bluuebunny/crossref_metadata_2025 huggingface dataset:
Parents’ perceptions and attitudes on childhood obesity: A Q‐methodology study
Authors: Akhtar‐Danesh Noori , Dehghan Mahshid , Morrison Katherine M. , Fonseka Sujeewa
Published: January 2011

Purpose: The purpose of this study was to investigate parents of young children for their perceptions on the causes of obesity, the impact of childhood obesity on health, and the barriers to successful prevention of childhood obesity.

Data sources: The target population included parents who attended a clinic for their well‐baby check‐up. The study was conducted in two phases. Using Q‐methodology, 33 parents were classified into two groups representing two viewpoints: “confident in delivering healthy nutrition” and “family physical activity focused.”

Conclusion: This work indicates that parents have varying foci on causation of obesity, and differ in focus on nutrition and physical activity. Most of the parents in this study were aware of healthy nutrition, and about one third of them believed in the benefits of physical activity for children and did not see being overweight or obese as a barrier to physical activity. The first group was confident in being able to deliver healthy nutrition to their family, and the second group was characterized by a focus on physical activity and its role in childhood obesity. Both groups agreed that exercising and sports are very important to a child's health status.

Implications for practice: Nurse practitioners have a unique role in the health system and are one of the best facilitators to deliver health messages to the public; thus, they are able to educate parents and increase their awareness about the causes and consequences of childhood obesity.
Overweight and obesity: Pharmacotherapeutic considerations
Authors: Balkon Nancy , Balkon Craig , Zitkus Bruce S.
Published: January 2011

Purpose: This article reviews current trends for using pharmacotherapy in combination with other weight loss modalities and offers points for consideration by clinicians in practice.

Data sources: Selected evidence‐based articles and government websites.

Conclusions: Pharmacotherapy as a strategy for managing overweight, obese, and extremely obese individuals remains controversial. Risk versus benefit and overall safety of prescription drugs for weight loss management remains a primary focus for consideration among clinicians and a viable topic for evidence‐based outcomes research.

Implications for practice: Overweight and obesity are well accepted as critical risk factors and predictors of morbidity and mortality in individuals of all ages from childhood to senescence. In the United States, overweight and obesity exist in epidemic proportions. It is critical that primary care providers be knowledgeable about pharmacologic factors related to obesity.
Achieving consensus in follow‐up practice for routine ENT procedures: a Delphi exercise
Authors: Powell J. , El Dean H. , Carrie S. , Wilson J.A. , Paleri V.
Published: January 2011

Clin. Otolaryngol. 2011, 36, 45–50

Objectives:  To generate consensus amongst faculty members regarding follow‐up practice for well‐defined clinical scenarios using a Delphi exercise and to identify whether disseminating the consensus guidelines changed follow‐up practice.

Study Design:  Generation of consensus using a Delphi exercise and an audit of follow‐up practice before and after dissemination of the resultant guidelines.

Setting:  The department of Otorhinolaryngology‐Head and Neck Surgery at the Freeman Hospital, Newcastle upon Tyne, UK.

Participants and methods:  Panel members for this exercise included 11 consultants and two associate specialists and one co‐ordinator. We identified clinical scenarios where ≥80% agreement existed that routine follow‐up appointments should not be made and subsequently disseminated guidelines widely to all medical staff. The follow‐up rates for the scenarios where consensus existed regarding follow‐up practice were audited from clinic letters before and after the guidelines were disseminated.

Main outcome measures:  Agreement on scenarios where routine follow‐up appointments should not be made was assessed using a Likert scale (1–5).

Results:  Of 13 faculty members, 12 responded to rounds one and two, and 11 responded to round three. The Delphi exercise identified 18 clinical scenarios where there was ≥80% agreement on patients not routinely being followed up. Comparison of the follow‐up practice prior to and after the Delphi exercise identified a reduction in follow‐up for all 18 scenarios of 48%.

Conclusion:  Consensus regarding routine follow‐up can be reached by using the Delphi process in ENT practice. This can translate into a real change in clinical practice. Furthermore, this process could be applied for consensus building in other related areas.
Structural basis of influenza virus neutralization
Authors: Han Thomas , Marasco Wayne A.
Published: January 2011

Although seasonal influenza vaccines play a valuable role in reducing the spread of virus at the population level, ongoing viral evolution to evade immune responses remains problematic. No current vaccines elicit enduring protection in the face of emerging and re‐emerging influenza viruses that are rapidly undergoing antigenic drift. Eliciting broadly cross‐neutralizing antibody (nAb) responses against influenza virus is a crucial goal for seasonal and pandemic influenza vaccine preparation. Recent three‐dimensional structure information obtained from crystallization of influenza antigens in complex with nAbs has provided a framework for interpreting antibody‐based viral neutralization that should aid in the design of vaccine immunogens. Here, we will review current knowledge of the structure‐based mechanisms contributing to the neutralization and neutralization escape of influenza viruses. We will also explore the potential for this structure‐based approach to overcome the obstacles in developing the highly desired “universal” influenza vaccine.
Photosensitive Cross‐linked Block Copolymers with Controllable Release
Authors: Yu LiLi , Lv Cong , Wu LiZhu , Tung ChenHo , Lv WanLiang , Li ZhongJin , Tang XinJing
Published: January 2011

We intend to form photosensitive block copolymer micelles for controllable release of encapsulated substances. Here, we designed and synthesized a new photocleavable cross‐linker (2‐nitrophenyl ethylene glycol dimethacrylate) for methyl methacrylate (MMA) atom transfer radical polymerization. Four different ratios (0:1, 1:26, 1:16, 1:8.8) of the photocleavable cross‐linker to MMA monomer were used and four block copolymers (P0, P1, P2, P3) were synthesized with PEO‐Br as the macroinitiator. Gel permeation chromatography and 1H NMR studies showed that linear polymer molecules could be cross‐linked by the photocleavable linker. The fluorescence studies of the encapsulated Nile Red (NR) showed that there were lower critical micelle concentrations for the polymer P1, P2 and P3 than polymer P0. And dynamic light scattering and SEM confirmed the formation of polymer micelles. Photolysis experiments demonstrated that NR encapsulated in the polymer micelles could be released upon UV irradiation (365 nm, 11 mW cm−2) due to the breakage of the photocleavable linker and the generation of more hydrophilic acid moieties, which destabilized polymer micelles. Our study shows a new strategy for the possibility of photocontrollable drug release for hydrophobic drugs.
Inbreeding effective population size and parentage analysis without parents
Authors: WAPLES ROBIN S. , WAPLES RYAN K.
Published: January 2011

An important use of genetic parentage analysis is the ability to directly calculate the number of offspring produced by each parent (ki) and hence effective population size, Ne. But what if parental genotypes are not available? In theory, given enough markers, it should be possible to reconstruct parental genotypes based entirely on a sample of progeny, and if so the vector of parental ki values. However, this would provide information only about parents that actually contributed offspring to the sample. How would ignoring the ‘null’ parents (those that produced no offspring) affect an estimate of Ne? The surprising answer is that null parents have no effect at all. We show that: (i) The standard formula for inbreeding Ne can be rewritten so that it is a function only of sample size and ; it is not necessary to know the total number of parents (N). This same relationship does not hold for variance Ne. (ii) This novel formula provides an unbiased estimate of Ne even if only a subset of progeny is available, provided the parental contributions are accurately determined, in which case precision is also high compared to other single‐sample estimators of Ne. (iii) It is not necessary to actually reconstruct parental genotypes; from a matrix of pairwise relationships (as can be estimated by some current software programs), it is possible to construct the vector of ki values and estimate Ne. The new method based on parentage analysis without parents (PwoP) can potentially be useful as a single‐sample estimator of contemporary Ne, provided that either (i) relationships can be accurately determined, or (ii) can be estimated directly.
The Monitor Practice Programme: is non‐invasive management of dental caries in private practice cost‐effective?
Authors: Curtis B , Warren E , Pollicino C , Evans RW , Schwarz E , Sbaraini A
Published: January 2011

Background:  The objective of this research was to assess the efficacy and cost‐effectiveness of a non‐invasive approach to dental caries management in private dental practice.

Methods:  Private dental practices from a variety of locations in New South Wales were randomly allocated to either non‐invasive management of caries, or continue with usual care. Patients were followed for three years and caries incidence assessed. A patient‐level decision analytic model was constructed to assess the cost‐effectiveness of the intervention at two years, three years, and hypothetical lifetime.

Results:  Twenty‐two dental practices and 920 patients were recruited. Within the clinical trial there was a significant difference in caries increment favouring non‐invasive therapy at both two and three years. Efficacy was independent of age, gender, medical concerns, fluoride history, or previous history of dental caries, in a population of patients attending for treatment in private dental practices, in a variety of locations both urban and rural. Cost per DMFT avoided estimate was A$1287.07 (two years), A$1148.91 (three years) decreasing to A$702.52 in (medium) and A$545.93 (high) risk patients (three years).

Conclusions:  A joint preventive and non‐invasive therapeutic approach appears to be cost‐effective in patients at medium and high risk of developing dental caries when compared to the standard care provided by private dental practice.
Temporomandibular joint reconstruction with total alloplastic joint replacement
Authors: Jones RHB
Published: January 2011

This paper is a preliminary paper which presents the early findings of an ongoing prospective trial on the use of the TMJ Concepts and Biomet Lorenz total joint replacement systems for the reconstruction of the temporomandibular joint (TMJ).

Total alloplastic replacement of the TMJ has become a viable option for many people who suffer from TMJ disease where surgical reconstruction is indicated. Degenerative joint diseases such as osteoarthritis, rheumatoid arthritis, psoriatic arthritis, TMJ ankylosis, malunited condylar fractures and tumours can be successfully treated using this technique.

There are a number of TMJ prostheses available. Two of the joint replacement products, which have been found to be most reliable and have FDA approval in the United States, are the TMJ Concepts system and the Biomet Lorenz system, and for this reason they are being investigated in this study.

This study presents the findings of seven patients with a total of 12 joint replacements using either the TMJ Concepts system or the Biomet Lorenz joint system. Two patients (3 joints) had the TMJ Concepts system and five patients (9 joints) had the Biomet Lorenz system.

Although still early, the results were generally pleasing, with the longest replacement having been in position for three years and the most recent six months. The average postoperative mouth opening was 29.7 mm (range 25–35 mm) with an average pain score of 1.7 (range 0–3, minimum score of 0 and maximum 10). Complications were minimal and related to sensory disturbance to the lip in one patient and joint dislocation in two patients.
How the World Is Measured Up in Size Experience
Authors: BENNETT DAVID J.
Published: January 2011

I develop a Russellian representationalist account of size experience that draws importantly from contemporary vision science research on size perception. The core view is that size is experienced in ‘body‐scaled’ units. So, an object might, say, be experienced as two eye‐level units high. The view is sharpened in response to Thompson’s (forthcoming) Doubled Earth example. This example is presented by Thompson as part of an argument for a Fregean view of size experience. But I argue that the Russellian view I develop handles the Doubled Earth example in a natural and illuminating way, thereby avoiding the need to posit irreducible experiential ‘modes of presentation’. I also address a kind of neo‐Fregean ‘reference‐fixing’ view of size experience, that shares features with the Russellian view developed. I give reasons for favoring the latter. Finally, I argue that Peacocke’s claim that spatial experience is ‘unit free’ is not persuasive.
Do Extrinsic Dispositions Need Extrinsic Causal Bases?
Authors: CONTESSA GABRIELE
Published: January 2011

In this paper, I distinguish two often‐conflated theses—the thesis that all dispositions are intrinsic properties and the thesis that the causal bases of all dispositions are intrinsic properties—and argue that the falsity of the former does not entail the falsity of the latter. In particular, I argue that extrinsic dispositions are a counterexample to first thesis but not necessarily to the second thesis, because an extrinsic disposition does not need to include any extrinsic property in its causal basis. I conclude by drawing some general lessons about the nature of dispositions and their relation to their causal bases.
On the Reduction of Necessity to Essence
Authors: CORREIA FABRICE
Published: January 2011

In his influential paper ‘‘Essence and Modality’’, Kit Fine argues that no account of essence framed in terms of metaphysical necessity is possible, and that it is rather metaphysical necessity which is to be understood in terms of essence. On his account, the concept of essence is primitive, and for a proposition to be metaphysically necessary is for it to be true in virtue of the nature of all things. Fine also proposes a reduction of conceptual and logical necessity in the same vein: a conceptual necessity is a proposition true in virtue of the nature of all concepts, and a logical necessity a proposition true in virtue of the nature of all logical concepts. I argue that the plausibility of Fine's view crucially requires that certain apparent explanatory links between essentialist facts be admitted and accounted for, and I make a suggestion about how this can be done. I then argue against the reductions of conceptual and logical necessity proposed by Fine and suggest alternative reductions, which remain nevertheless Finean in spirit.
Splitting Water and Carbon Dioxide via the Heterogeneous Oxidation of Zinc Vapor: Thermodynamic Considerations
Authors: Venstrom Luke J. , Davidson Jane H.
Published: January 2011

The heterogeneous hydrolysis/oxidation of zinc vapor is proposed as a promising reaction path for the exothermic step in two-step Zn/ZnO solar thermochemical water and carbon dioxide splitting cycles. This approach circumvents mass transfer limitations encountered in the oxidation of solid or liquid zinc, promising rapid hydrogen/carbon monoxide production rates and complete conversion of zinc. In this paper, a parametric thermodynamic analysis is presented to quantify the penalty of generating zinc vapor as well as the benefit of achieving complete conversion of zinc via the heterogeneous oxidation of zinc vapor. The penalty for generating zinc vapor is a reduction in water splitting efficiency from 36% to 27% and a reduction in carbon dioxide splitting efficiency from 39% to 31%. However, with heat recuperation this penalty can be avoided. The benefit of completely converting zinc via the heterogeneous oxidation of zinc vapor is an increase in efficiency from ∼6% to 27% and 31% for water and carbon dioxide splitting, respectively.
Analytical Thermal Analysis of Solar Chimney Power Plant
Authors: Hamdan Mohammad O.
Published: January 2011

An analytical model and a thermodynamics study of the steady airflow inside a solar chimney are performed in this paper. A simplified Bernoulli equation combined with fluid dynamics and ideal gas equation are modeled and solved using EES solver to predict the performance of a solar chimney power plant. The analytical model is validated against an experimental and numerical data available in the literature. The developed analytical model is used to evaluate the effect of geometric parameters on the solar plant power generation. The analysis is showing that the height and diameter of the tower are the most important physical variables for the solar chimney design. The collector area has minimal effect on second-law efficiency but strong effect on harvested energy. The second law efficiency has non-monotonic relation with the turbine head.
Leveraging Refinery Dominance in Transportation Fuel Supply to Encourage Adoption of Climate Change-Mitigating Transportation Technologies in California
Authors: Grubert Emily A.
Published: January 2011

California’s main source of greenhouse gas emissions is transportation, a relatively uncontrolled sector. Of the major energy commodities used by individuals, transport fuels are alone in lack of utility regulation: the dominance of refineries as transportation fuel suppliers suggests there may be an opportunity for California to engage its refining industry about transitioning into a transportation fuel utility role. While this concept could be extended beyond California, it is uniquely suited to California because of the State’s fuel isolation from the rest of the country: with its demand for a boutique low-pollution fuel, California is served almost exclusively by Californian refineries that face a different set of regulations than most other American refineries do. Due to infrastructural barriers and long vehicle lifetime, most forecasts predict slow penetration of alternative transportation technologies, even as policymakers suggest an urgent need for rethinking the transportation system. These infrastructural barriers, including the chicken-and-egg problem of building fuel supply stations and vehicles that use alternative fuels, may be more easily overcome by a single planning body than by a market that only uncertainly rewards first movers. By ensuring supply of fuels the state wishes to promote, California can more easily launch alternative vehicle policies and incentives.
Experimental Investigation of a Bio-Based Phase Change Material to Improve Building Energy Performance
Authors: Muruganantham Karthik , Phelan Patrick , Horwath Peter , Ludlam David , McDonald Timothy
Published: January 2011

Phase Change Material (PCM) plays an important role as a thermal energy storage device by utilizing its high storage density and latent heat property. One of the potential applications of the PCM is in buildings by incorporating them in the envelope for energy conservation. During the summer cooling season, the main benefits are a decrease in overall energy consumption by the air conditioning unit and the time shift in peak load during the day. Experimental work was carried out by Arizona Public Service (APS) in collaboration with Phase Change Energy Solutions (PCES) Inc. with a new class of organic-based PCM. The experimental setup showed maximum energy savings of about 30%, a maximum peak load shift of ∼ 60 min, and maximum cost savings of about 30%.
Combustion Emissions Modeling and Testing of Conventional Diesel Fuel
Authors: Liu Hsing-Pang , Strank Shannon , Werst Mike , Hebner Robert , Osara Jude
Published: January 2011

This paper presents emissions modeling and testing of a four-stroke single cylinder diesel engine using conventional No. 2 diesel fuel. A system level engine simulation tool developed by Gamma Technologies, GT-Power, has been used to perform engine combustion simulations. The simulation approach is a predictive combustion simulation, direct-injection jet modeling, which is primarily used to predict the burn rate and NOx emissions. Crank angle dependent fuel injector sac pressure profiles have been measured during combustion tests and used as fuel jet inputs in the combustion modeling to predict injected fuel mass and fuel jet velocity as a function of time. In each emissions test, an in-cylinder pressure profile was measured and used for combustion model calibration to assure a correct burn rate profile was predicted and the exhaust emissions prediction was based on a calibrated burn rate profile which closely resembled the one measured in the test. Engine emissions, which include NOx, HC, CO, and CO2, measured at various engine speeds and loads were compared to those predicted by the combustion simulations. The maximum differences between simulation-predicted and test-measured emissions data are 30% for the NOx emissions and 68% for the CO2 emissions. However, the results for CO and HC emissions could differ by more than an order of magnitude under the conditions tested. The modeling and testing evaluation of conventional diesel was chosen to provide a comparative baseline analysis that can be extended for predicting combustion emissions of renewable feedstock fuels in development.
Photovoltaic Module Assembly as Appropriate Technology in Pakistan
Authors: Ahmad Faizan , Komp Richard , Ahmad Irfan , Kissock Kelly
Published: January 2011

This paper describes photovoltaic module assembly as appropriate technology in Pakistan. The paper begins by describing a three-week workshop in July 2009, in which a group of twenty unemployed people in Karachi, Pakistan were successfully trained in photovoltaic module assembly. Module components and assembly techniques are summarized. Factors pertinent to sustaining the project as a viable business enterprise, including the beneficial social externalities are discussed and analyzed. System designs for use in both urban and off-grid rural settings are proposed and energy outputs from the systems are simulated. In summary, the paper presents a thorough case study for expanding the utilization of photovoltaic technology in developing nations.
Freeze-Thaw Tests on Trough Receivers Employing a Molten Salt Working Fluid
Authors: Kolb Gregory , Ho Clifford , Iverson Brian , Moss Timothy , Siegel Nathan
Published: January 2011

Several studies predict an economic benefit of using nitrate-based salts instead of the current synthetic oil within a solar parabolic trough field. However, the expected economic benefit can only be realized if the reliability and optical performance of the salt trough system is comparable to today’s oil trough. Of primary concern is whether a salt-freeze accident and subsequent thaw will lead to damage of the heat collection elements (HCEs). This topic was investigated by experiments and analytical analysis. Results to date suggest that damage will not occur if the HCEs are not completely filled with salt. However, if the HCE is completely filled at the time of the freeze, the subsequent thaw can lead to plastic deformation and significant bending of the absorber tube.
A Compact External Combustion Engine With High Part-Load Efficiency
Authors: Bourque Robert
Published: January 2011

An external combustion engine design using steam is described which has good efficiency at full power and even better efficiency at the low power settings common for passenger vehicles. The engine is compact with low weight per unit power. All of its components fit in the engine compartment of a front-wheel drive vehicle despite the space occupied by the transaxle. It readily fits in a rear-drive vehicle. Calculated net efficiencies, after accounting for all losses, range, depending on engine size, from 28–32% at full power increasing to 33–36% at normal road power settings. A two-stage burner, 100% excess air, and combustion temperature below 1500°C assure complete combustion of the fuel and negligible NOx. The engine can burn a variety of fuels and fuel mixes, which should encourage the development of new fuels. Extensive software has been written that calculates full power and part-load energy balances, structural analysis and heat transfer, and performance in specified vehicles including using SAE driving cycles. Engines have been sized from 30 to 3200 hp. In general, fuel consumption should be at least 1.5 times lower than gasoline engines and about the same as diesels operating at low to moderate load settings. Due to this analysis, a prototype, when built, should perform as expected.
Organic Solar Cell With Carbon Nanotube Anode
Authors: Ren Liqiang , Wang Shiren
Published: January 2011

In last decade, organic solar cell (OSC) has attracted many attentions due to its special advantages such as low cost, easy large scale fabrication and high flexibility. However, the stylish OSC anode Indium Tin Oxide (ITO) is not flexible and would undergo breakdown on bending of flexible substrates. What’s more, ITO is costly since the limited indium in the nature. Recently, carbon nanotubes (CNTs) film shows potential to alternate ITO as high performance flexible anode since its ability to surmount these constrains and similar work function with ITO. Nevertheless the conductivity and transparence of CNTs film are still far below its counterpart. Additionally, a dependable model of OSC with CNTs film anode is not well established. In this paper, transparent conductive CNTs film is prepared on glass and plastic substrates at first. A facile filtration and pressing fabrication method is introduced. Our empirical model shows that dimension of CNTs bundles has significant effect on CNT network performance. FTIR shows the post-treatment effect on CNTs film. The OSC with high performance CNTs film anode shows similar efficiency compared with regular OSC with ITO anode.
Leveling Intermittent Renewable Energy Production Through Biomass Gasification-Based Hybrid Systems
Authors: Dean Jered , Braun Robert , Penev Michael , Kinchin Christopher , Mun˜oz David
Published: January 2011

The increased use of intermittent renewable power in the United States is forcing utilities to manage increasingly complex supply and demand interactions. This paper evaluates biomass pathways for hydrogen production and how they can be integrated with renewable resources to improve the efficiency, reliability, dispatchability, and cost of other renewable technologies. Two hybrid concepts were analyzed that involve co-production of gaseous hydrogen and electric power from thermochemical biorefineries. Both of the concepts analyzed share the basic idea of combining intermittent wind-generated electricity with a biomass gasification plant. The systems were studied in detail for process feasibility and economic performance. The best performing system was estimated to produce hydrogen at a cost of $1.67/kg. The proposed hybrid systems seek to either fill energy shortfalls by supplying hydrogen to a peaking natural gas turbine or to absorb excess renewable power during low-demand hours. Direct leveling of intermittent renewable electricity production is accomplished with either an indirectly heated biomass gasifier, or a directly heated biomass gasifier. The indirect gasification concepts studied were found to be cost competitive in cases where value is placed on controlling carbon emissions. A carbon tax in the range of $26–40 per metric ton of CO2 equivalent (CO2e) emission makes the systems studied cost competitive with steam methane reforming (SMR) to produce hydrogen. However, some additional value must be placed on energy peaking or sinking for these plants to be economically viable. The direct gasification concept studied replaces the air separation unit (ASU) with an electrolyzer bank and is unlikely to be cost competitive in the near future. High electrolyzer costs and wind power requirements make the hybridization difficult to justify economically without downsizing the system. Based on a direct replacement of the ASU with electrolyzers, hydrogen can be produced for $0.27 premium per kilogram. Additionally, if a non-renewable, grid-mix electricity is used, the hybrid system is found to be a net CO2e emitter.
Evaluation of Environmental Loads for the Synthesis of a Trigeneration System
Authors: Serra Luis M. , Lozano Miguel A. , Carvalho Monica
Published: January 2011

This paper details the calculation of the environmental loads associated with the construction of each piece of equipment (considering that the materials were not reused at the end of the equipment’s lifetime, which is the worst case scenario) and operation of a trigeneration system. The purpose of a trigeneration system is to meet the demands of a consumer center — in this case, a medium-sized hospital located in Zaragoza, Spain. The evaluation extended over a period of one year, considering previously specified energy service demands (electricity, heat - sanitary hot water and heating -, and cooling). The system interacted with the economic environment (market) through the purchase of natural gas and electricity from the grid, and also through the sale of autogenerated electricity to the grid, according to Spanish regulations. Therefore, the environmental loads regarding the operation of the system were associated with the consumption of natural gas and electricity purchased/sold from/to the grid. Technical information on each piece of equipment was obtained from catalogs and from consultation with manufacturers. Regarding natural gas, special care was taken to correctly identify the natural gas supplied to a user in Spain (it was considered that the gas comes from Algeria, transported in Liquefied Natural Gas (LNG) carriers, including pipeline transportation to the user and controlled burning). The electricity supplied by the Spanish electric grid was also properly specified and characterized. The environmental loads were calculated utilizing SimaPro, a specialized Life Cycle Assessment tool, and then incorporated into a linear programming model, solved by LINGO optimization software. Environmental criteria were used to obtain the optimal configuration and operation of the system simultaneously.
Effect of High Temperatures and Heating Rates on High Strength Concrete for Use as Thermal Energy Storage
Authors: John Emerson E. , Hale W. Micah , Selvam R. Panneer
Published: January 2011

In recent years due to rising energy costs as well as an increased interest in the reduction of greenhouse gas emissions, there is great interest in developing alternative sources of energy. One of the most viable alternative energy resources is solar energy. Concentrating solar power (CSP) technologies have been identified as an option for meeting utility needs in the U.S. Southwest. Areas where CSP technologies can be improved are improved heat transfer fluid (HTF) and improved methods of thermal energy storage (TES). One viable option for TES storage media is concrete. The material costs of concrete can be very inexpensive and the costs/ kWhthermal, which is based on the operating temperature, are reported to be approximately $1. Researchers using concrete as a TES storage media have achieved maximum operating temperatures of 400°C. However, there are concerns for using concrete as the TES medium, and these concerns center on the effects and the limitations that the high temperatures may have on the concrete. As the concrete temperature increases, decomposition of the calcium hydroxide (CH) occurs at 500°C, and there is significant strength loss due to degeneration of the calcium silicate hydrates (C-S-H). Additionally concrete exposed to high temperatures has a propensity to spall explosively. This proposed paper examines the effect of heating rates on high performance concrete mixtures. Concrete mixtures with water to cementitious material ratios (w/cm) of 0.15 to 0.30 and compressive strengths of up to 180 MPa (26 ksi) were cast and subjected to heating rates of 3, 5, 7, and 9° C/min. These concrete mixtures are to be used in tests modules where molten salt is used as the heat transfer fluid. Molten salt becomes liquid at temperatures exceeding 220°C and therefore the concrete will be exposed to high initial temperatures and subsequently at controlled heating rates up to desired operating temperatures. Preliminary results consistently show that concrete mixtures without polypropylene fibres (PP) cannot resist temperatures beyond 500° C, regardless of the heating rate employed. These mixtures spall at higher temperatures when heated at a faster rate (7° C/min). Additionally, mixtures which incorporate PP fibres can withstand temperatures up to 600° C without spalling irrespective of the heating rate.
Molten-Salt Tubular Absorber/Reformer (MoSTAR) Project: Reforming Performance of Reactor Tubes During Intermittent Heating
Authors: Gokon Nobuyuki , Kodama Tatsuya , Yamashita Shingo , Hatamachi Tsuyoshi , Seo Taebeom
Published: January 2011

Reforming performances for the double-walled reactor tubes with Na2CO3/MgO composite thermal storage was examined by an intermittent heating. The intermittent heating of the reactor tubes is composed of the heat-discharge (or cooling) mode and the subsequent heating mode. The heat-discharging mode simulates a fluctuating insolation for cloud passages. The heating mode simulates a heating of reactor due to concentrated solar radiation by using an electric furnace. The internal tube of the reactor was packed with the 2wt%Ru/Al2O3 catalyst balls while the thermal storage materials were filled in the annular region of the reactor tubes. The reactor was heated up to 920°C in the cylindrical electric furnace and the CH4/CO2 mixture was fed into the internal catalyst tube at gas hourly space velocity (GHSV) of 12500 h−1. Through the cooling mode and the subsequent heating mode, temperature variations of reactor tubes, catalyst and composite material, H2/CO ratio variations of effluent gas from the reactor, higher heating value (HHV) power of reformed gas were respectively examined for the double-walled reactor tubes and a single-wall reactor tube without the thermal storage.
Numerical Optimization of a Volumetric Solar Receiver-Reactor for Thermochemical Hydrogen Generation via Decomposition of Sulfur Trioxide
Authors: Noglik Adam , Roeb Martin , Sattler Christian , Pitz-Paal Robert
Published: January 2011

A basic concept for a receiver-reactor for solar sulfuric acid decomposition as the key step of thermochemical cycles for hydrogen production has been developed and realized. A prototype reactor has been built and is specialized for the second part of the reaction, the decomposition of sulfur trioxide. For a detailed understanding of the operational behaviour of the developed reactor type a mathematical model was developed. The reactor model was validated using experimental data from the prototype reactor test operation. The present work deals with the optimization of process and design parameters and the evaluation of the achievable performance of the reactor type. Furthermore the reactor model is used for numerical simulations to predict operational points, which are not easy to realize in experiments due to hardware limitations, to save the experimental effort, and to predict the performance of a large-scale reactor on a solar tower. The results of the simulation confirm a central finding of the experiments: Depending on the operation conditions an optimum of reactor efficiency emerges if one parameter is varied. This is in particular true for the absorber temperature. Two oppositional effects compensate each other in a way that the reactor efficiency exhibits a maximum at a certain temperature: by increasing process temperature the reradiation losses increase disproportionately high whereas the chemical conversion decreases when lowering the temperature. Beyond that influences of other operational parameters like feed mass flow, residence time, and initial concentration of the acid were also analyzed. In a scale-up study the reactor was simulated as being part of the aperture area of a large scale tower receiver. The main differences to the prototype system are the diminished gradients of solar flux on the receiver front face and the reduced thermal conduction losses due to the presence of several neighbor modules at comparable temperature level. This leads to higher chemical conversions and better efficiencies. Reactor efficiencies up to 75% are predicted. Even higher efficiencies are possible if re-radiation losses can be decreased, e.g. by considering a cavity design.
Solar Thermal Driven Cooling System for a Data Center in Albuquerque New Mexico
Authors: Fumo N. , Bortone V. , Zambrano J. C.
Published: January 2011

Data centers are facilities that primarily contain electronic equipment used for data processing, data storage, and communications networking. Regardless of their use and configuration, most data centers are more energy intensive than other buildings. The continuous operation of Information Technology equipment and power delivery systems generates a significant amount of heat that must be removed from the data center for the electronic equipment to operate properly. Since data centers spend up to half their energy on cooling, cooling systems becomes a key factor for energy consumption reduction strategies and alternatives in data centers. This paper presents a theoretical analysis of an absorption chiller driven by solar thermal energy as cooling plant alternative for data centers. Source primary energy consumption is used to compare the performance of different solar cooling plants with a standard cooling plant. The solar cooling plants correspond to different combinations of solar collector arrays and thermal storage tank, with a boiler as source of energy to ensure continuous operation of the absorption chiller. The standard cooling plant uses an electric chiller. Results suggest that the solar cooling plant with flat-plate solar collectors is a better option over the solar cooling plant with evacuated-tube solar collectors. However, although solar cooling plants can decrease the primary energy consumption when compared with the standard cooling plant, the net present value of the cost to install and operate the solar cooling plants are higher than the one for the standard cooling plant.
Technical and Economic Analysis of a Waste-to-Energy Plant for Austin, Texas Under a Range of Greenhouse Gas Emissions Prices
Authors: Townsend Aaron K. , Webber Michael E.
Published: January 2011

Technical and economic metrics of electricity generation from a Waste to Energy (WTE) plant are compared to coal, natural gas combined cycle, biomass, and landfill gas generation alternatives for Austin, Texas under a range of greenhouse gas emissions prices. The WTE technology and history is described, as well as details relevant to a WTE plant in Austin. Technical and economic values for WTE from the literature are discussed. The upper limit of electricity generation from Austin’s MSW stream is 5% of Austin’s 2007 annual electricity consumption. Selection of appropriate values for capital, operating, and fuel costs indicates that WTE is more expensive than all of the alternative generation technologies considered (coal, natural gas combined cycle, landfill gas, and biomass). If greenhouse gas emissions are priced and offsets from fugitive landfill gas emissions are allowed, WTE becomes more cost-competitive by taking credit for offset landfill gas emissions. Under this scenario WTE becomes cost-competitive with biomass at $33 per ton CO2 equivalent, coal at $92 per ton CO2 equivalent, and natural gas at $115 per ton CO2 equivalent.
A New Approach to Determine Optimum Insulation Thickness for All Buildings in Turkey Based on Heating Loads and Heat Gains
Authors: O¨zkan Derya B. , Onan Cenk
Published: January 2011

In Turkey, “Thermal Insulation Requirements for Buildings” was implemented to provide energy saving in buildings in 2000. After this, more then seven hundred thousand new buildings are constructed. Determining the correct material and optimum insulation thickness are very important issues in these buildings for thermal insulation. Calculations using monthly outdoor temperatures and solar radiation are done for XPS insulation material and 4 different climatic regions in Turkey. Natural gas, the most preferred in our country is selected as fuel. P1-P2 method is used to obtain energy saving and payback period. New correlations are specified to determine optimum insulation thickness depending on building heat gains and areas. Furthermore, buildings are categorized into three building class according to external wall area and floor/roof area. Effect of change in building external wall area, floor or roof area, window area to payback period, energy saving and optimum thickness are investigated. As a result, effect of architectural design is determined on thermal insulation. All calculation results are shown in a table for four different climatic regions and three different types of buildings which have the same gross volume.
An Updated Estimate for Energy Use in U.S. Food Production and Policy Implications
Authors: Cuellar Amanda D. , Webber Michael E.
Published: January 2011

In this work we estimate the amount of energy required to produce the food consumed in the United States in 2002 and 2007. Data from government sources and the scientific literature were used to calculate the energy intensity of food production from agriculture, transportation, manufacturing, food sales, storage and preparation. Most data were from 2002; consequently we scaled all data from other years to 2002 by using ratios of total energy consumption in 2002 to total energy consumption in the year data were reported. We concluded that food production required at least 7,880±733 trillion BTU in 2002 and 8,080±752 trillion BTU of energy in 2007, over a third of which came from food handling in homes, restaurants and grocery stores. The energy used to produce food represents approximately 8% of energy consumption. Our estimate is for the energy required to produce the food consumed in the United States and takes into account food imports and exports. To account for net food exports in the agriculture sector we calculated values for the energy intensity of ten food categories and then used the mass of domestic food consumption in each category to calculate the energy embedded in the food consumed in the United States. The amount of energy required to produce the food consumed in the United States has policy implications because it is a substantial fraction of total energy consumption and is responsible for a commensurate amount of greenhouse gas emissions. There are many opportunities for decreasing the energy intensity of food production at all steps of the food system. Education of the public and policy measures that promote energy efficiency in the food sector have the potential for decreasing food waste and the energy intensity of the food system.
Heat Pipe Augmented Solar Heating System
Authors: Robinson Brian S. , Albanese Michael V. , Chmielewski Nick , Brehob Ellen G. , Sharp M. Keith
Published: January 2011

The focus of this project is on simulation and testing of a novel passive solar heating system that utilizes the one-way heat transfer of heat pipes to significantly improve heating performance relative to conventional passive solar systems. A set of programmed thermal networks were used to simulate the performance of several conventional passive solar heating systems, including direct gain, concrete wall indirect gain and water wall indirect gain, and the heat pipe system. Simulations performed for four US locations representing a range of winter temperatures and available insolation exhibited higher performance for the heat pipe system, particularly in cold climates with low insolation. A small-scale laboratory model was constructed and tested under controlled conditions to confirm simulated system component performance and to test a range of component variations. Measured system efficiency was 85.1 ± 0.72%. A full-scale prototype was constructed, installed and instrumented. Results from a 21-day period in April show a prototype thermal efficiency range from 60–75% and an average of 66.2%; and a 30-day period in October and November ranges from 60–85% with an average of 73.9%. An opaque cover over the prototype, periodically installed to minimize unwanted gains during the cooling season, reduced overall gains by an average of 75%.
Liquid Calcium Chloride Solar Storage: Concept and Analysis
Authors: Quinnell Josh A. , Davidson Jane H. , Burch Jay
Published: January 2011

Aqueous calcium chloride has a number of potential advantages as a compact and long-term solar storage medium compared to sensibly heated water. The combination of sensible and chemical binding energy of the liquid desiccant provides higher energy densities and lower thermal losses, as well as a temperature lift during discharge via an absorption heat pump. Calcium chloride is an excellent choice among desiccant materials because it is relatively inexpensive, non-toxic, and environmentally safe. This paper provides an overview of its application for solar storage and presents a novel concept for storing the liquid desiccant in a single storage vessel. The storage system uses an internal heat exchanger to add and discharge thermal energy and to help manage the mass, momentum, and energy transfer in the tank. The feasibility of the proposed concept is demonstrated via a computational fluid dynamic study of heat and mass transfer in the system over a range of Rayleigh, Lewis, Prandtl, and buoyancy ratio numbers expected in practice.