bluuebunny/crossref_metadata_2025 huggingface dataset:
The assessment of aspirin resistance by using light transmission and multiple electrode aggregometry
Authors: ULEHLOVA J. , SLAVIK L. , KRCOVA V. , HUTYRA M. , GALUSZKA J. , INDRAK K.
Published: January 2011

Introduction:  The issues related to aspirin [acetylsalicylic acid (ASA)] resistance are still under debate. Depending on the method of assessment and studied patients, the prevalence of ASA resistance is rather heterogeneous, ranging from 5% to 45%. The method most commonly used for assessing platelet function is their aggregation. ASA irreversibly inhibits cyclooxygenase‐1 (COX‐1) by acetylation.

Methods:  This study aimed to compare light transmission aggregometry (LTA) and multiple electrode aggregometry (MEA) for the measurement of ASA resistance, using arachidonic acid as an inducer of the reaction.

Results:  The study comprised 101 patients with stable ischemic heart disease taking a daily dose of 100 mg of ASA. The rates of ASA resistance were 22.22% and 21.21% as detected by LTA and MEA, respectively. The two methods were statistically compared using Spearman’s nonparametric correlation analysis, with a positive significant correlation (P = 0.01) and medium positive dependence between the methods (r = 0.0539).

Conclusion:  If ASA resistance is detected by laboratory tests, replacement of ASA or its combination with other antiplatelet drugs as well as increased dosage may be considered.
Oligonucleotide primers, probes and molecular methods for the environmental monitoring of methanogenic archaea
Authors: Narihiro Takashi , Sekiguchi Yuji
Published: January 2011

For the identification and quantification of methanogenic archaea (methanogens) in environmental samples, various oligonucleotide probes/primers targeting phylogenetic markers of methanogens, such as 16S rRNA, 16S rRNA gene and the gene for the α‐subunit of methyl coenzyme M reductase (mcrA), have been extensively developed and characterized experimentally. These oligonucleotides were designed to resolve different groups of methanogens at different taxonomic levels, and have been widely used as hybridization probes or polymerase chain reaction primers for membrane hybridization, fluorescence in situ hybridization, rRNA cleavage method, gene cloning, DNA microarray and quantitative polymerase chain reaction for studies in environmental and determinative microbiology. In this review, we present a comprehensive list of such oligonucleotide probes/primers, which enable us to determine methanogen populations in an environment quantitatively and hierarchically, with examples of the practical applications of the probes and primers.
Disruption of the siderophore‐binding desE receptor gene in Streptomyces coelicolor A3(2) results in impaired growth in spite of multiple iron–siderophore transport systems
Authors: Tierrafría Víctor H. , Ramos‐Aboites Hilda E. , Gosset Guillermo , Barona‐Gómez Francisco
Published: January 2011

Ferrioxamines‐mediated iron acquisition by Streptomyces coelicolor A3(2) has recently received increased attention. In addition to the biological role of desferrioxamines (dFOs) as hydroxamate siderophores, and the pharmaceutical application of dFO‐B as an iron‐chelator, the ferrioxamines have been shown to mediate microbial interactions. In S. coelicolor the siderophore‐binding receptors DesE (Sco2780) and CdtB (Sco7399) have been postulated to specifically recognize and uptake FO‐E (cyclic) and FO‐B (linear) respectively. Here, disruption of the desE gene in S. coelicolor, and subsequent phenotypic analysis, is used to demonstrate a link between iron metabolism and physiological and morphological development. Streptomyces coelicolor desE mutants, isolated in both wild‐type (M145) and a coelichelin biosynthesis and transport minus background (mutant W3), a second hydroxamate siderophore system only found in S. coelicolor and related species, resulted in impaired growth and lack of sporulation. This phenotype could only be partially rescued by expression in trans of either desE and cdtB genes, which contrasted with the ability of FO‐E, and to a lesser extent of FO‐B, to fully restore growth at µM concentrations, with a concomitant induction of a marked phenotypic response involving precocious synthesis of actinorhodin and sporulation. Moreover, growth restoration of the desE mutant by complementation with desE and cdtB showed that DesE, which is universally conserved in Streptomyces, and CdtB, only present in certain streptomycetes, have partial equivalent functional roles under laboratory conditions, implying overlapping ferrioxamine specificities. The biotechnological and ecological implications of these observations are discussed.
Adenoid ameloblastoma with dentinoid and ghost cells. A composite odontogenic tumour: a rare case report and review of the literature
Authors: Sonone A. , Hande A. , Chaudhary M. , Bonde R. , Sheorain A. , Agni N.
Published: January 2011

In this article we report a case of rare composite odontogenic tumor, having features similar to adenoid ameloblastoma with dentinoid described previously. The histological features are similar to both ameloblastoma and AOT and show evidence of induction in the form of dentinoid. The patient was a 35 years old female. The lesion was located on right side of the mandible in premolar‐molar area. Radiograph revealed unilocular radiolucency with foci of radio‐opacities. On gross examination the tumor was cystic at places. The histopathological features consists of two patterns, one resembling AOT and other plexiform ameloblastoma. The formation of dentinoid like material was observed in association with odontogenic epithelium. Apart from this the presence of ghost cells was a unique histopathological feature.

This article also reviews the various cases reported in literature and provides an insight into the nature of composite odontogenic tumor. To date only 12 cases of this uncommon composite odontogenic tumor are reported in the literature.
Application of SNPs for population genetics of nonmodel organisms: new opportunities and challenges
Authors: HELYAR S. J. , HEMMER‐HANSEN J. , BEKKEVOLD D. , TAYLOR M. I. , OGDEN R. , LIMBORG M. T. , CARIANI A. , MAES G. E. , DIOPERE E. , CARVALHO G. R. , NIELSEN E. E.
Published: January 2011

Recent improvements in the speed, cost and accuracy of next generation sequencing are revolutionizing the discovery of single nucleotide polymorphisms (SNPs). SNPs are increasingly being used as an addition to the molecular ecology toolkit in nonmodel organisms, but their efficient use remains challenging. Here, we discuss common issues when employing SNP markers, including the high numbers of markers typically employed, the effects of ascertainment bias and the inclusion of nonneutral loci in a marker panel. We provide a critique of considerations specifically associated with the application and population genetic analysis of SNPs in nonmodel taxa, focusing specifically on some of the most commonly applied methods.
Effect of Acute Posttrauma Propranolol on PTSD Outcome and Physiological Responses During Script‐Driven Imagery
Authors: Hoge Elizabeth A. , Worthington John J. , Nagurney John T. , Chang Yuchiao , Kay Elaine B. , Feterowski Christine M. , Katzman Anna R. , Goetz Jared M. , Rosasco Maria L. , Lasko Natasha B. , Zusman Randall M. , Pollack Mark H. , Orr Scott. P. , Pitman Roger K.
Published: January 2011

Introduction: Animal and human research suggests that the development of posttraumatic stress disorder (PTSD) may involve the overconsolidation of memories of a traumatic experience. Previous studies have attempted to use pharmaceutical agents, especially the β‐adrenergic blocker propranolol, to reduce this overconsolidation. Aims: In this randomized, placebo‐controlled study of the efficacy of propranolol in reducing the development of PTSD, we optimized dosages and conducted both psychophysiological and clinical assessments 1 and 3 months after the traumatic event. Forty‐one emergency department patients who had experienced a qualifying acute psychological trauma were randomized to receive up to 240 mg/day of propranolol or placebo for 19 days. At 4 and 12 weeks post‐trauma, PTSD symptoms were assessed. One week later, participants engaged in script‐driven imagery of their traumatic event while psychophysiological responses were measured. Results: Physiological reactivity during script‐driven traumatic imagery, severity of PTSD symptoms, and the rate of the PTSD diagnostic outcome were not significantly different between the two groups. However, post hoc subgroup analyses showed that in participants with high drug adherence, at the 5‐week posttrauma assessment, physiological reactivity was significantly lower during script‐driven imagery in the propranolol than in the placebo subjects. Conclusions: The physiological results provide some limited support for a model of PTSD in which a traumatic conditioned response is reduced by posttrauma propranolol. However, the clinical results from this study do not support the preventive use of propranolol in the acute aftermath of a traumatic event.
Management challenges in psychiatric patients with severe mandibular pain: a case report
Authors: Cheng A , Kunchur R , Goss AN
Published: January 2011

A 68‐year‐old man was admitted to the psychiatric unit of a major hospital as he was threatening self‐harm due to uncontrolled left mandibular pain. Although he had significant psychiatric issues, psychiatric treatment did not help him. Further review at three weeks post‐admission showed that he had had many months of unsuccessful dental treatment and this had triggered his psychiatric crisis. Multidisciplinary investigation and communication showed that he had trigeminal neuralgia secondary to vascular changes in his temporal lobe. He responded well to explanation and anti‐neuralgic medication. Simple guidelines on how dental practitioners can cope with such patients are presented.
Composition as Identity Doesn’t Settle the Special Composition Question1
Authors: CAMERON ROSS P.
Published: January 2011

Orthodoxy says that the thesis that composition is identity (CAI) entails universalism: the claim that any collection of entities has a sum. If this is true it counts in favour of CAI, since a thesis about the nature of composition that settles the otherwise intractable special composition question (SCQ) is desirable. But I argue that it is false: CAI is compatible with the many forms of restricted composition, and SCQ is no easier to answer given CAI than otherwise. Furthermore, in seeing why this is the case we reveal an objection to CAI: that it allows for the facts concerning what there is to be settled whilst leaving open the question about what is identical to what.
The human circadian system adapts to prior photic history
Authors: Chang Anne‐Marie , Scheer Frank A. J. L. , Czeisler Charles A.
Published: January 2011

Non‐technical summary  The human biological clock organizes and regulates the timing of many biochemical and physiological processes, including the timing of sleep, on a daily basis. Light is the strongest time cue to the circadian clock that keeps these rhythms entrained to the 24 h day. Light exposure at night results in ‘resetting’ of the clock (phase shifting). In the current study, we examined the effects of exposing subjects to two different light levels (very dim light vs. typical room light) before exposure to a 6.5 h light exposure at night. Results showed that the very dim light level, compared to the typical room light level, prior to the light exposure at night caused a substantially greater phase shift of the melatonin rhythm and substantially greater acute melatonin suppression. Thus, prior dim light history sensitizes the human biological clock to the effect of a subsequent light exposure.
‘Systems biology’ in human exercise physiology: is it something different from integrative physiology?
Authors: Greenhaff Paul L. , Hargreaves Mark
Published: January 2011

Abstract On first impression the ‘whole‐istic approach to understanding biology’ that has been used to describe Systems Biology bears a striking resemblance to what many of us know as Integrative Physiology. However, closer scrutiny reveals that at the present time Systems Biology is rooted in processes operating at a cellular level (‘the study of an organism, viewed as an integrated and interacting network of genes, proteins and biochemical reactions which give rise to life … ultimately responsible for an organism's form and functions’;http://www.systemsbiology.org), and appears to have evolved as a direct result of advances in high throughput molecular biology platforms (and associated bioinformatics) over the past decade. The Systems Biology approach is in many ways laudable, but it will be immediately apparent to most exercise or integrative physiologists that the challenge of understanding the whole‐animal response to exercise as a network of integrated and interacting genes, proteins and biochemical reactions is unlikely to be realized in the near future. This short review will attempt to clarify conceptual inconsistencies between the fields of Systems Biology and Integrative Physiology in the context of exercise science, and will attempt to identify the challenges to whole‐body physiologists wishing to harness the tools of Systems Biology.
Lateral transmission of force is impaired in skeletal muscles of dystrophic mice and very old rats
Authors: Ramaswamy Krishnan S. , Palmer Mark L. , van der Meulen Jack H. , Renoux Abigail , Kostrominova Tatiana Y. , Michele Daniel E. , Faulkner John A.
Published: January 2011

Non‐technical summary  The force developed by a single fibre in frog muscles is transmitted laterally to the muscle surface with little or no loss. To demonstrate this phenomenon in mammals, a ‘yoke’ apparatus was developed that attached to the surface of whole, parallel‐fibred muscles and permitted measurements of the lateral transmission of forces. We then demonstrated that for wild‐type mice and rats longitudinal and lateral transmission of forces in muscles were not different. In contrast, for skeletal muscles of dystrophic mice and very old rats, in which the dystrophin‐associated glycoprotein complex (DGC) of fibres was disrupted, the forces transmitted laterally were impaired severely. We conclude that during contractions of skeletal muscles, an intact DGC is essential for the lateral transmission of force and disruptions of the DGC lead to sarcomere instability and contraction‐induced injury.
Hippocampal microcircuit dynamics probed using optical imaging approaches
Authors: Coulter Douglas A. , Yue Cuiyong , Ang Chyze Whee , Weissinger Florian , Goldberg Ethan , Hsu Fu‐Chun , Carlson Gregory C. , Takano Hajime
Published: January 2011

Abstract  Mammalian cortical structures are endowed with the capacity for plasticity, which emerges from a combination of the dynamics of circuit connectivity and function, and the intrinsic function of the neurons within the circuit. However, this capacity is accompanied by a significant risk: the capability to generate seizure discharges is also a property of all mammalian cortices. How do cortical circuits reconcile the requirement to maintain plasticity, but at the same time control seizure initiation? These issues come into particular focus in the hippocampus. The hippocampus is one of the main plasticity engines in the brain, and is also a structure frequently implicated in the generation of epileptic seizures, with temporal lobe epilepsy constituting the most prevalent form of epilepsy in the adult population. One aspect of hippocampal circuitry that is particularly prominent is its intimate interconnections with the entorhinal cortex. These interconnections create a number of excitatory synaptic loops within the limbic system, which, in addition to being important in cognitive function, can support reentrant activation and seizure generation. In the present review, using optical imaging approaches to elucidate circuit processing at high temporal and spatial resolution, we examine how two targets of entorhinal cortical input within the hippocampus, the dentate gyrus and area CA1, regulate these synaptic pathways in ways that can maintain functions important in generation of normal activity patterns, but that dampen the ability of these inputs to generate seizure discharges.
Heat Transfer Enhancement Using Laminar Gas-Liquid Segmented Plug Flows
Authors: Muzychka Y. S. , Walsh E. J. , Walsh P.
Published: January 2011

Heat transfer enhancement using segmented nonboiling gas-liquid flow is examined. Segmentation results in a two phase flow of liquid/gas having a constant liquid fraction; i.e., no phase change occurs. In this flow configuration, enhanced heat transfer occurs as a result of a shorter effective thermal length due to internal fluid circulation in the liquid plugs. A simple theory for laminar segmented flows is developed based on scaled Graetz theory and comparisons made with existing published data from the literature and new experimental data obtained in a companion study. The proposed model is valid for an isothermal tube wall provided that the axial residence time of the flow is such that dimensionless tube length L⋆<0.1.
A New
Technique to Determine Convection Coefficients With Flow Through Particle
Beds
Authors: Nie Xiaodong , Evitts Richard , Besant Robert , Bolster John
Published: January 2011

A new method for determining the heat transfer coefficient for air flowing steadily through beds of particles is presented. In this technique, a step change in the inlet air temperature is applied to a small test bed and temperature distributions in the bed and at the air outlet are sampled over a short time period. The convective heat transfer coefficient is determined using data from the convective heat transfer process in the bed where the analysis includes the partial differential equation that describes the transient energy storage in the particles within the bed. The analysis is performed for a short time duration when the temperature distribution in the particle bed is almost linear along the axis of the bed. This time period permits the most accurate determination of the heat transfer coefficient using the data. Using beds of spherical particles a new correlation is developed for the Nusselt number versus the Reynolds number (5<Redh<280) and includes the uncertainty bounds. This new correlation compares well with correlations developed by some other researchers for similar spherical particle beds.
An Improved Volume of Fluid Method for Two-Phase Flow Computations on Collocated Grid System
Authors: Sun Dong-Liang , Yang Yong-Ping , Xu Jin-Liang , Tao Wen-Quan
Published: January 2011

An improved volume of fluid method called the accurate density and viscosity volume of fluid (ADV-VOF) method is proposed to solve two-phase flow problems. The method has the following features: (1) All operations are performed on a collocated grid system. (2) The piecewise linear interface calculation is used to capture interfaces and perform accurate estimations of cell-edged density and viscosity. (3) The conservative Navier–Stokes equations are solved with the convective term discretized by a second and third order interpolation for convection scheme. (4) A fractional-step method is applied to solve the conservative Navier–Stokes equations, and the BiCGSTAB algorithm is used to solve the algebraic equations by discretizing the pressure-correction equation. The above features guarantee a simple, stable, efficient, and accurate simulation of two-phase flow problems. The effectiveness of the ADV-VOF method is verified by comparing it with the conventional volume of fluid method with rough treatment of cell-edged density and viscosity. It is found that the ADV-VOF method could successfully model the two-phase problems with large density ratio and viscosity ratio between two phases and is better than the conventional volume of fluid method in this respect.
Drilling Action of Roller-Cone Bits: Modeling and Experimental Validation
Authors: Franca Luiz F. P.
Published: January 2011

This paper presents a new model of the drilling response of roller-cone bits. First, a set of relations between the weight-on-bit W, the torque-on-bit T, the rate of penetration V, and the angular velocity Ω is established in the spirit of the model developed for polycrystalline diamond compact (PDC) bits. In contrast to models that depend on a precise description of the bit, the drilling response is investigated by lumping the effect of the bit geometry into a few parameters and on averaging the drilling quantities (W,T,V,Ω) over at least one revolution of the bit. Within the framework of the model, quantitative information from drilling data related to rock properties, bit conditions, and drilling efficiency can be extracted. Finally, a series of laboratory tests at atmospheric pressure conducted with an in-house designed drilling rig, together with published experimental data, is used to evaluate the proposed model. The good match between the experimental results and the theoretical predictions are promising in regard to the potential use of this model to investigate the drilling response of roller-cone bits.
Green Energy Storage for Better Gas Turbine Efficiency
Authors: Langaker John T.
Published: January 2011

Everyone with green ambitions wants to see a full fleet of 100 percent renewable energy sources drive the world’s electric power grids. Until that happens, the next best solution integrates renewable energy generators with existing gas-fired power plants to improve their warmer-weather efficiency when generating on their larger scale by using methods of energy storage and distribution. Relatively clean burning on their own, large gas turbine generators are examples of proven opportunities to gain significant efficiency and recover output by using stored thermal energy to cool their inlet air when called to operate during hotter seasons of the year. Sustainable energy sources like wind and solar, which today generate in peaks and troughs that are hard to manage on electric power grids, beckon to be put into service for thermal energy storage instead of direct on-line grid interconnection. This article steps through the implementation of such storage.
Tuning the Extinction Coefficient for Direct Absorption Solar Thermal Collector Optimization
Authors: Otanicar Todd P. , Phelan Patrick E. , Taylor Robert A. , Tyagi Himanshu
Published: January 2011

Direct-absorption solar thermal collectors have recently been shown to be a promising technology for photothermal energy conversion but many parameters affecting the overall performance of such systems haven’t been studied in depth, yet alone optimized. Earlier work has shown that the overall magnitude of the extinction coefficient can play a drastic role, with too high of an extinction coefficient actually reducing the efficiency. This study investigates how the extinction coefficient impacts the collector efficiency and how it can be tuned as a function of depth to optimize the efficiency, and why this presents a unique design over conventional solar thermal collection systems. Three extinction profiles are investigated: uniform, linearly increasing, and exponentially increasing.
Passive House Design Guidelines for Residential Buildings in El Salvador
Authors: Martinez Luis Aaron
Published: January 2011

The reduction of anthropogenic green house gas emissions through increased building energy efficiency is a global effort, which is a responsibility of both developed and developing nations. The Passive House concept is a building design methodology that advocates for a systematic optimization and integration of the building envelope and internal loads in order to achieve a passive yet comfortable performance. Multiple passive houses have been built and monitored in Europe and the United States. The present paper attempts to determine what design features are required for tropical residential buildings to meet the Passive House Standard. This study was conducted in El Salvador, which experiences a warm and humid climate throughout the year. For economic and cultural reasons, few residential buildings in the country have air conditioning systems. However, the vast majority of residential buildings have not been designed using passive principles, causing great occupant discomfort and increasing energy consumption for cooling. Both the Passive House Planning Package (PHPP) software and EnergyPlus were used in order to determine the design parameters that would yield a passive house for this climate. In addition, the paper discusses the technical and economic feasibility of modifying a typical house to meet the standard. The potential benefits related to occupant comfort and energy cost savings are also discussed.
Development of a “Solar Patch” Calculator to Evaluate Heliostat-Field Irradiance as a Boundary Condition in CFD Models
Authors: Khalsa Siri Sahib S. , Ho Clifford K.
Published: January 2011

A rigorous computational fluid dynamics (CFD) approach to calculating temperature distributions, radiative and convective losses, and flow fields in a cavity receiver irradiated by a heliostat field is typically limited to the receiver domain alone for computational reasons. A CFD simulation cannot realistically yield a precise solution that includes the details within the vast domain of an entire heliostat field in addition to the detailed processes and features within a cavity receiver. Instead, the incoming field irradiance can be represented as a boundary condition on the receiver domain. This paper describes a program, the Solar Patch Calculator, written in Microsoft Excel VBA to characterize multiple beams emanating from a “solar patch” located at the aperture of a cavity receiver, in order to represent the incoming irradiance from any field of heliostats as a boundary condition on the receiver domain. This program accounts for cosine losses; receiver location; heliostat reflectivity, areas and locations; field location; time of day and day of year. This paper also describes the implementation of the boundary conditions calculated by this program into a Discrete Ordinates radiation model using Ansys® FLUENT (www.fluent.com), and compares the results to experimental data and to results generated by the code DELSOL.
Methodology to Assess Potential Glint and Glare Hazards From Concentrating Solar Power Plants: Analytical Models and Experimental Validation
Authors: Ho Clifford K. , Ghanbari Cheryl M. , Diver Richard B.
Published: January 2011

With growing numbers of concentrating solar power systems being designed and developed, glint and glare from concentrating solar collectors and receivers is receiving increased attention as a potential hazard or distraction for motorists, pilots, and pedestrians. This paper provides analytical methods to evaluate the irradiance originating from specularly and diffusely reflecting sources as a function of distance and characteristics of the source. Sample problems are provided for both specular and diffuse sources, and validation of the models is performed via testing. In addition, a summary of safety metrics is compiled from the literature to evaluate the potential hazards of calculated irradiances from glint and glare. Previous safety metrics have focused on prevention of permanent eye damage (e.g., retinal burn). New metrics used in this paper account for temporary flash blindness, which can occur at irradiance values several orders of magnitude lower than the irradiance values required for irreversible eye damage.
Learnable Lessons on Sustainability From the Provision of Electricity in South Africa
Authors: Heun M. K. , van Niekerk J. L. , Swilling M. , Meyer A. J. , Brent A. , Fluri T. P.
Published: January 2011

South Africa is a “canary in a coal mine” for the world’s upcoming ecological crises, especially regarding electrical energy provision for a developing modern society, because aspects of the South African situation may be repeated elsewhere when ecological limits constrain economic activity. We describe the South African context in terms of social issues and economic development policies, environmental issues, and the electrical energy situation in the country. We explore implications of the South African context for the provision of electrical energy in terms of development objectives, climate change, the electrical grid, water, and solar, wind, ocean, and hydro energy resources. Thereafter, we explore future directions for electrical energy provision in the country, including some important questions to be answered. Next, we offer a rational way forward, including an assessment favoring concentrated solar power (CSP) as a path of least resistance for decoupling South Africa’s energy use from upstream and downstream environmental impacts. We conclude with some learnable lessons from the South African context for the rest of the developing and developed world.
Using Core Sunlighting to Improve Illumination Quality and Increase Energy Efficiency of Commercial Buildings
Authors: Whitehead Lorne , Upward Allen , Friedel Peter , Cox Guthrie , Mossman Michele
Published: January 2011

The lighting industry has been challenged to deliver high quality illumination while using less electrical energy and, to achieve this, it is generally agreed that it is a good idea to incorporate daylighting strategies. We have developed a new system that is capable of delivering sunlight deep into the core of multi-floor buildings. This system has the potential to reduce the energy required for illumination in standard commercial buildings by at least 25%, reduce peak electrical power demand when it is needed, and provide high quality illumination with excellent color rendering characteristics. This result is achieved by delivering sunlight to the interior regions of the building, thereby replacing electric lighting on average 75% of the time each day that the sun shines within six core daylight hours. As a result of both its cost-effectiveness and the ease with which it can be integrated into standard building construction, this is the first core sunlighting system with potential for widespread adoption. An initial demonstration shows a substantial reduction in the electrical lighting load and enables an evaluation of the spectral quality of the sunlight illumination from the perspective of the occupants.
IT-Enabled Resource Management
Authors: Shah Amip , Sharma Ratnesh , Bash Cullen , Marwah Manish , Christian Tom , Patel Chandrakant , Corrigan Kiara
Published: January 2011

As information technology becomes more widespread, access to real-time data regarding the supply and demand for resources is becoming central to the management of physical infrastructures. Current information systems for resource management are mostly static, so an underlying challenge in the management of resources is how to overcome time-lags in information transfer for efficiently measuring demand and then adequately provisioning a supply of resources to meet that demand. Particularly in the context of ‘smart cities’, a new framework is required for information management in the context of resource management. In this paper, we propose an information architecture consisting of life-cycle design, scalable and flexible resource microgrids, pervasive sensing, data analytics and visualization, and policy-based autonomous control that directly links real-time demand patterns to the state of various supply-side management systems. This integrated supply-demand information system is used to obtain a more holistic view of information flow through the infrastructure. We show that such an architecture is more efficient at information transfer than existing systems, and posit that this increased efficiency in turn enables improved management of resources within the infrastructure because of the availability of a higher number of degrees of freedom in the management of the infrastructure. The paper concludes by illustrating the applicability of the proposed architecture for a case study of two large-scale infrastructures.
Cerium Oxide Materials for the Solar Thermochemical Decomposition of Carbon Dioxide
Authors: Siegel Nathan P. , Livers Stephanie , Miller James E. , Diver Richard B.
Published: January 2011

We have experimentally investigated the thermochemical decomposition of carbon dioxide using pure cerium oxide fibrous structures. Experiments were conducted on-sun with a solar furnace and include two reaction steps: the thermal reduction of CeOα to CeOβ between 1500°C and 1600°C, and the re-oxidation of CeOβ to produce carbon monoxide under flowing carbon dioxide at temperatures between 800°C and 1200°C. A ceria-based cycle offers some advantages over similar thermochemical cycles including the reduction of sintering and volatility issues during thermal reduction, a stable crystal structure over the range of operating temperatures, and the ability for all of the material to participate in the thermochemical reactions, i.e. there is no inert support. We present experimental results indicating that pure ceria structures perform at a level comparable to ferrite-based structures with respect to material utilization and better than the ferrites with respect to the carbon monoxide production rate during the oxidation step. We also discuss the performance potential of a solar reactor that continuously produces carbon monoxide using ceria in a two-step thermochemical cycle.
Testing of a CR5 Solar Thermochemical Heat Engine Prototype
Authors: Diver Richard B. , Miller James E. , Siegel Nathan P. , Moss Timothy A.
Published: January 2011

Sandia National Laboratories (SNL) is investigating thermochemical approaches for reenergizing CO2 and H2O feed stocks for input to synthetic liquid hydrocarbon fuels production. Key to the approach is the Counter-Rotating-Ring Receiver/Reactor/Recuperator (CR5), a novel solar-driven thermochemical heat engine concept for high-temperature carbon dioxide and water splitting based on two-step, nonvolatile metal oxide thermochemical cycles. The CR5 integrates two reactors, recuperators, and solar receiver and intrinsically separates the product gases. The CR5 thermochemical heat engine concept and the underlying thermodynamics and kinetics have many uncertainties. While results from laboratory scale material tests are promising, they are different than what occurs in a CR5. To evaluate the potential of the CR5 we have designed and built a CR5 prototype. The overall objective of the SNL Sunshine to Petrol (S2P) project is to show a solar thermochemical pathway for the efficient production of liquid fuels from CO2 and H2O feed stocks. To achieve the overall long-term goal of 10% efficient conversion of sunlight to petroleum, the thermochemical solar conversion of sunlight to CO needs to be 20% efficient. The short-term goal for the CR5 prototype is to demonstrate a solar to chemical conversion efficiency of at least 2%. In this paper, we present initial test results for the CR5 prototype in the 16 kWt National Solar Thermal Test Facility (NSTTF) solar furnace in Albuquerque, NM. Lessons learned from the initial tests and approaches for improving performance to achieve our goals are also presented.
An Air-Based Cavity-Receiver for Solar Trough Concentrators
Authors: Bader Roman , Barbato Maurizio , Pedretti Andrea , Steinfeld Aldo
Published: January 2011

A cylindrical cavity-receiver containing a tubular absorber that uses air as the heat transfer fluid is proposed for a novel solar trough concentrator design. A numerical heat transfer model is developed to determine the receiver’s absorption efficiency and pumping power requirement. The 2D steady-state energy conservation equation coupling radiation, convection and conduction heat transfer is formulated and solved numerically by finite-difference techniques. The Monte Carlo ray-tracing and radiosity methods are applied to establish the solar radiation distribution and radiative exchange within the receiver. Simulations were conducted for a 50 m-long and 9.5 m-wide collector section with 120°C air inlet temperature, and air mass flows in the range 0.1–1.2 kg/s. Outlet air temperatures ranged from 260 to 601 °C, and corresponding absorption efficiencies varied between 60 and 18%. Main heat losses integrated over the receiver length were due to reflection and spillage at the receiver’s windowed aperture, amounting to 13% and 9% of the solar power input, respectively. The pressure drop along the 50 m module was in the range 0.23 to 11.84 mbar, resulting in isentropic pumping power requirements of 6.45·10−4%–0.395% of the solar power input.
Solar Absorption Chiller Optimization by Using Genetic Algorithms
Authors: Godarzi Ali Abbasi , Samimi Jalal , Jalilian Masoud , Vesaghi Mohammad Ali
Published: January 2011

The main propose of this research is providing a tool for suitable modeling, increase efficiency and decrease construction cost of solar absorption chiller. At first, the solar absorption chiller is modeled by the thermodynamic laws. Then, this model is converted to the new standard mathematical programming model with considering all technical and economic constrains. This mathematical model is optimized by Genetic algorithm (GA). After applying GA, optimized parameters of chiller heat exchanger designing and its electricity consumption are calculated. These parameters consist of heat exchanger effectiveness, heat transfer cross section area, heat transfer coefficient, efficiency of pump and motor. The effect of costs economic optimization is shown with comparing the optimum point and a system base case. It will be shown that for optimum point the total investment cost increases 2.0568% while the sum of destruction and loss exergy decreases 0.21% and annual cost decrease about 8.91% rather than base case. Coaling load of evaporator is related to an apartment with 50 m2 Area in Tehran (case study).
Enhanced Efficiency in a Coupled Photovoltaic/Thermal Concentrating Solar Collector
Authors: Chowdhury Ihtesham , Otanicar Todd , Prasher Ravi , Sherbeck Jonathan , Phelan Patrick , Burrell Marc
Published: January 2011

We present an analysis of combined efficiencies in a coupled photovoltaic/thermal concentrating solar collector. The calculations take into account the drop in efficiency that accompanies the operation of photovoltaic cells at elevated temperatures along with a detailed analysis of the thermal system including all losses. An iterative numerical scheme is described that involves a coupled electro-thermal simulation of the solar energy conversion process. In the proposed configuration losses in the photovoltaic cell due to reduced efficiencies at elevated temperatures and the incident solar energy below the PV bandgap are both harnessed as heat. This thermal energy is then used to run a thermodynamic power cycle. The simulations show that it is possible to optimize the overall efficiency of the system by variation of key factors such as the solar concentration factor, band gap of the photovoltaic material, and the system thermal design configuration.
3D Modeling of Polymer Electrolyte Fuel Cell and Hydride Hydrogen Storage Tank
Authors: Wang Yun
Published: January 2011

3D dynamic models are developed for polymer electrolyte fuel cells (PEFCs) and hydrogen tanks, respectively. In the fuel cell model, we consider the major transport and electrochemical processes within the key components of a single PEFC that govern fuel cell transient including the electrochemical double-layer behavior, mass/heat transport, liquid water dynamics, and membrane water uptake. As to modeling hydrogen tanks, we consider a LaNi5-based system and develop a general formula that describes hydrogen absorption/desorption. The model couples the hydride reaction kinetics and mass/heat transport. The dynamic characteristics of the PEFC and hydrogen tank, together with the possible coupling of the two systems, are discussed.
Modeling and Analysis of Polymer Electrolyte Fuel Cell Cold-Start
Authors: Wang Yun , Mishler Jeffrey
Published: January 2011

In this paper, we develop a model to investigate the cold-start operation of polymer electrolyte fuel cell (PEFC). The model describes the electrochemical kinetics, heat/mass transport, and solid water formation in polymer electrolyte fuel cell (PEFC) during cold start. A simplified analysis is developed to investigate the temperature-dependent change of the ohmic voltage loss based on the ionic conductivity of the membrane at subfreezing temperature. 3D numerical simulation is also conducted to study the dynamics of the solid water during cold start and the distributions of ice volume fraction and current density. This study is valuable for improving the characteristics of PEFC cold-start.
Fabrication of Micro PEM Fuel Cells Using Pyrolysis and Experimental Testing
Authors: Wang Yun , Pham Liem , Vasconcellos Guilherme Porto
Published: January 2011

In this paper, we propose a relatively new fabrication technique for micro proton exchange membrane fuel cell (μPEMFC) fabrication. Microgrooves are fabricated on the polymer Circlex plate first which is relatively easy to manufacture comparing with directly patterning on carbon, cheap, and mechanically robust (in contrast to graphite). By carbonizing the machined polymer at high temperature, the bipolar plates are produced for a μPEMFC assembly to distribute the reactants via its micro groove structure. A μPEMFC with 0.64 cm2 active surface is fabricated. A maximum power of ∼70 mW/cm2 is achieved for 1 atm at 25 °C, which is comparable with most of data reported in the literature. The Electrochemical Impedance Spectroscopy (EIS) and performance test are conducted on fuel cell steady-state operation.
Towards Optimizing Building Energy Use to Reduce Electric System Carbon Emissions
Authors: Greensfelder Erik M. , Henze Gregor P. , Cushing Vincent J.
Published: January 2011

In spite of heightened interest in anthropogenic climate change, little attention has been paid to optimizing a building’s carbon emissions at the source. Most work in building efficiency has assumed that generating plant carbon emissions are constant at their long-term average values. This study sought to improve our understanding of the temporal variations in carbon emissions on a diurnal time scale and their relation to electric system dispatch and load in order to motivate future work in optimizing building operation to reduce carbon emissions. Hourly fossil fuel plant emissions and load data, available from the EPA, were used to characterize power system performance for four US locations (IL, NY, TX, and CA). The study had set out with a hypothesis hoping to find a simple relationship between electric system load and emissions. It was found that there is a significant correlation between increased system load and decreased emissions rates, yet this correlation is not easily defined. During high load conditions, emissions reductions are related to the increased use of gas generators, or may be related to operating plants at more efficient part load ratios. The work conducted in this study shows that, while more complex than hoped for, there is indeed a strong relationship between electric system load and carbon emissions rates.
Analysis of Carbon Dioxide Emission Reductions From Energy Efficiency Upgrades in Consideration of Climate Change and Renewable Energy Policy Initiatives Using eQUEST
Authors: Sclafani Anthony
Published: January 2011

In January 2008 the Governor of Hawaii announced the Hawaii Clean Energy Initiative; an initiative that aims to have at least 70 percent of Hawaii’s power come from clean energy by 2030 [4]. In July 2009, the Hawaii Department of Accounting and General Services awarded NORESCO, an energy service company, a $33.9M contract to improve the energy efficiency of 10 government buildings. The avoided utility cost of the energy and water savings from the improvements is the project funding mechanism. The energy savings realized by the project will reduce carbon dioxide emissions associated with utility power generation. However, as renewable energy becomes a larger portion of the utility generation profile through the Hawaii Clean Energy Initiative, the carbon dioxide emissions reductions from specific energy efficiency measures may erode over time. This work presents a method of analysis to quantify the carbon dioxide emissions reduction over the life of a project generated by energy efficiency upgrades that accounts for both the impact of policy initiatives and climate change using DOE-2/eQUEST. The analysis is based on the fact that HVAC energy usage will vary with climate changes and that carbon dioxide emission reductions will vary with both energy savings and the corresponding utility’s power generation portfolio. The energy savings related to HVAC system energy efficiency improvements are calculated over the life of a 20 year performance contract using a calibrated DOE-2/eQUEST model of an existing building that utilizes weather data adjusted to match the predictions of the Intergovernmental Panel on Climate Change. The carbon dioxide emissions reductions are calculated using the energy savings results and a projection of the implementation of the Hawaii Clean Energy Initiative. The emissions reductions are compared with other analysis methods and discussed to establish more refined expectations of the impact of energy efficiency projects in context with climate changes and policy initiatives.
Exergy Analysis of an Integrated Gas Turbine Thermoacoustic Engine
Authors: Ghorbanian Kaveh , Karimi Mohsen
Published: January 2011

An attempt is made to utilize exhaust gases of a small gas turbine in augmenting power output through the employment of a thermoacoustic system. It is assumed that the thermoacoustic system is powered only by the waste heat of the gas turbine. A comprehensive cycle analysis of the integrated gas turbine thermoacoustic engine “IGTTE” is carried out from energy and exergy point of view. Results indicate the thermodynamic advantages of the IGTTE.
Installation and Operation of Southern Nevada Water Authority High Concentration Amonix Multi-Junction System
Authors: Wood Gary , Sahm Aaron , Hurt Rick , Boehm Robert , Stone Kenneth W.
Published: January 2011

The Southern Nevada Water Authority contracted with Amonix, Inc. in 2008 to procure 220 kWdc of their latest generation multi-junction cell High Concentration Photovoltaic system. This paper describes the installation of the six HCPV systems including the design layout of the field, installation of the foundations, the PV modules, and tracking control systems. In addition, the basic operation and features of the Amonix HCPV system are discussed, along with data showing the performance of each system since the start of operation.