bluuebunny/crossref_metadata_2025 huggingface dataset:
Airline Safety Improvement Through Experience with Near‐Misses: A Cautionary Tale
Authors: Madsen Peter , Dillon Robin L. , Tinsley Catherine H.
Published: October 2015

In recent years, the U.S. commercial airline industry has achieved unprecedented levels of safety, with the statistical risk associated with U.S. commercial aviation falling to 0.003 fatalities per 100 million passengers. But decades of research on organizational learning show that success often breeds complacency and failure inspires improvement. With accidents as rare events, can the airline industry continue safety advancements? This question is complicated by the complex system in which the industry operates where chance combinations of multiple factors contribute to what are largely probabilistic (rather than deterministic) outcomes. Thus, some apparent successes are realized because of good fortune rather than good processes, and this research intends to bring attention to these events, the near‐misses. The processes that create these near‐misses could pose a threat if multiple contributing factors combine in adverse ways without the intervention of good fortune. Yet, near‐misses (if recognized as such) can, theoretically, offer a mechanism for continuing safety improvements, above and beyond learning gleaned from observable failure. We test whether or not this learning is apparent in the airline industry. Using data from 1990 to 2007, fixed effects Poisson regressions show that airlines learn from accidents (their own and others), and from one category of near‐misses—those where the possible dangers are salient. Unfortunately, airlines do not improve following near‐miss incidents when the focal event has no clear warnings of significant danger. Therefore, while airlines need to and can learn from certain near‐misses, we conclude with recommendations for improving airline learning from all near‐misses.
Two-Stage Model for Time Varying Effects of Zero-Inflated Count Longitudinal Covariates with Applications in Health Behaviour Research
Authors: Yang Hanyu , Li Runze , Zucker Robert A. , Buu Anne
Published: October 2015

This study proposes a two-stage approach to characterize individual developmental trajectories of health risk behaviours and to delineate their time varying effects on short-term or long-term health outcomes. Our model can accommodate longitudinal covariates with zero-inflated counts and discrete outcomes. The longitudinal data of a well-known study of youths at high risk of substance abuse are presented as a motivating example to demonstrate the effectiveness of the model in delineating critical developmental periods of prevention and intervention. Our simulation study shows that the performance of the model proposed improves as the sample size or number of time points increases. When there are excess 0s in the data, the regular Poisson model cannot estimate either the longitudinal covariate process or its time varying effect well. This result, therefore, emphasizes the important role that the model proposed plays in handling zero inflation in the data.
Life Expectancy Heterogeneity and the Political Support for Collective Annuities
Authors: Cremer Helmuth , De Donder Philippe
Published: October 2015

Individuals, differing in productivity and life expectancy, vote over the size and type of a collective annuity. Its type is represented by the fraction of the contributive (Bismarckian) component (based on the worker's past earnings) as opposed to the non‐contributive (Beveridgean) part (based on average contribution). The equilibrium collective annuity is either a large mostly Bismarckian program, a smaller pure Beveridgean one (in accordance with empirical evidence), or nil. A larger correlation between longevity and productivity, or a larger average life expectancy, both make the equilibrium collective annuity program more Beveridgean, although at the expense of its size.
Comparative morphology of the mandibles and head structures of corbiculate bees (Hymenoptera: Apidae: Apini)
Authors: PORTO DIEGO S. , VILHELMSEN LARS , ALMEIDA EDUARDO A. B.
Published: October 2015

Phylogenetic relationships of corbiculate bees have been a well‐known focus of controversies over the past 30 years. The majority of the morphological datasets support the monophyly of Apina + Meliponina, whereas molecular datasets recover Meliponina as sister to Bombina. This issue is especially critical to the proper understanding of the evolution of clusters of traits that define the corbiculate eusocial behaviour. This work provides a description and discussion on characters of the head capsule, mandibles and sitophore of bees. Thirty‐three characters are proposed and optimized within concurrent phylogenetic hypotheses for corbiculate bees, which results in seven derived character‐states supporting the monophyly of the Apina + Meliponina + Bombina and nine supporting the Apina + Meliponina clades. Although some striking synapomorphies (e.g. tentorial bridge, pleurostomal condyle, hypopharyngeal lobe) support the former clade, most characters supporting the latter (i.e. Apina + Meliponina) were losses/reductions. Moreover, two previously undescribed character transformations on hypostoma and sitophore favour the Bombina + Meliponina clade. Internal head capsule characters are useful for phylogenetic analysis in comparative studies of bees, and corbiculate bees in particular, when efforts are made to solve the ‘corbiculate controversy’. An attempt is made to standardize the current terminology used for bees and for other Hymenoptera.
Quality of antenatal and childbirth care in rural health facilities in Burkina Faso, Ghana and Tanzania: an intervention study
Authors: Duysburgh Els , Temmerman Marleen , Yé Maurice , Williams Afua , Massawe Siriel , Williams John , Mpembeni Rose , Loukanova Svetla , Haefeli Walter E. , Blank Antje
Published: October 2015

Objective

To assess the impact of an intervention consisting of a computer‐assisted clinical decision support system and performance‐based incentives, aiming at improving quality of antenatal and childbirth care.

Methods

Intervention study in rural primary healthcare (PHC) facilities in Burkina Faso, Ghana and Tanzania. In each country, six intervention and six non‐intervention PHC facilities, located in one intervention and one non‐intervention rural districts, were selected. Quality was assessed in each facility by health facility surveys, direct observation of antenatal and childbirth care, exit interviews, and reviews of patient records and maternal and child health registers. Findings of pre‐ and post‐intervention and of intervention and non‐intervention health facility quality assessments were analysed and assessed for significant (P < 0.05) quality of care differences.

Results

Post‐intervention quality scores do not show a clear difference to pre‐intervention scores and scores at non‐intervention facilities. Only a few variables had a statistically significant better post‐intervention quality score and when this is the case this is mostly observed in only one study‐arm, being pre‐/post‐intervention or intervention/non‐intervention. Post‐intervention care shows similar deficiencies in quality of antenatal and childbirth care and in detection, prevention, and management of obstetric complications as at baseline and non‐intervention study facilities.

Conclusion

Our intervention study did not show a significant improvement in quality of care during the study period. However, the use of new technology seems acceptable and feasible in rural PHC facilities in resource‐constrained settings, creating the opportunity to use this technology to improve quality of care.
Anthropology with a Paintbrush: Naturalist–Realist Painting as “Thick Description”
Authors: Bray Zoe
Published: October 2015

This article introduces the art of naturalist–realist portrait painting as a method and medium of visual anthropology. It makes the case for this art form as an integral part of both ethnography and anthropology. Like ethnography, naturalist–realist portrait painting seeks to apprehend the world in a way that goes beyond superficial observation. Both disciplines have in common an empathetic and sensitive process of long‐term observation and contextual interaction—a process in which the artist–anthropologist must navigate the tension between objectivity and subjectivity. The article introduces the various techniques used by naturalist–realist painters, including the sight‐size method, arguing that these techniques often parallel those of ethnography and have the potential to add further value not only to the ethnographic research process but also to analysis. In particular, since ethnography is today considered a collaborative process, the close interaction between painter and model in naturalist–realist portrait painting can be considered as a means by which anthropologists can create “thick descriptions.”
Waiting Subjects: Social Media–Inspired Self‐Portraits as Gallery Exhibition inDelhi,India
Authors: Dattatreyan Ethiraj Gabriel
Published: October 2015

In this article, I reflect on a gallery exhibition of self‐portraits by youngSomali refugees. These images were selected from a collection of digital photographs that were shot while producing a collaborative ethnographic film project on the racialization ofAfrican nationals inDelhi,India. The images that my youthful interlocutors produced while shooting for our collaborative film project, however, were not originally intended for display but were an extension of their already prolific visual and textual self‐documentation on social media. Utilizing select images and texts from the exhibition we culled from this “accidental” photographic archive to evoke what it means for these youngSomalis to wait for asylum inEurope orNorthAmerica while they make their lives inIndia, I argue for an attention to the digital image‐making practices of young people as a site where subjectivities are self‐fashioned and ethnographic insights emerge.
Inside the Frame, Outside the Box:BindiCole's Photographic Practice and Production of Aboriginality in ContemporaryAustralia
Authors: Thorner Sabra G.
Published: October 2015

In this article, I seek to locateBindiCole in a movement ofAustralianIndigenous photo‐media artists who are mobilizing the photographic archive as a form of both aesthetic intervention and cultural activism. Via a close analysis of her work,WathaurongMob(2008), I argue that high art photography can be used to unsettle dominant stereotypes by producing an alternative visibility, calling attention to pervasive assumptions equatingAboriginality with skin color (and how this is actually a persistent and harmful form of racism), and offering a corrective: a more nuanced understanding ofAboriginality that includes notions of kinship and community.
English and language shift in Paraguay's New Australia
Authors: PEREZ DANAE
Published: October 2015

This paper sheds new light on English in Latin America, more specifically in Paraguay, a still relatively underresearched region in the context of world Englishes. At the turn of the 20th century, almost 600 colonizers from Australia and the UK settled in Paraguay with the goal of setting up an independent English‐speaking society. However, the New Australia community was soon divided, and its English language and culture faded away. This paper describes the sociolinguistic history of the Anglo‐Paraguayan community and addresses the question of why English disappeared in Paraguay.
Economy, modernity, Islam, and English in Egypt
Authors: ABOUELHASSAN RADI S. MOUSTAFA , MEYER LOIS M.
Published: October 2015

After the January 2011 Egyptian revolution led to the fall of the pro‐western dictator Hosni Mubarak and popular elections that brought Islamist parties to the political forefront, the international community speculated about the country's future. Discussion about Egypt's future involved diverse issues, among them globalization, the English language, and how Islam and modernity interact. In this paper, the authors examine the story of English and its widespread use in Egypt to illustrate how modernization and Islamization have contributed to the spread of the once colonial, now global language—English—in the Arab Republic of Egypt.
Rhoticity in Yunnan English
Authors: SUNDKVIST PETER , GAO MAN
Published: October 2015

This paper presents a study of the pronunciation of English by speakers from Yunnan Province in Southwest China. Eight non‐English major undergraduate students participated in three tasks: an informal interview, reading a text, and a dialectological‐style questionnaire. The degree of rhoticity was assessed based on auditory analysis, with an inter‐rater agreement of 97 per cent. The results revealed significant inter‐speaker variation: two informants were virtually non‐rhotic whereas the remaining six were rhotic to a considerable degree. Intra‐speaker variation among these six was furthermore systematic: the degree of rhoticity was lowest in the interview, intermediate in reading, and highest in the questionnaire. These results are discussed with reference to several factors, including the level of formality and attention to speech triggered by the tasks, potentially emerging norms for rhoticity, and the stage of development of a local form of ‘Yunnan English’.
Bahin Singapore English
Authors: LEIMGRUBER JAKOB R. E.
Published: October 2015

Colloquial Singapore English (‘Singlish’) is well known, among other features, for its class of discourse particles derived from substrate languages. These particles have been ascribed to various languages, chief among them Southern Min, Malay, and Cantonese. Previous research has also shown this class to be open to newcomers, with Lim (2007) concentrating on particles of Cantonese origin appearing in the 1980s. In this paper, I present evidence of a previously undocumented particle,bah, whose origins are suspected in Mandarin, a variety that has hitherto contributed only little to the grammatical structure of Singlish. Using corpus data complemented by data from online discussion forums, as well as responses to an online survey, the paper describesbah's pragmatic meanings and the socio‐historical and sociolinguistic reasons for its emergence.
Beneficial effects of exercise on age‐related mitochondrial dysfunction and oxidative stress in skeletal muscle
Authors: Joseph Anna‐Maria , Adhihetty Peter J. , Leeuwenburgh Christiaan
Published: October 2015

Mitochondria are negatively affected by ageing leading to their inability to adapt to higher levels of oxidative stress and this ultimately contributes to the systemic loss of muscle mass and function termed sarcopenia. Since mitochondria are central mediators of muscle health, they have become highly sought‐after targets of physiological and pharmacological interventions. Exercise is the only known strategy to combat sarcopenia and this is largely mediated through improvements in mitochondrial plasticity. More recently a critical role for mitochondrial turnover in preserving muscle has been postulated. Specifically, cellular pathways responsible for the regulation of mitochondrial turnover including biogenesis, dynamics and autophagy may become dysregulated during ageing resulting in the reduced clearance and accumulation of damaged organelles within the cell. When mitochondrial quality is compromised and homeostasis is not re‐established, myonuclear cell death is activated and muscle atrophy ensues. In contrast, acute and chronic exercise attenuates these deficits, restoring mitochondrial turnover and promoting a healthier mitochondrial pool that leads to the preservation of muscle. Additionally, the magnitude of these exercise‐induced mitochondrial adaptations is currently debated with several studies reporting a lower adaptability of old muscle relative to young, but the processes responsible for this diminished training response are unclear. Based on these observations, understanding the molecular details of how advancing age and exercise influence mitochondria in older muscle will provide invaluable insight into the development of exercise protocols that will maximize beneficial adaptations in the elderly. This information will also be imperative for future research exploring pharmacological targets of mitochondrial plasticity.

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Ageing‐related changes in GABAergic inhibition in mouse auditory cortex, measured using in vitro flavoprotein autofluorescence imaging
Authors: Stebbings K. A. , Choi H. W. , Ravindra A. , Caspary D. M. , Turner J. G. , Llano D. A.
Published: October 2015

Key points

Ageing is associated with hearing loss and changes in GABAergic signalling in the auditory system.

We tested whether GABAergic signalling in an isolated forebrain preparation also showed ageing‐related changes.

A novel approach was used, whereby population imaging was coupled to quantitative pharmacological sensitivity.

Sensitivity to GABAA blockade was inversely associated with age and cortical thickness, but hearing loss did not independently contribute to the change in GABAAergic sensitivity.

Redox states in the auditory cortex of young and aged animals were similar, suggesting that the differences in GABAAergic sensitivity are unlikely to be due to differences in slice health.

To examine ageing‐related changes in the earliest stages of auditory cortical processing, population auditory cortical responses to thalamic afferent stimulation were studied in brain slices obtained from young and aged CBA/CAj mice (up to 28 months of age). Cortical responses were measured using flavoprotein autofluorescence imaging, and ageing‐related changes in inhibition were assessed by measuring the sensitivity of these responses to blockade of GABAA receptors using bath‐applied SR95531. The maximum auditory cortical response to afferent stimulation was not different between young and aged animals under control conditions, but responses to afferent stimulation in aged animals showed a significantly lower sensitivity to GABA blockade with SR95531. Cortical thickness, but not hearing loss, improved the prediction of all imaging variables when combined with age, particularly sensitivity to GABA blockade for the maximum response. To determine if the observed differences between slices from young and aged animals were due to differences in slice health, the redox state in the auditory cortex was assessed by measuring the FAD+/NADH ratio using fluorescence imaging. We found that this ratio is highly sensitive to known redox stressors such as H2O2 and NaCN; however, no difference was found between young and aged animals. By using a new approach to quantitatively assess pharmacological sensitivity of population‐level cortical responses to afferent stimulation, these data demonstrate that auditory cortical inhibition diminishes with ageing. Furthermore, these data establish a significant relationship between cortical thickness and GABAergic sensitivity, which had not previously been observed in an animal model of ageing.
WINDGRABBER™: A Novel Approach to Small Wind Turbine Design and Operation for Use on or Above the Rooftops of Homes and Small Office Buildings
Authors: Krippene Brett C. , Chen Gerald C. , Starcher Kenneth L. , Urich Joseph A. , McConnell Ralph W. , Jenks Robert P.
Published: October 2015

WINDGRABBER™ (WG) is a novel new roof or pole top mounted wind turbine system proposed for product commercialization up to 50 kWe. WG is projected to be cost-attractive in an environmentally friendly manner. The WG system uses the available energy in the wind via (1) a passively yawed air impact inlet air scoop, (2) a flow tube, (3) an air turbine and (4) a multiphased air inlet with an air impact - drag type outlet section.

The WG wind turbine system preferentially utilizes a combination enclosed - radial out-flow, cross-flow, reaction-impulse air turbine of squirrel cage configuration, using either a single or double axial flow inlet of centrifugal fan design with backwardly curved, air foil air blades mounted on the discharge end of a flow tube. The WG wind turbine design is based on the air power instead of the wind power equations, combined with duct resistance, wind impact and wind drag calculations, to determine system wind energy conversion effectiveness with respect to the Betz limit, as well as overall system efficiency. Low pressure drop screens may be provided at the various inlets and outlets to protect birds and small mammals from being drawn into rotating components. A currently proposed Phase I – CAE modeling for conceptual design verification, system optimization and 300 watt pilot plant test program, followed by a Phase II – design improvement and scale up to 3,000 watt prototype demonstration program and followed by a Phase III cost reduction, product improvement and scale up to a 5,000 watt commercial demonstration program is currently being considered by BCK Consulting, L.L.C. (BCK) and West Texas A & M University (WTAMU).

The history of WG, up to and including its latest developmental status, will be discussed in this paper with projections offered regarding its future product commercialization prospects. Please see ASME paper ES2010-90062 presented previously [Ref.1].
Adapting Steady State Solar Power Models to Include Transients
Authors: Abutayeh Mohammad
Published: October 2015

Quite a few computer programs have been developed to model power plant performance. These software codes are geared towards modeling steady state operations which is usually sufficient for conventional power plants. Solar thermal power plants undergo lengthy transient start–up and shut–down operations due to the sporadic nature of solar radiation; therefore, valid modeling of their performance must address those unsteady state operations.

A novel scheme has been developed to fine–tune steady state solar power generation models to accurately take account of the impact of those transient operations. The suggested new scheme is implemented by adjusting solar radiation input data and has been shown to significantly improve modeling accuracy by moving modeled results closer to matching real operating data.
Energy Integration Methodology for the Dairy Industry Through the Implementation of a Cogeneration System Assessed by Pinch Technology
Authors: Orozco L. Wilman , Bula S. Antonio , Bermejo A. Fabio
Published: October 2015

The Pinch energy saving technology is an appropriate technology to design and optimize cogeneration processes. This research achieved the development of a cogeneration methodology for an enterprise from the dairy industry with an energy characterization; a viable energy source is coupled to heat exchanger equipment, which will be evaluated by technology Pinch and obtain efficient use of heat and subsequent use. According to the methodology designed, conventional system handles an energy efficiency of about 37% and cogeneration system proposed 80.1%; in primary energy consumption (natural gas) this is reduced by 30% with a reduced cost of 50%kWh.
Optimization of the Wind Turbine Designs for Areas With Low Wind Speeds
Authors: Mayeed Mohammed S. , Khalid Adeel
Published: October 2015

Wind energy has been identified as an important source of renewable energy. In this study, several wind turbine designs have been analyzed and optimized designs have been proposed for low wind speed areas around the world mainly for domestic energy consumption. The wind speed range of 4–12 mph is considered, which is selected based on the average wind speeds in the Atlanta, GA and surrounding areas. These areas have relatively low average wind speeds compared to various other parts of the United States. Traditionally wind energy utilization is limited to areas with higher wind speeds. In reality a lot of areas in the world have low average wind speeds and demand high energy consumption. In most cases, wind turbines are installed in remote offshore or away from habitat high wind locations, causing heavy investment in installation and maintenance, and loss of energy transfer over long distance. A few more advantages of small scale wind turbines include reduced visibility, less noise and reduced detrimental environmental effects such as killing of birds, when compared to traditional large turbines. With the latest development in wind turbine technology it is now possible to employ small scale wind turbines that have much smaller foot print and can generate enough energy for small businesses or residential applications. The low speed wind turbines are typically located near residential areas, and are much smaller in sizes compared to the large out of habitat wind turbines. In this study, several designs of vertical and horizontal axes wind turbines are modeled using SolidWorks e.g. no-airfoil theme, airfoil blade, Savonius rotor etc. Virtual aerodynamic analysis is performed using SolidWorks Flow simulation software, and then optimization of the designs is performed based on maximizing the starting rotational torque and ultimate power generation capacity. From flow simulations, forces on the wind turbine blades and structures are calculated, and used in subsequent stress analysis to confirm structural integrity. Critical insight into low wind speed turbines is obtained using various configurations, and optimized designs have been proposed. The study will help in the practical and effective utilization of wind energy for the areas around the globe having low average wind speeds.
An Energy Transition Scenario for the State of Kuwait
Authors: Alsayegh Osamah A. , Al-Ragom Fotouh A.
Published: October 2015

With population of 3.9 million and area of 17,818 km2, the State of Kuwait holds about 8% and 1% of the world proven oil and gas reserves, respectively. Its total primary energy (oil and gas) production is about 3.5 million barrel oil equivalent per day (Mboe/d). Yet, Kuwait is facing energy challenges as a result of high and rapid growth of domestic energy consumption that has reached 18% of its total primary energy production. Therefore, adopting policies to transform the present energy system to a sustainable system has become indispensable national requirement. In this paper, a transition scenario for Kuwait’s energy system is proposed. The transition scenario addresses both the supply and demand sides through diversifying primary energy mix and energy demand management measures. The energy mix scenario is the optimum outcome of MARKAL-TIMES model of the energy system of Kuwait. Modeling results show that meeting 10% of the country’s energy demand through the exploitation of solar and wind energies by 2030 is the technical and economical optimal scenario. While the demand management measures are based on pilot energy conservation and efficiency study that shows energy saving could reach 24% and leading to savings of 4% reduction in power installation capacity. Utilization of efficient water desalination systems can reduce national energy consumption by 5%. The paper concludes with policy implications that are essential to launch the transformation toward sustainability.
Finding an Optimal Driving Strategy for an Electric Bus Based on Operational Data
Authors: Vaz Warren , Nandi Arup K. , Koylu Umit O.
Published: October 2015

One of the clean energy initiatives at Missouri S&T is an electric shuttle bus service, the Ebus. It provides valuable operational data for a fleet-type electric vehicle (EV) operating over a fixed route. The primary aim of this study is to use the daily operational data obtained from the Ebus in order to formulate an optimal driving strategy. Existing research efforts to improve EVs focus on improvements to the architecture and the energy management strategy. However, they fail to provide the driver with an optimal driving strategy leading to suboptimal use of the stored battery energy. This shortcoming was addressed here by implementing a multi-objective approach to find an optimal driving strategy for an electric bus. The driving strategy was taken to comprise two parts: a constant trip speed and an acceleration value to achieve that speed. From the operational data, the efficiency and power consumption of the electric motor were computed for different speeds. By assuming the entire trip was executed at a constant speed, the range for each speed was calculated. The speeds were ranked based on their corresponding ranges. Then, to achieve the optimal speed, the acceleration duration and energy consumption for different acceleration values were computed. The values were ranked based on the trade-off between duration and energy. The choice of driving strategy (exact speed and acceleration values) is left to the driver since different strategies would be needed for different road conditions. This multi-objective approach gives flexibility to the driver and promotes optimal use of the stored battery energy, thereby enhancing the energy efficiency and range of the Ebus. It can be easily implemented in other electric vehicles as well.
Toward Building a Model of Wind and Solar Energy Source
Authors: Monemi Sean , Kifle Daniel
Published: October 2015

Generation of renewable energy sources are being adopted more widely in both large and small scales by federal agencies and private industries. We will explore to investigate what their impact would be by building a prototype model of wind and solar energy Source generation. This model will be integrated into our current model of the smart grid. The generation model consists of a solar panel and an array of wind turbines connected to a battery storage system. The energy output is being monitored and reported in real time. This energy will supply the already built model of the electric grid.
The Economic and Environmental Benefits From Distributed PV and Wind Technologies in a Colorado Community
Authors: Krarti Moncef
Published: October 2015

This paper presents the results from an economic and environmental feasibility study on photovoltaic PV and wind technologies for a community of 200 homes in Superior, CO. The electrical load profile assumed for the community, the solar resources available, and the wind resources are defined. Specific PV modules and wind turbines are identified. A simulation model was created in HOMER software and the specific model assumptions and reasoning presented. The results of the simulation show that the baseline scenario of grid electricity use is the best economic decision under the status quo system parameters. However, it is shown through sensitivity analyses and requirements for specific levels of renewable energy use, that the best possible system for the community should not be evaluated solely on the status quo economic parameters. PV is shown to be the best renewable technology to consider while wind energy proves to be a poor choice for the specific location of the community. Emissions of CO2 and other pollutants are greatly reduced under the recommended system design.
The Potential of Night Sky Radiation for Humidity Control
Authors: Springer Zachary , Sharp M. Keith
Published: October 2015

Ambient energy sources, including ambient air, ground and night sky, have potential for space cooling. The night sky offers the lowest temperature and, therefore, the greatest potential across most of the US. Compared to a previous analysis that considered only the sensible cooling load, the objective of this new project was to evaluate the potential of night-sky radiation (NSR) to also serve the latent cooling load. ASHRAE standard 55 was used to establish the comfort limits (22°C for room temperature and 60% relative humidity). Condensation was evaluated as the mechanism for humidity reduction, thus the dew-point temperature, 13.9°C, corresponding to the ASHRAE limits was the maximum target temperature for night-sky cooling. Typical meteorological year (TMY3) weather data was used for eleven locations representing ASHRAE climate zones. Building heat gain, infiltration/ventilation requirements and night-sky radiator size were characterized by a load-to-radiator ratio LRR defined as the infiltration/ventilation volume flow rate times the ratio of building floor area to radiator area. Three values of LRR were evaluated: 0.35, 3.5 and 35 m/hr. Three thermal storage cases were considered: 1. Annual NSR cooling potential (seasonal storage), 2. Diurnal storage, and 3. The minimum storage capacity to serve the entire annual load, as well as the effects of capacity less than the minimum. To evaluate the effect of night-sky radiator temperature on storage capacity, six NSR temperatures Trad = 13.9 to −26.1°C were tested. Results showed that even in Miami, FL (the most challenging climate evaluated), annual NSR potential exceeded the total sensible and latent cooling load, at least for the lowest LRR and highest Trad. For diurnal storage, NSR could serve less than 20% of the load in the hot and humid southeast, but the entire load in the mountain west. The minimum storage capacity to meet the entire annual load corresponds to the capacity required to bridge the span of time without NSR availability during which the largest cooling load occurs. This capacity decreases with decreasing LRR and decreasing Trad. For the southeast, large capacity is required, but for Louisville, for instance, sufficient capacity is provided by the equivalent of as little as 0.05 m of water over the floor area of the building for LRR = 0.35 m/hr. These results demonstrate that for much of the US, night-sky radiation has the potential to serve the entire annual sensible and latent cooling load.
Transient Numerical Analysis of Different Finned Tube Designs for Use in Latent Heat Thermal Energy Storage Devices
Authors: Beck Anton , Koller Martin , Walter Heimo , Hameter Michael
Published: October 2015

In this paper the results of a numerical investigation of the melting and solidification process of sodium nitrate, which is used as phase change material, will be presented. For the heat transfer to the sodium nitrate different finned tube designs, namely helical-, transversal- and longitudinal finned tubes, are used. The numerical results of the melting and solidification process for the different design cases will be compared. The numerical analysis of the melting process has shown that apart from the first period of the charging process natural convection is the dominant heat transfer mechanism. The numerical analysis of the melting process has also shown that for a fast melting process heat exchanger tubes should be designed in such a way that an unrestricted natural convection is guaranteed.

The numerical investigation for the solidification process has shown that the dominant heat transfer mechanism is heat conduction. The investigation has also shown that the solidification front grows more uniformly from the tube surface to the outer shell compared to the melting front. Therefore no significant differences between the different tube designs are detected concerning the solidification process.
Economic Optimization of Indirect Sewage Sludge Heat Dryer Unit for Sewage Sludge Incineration Plants
Authors: Demir Sinan , Karabasoglu Orkun , Akkerman V'Yacheslav , Abusoglu Aysegul
Published: October 2015

This paper presents the economic optimization of indirect sewage sludge heat dryer for sewage sludge incineration plants. The objective function based on two-phase heat transfer, and economic relations is provided to demonstrate the optimum size for the minimum investment cost. De-watered sludge is fed into the dryer with a mass flow rate of 165 tons per day and consists of 27% dry matter. After the sludge drying process, the dryness of sludge increases up to 40%. In the indirect sludge dryer unit, thermal oil is used to heat the dryer wall and to prevent heat loss. Thermal oil is circulated in a closed cycle and gathered into an oil tank. Total cost of the sludge dryer unit changes proportional to the dryer area. The optimum dryer area is found as 32.54 m2. The corresponding minimum cost is found as $35,700.
Wind Flow Over a Complex Terrain in Nygårdsfjell, Norway
Authors: Bilal Muhammad , Sridhar Narendran , Araya Guillermo , Parameswaran Sivapathas , Birkelund Yngve
Published: October 2015

The understanding of atmospheric flows is crucial in the analysis of dispersion of a contaminant or pollutant, wind energy and air-quality assessment to name a few. Additionally, the effects of complex terrain and associated orographic forcing are crucial in wind energy production. Furthermore, the use of the Reynolds-averaged Navier-Stokes (RANS) equations in the analysis of complex terrain is still considered the “workhorse” since millions of mesh points are required to accurately capture the details of the surface. On the other hand, solving the same problem by means of the instantaneous governing equations of the flow (i.e., in a suite of DNS or LES) would imply almost prohibitive computational resources. In this study, numerical predictions of atmospheric boundary layers are performed over a complex topography located in Nygårdsfjell, Norway. The Nygårdsfjell wind farm is located in a valley at approximately 420 meters above sea level surrounded by mountains in the north and south near the Swedish border. Majority of the winds are believed to be originated from Torneträsk lake in the east which is covered with ice during the winter time. The air closest to the surface on surrounding mountains gets colder and denser. The air then slides down the hill and accumulates over the lake. Later, the air spills out westward towards Ofotfjord through the broader channel that directs and transforms it into highly accelerated winds.

Consequently, one of the objectives of the present article is to study the influence of local terrain on shaping these winds over the wind farm. It is worth mentioning that we are not considering any wind turbine model in the present investigation, being the main purpose to understand the influence of the local surface topography and roughness on the wind flow. Nevertheless, future research will include modeling the presence of a wind turbine and will be published elsewhere. The governing equations of the flow are solved by using a RANS approach and by considering three different two-equation turbulence models: k-omega (k–ω), k-epsilon (k–ε) and shear stress transport (SST). Furthermore, the real topographical characteristics of the terrain have been modeled by extracting the required area from the larger digital elevation model (DEM) spanning over 100 km square. The geometry is then extruded using Rhino and meshed in ANSYS Fluent. The terrain dimensions are approximately 2000×1000 meter square.
Thermochemical Processing of Animal Fat and Meat and Bone Meal to Hydrocarbon Based Fuels
Authors: Eichenauer Sabrina , Weber Bernd , Stadlbauer Ernst A.
Published: October 2015

The results of the study at hand may have implications for treatment of grease, lipid fractions, free fatty acids (FFA) and salts of FFA extracted from wastes of food industry, bio-refineries or sewage sludge as well as contaminated lipid containing forage. The goal of the study is, to prevent such contaminated wastes from entering the food chain. The following ways of treatment are proposed. Thermal conversion of waste fats from rendering plants or lipids in the presence of aluminosilicates of the zeolite family produce hydrocarbons with net calorific values in the range of 40–42 MJ/kg. NMR studies show aliphatic hydrocarbons as main product at T = 400°C. The spectrum of products is shifted to alkyl benzenes at T = 550°C. In case of sodium carbonate conversion is achieved in the presence of 5% water at T = 430 ± 20°C yielding mainly a liquid bio-crude with a low acid index, a mixture of non-condensable gases and minor amounts of coke. Rectification of bio-crude from animal fat produces 65.8% of hydrocarbon based bio-diesel and 13.3% of gasoline type hydrocarbons. Distillation curve for bio-diesel is in accordance with DIN EN 490. However, the gasoline fraction lacks low boiling hydrocarbons indicating the necessity for technical improvements of condensers. Sodium carbonate is found to be effective as well as being relatively inexpensive compared to zeolite catalysts. Finally, successful conversion of meat and bone meal to biochar is proved by solid-state 13C-NMR.
Building Peak Load Management With High Resolution Weather Data
Authors: Tibana Yehisson , Gutierrez Estatio , Arend M. , Gonzalez J. E.
Published: October 2015

Dense urban environments are exposed to the combined effects of rising global temperatures and urban heat islands. This combination is resulting in increasing trends of energy consumption in cities, associated mostly with air conditioning to maintain indoor human comfort conditions. During periods of extreme summer weather, electrical usage usually reaches peak loads, stressing the electrical grid. The purpose of this study is to explore the use of available, high resolution weather data by effectively preparing a building for peak load management.

The subject of study is a 14 floor, 620,782 sq ft building located in uptown Manhattan, New York City (40.819257 N, −73.949288 W). To precisely quantify thermal loads of the buildings for the summer conditions; a single building energy model (SBEM), the US Department of Energy EnergyPlus™ was used. The SBEM was driven by a weather file built from weather data of the urbanized weather forecasting model (uWRF), a high resolution weather model coupled to a building energy model. The SBEM configuration and simulations were calibrated with winter actual gas and electricity data using 2010 as the benchmark year. In order to show the building peak load management, demand response techniques and technologies were implemented. The methods used to prepare the building included generator usage during high peak loads and use of a thermal storage system. An ensemble of cases was analyzed using current practice, use of high resolution weather data, and use of building preparation technologies. Results indicated an average summer peak savings of more than 30% with high resolution weather data.
Solar-Driven Sorption Chillers for Residential Space Cooling: A Review of Recent Developments and Possible Applications in Canada
Authors: Bowie Daniel , Cruickshank Cynthia A.
Published: October 2015

Energy use for space cooling has increased by 156% from 1990 to 2010 in the Canadian residential sector. In many parts of the country, the increasing use of electrically driven air-conditioners has begun to shift the peak load on the electricity grid from the coldest days of winter to the hottest days of summer. Many of Canada’s major electric utilities providers rely on fossil fuels to generate the additional capacity needed to meet the peak demand, resulting in significant greenhouse gas emissions. Solar-driven sorption chillers remain one of the possible solutions for shaving the peak loads experienced by the electricity grid.

This paper presents a review of the recent developments in the research of adsorption and absorption chillers, as well as a comparison of the two technologies based on the latest published experimental results found in the literature. Adsorption chillers continue to evolve in their design, including the use of new consolidated and composite adsorbents, the integration of coated adsorbers into internal heat exchangers, and newly developed advanced cycles for heat and mass recovery. While the physical design of adsorption chillers continues to be advanced, the development of absorption chillers for solar cooling applications has largely been focused on optimizing the system as a whole through improved control strategies and the implementation of newly developed high performance solar collectors.

Finally, the paper aims to assess the current state of development of solar-driven sorption chillers to provide insight into their applicability in the Canadian residential sector, as well as the remaining challenges facing this technology.
Analysis of a Combined Cycle Plant Using a Small Particle Receiver to Drive a Primary Brayton Cycle
Authors: Virgen Matthew Miguel , Miller Fletcher
Published: October 2015

All current commercial CSP plants operate at relatively low thermodynamic efficiency due to lower temperatures than similar conventional plants and due to the fact that they all employ Rankine conversion cycles. We present here an investigation on the effects of adding a bottoming steam power cycle to a hybrid CSP plant based on a Small Particle Heat Exchange Receiver (SPHER) driving a gas turbine as the primary cycle. Due to the high operating temperature of the SPHER being considered (over 1000 Celsius), the exhaust air from the primary Brayton cycle still contains a tremendous amount of exergy. While in the previous analysis this fluid was only used in a recuperator to preheat the Brayton working fluid, the current analysis explores the potential power and efficiency gains from instead directing the exhaust fluid through a heat exchanger to power a Rankine steam cycle. Not only do we expect the efficiency of this model to be competitive with conventional power plants, but the water consumption per kilowatt-hour will also be reduced by nearly two thirds as compared to most existing concentrating solar thermal power plants as a benefit of having air as the primary working fluid, which eliminates the condensation step present in Rankine-cycle systems.

Coupling a new steam cycle model with the gas-turbine CSP model previously developed at SDSU, a wide range of cases were run to explore options for maximizing both power and efficiency from the proposed CSP combined cycle gas turbine (CCGT) plant. Due to the generalized nature of the bottoming cycle modeling, and the varying nature of solar power, special consideration had to be given to the behavior of the heat exchanger and Rankine cycle in off-design scenarios. The trade-offs of removing the recuperator for preheating the primary fluid are compared to potential overall power and efficiency gains in the combined cycle case.
Analysis of Heavy Organic Fluids Dispersion Inside Industrial Buildings Hosting Turbomachinery Test Facilities
Authors: Fiaschi Daniele , Manfrida Giampaolo , Russo Luigi
Published: October 2015

The use of heavy fluids (typically refrigerants) for tests on turbomachinery equipment, like centrifugal compressors, under similitude with real working conditions is a common practice in the test facilities of manufacturers. This practice leads to the release of the test gas to the environment, mainly coming from seals, test circuit connections, valve gaskets and from operations of circuit assembling/disassembling necessary to replace or service the machine under test.

The spatial distribution and flow of these emissions inside the test building is a complex issue, which depends on the specific circuit features, location of sources, geometry and openings of the building and variable climatic conditions of the location. For a preliminary assessment of the health and safety conditions, a NIST computational package — including a CFD solver — was applied. The aim was to validate the applicability and reliability of this tool, which was developed for other types of buildings; from the industrial side, knowledge of the diffusion scenario is important to define test protocols to guarantee acceptable emissions levels for manpower in working areas.

The industrial building is organized in multiple inside workspaces. The concentration of the contaminant in the area of the test benches, determined by the internal fluid dynamics, is calculated with the CFD solver included in the NIST package. In the building, air motion is only affected by natural ventilation. For this reason, the interactions between the outside and the interior climatic and microclimatic parameters must be considered, taking into account also the different possible assumptions about the daily management of the openings of the building envelope. Several cases of release and dispersion of heavy fluid inside the working areas, under different boundary conditions, were considered. The sensitivity of the results to the different seasonal conditions was assessed and discussed. The complex internal geometry of the building was simulated by a combination of single zone models. The results showed an expectable presence of test gas emissions in the neighborhood of the test area and the possibility of buoyancy effects within the large building. A relatively stable concentration of the test gas emissions resulted from the application of the model, which was affected only by substantial variations of the climatic conditions.