escalas de detalle y su posterior utilización requiere de una precisa delimitación geométrica y del establecimiento de criterios rigurosos para su definición. Éstos últimos deben ser seleccionados con una clara intencionalidad aplicada de acuerdo a su uso posterior. En este sentido, el uso de los Sistemas de Información Geográfica, las bases de datos espaciales y un adecuado modelo de datos, resultan elementos clave para el levantamiento de líneas de costa, así como para los análisis posteriores realizados sobre ellas. En este trabajo se presenta, en primer lugar, la metodología utilizada para la definición geométrica de la línea de costa en Andalucía a una escala detallada (1:2.500) sobre ortofotos y ortoimágenes de resolución métrica y submétrica y el modelo de datos que soporta cada tramo topológicamente independiente digitalizado. Tras su digitalización geométrica e integración en una base de datos espacial (PostGres/PostGis) se utilizan las capacidades analíticas de las TIG para la construcción de diferentes indicadores utilizados en su caracterización fisiográfica, estado, seguimiento y evaluación ambiental en la costa andaluza.
Propuesta inicial de una red ampliada de Áreas Protegidas en España peninsular bajo el enfoque de su conexión con la matriz territorial
Authors: Martínez Vega Javier , Echevarría Daspet Pilar
Published: December 2013

Se propone la oportunidad de ampliar la actual red de Áreas Protegidas de España peninsular bajo una estrategia global de conservación de la naturaleza que vaya más allá de la preservación de los espacios que ya disponen de una figura de protección. Mediante el empleo de Tecnologías de Información Geográfica se han diseñado zonas de amortiguación y corredores ecológicos para que funcionen como conectores de las áreas núcleo que son los actuales Espacios Naturales Protegidos. Esta red ecológica ampliada ocupa 345.733 km2, equivalente al 70 % de la superficie total del área de estudio. A modo de validación, se ha combinado esta cobertura de Áreas Protegidas con mapas de rareza, representatividad y diversidad de los ecosistemas forestales. De acuerdo a estos indicadores de Ecología del Paisaje, el 82,25 % de los ecosistemas forestales más raros de España peninsular se encuentran dentro de la red ampliada de Áreas Protegidas propuesta, al igual que el 82,88 % de los montes de mayor representatividad y el 89,21 % de las áreas forestales más diversas.
Modelo de evaluación de la capacidad de acogida del territorio con SIG y técnicas de decisión multicriterio respecto a la implantación de edificaciones en espacios rurales
Authors: Galacho Jiménez Federico Benjamín , Arrebola Castaño Juan Antonio
Published: December 2013

Se muestra un método, que apoyado en propuestas científicas, ayuda en la planificación del uso sostenible del territorio. Dicho método se basa en los modelos de evaluación de la capacidad de acogida del territorio. Su fundamento es el desarrollo de una metodología de evaluación con una perspectiva amplia de la sostenibilidad rural y contempla la necesaria puesta en valor de los recursos naturales, la preservación del medio por su calidad ambiental y la minimización de los riesgos naturales. Con él se evaluará la implantación de edificaciones relacionadas con el proceso de urbanización difusa en los espacios rurales. Para ello se aborda la evaluación de las condiciones particulares del medio rural en orden a la mejor estimación de sus posibilidades y de su vulnerabilidad respecto a los riesgos naturales. Como resultado se ha realizado una evaluación basada en juicios de valor claramente definidos y en atributos concretos del territorio. Mediante este proceso se obtiene una capa de información que muestra una clasificación del espacio estudiado con una valoración asignada a cada parte del territorio en función de su capacidad para acoger los usos que han sido evaluados.
REQUES VELASCO, P. (2012): Un mundo asimétrico. Cambio demográfico, globalización y territorio (Microensayos). Santander: PUbliCan, Ediciones de la Universidad de Cantabria, 205 p.
Authors: Cutillas Orgilés Ernesto
Published: December 2013

La velocidad con la que se suceden los procesos de cambio político, económico, tecnológico, social, cultural o incluso ambiental en un contexto de globalización sin precedentes, es uno de los rasgos que mejor define lo que Immanuel Wallerstein vino a denominar Sistema-Mundo y que, a diferentes escalas geográficas, se manifiesta con una serie de desafíos, desafíos globales, pero con repercusiones locales. En efecto, si el siglo XIX fue el siglo de la política, el siglo XX el de la economía, el siglo XXI será sin duda el de la demografía puesto que las transformaciones demográficas muestran cuáles son los múltiples retos a los que se enfrenta y se deberá enfrentar la humanidad en los próximos años. Bajo este planteamiento y con un manifiesto compromiso social, el geógrafo Pedro Reques agrupa treinta y dos artículos de opinión que fueron publicados originalmente entre 2001 y 2012 en el diario económico Cinco Días y, como ya hiciera en su libro El factor D. Los nueve retos demográficos de la España actual (2011), la idea de analizar éticamente y dar respuesta justa a los problemas sociales, demográficos y territoriales subyace en el corolario de su argumentación. Sin renunciar al rigor científico, el autor emplea un lenguaje claro, directo, ameno y accesible incluso para el lector no especializado que recuerda a la mejor tradición francesa en la elaboración de atlas temáticos mundiales como los de Yves Lacoste (2006), Durand, Copinschi, Martin, Placidi (2008) o los dossieres que regularmente edita Le Monde Diplomatique. No en vano, el libro viene acompañado por abundante material gráfico, estadístico y cartográfico elaborado con la colaboración de María Marañón y a partir de fuentes de información estadística procedentes de organismos internacionales como las Naciones Unidas, el Banco Mundial o la OCDE, entre otros. La monografía se compone de tres grandes bloques temáticos, un anexo cartográfico y un repertorio bibliográfico.
Using a Cyclical Diagram to Visualize the Events of the Ovulatory Menstrual Cycle
Authors: Ho Ivan Shun , Parmar Navneet K.
Published: December 2013

Over the past 10 years, college textbooks in human anatomy and physiology have typically presented the events of the ovulatory menstrual cycle in a linear format, with time in days shown on the x-axis, and hormone levels, follicular development, and uterine lining on the y-axis. In addition, the various events are often shown over a 28-day cycle, when they can take place over 21–35 days and may not be regular at all. Here, we propose a circular diagram that is independent of a set cycle time and readily shows the cyclic nature of the events. This diagram can be presented sequentially in organized layers, and additional complexity can be added. In addition, we present questions here that can promote self-learning before and critical thinking after the discussion of the cycle to enhance understanding of the physiological events.
Preparing Future Biology Faculty
Authors: Lockwood Stephanie A. , Miller Amanda J. , Cromie Meghan M.
Published: December 2013

Formal professional development programs for biology graduate students interested in becoming faculty members have come far; however, programs that provide advanced teaching experience for seasoned graduate teaching assistants are scarce. We outline an advanced program that focuses on further training of graduate teaching assistants in pedagogy and mentoring opportunities within a biology department. The Graduate Teaching Scholars Program provides opportunities for individualized instruction and learning while working with a faculty mentor. Graduate teaching scholars attend workshops, have their teaching evaluated, and serve as mentors for new graduate teaching assistants in the department. Students in the program are able to contribute to departmental education initiatives while growing professionally as teachers and future faculty.
The Jealousy of Scientific Men
Authors: Walsh Joseph A.
Published: December 2013

A look back at some famous discoveries in biology highlights the competitive nature of science, the trophy being priority by publication.
A New Species of Science Education
Authors: Reddy Christopher
Published: December 2013

Interactive television is a type of distance education that uses streaming audio and video technology for real-time student–teacher interaction. Here, I discuss the design and logistics for developing a high school laboratory-based science course taught to students at a distance using interactive technologies. The goal is to share a successful model of science implementation that has the potential to alleviate financially induced stress on science programs.
Size-controllable Synthesis of Hierarchically Structured Mesoporous Anatase TiO2 Microspheres Covered With {001} Facet
Authors: Zhao Zhao , Zhao Haifeng , Zhang Guoqiang , Zhang Ligong , Sun Zaicheng
Published: December 2013

Synthesis of anatase titanium dioxide (TiO2) with both controllable size and high energy facets is technologically important for its application in photocatalysis, photoelectrochemical cell, and solar cells. Herein, we report a simple and fluorine free hydrothermal method to synthesize hierarchically nanostructured mesoporous anatase TiO2 spheres (MATS) with controllable size, which covered with nearly 100% {001} facet. Mild H2SO4 was used as both a phase-inducer formation of anatase phase and a capping agent to promote oriented growth and formation of {001} facet. PVP acted as morphology control agent to prevent growing larger of the mesoporous anatase TiO2 spheres (MATS) with ∼600 nm in size. Detailed XRD and SEM studies suggested that formation of MTAS is a typical nucleation and growth process. The refining or reconstruction of TiO2 crystal structure during growth resulted in mesoporous crystalline framework that exhibits enhanced photocatalytic degradation of rhodamine B.
Growth, structure and properties of magnetron sputtered ultra-thin WTi films
Authors: Le Priol A. , Le Bourhis E. , Renault P.-O. , Simonot L. , Abadias G. , Muller P. , Sik H.
Published: December 2013

Refractory metal alloy WTi films were elaborated by magnetron sputtering from an alloyed target (W:Ti ∼ 70:30 at%). Film continuity threshold has been determined at 4.5 ± 0.2 nm using in situ surface differential reflectance (SDR) technique. Prior to film continuity, deposition of a continuous interfacial layer is suggested by both in situ and real-time SDR and wafer-curvature techniques. After continuity, WxTi1-x films (9.5 nm thick WTi films) have a body-centered structure with a {110} fiber texture. Composition (x) and microstructure can be tuned varying working pressure. A transition from compressive to tensile residual stresses was observed by ex situ XRD and wafer-curvature methods. Size dependent resistivity is obtained and slightly varies as a function of working pressure.
Development of high-current ionic liquid ion source toward surface modification
Authors: Takeuchi Mitsuaki , Hamaguchi Takuya , Ryuto Hiromichi , Takaoka Gikan H
Published: December 2013

Ionic liquid (IL) ion sources with different emitter tip materials and tip numbers were developed and examined on ion beam characteristics with respect to its ILs wettability. As a result of ion current measurements, the most stable emission current was obtained for the graphite emitter tip and the ion current increased with increase of the tip number. The results indicate that the emitter wettability corresponding to the supplying flow rate and the number of emission site play an important role to stabilize and increase the beam current.
Protic ionic liquid-based thermoelectrochemical cells for the harvesting of waste heat.
Authors: Abraham Theodore J. , MacFarlane Douglas R. , Baughman Ray H. , Li Na , Chen Yongshen , Pringle Jennifer M.
Published: December 2013

The ability to efficiently harvest heat as a source of sustainable energy would make a significant contribution to reducing our current reliance on fossil fuels. Waste heat sources, such as those produced in industrial processes or through geothermal activity, are extensive, often continuous, and at present severely underutilised. Thermoelectrochemical cells offer an alternative design to the traditional semiconductor-based thermoelectric devices and offer thepromise of continuous and cheap operation at moderate temperatures, low maintenance and with no carbon emissions. They utilise two electrodes, held at different temperatures, separated by an electrolyte containing a redox couple. It is the temperature dependence of the electrochemical redox potential that generates the potential difference across the device as a result of the appliedtemperature difference. The magnitude of this redox potential temperature dependence is given by the Seebeck coefficient, Se. Until recently, research into thermoelectrochemical cells had primarily focused on aqueous media, predominantly with the Fe(CN)63-/4- redox couple.[1] However, the good thermal and electrochemical stability, non-volatility and non-flammability ofmany ionic liquids make them promising alternative electrolytes for these devices. The use of ionic liquid (IL) electrolytes offers potential advantages that include increased thermoelectrochemical device efficiencies and lifetimes and the ability to utilise low temperature (often “waste”) heat sources in the 100 – 200 °C temperature range.[2] Here we discuss our research into the use of the Fe(CN)63-/4- redox couple in protic IL electrolytes, with different amounts of added water, in a thermoelectrochemical device with platinum and single walled carbon nanotube (SWNT) electrodes.
Atmospheric Pressure Plasma Functionalization of Dry-spun Multi-walled Carbon Nanotubes Sheets and its application in CNT-Polyvinyl Alcohol (PVA) Composites
Authors: Malik Rachit , Song Yi , Alvarez Noe , Ruff Brad , Haase Mark , Suberu Bolaji , Gilpin Andrew , Schulz Mark , Shanov Vesselin
Published: December 2013

Robust sheets comprised of aligned multi-walled carbon nanotubes (MWNTs) drawn from spin-able carbon nanotube (CNT) arrays were developed. Surface modification of these sheets was carried out via an atmospheric pressure plasma jet as a post-treatment process. Helium/Oxygen plasma was utilized to produce carboxyl (-COO-) functionality on the surface of the nanotubes. Raman Spectroscopy, X-Ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared (FTIR) Spectroscopy confirm the presence of functional groups on the nanotube surface. Composite laminates made from functionalized CNT sheets in a polyvinyl alcohol (PVA) matrix demonstrate increase in tensile strength over those made with pristine sheets used as reinforcement material.
Interaction of phase transformation and magneto- and elastocaloric properties of Heusler alloys
Authors: Entel Peter , Sokolovskiy Vladimir V. , Buchelnikov Vasiliy D. , Comtesse Denis , Acet Mehmet
Published: December 2013

The structural, electronic and magnetic properties of functional Ni-Mn-(Ga, In, Sn) and Pt-Ni-(Ga, Sn) alloys are studied by first-principles and Monte Carlo tools. The ab initio calculations give a basic understanding of the underlying physics which is associated with the complex magnetic behavior arising from the competition of ferro- and antiferromagnetic interactions for excess Mn atoms in the unit cell. We show that the resulting complex magnetic ordering is the driving mechanism of structural transformations and multifunctional properties of Heusler alloys associated with magnetic shape-memory, magnetocaloric and elastocaloric effects. The thermodynamic properties can be calculated by using the ab initio magnetic exchange parameters in finite-temperature Monte Carlo simulations. Entropy and specific heat changes associated with the magnetic changes and emergence of microstructure across the magnetostructural transition are pointed out. We show how to optimize the functional properties by tuning the compositional changes, for example, a magnetic shape-memory effect of more than 14% can be achieved in Pt-Ni-Mn-Ga alloys. The theoretical studies are accompanied by experimental investigations.
Shape Memory Alloys and Their Applications in Power Generation and Refrigeration
Authors: Cui Jun
Published: December 2013

The shape memory effect is closely related to the reversible martensitic phase transformation, which is diffusionless and involves shear deformation. The recoverable transformation between the two phases with different crystalline symmetry results in reversible changes in physical properties such as electrical conductivity, magnetization, and elasticity. Accompanying the transformation is a change of entropy. Fascinating applications are developed based on these changes. In this paper, the history, fundamentals and technical challenges of both thermoelastic and ferromagnetic shape memory alloys are briefly reviewed; applications related to energy conversion such as power generation and refrigeration as well as recent developments will be discussed.
Adventures with a Flipped Classroom and a Materials Science and Engineering MOOC : “Fools Go Where Angels Fear to Tread”
Authors: Clemens Bruce M. , Nivargi Chinmay , Jan Antony , Lu Yuxiang , Schneider Emily , Manning Jane
Published: December 2013

In the fall of 2012 the Stanford University materials science course Solar Cells, Fuel Cells and Batteries: Materials for the Energy Solution was offered as a flipped class and a massively open online course (MOOC). To the best of our knowledge, this was the first materials science MOOC. Here we describe how the course was implemented, and present results on performance, demographics and other observations that were made. Finally, we provide some perspectives for the future of the implementation of these engineering MOOCs.
Photocatalytic Activity of Bare and Amine-Treated TiO2 Nanoparticles
Authors: Hossain Fahim , Perez Oscar Perales , Hwang Sangchul
Published: December 2013

The capability of tuning the functional properties of nanosize TiO2 nanoparticles (NPs) by suitable control of surface chemistry, phase stability and crystal size plays a key role on their safe use and enhanced efficacy in actual and envisioned applications, including nanomedicine, environmental remediation, and food safety, among others. On this basis, any attempt to develop a size-controlled synthesis method and an efficient surface treatment protocol becomes indispensable. Accordingly, we have synthesized TiO2 NPs via a modified aqueous processing route using HNO3 as a catalyst and polyvinylpyrrolidone as particle size controller and a dispersing agent. The NPs surface was treated by using Ethylenediamine (EDA) as a source for amine species. Bare and amine-treated TiO2 NPs were characterized by X-ray diffraction (XRD) and FTIR spectroscopy. The photocatalytic activity of TiO2 NPs was assessed by irradiating an aqueous solution of Methylene Blue (MB) dye containing different amounts of the NPs. XRD analyses evidenced the formation of two phases of crystalline TiO2 with an average crystallite size estimated at 15.3 nm. Bare and amine-treated TiO2 NPs exhibited significant activity under UV light illumination (365 nm). Bare NPs exhibited a dye photo degradation capability of about 38.02% with particle concentration of 0.5 g/l while amine-treated NPs reported 66.18% dye photo degradation capability with particle concentration of 0.5 g/l.
Effect of the Nature of the Metal Co-Catalyst on CO2 Photoreduction Using Fast-Grown Periodically Modulated Titanium Dioxide Nanotube Arrays (PMTiNTs)
Authors: Amirsolaimani Babak , Zhang Xiaojiang , Han Fei , Farsinezhad Samira , Mohammadpour Arash , Dechaine Greg , Shankar Karthik
Published: December 2013

Anodically formed TiO2 nanotube arrays composed of the anatase phase with periodically modulated diameters (PMTiNTs) are excellent photocatalysts for the sunlight-driven transformation of carbon dioxide into hydrocarbons. Exploiting the full potential of this nanoarchitecture for CO2 photoreduction requires integration with metal nanoparticles that function as catalytic promoters for multistep electron transfer reactions. We studied the effect of different metallic and bimetallic nanoparticles on the rate of generation of light hydrocarbons by the photoreduction of CO2. All the metal nanoparticles were loaded on to the TiO2nanotubes using the technique of photodeposition, which standardized the coating process and enabled examination purely of the effect of different metals. Photodeposition was used not only due to its simplicity but also because it enabled us to engineer very fine coatings possessing excellent uniformity and depth penetration into the nanotubes. The best performing co-catalysts were found to be CuPt (atomic ratio of 0.33:0.67), Pt and NiPt (1:2), which when loaded onto the PMTiNTs yielded total hydrocarbon generation rates of 3.5, 0.85 and 0.8 mL g-1 hr-1 respectively. The time required to form PMTiNTs was reduced by a factor of 160 by using a recently reported recipe based on fluoride ion bearing electrolyte containing lactic acid. PMTiNTs formed using the ultrafast growth lactic acid-based electrolytes exhibited similar photocatalytic properties to samples obtained more slowly using conventional ethylene glycol-based electrolytes.
A Highly Efficient On-chip 3D Plasmonic Nanofocusing Structure
Authors: Kim Myung-Ki , Choo Hyuck
Published: December 2013

We demonstrate and analyze a highly efficient on-chip 3D metal-insulator-metal (MIM) nanofocusing structure. Here, we show the in-depth theoretical design, analysis and discussion to provide a detailed picture of the highly efficient, on-chip nanofocusing process which is linearly tapered in 3D.
Mechanical Characterisation of the NiTi Shape Memory Alloy for Microfluidic Valve Applications
Authors: Waddell Alistair M. , Punch Jeff , Stanley Walter , Jeffers Nicholas , Stafford Jason
Published: December 2013

Photonics Integrated Circuits (PICs) are being applied by the telecommunications industry as transceivers for fibre optic networks. The core component of a typical PIC is the laser array and these devices can have relatively low operating temperatures (15°C - 25°C) with a tight operating range (±0.1K). To accommodate such a specification, a thermal control system is required that can change the cooling rate through feedback. The power density of next generation PICs is at such a level to demand novel thermal management architectures including developments such as near source liquid cooling. In order to control the thermal performance of fluidic devices, effective methods for varying the rate of coolant are an essential component. Consequently, micro-valve structures are required, ideally involving passive actuation to meet stringent reliability standards. One solution to this challenge is to exploit the phase-change driven shape memory effect of the NiTi Shape Memory Alloy (SMA). A micro-valve could be developed from the NiTi SMA, thermally coupled to the laser array component in order to work passively to regulate the flow of coolant in a micro-channel. Such a valve would have to be intrinsically reliable, and the goal of this paper is to investigate the conditions that will affect this reliability. The objective of the work is to investigate the mechanical properties relevant to the design of a passive NiTi SMA micro-valve, with a focus on the formation of stress-induced Martensite bands. It is not understood why these bands form on a plane inclined at ∼55° to the axis of loading and in this paper theory is presented that suggests a reasoning for this. A plate sample of NiTi was tested in uni-axial tension and Digital Image Correlation (DIC) used to analyse the strain fields across the surface of the sample. The DIC results revealed areas of high stress concentrations occurring in bands inclined on average 53.86° to the axis of loading. The theory and experimental observations are in agreement with the literature but to validate the theory the crystal texture needs to be analysed in the stress concentration regions. This paper provides valuable insight into the mechanical behaviour of a passive NiTi SMA micro-valve subjected to a sufficient pressure to form stress-induced Martensite.
Ab initio study of magnetic properties of Fe-Mn-Al Heusler alloys
Authors: Sokolovskiy Vladimir V. , Buchelnikov Vasiliy D. , Zagrebin Mikhail A. , Taskaev Sergey V. , Khovaylo Vladimir V. , Entel Peter
Published: December 2013

Density functional theory (DFT) based on the spin-polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) method is used to investigate the magnetic properties of nonstoichiometric Fe2+xMn1-xAl Heusler alloys, where 0 ≤ x ≤ 0.9. The composition dependences of the magnetic exchange couplings and the Curie temperature for the cubic L21 phase are obtained. Our simulations have shown that the Fe-Fe nearest neighbors present a strong ferromagnetic coupling. Moreover, these exchange interactions are larger than other interactions. The substitution of Mn by Fe in Fe2+xMn1-xAl (0 ≤ x ≤ 0.9) leads to an increase in the Curie temperature. This tendency and the values of Curie temperatures are in agreement with the experimental results for Fe2+xMn1-xAl (x = 0, and 0.1). The highest Curie temperature was observed for the Fe-richer alloy.
The Supercell Scaling Investigation of Magnetic Properties in Ni-Mn-X (X=Ga, In, Sn, Sb) Heusler Alloys by Means of First-principles Methods
Authors: Buchelnikov Vasiliy , Sokolovskiy Vladimir , Zagrebin Mikhail , Taskaev Sergey , Khovaylo Vladimir , Entel Peter
Published: December 2013

In this work we study the influence of supercell scaling on magnetic properties in Ni-Mn-X-Z alloys by means of ab initio calculations with the help of Quantum Espresso PWSCF package and the spin-polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) code based on DFT approximation. It is shown that the supercell calculations for the equilibrium lattice parameter are coincided with the calculations for simple primitive lattice. The exchange parameters for Ni-Mn-X alloys obtained from supercell calculations are large than calculated for simple primitive lattice.
Cyclodextrin-based biodegradable polymer stars: synthesis and fluorescence studies
Authors: Tennekone Gayan K. , Wagner Brian D. , Shaver Michael P.
Published: December 2013

Polymer stars built using aliphatic polyester arms and a β-cyclodextrin (β-CD) core are prepared by two synthetic methodologies. The CD core stars offer the intriguing potential of loading molecules of interest into two zones by exploiting the host–guest chemistry of the hydrophobic CD core and by physical trapping in the polymer arms. Core-first syntheses were achieved through the ring-opening polymerization of rac-lactide, l-lactide, β-butyrolactone and lactide/glycolide monomers generating seven-armed stars with a heptakis(2,6-di-O-methyl)-β-CD core. Arm-first syntheses were achieved through the copper-catalyzed azide-alkyne cycloaddition of alkyne-terminated poly(lactic acid)s, poly(3-hydroxybutyrate) and a heptakis-azido-β-CD. For both synthetic strategies, use of the industry standard catalyst, Sn(Oct)2, gave polymers with broadened dispersities (1·3–1·7) when compared to aluminum complexes supported by salen ligands (<1·2). Synthetic strategies were compared by both measures of reaction control (molecular weight, dispersity, conversion) and controlled release (fluorescence spectroscopy of hydrolytic and enzymatic degradation), each offering benefits to the synthetic polymer chemistry, variable sustainability and scalability and a clear direction for further star design. Fluorescence-based controlled release studies were performed in water or methanol, releasing the encapsulated 7-methoxycoumarin fluorescent probe through both hydrolytic and enzymatic degradation. The release was shown to be strongly accelerated in the presence of the enzyme. This article contains supporting information that will be made available online once the issue is published.
Briefing: Visions of a resilient city
Authors: Yanez Karol , Kernaghan Sam
Published: December 2013

Cities, particularly in the global south, face numerous challenges in responding to a rapidly growing population. Ensuring the wellbeing of urban dwellers, particularly in the face of known natural hazards and an increasingly unpredictable climate, is leading cities to take resilience-based approaches to meet these challenges. Arup and Engineers Without Borders UK hosted a competition to unearth perspectives from the next generation of urban professionals on what resilient cities might look like. From the top ten shortlisted posters, the key messages emerging were: (a) building urban resilience requires action and systemic change across all four key components of an urban system – infrastructure, institutions, knowledge, and ecosystems; (b) resilient cities are the result of multiple interventions including transport and energy, food security, urban planning and waste management; (c) resilience is not location specific and is distinct from disaster risk reduction; and (d) building resilience is a progressive and evolving process of urban development – more practical examples are needed to help visualise it.
Integration of Dielectric Dispersion and 3D NMR Characterizes the Texture and Wettability of a Cretaceous Carbonate Reservoir
Authors: Abdelaal Atef Farouk , Al Daghar Khadija Ahmed , Ramamoorthy Raghu , Brahmakulam Jacob , Hall Jonathan C. , Baguenane Boussad , Al Marzooqi Mohammed Bin , Faivre Ollivier
Published: December 2013

Knowledge of rock texture and wettability are vital for the static and dynamic description of carbonate reservoirs. Conventional log measurements are limited in their applicability for the quantitative assessment of these attributes. Rapid variations of texture in carbonates diminishes the usefulness of core measurements on samples of limited size. Obtaining representative relative permeability by restoring core to native reservoir conditions, especially the original wettability state, is also very challenging.

The dielectric response of clean carbonate rocks exhibit characteristic frequency dispersion patterns which depend on their texture and wettability. Dielectric measurements with multiple frequencies have become available enabling us to extract this information by inverting the tool data using a dispersive petrophysical model.

The dielectric response is primarily sensitive to water, and provides a measure of the water phase tortuosity, which is a combination of texture and wettability, captured in the Archie’s exponents m and n. Previous work has demonstrated the estimation of m from pore size distribution obtained from NMR data using an effective medium model. Formation Resistivity Factor data from core is presented to validate the model-derived m. In this work we propose a way to combine the cementation exponent so derived with the textural answers from the dielectric measurement to make a wettability estimate. We also assess the wettability from 3D NMR stations, using the increase in relaxation of oil manifested as shortening of the oil T2 signal due to partial wetting of the oil phase.

The methods are illustrated on a dataset from a Cretaceous carbonate, onshore Abu Dhabi. The interval surveyed in the subject well straddles an oil/water contact (OWC). The n exponent value derived by the method shows that the rock above the OWC is oil-wet in varying degrees. The inference on wettability state from the NMR data further supports the conclusions.
Field Experience with Still Pipes Installation and Supporting in KOC Storage Tanks
Authors: Nassar Raga Hanna , Al-Hajri Abdul Rahman
Published: December 2013

In continuation with the efforts being done to achieve accurate liquid measurement performance at tank farms and to empower the commitment towards protecting the Company’s net worth, high level of accuracy must be achieved when conducting manual and/or automatic measurement of the basic variables required for the determination of the net liquid asset at any time; i.e., level, temperature, density, free water, mass, amongst others. In this line and with the aim of maximizing the overall accuracy of the installed Automatic Tank Gauging (ATG) system by reducing the effects caused by installation and operating conditions, an initiative has been implemented to upgrade the installation and supporting of the still pipe were the ATG is mounted and that of the official manual tank gauging (OMTG) still pipe utilized to verify the accuracy of the ATG. As a result of this initiative, minimal or no vertical movement of the ATG mounting location has been recorded and more stable ATG verification test results are obtained nowadays, enabling the reduction of radar calibrations basically enforced by this mounting movement. This paper will examine the operational problems faced with the design principles considered for the ATG installation on the new and existing storage tanks in KOC and provides recommendations to overcome/minimize the impact of these issues on the liquid measurements process.
Application of a New Integrated Technique for Servo Adjustable Water Detection and Water Shuto ff in Sudan Oilfield
Authors: Fuwei Zhong , Dekui Xu , Xiaohui Han , Xiaoyu Xu , Zhongchao Lin , Yuan Gao , Wenlin Xu , Xiaojing Zhang , Fei Gao , Rongxi Li
Published: December 2013

The Block 3/7 of Sudan Oilfield has been in the period of high water production. The water cut of many wells is more than 80%, and still rising. Besides, there are many sandy wells in this area. In order to reduce the water cut, the conventional technique involves two string trips—water detection primarily, and then water shutoff treatment according to the result of testing. Obviously, high cost and low efficiency restrict its application. Therefore, based on the conventional technique, a new integrated technique for servo adjustable water detection and water shutoff has been researched by Daqing Oilfield Limited Company, which is mainly made up of drillable packers to divide layers, intelligent controlled piezoelectric valves, inserted seal sections and releasing subs. With the integrated technique, dynamic adjustment and water shutoff treatment can be achieved at any layer without pulling the string upward or downward. Applying casing pressure signals can open the appointed position’s valve when detecting water, then get its single layer’s production, meanwhile record and test on the ground to confirm this layer’s production and water cut. Applying casing pressure signals closes the appointed position valve after testing. Repeating the above steps can get all the layers water production and water cut. According to the result of water detection test, open the intelligent controlled piezoelectric valves of the lower water cut layers to stabilize the oil production.

This new technique has been successfully applied to 8 wells in the Block 3/7 of Sudan Oilfield, which features low cost and high efficiency. It could meet the requirements of water detection and water shutoff for the remaining 30 wells of high water production. Similarly, it could apply to many wells of high water production in Daqing Oilfield.
Modeling, Simulation and Comparison of Common Control Techniques of AC Induction Motor Drive
Authors: Al-Khaledi Sadoun , Al-Qallaf Ahmad
Published: December 2013

AC induction motor drives are now finding increasing acceptance in various industrial applications because of the performance they can provide. Applications of AC drives vary from running simple conveyor belts and blowers to implementing a sophisticated variable speed variable frequency drives (VFD), in which torque and speed are wellregulated. Based on the type of application, choice of an appropriate control technique is made.

This paper presents a comparative study on most popular control strategies of Induction Motor Drives; constant V/Hz open/ closed loop control, field-oriented control (FOC), and Direct Torque Control (DTC).

The comparison is based on various criteria including basic control characteristics, torque performance, speed performance and transient response with respect to the load torque and speed variations.

Simulations of the above control techniques have been performed using MATLAB/SIMULINK™ software.

The Adjustable Speed Drives are generally used in industry. In most drives AC motors are applied. The standard in those drives are Induction Motors (IM). Induction motors are widely used in application such as pumps, fans, elevators, electrical vehicles, heating, ventilation and air-conditioning (HVAC), robotics, wind generation systems, etc.

Previously, DC machines were preferred for variable speed drives. However, DC motors have disadvantages of higher cost, higher rotor inertia and maintenance problem with commutators and brushes. In addition they cannot operate in dirty and explosive environments. The AC motors do not have the disadvantages of DC machines. Therefore, DC motors are progressively replaced by AC drives. The accountable for those results are the development of modern semiconductor devices, especially power insulated gate bipolar transistors (IGBT).

The most economical IM speed control methods are realized by using frequency converters. Many different strategies of frequency converters are proposed and investigated in this paper. However, a converter consisting of a diode rectifier, a dc-link and a pulse width modulated (PWM) voltage inverter is the most applied used in industry.

The high-performance frequency controlled PWM inverter – fed IM drive should be characterized by: Fast flux and torque response.Constant switching frequency.Low flux and torque ripple.Robustness for parameter variation.

The abovesaid features depend on the applied control strategy. The main goal of the chosen control method is to provide the best possible parameters of the drive. Additionally, a very important requirement regarding control method is the simplicity (simple algorithm, simple tuning and operation with small controller dimension leads to low price of final product).

A general classification of the variable frequency IM control methods is presented in Fig. 1
Corrosion Monitoring for Kuwait’s Pipeline Network System
Authors: Al-Shamari A. , Al-Sulaiman S. , Al-Mithin A. , Jarragh Amer , Prakash S. S.
Published: December 2013

Kuwait is the 5th largest oil producer in the world with a current crude oil production represents about 9% of the world’s oil. The country’s goal is to increase the production through the Strategic Plan 2020 and the Strategic Plan 2030. The Kuwait Oil Company (KOC) is the primary national organization responsible for exploration, drilling, production a- processing of the crude. The number and length of crude pipelines as well as the pipelines for other products (condensate, gas and water) have cumulatively grown to become about 4750 km over the last 60 years.

In-line inspection (ILI) pigging data has indicated internal corrosion damages in some pipelines. In addition, corrosion probes and coupons data along with fluid and bacteria analyses from various locations have confirmed internal corrosion damage. Therefore, a comprehensive Corrosion Management Plan for the Pipeline Network System has been established involving the following: (a) installation of internal corrosion monitoring equipment, (b) external corrosion protection by using coatings and cathodic protection (CP), (c) periodic cleaning pigging operations for internal cleaning, and (d) conducing in-line inspection (ILI).

The present paper will discuss the salient features of the Internal Corrosion Management Plan and its implementation in crude pipeline network.
The Impact of Black Powder on Gas Plant Safety Relief Valve Isolation Valve
Authors: Al-Jumayiah Khalid Abdullah
Published: December 2013

Black powder is a common problem in any upstream gas facilities. Black powder causes many problems to the gas treating facility. These problems can be in a form of erosion of gas transportation pipeline, erosion of processing equipment such as gas compressor, impurities in the product and accumulation in flow reduction components and clogging on isolation valves. This all leads to upsetting gas plant operation resulting in numerous cost to restore the plant operation and resolve the problem. One of the critical equipment that encounter black powder problem is isolation valve of safety relief valve. As known, safety relief valves are among the critical equipment in any plant. Safety relief valves are usually installed with an upstream block valve to maintain the operation and facilitate maintenance of the safety relief valve. Therefore, failure of this critical isolation valve will cause difficulties when dismantling the isolation valve as black powder will get accumulated in the cavity area of the valve and damage the seating which will, in turn, prevent full closure of the isolation valve. Realizing this detrimental effect of black powder on isolation valve entails proper selection process of isolation valve type. Nowadays, the industry offers various type of isolation valve. Each type has its own design aspects in terms of the capacity, strength, operator and nature of fluid media. However, the long term reliability comes from experience when valve is put into service. Under black powder operation conditions, passing or leaking after short period of time of operation usually not a good sign of proper valve selection. That is why emphasis have to be given to understand the nature of the processed product and select the right type of isolation valve that will serve for a long time to insure plant safety, reliability and smooth operation. In this paper, a Saudi Aramco gas plant experience will be shared of black powder problem on isolation gate valve of safety relief valve and the remedial action that has been taken to rectify this repeated problem.
Formulating Sag-Resistant, Low-Gravity Solids-Free Invert Emulsion Fluids
Authors: Wagle Vikrant , Maghrabi Shadaab , Kulkarni Dhanashree
Published: December 2013

Invert-emulsion fluid (IEF) systems formulated without organophilic clay have successfully addressed issues of barite sag and reservoir productivity. While ‘clay-free’ IEFs provide robust properties, additional materials in the form of low-gravity solids (LGS), like sized calcium carbonate or clay-type materials are required to bolster the rheological properties and suspension character of the system. This increases the plastic viscosity of the fluid, thereby resulting in a lower rate of penetration (ROP) and higher equivalent circulating densities (ECD). In the absence of LGS, the loss of suspension, especially in an inclined well, can lead to sag and cause a density gradient along the fluid column that may fracture the formation.

This paper presents a solution towards sag in an IEF that is free of LGS viz. fine sized calcium carbonate or clay-type material, and is formulated with a novel sag control additive to suspend barite. The additive was shown to prevent sag in 9-ppg, 12-ppg, and 16-ppg clay-free IEFs in a static-aging cell held vertical at 90° and then inclined at 45°. The additive provided sag control in different base oils with less than 5-mL oil separation. Extended sag testing with the sag-control additive at 250°F for 24 hours and at 150°F for 60 hours gave minimal oil separation and no barite sag. High temperature-high pressure (HTHP) testing on 9-ppg and 12-ppg demonstrates a flat rheological profile in the presence of this additive. Contamination testing of IEFs containing this additive shows that the suspension characteristics remain unaffected and the mud properties are tolerant to the presence of contaminants. The additive is North Sea compliant with a biodegradability of 71.4% in 42 days and LC50 of >10 g/mL for aquatic organisms. Experimental data demonstrating both the environmental and anti-sag performance of the novel sag control agent is presented and compared to fluids without the sag control agent.
Field Experience in Identification of HIC in Pressure Vessels
Authors: Al-Sulaiman Saleh , Sardesai Vinayak , Al-Harbi Bader , Srinivasa Murthy Hari , George Saji A. , John Reji P.
Published: December 2013

Hydrogen Induced Cracking (HIC) is a damage mechanism that may cause extensive damage to the pressure vessels in sour service in crude oil & gas production facilities. HIC damages could occur and further propagate in the pressure vessels with inherent manufacturing defects due to the impurities in the steel plates. The decisions involving continuation of such vessels in operation after detecting the HIC damages are complex even after suitable engineering assessment. The results of periodic monitoring of defects during operation are assessed to infuse confidence for continued service.

This paper presents a case study for identifying service induced embedded defects in a Gas Interstage Separator Vessel by the application of selected NDT methods and allowing continued service of the vessel with the help of engineering evaluation and frequent periodic NDT inspection follow-ups. The pressure vessel, made of carbon steel, was manufactured to ASME Section VIII Div. 1 during the 1960s. The vessel was identified with embedded defects which had further grown into minor internal cracks along the thickness perpendicular to the surface as detected during initial follow-up inspections. The vessel was allowed to continue operation with very close monitoring, continuous engineering evaluation and frequent follow up inspection involving advanced NDT. This approach helped us extend the vessel service life by 8 years and gave us ample time to replace it with a new one.

The NDT methods adopted included Automated Ultrasonic Testing (AUT) Phased Array technique and the engineering evaluations involved the Fitness-for-Service approach as per API-579.