bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal sensitivity of native and invasive seabreams
Authors: Vinagre Catarina , Narciso Luís , Cabral Henrique N. , Costa Maria J. , Rosa Rui
Published: July 2013

This study compared the mortality and metabolic response of the Senegal seabream, Diplodus bellottii, an African species recently reported in Southern Europe and the white seabream Diplodus sargus, a native species, across a range of temperatures. The temperatures tested were 18, 26, 28 and 30 °C. Mortality was zero at 18 °C and very low at all other temperatures for both species, with the exception of D. bellottii, which experienced 32% mortality at 30 °C. Metabolic rates increased steadily with increasing temperatures, with a steep increase at 30 °C for D. bellottii. Thermal sensitivity ranged between 2 and 3 for both species and for all thermal intervals, with the exception of the thermal sensitivity between 28 and 30 °C for D. bellottii, which was 7. It was concluded that D. bellottii is under thermal stress at 30 °C. Diplodus bellottii may have expanded its distribution northwards due to an increase in sea surface temperatures. However, further warming may result in habitat loss for the juveniles, since Southern European estuarine systems will reach temperatures that may lead to lower fitness in juveniles of this species.
Inferring asteroid surface properties from radar albedos and circular‐polarization ratios
Authors: Virkki A. , Muinonen K. , Penttilä A.
Published: July 2013

We model electromagnetic scattering from varying closely packed random aggregates of spheres imitating piles of rocks on the surface of an asteroid. We utilize the Multiple Sphere T‐Matrix Method software to study how different parameters affect the radar albedo and the circular‐polarization ratio, for example, the size distribution and electric permittivities of the spherical particles forming the aggregates, and to see if the computed radar albedos and circular‐polarization ratios can be linked to the observational data of asteroids detected using radar. The results of the simulations show the radar albedo and the circular‐polarization ratio as a function of size parameter for different silicate minerals, including anorthosite, peridotite olivine, and basalt. A direct vacuum‐rock surface interface will be considered as well as an approximation for a case in which the rocks are covered by a layer of powdered material, that is, fine regolith. The promising results show values on the range of observed values and imply that the highest circular‐polarization values (μc > 1) are measurable only for targets with surface material of high electric permittivity (ε′ > 4.0). However, the asteroid surface model requires further development before more robust conclusions can be made of the surface chemical and structural composition.
Thermal processing and crystallization of amorphous Mg‐Ca silicates
Authors: Day Sarah J. , Thompson Stephen P. , Evans Aneurin , Parker Julia E. , Connor Leigh D. , Tang Chiu C.
Published: July 2013

The structural evolution of sol–gel‐produced amorphous Mg(x)Ca(1–x)SiO3 silicates is investigated. Mid‐IR Fourier transform infrared spectroscopy and synchrotron X‐ray diffraction are used to confirm the amorphous nature of the as‐prepared silicates, while subsequent in situ synchrotron X‐ray powder diffraction measurements are used to study the evolution of crystalline mineral phases as a function of annealing temperature. Multiple silicate phases, including diopside, enstatite, forsterite, and SiO2, are identified, while Rietveld (i.e., structure) refinement of the diffraction data is used to quantify phase change relationships. Investigated as possible analogs for the refractory dust grain materials likely to have been present in the early solar nebula, the likely relevance of these investigations to the observed silicate compositions of chondritic meteorites and cometary bodies and the processing of their precursor materials is discussed.
Restriction to large‐scale gene flow vs. regional panmixia among cold seep Escarpia spp. (Polychaeta, Siboglinidae)
Authors: Cowart Dominique A. , Huang Chunya , Arnaud‐Haond Sophie , Carney Susan L. , Fisher Charles R. , Schaeffer Stephen W.
Published: July 2013

The history of colonization and dispersal in fauna distributed among deep‐sea chemosynthetic ecosystems remains enigmatic and poorly understood because of an inability to mark and track individuals. A combination of molecular, morphological and environmental data improves understanding of spatial and temporal scales at which panmixia, disruption of gene flow or even speciation may occur. Vestimentiferan tubeworms of the genus Escarpia are important components of deep ‐sea cold seep ecosystems, as they provide long‐term habitat for many other taxa. Three species of Escarpia, Escarpia spicata [Gulf of California (GoC)], Escarpia laminata [Gulf of Mexico (GoM)] and Escarpia southwardae (West African Cold Seeps), have been described based on morphology, but are not discriminated through the use of mitochondrial markers (cytochrome oxidase subunit 1; large ribosomal subunit rDNA, 16S; cytochrome b). Here, we also sequenced the exon‐primed intron‐crossing Haemoglobin subunit B2 intron and genotyped 28 microsatellites to (i) determine the level of genetic differentiation, if any, among the three geographically separated entities and (ii) identify possible population structure at the regional scale within the GoM and West Africa. Results at the global scale support the occurrence of three genetically distinct groups. At the regional scale among eight sampling sites of E. laminata (n = 129) and among three sampling sites of E. southwardae (n = 80), no population structure was detected. These findings suggest that despite the patchiness and isolation of seep habitats, connectivity is high on regional scales.
Population genetics of Wolbachia‐infected, parthenogenetic and uninfected, sexual populations of Tetrastichus coeruleus (Hymenoptera: Eulophidae)
Authors: Reumer Barbara M. , van Alphen Jacques J. M. , Kraaijeveld Ken
Published: July 2013

Wolbachia are endosymbiotic bacteria known to manipulate the reproduction of their hosts. These manipulations are expected to have consequences on the population genetics of the host, such as heterozygosity levels, genetic diversity and gene flow. The parasitoid wasp Tetrastichus coeruleus has populations that are infected with parthenogenesis‐inducing Wolbachia and populations that are not infected. We studied the population genetics of T. coeruleus between and within Wolbachia‐infected and uninfected populations, using nuclear microsatellites and mitochondrial DNA. We expected reduced genetic diversity in both DNA types in infected populations. However, migration and gene flow could introduce new DNA variants into populations. We therefore paid special attention to individuals with unexpected (genetic) characteristics. Based on nuclear and mitochondrial DNA, two genetic clusters were evident: a thelytokous cluster containing all Wolbachia‐infected, parthenogenetic populations and an arrhenotokous cluster containing all uninfected, sexual populations. Nuclear and mitochondrial DNA did not exhibit concordant patterns of variation, although there was reduced genetic diversity in infected populations for both DNA types. Within the thelytokous cluster, there was nuclear DNA variation, but no mitochondrial DNA variation. This nuclear DNA variation may be explained by occasional sex between infected females and males, by horizontal transmission of Wolbachia, and/or by novel mutations. Several females from thelytokous populations were uninfected and/or heterozygous for microsatellite loci. These unexpected characteristics may be explained by migration, by inefficient transmission of Wolbachia, by horizontal transmission of Wolbachia, and/or by novel mutations. However, migration has not prevented the build‐up of considerable genetic differentiation between thelytokous and arrhenotokous populations.
Alternative sigma factor RpoN and its modulation protein YhbH are indispensable for Erwinia amylovora virulence
Authors: Ancona Veronica , Li Wenting , Zhao Youfu
Published: July 2013

In Erwinia amylovora, ECF (extracytoplasmic functions) alternative sigma factor HrpL regulates the transcription of hrp (hypersensitive response and pathogenicity)‐type III secretion system (T3SS) genes by binding to a consensus sequence known as the hrp box in hrp gene promoters. In turn, the expression of hrpL has been proposed to be positively controlled by alternative sigma factor 54 (σ54) (RpoN) and HrpS, a member of the σ54 enhancer‐binding proteins (EBPs). However, the function of RpoN has not been characterized genetically in E. amylovora. In this study, we investigated the role of RpoN, a nitrogen limitation sigma factor, and its modulation protein YhbH, a novel ribosome‐associated protein, in E. amylovora virulence. Our results showed that mutations in hrpS, hrpL, rpoN and yhbH, but not yfiA and rmf3, resulted in a nonpathogenic phenotype on immature pear fruits and apple shoots. Consistently, the expression of T3SS genes, including hrpL, dspE, hrpN and hrpA, was barely detected in hrpS, hrpL, rpoN and yhbH mutants. These mutants were also not capable of eliciting a hypersensitive response (HR) on tobacco; however, the overexpression of hrpL using an inducible promoter rescued the HR‐eliciting abilities of these mutants. These results suggest that a sigma factor cascade exists in the regulatory networks of E. amylovora and regulates important virulence factors. On the basis of this study and previously reported data, a model is proposed for the regulation of T3SS in E. amylovora.
The Development of Schenker's Concept of Interruption
Authors: Marston Nicholas
Published: July 2013

This article draws on the rich resources of Heinrich Schenker's Nachlass in the Ernst Oster Collection (New York Public Library) to construct the development of interruption (Unterbrechung), a vital aspect of Schenker's mature understanding of musical form. In §90 of Der freie Satz (1935) Schenker makes a crucial distinction between the structural weight of the two configurations in an interrupted Ursatz, and gives priority to the first one: the effect of interruption depends on the sense that this will be succeeded by , rather than by the return to that is actually forthcoming. Subsequently, in §93, Schenker claims that the reasserted connects back to its first appearance, prior to the first arrival of . The article explores the tension between these two claims in relation to and Ursätze and reconstructs preliminary versions of the text relating to interruption in Der freie Satz. It concludes by suggesting that Schenker's shifting notation of interrupted structures reflects a continuing uneasiness with his own definition of interruption as a theoretical concept.
Overcoming Barriers to Mediation in Intake Calls to Services: Research‐Based Strategies for Mediators
Authors: Stokoe Elizabeth
Published: July 2013

In this article, I investigate intake calls to community mediation services in which disputing neighbors ask mediators to help them resolve their conflicts. These calls are the first point of contact between potential clients and mediators. To maintain their organization's funding, mediators must convert a sufficient number of these callers into clients of the service. Intake calls, however, are not treated as part of the mediation process proper, and mediators are not trained to handle them. I audio‐recorded and transcribed approximately two hundred calls to mediation services based in the United Kingdom and then analyzed them using conversation analysis. I identified several factors routinely present in these intake calls that seemed to prevent disputants from ultimately engaging in the mediation process; I characterize these factors as “barriers to mediation.” These barriers include callers' lack of knowledge about mediation as a service and mediators' often ineffective methods of explaining the process. In particular, callers rejected mediation services when the mediators explained that mediation is an impartial service. Some of the mediators, however, managed intake calls differently, describing it more effectively, expressing empathy or affiliation with callers, and thus were able to overcome many of the callers' most common concerns about the process. In this article, I also discuss this study's implications for understanding the institution of mediation and for training mediators.
World Championship in Negotiation? The Role of Competitions in Negotiation Pedagogy
Authors: Smolinski Remigiusz , Kesting Peter
Published: July 2013

The last decade has seen the emergence of several new negotiation competitions around the world. We think the two major drivers of this development are a general trend toward the increasing internationalization of higher education and a recognition of the specific benefits of competitions for negotiation pedagogy. These benefits include: the high level of student commitment generated by participation in a competition, which enhances the quality of negotiation; the opportunity that the competitions give students to experience authentic cultural diversity; and the networking opportunities for students and instructors that the competitions create. This article focuses on the role that negotiation competitions can play in negotiation pedagogy. We first present an overview of the currently most important international negotiation competitions. This is followed by an outline of the specific benefits of negotiation competitions for pedagogy. We then take a closer look at the organization and outcome of negotiation competitions and discuss the opportunities for their development and growth.
GLI2 cooperates with ZEB1 for transcriptional repression of CDH1 expression in human melanoma cells
Authors: Perrot Carole Y. , Gilbert Cristèle , Marsaud Véronique , Postigo Antonio , Javelaud Delphine , Mauviel Alain
Published: July 2013

In melanoma cells, high expression of the transcription factor GLI2 is associated with increased invasive potential and loss of E‐cadherin expression, an event reminiscent of the epithelial‐to‐mesenchymal transition (EMT). Herein, we provide evidence that GLI2 represses E‐cadherin gene (CDH1) expression in melanoma cells via distinct mechanisms, enhancing transcription of the EMT‐activator ZEB1 and cooperative repression of CDH1 gene transcription via direct binding of both GLI2 and ZEB1 to two closely positioned Kruppel‐like factor‐binding sites within the CDH1 promoter. GLI2 silencing rescued CDH1 expression except in melanoma cell lines in which the CDH1 promoter was hypermethylated. Proximity ligation assays identified GLI2–ZEB1 complexes in melanoma cell nuclei, proportional to endogenous GLI2 and ZEB1 expression, and whose accumulation was enhanced by the classical EMT inducer TGF‐β. These data identify GLI2 as a critical modulator of the cadherin switch in melanoma, a molecular process that is critical for metastatic spread of the disease.
Cognitive Penetrability of Perception
Authors: Stokes Dustin
Published: July 2013

Perception is typically distinguished from cognition. For example, seeing is importantly different from believing. And while what one sees clearly influences what one thinks, it is debatable whether what one believes and otherwise thinks can influence, in some direct and non‐trivial way, what one sees. The latter possible relation is the cognitive penetration of perception. Cognitive penetration, if it occurs, has implications for philosophy of science, epistemology, philosophy of mind, and cognitive science. This paper offers an analysis of the phenomenon, its theoretical consequences, and a variety of experimental results and possible interpretations of them. The paper concludes by proposing some constraints for analyses and definitions of cognitive penetrability.
Content, Mood, and Force
Authors: Recanati Francois
Published: July 2013

In this survey paper, I start from two classical theses of speech act theory: that speech act content is uniformly propositional and that sentence mood encodes illocutionary force. These theses have been questioned in recent work, both in philosophy and linguistics. The force/content distinction itself – a cornerstone of 20‐century philosophy of language – has come to be rejected by some theorists, unmoved by the famous ‘Frege–Geach’ argument. The paper reviews some of these debates.
Study of Sperm Concentration, Seminal Plasma Composition and their Physiological Correlation in the Persian Sturgeon, Acipenser persicus
Authors: Aramli MS , Kalbassi MR , Nazari RM
Published: July 2013

Contents

The objectives of the present study were to determine ionic and organic composition of seminal plasma, sperm concentration and their relationships in the Persian sturgeon (Acipenser persicus). In this regard, ionic content (Na+, K+, Cl−, Ca2+ and Mg2+) and organic content (total protein, glucose, cholesterol and triglyceride) along with sperm concentration were measured in 17 specimens of the Persian sturgeon. The seminal plasma contained 59.53 ± 2.56 mm/l sodium, 9.1 ± 1.42 mm chloride, 4.72 ± 0.3 mm potassium, 1.45 ± 0.075 mm calcium and 0.7 ± 0.072 mm magnesium. The following organic contents were found: total protein 0.11 ± 0.02 g/dl, glucose 22.18 ± 4.16 mg/dl, cholesterol 6.67 ± 1.04 mg/dl and triglyceride 15.2 ± 0.65 mg/dl. The mean sperm concentration was estimated to be 1.6 ± 0.12 (×109 sperm/ml). A significant relationship was found between sperm concentration and K+ of seminal plasma (r = 0.533, p < 0.05). Significant correlations were observed between ionic contents: Na+ vs Cl− (r = −0.854, p < 0.01) and Mg2+ vs K+ (−0.583, p < 0.05). Also, level of triglyceride was negatively correlated with Mg2+ (r = −0.503, p < 0.05). Presented data could be considered as a complementary study for developing special extenders and protectant solutions for improving artificial fertilization in this valuable species.
Trypan Blue/Giemsa Staining to Assess Sperm Membrane Integrity in Salernitano Stallions and its Relationship to Pregnancy Rates
Authors: Serafini R , Longobardi V , Spadetta M , Neri D , Ariota B , Gasparrini B , Di Palo R
Published: July 2013

Contents

Aim of this study was to test the reliability ofTrypan blue/Giemsa staining to evaluate sperm membrane integrity, acrosomal intactness and morphology in stallion to verify whether it could be appliedin vitroas useful tool for sperm fertilizing ability. Fertility data on inseminated mares were collected to evaluate the relationship of sperm quality to pregnancy rates. Forty‐one ejaculates were collected from 3 stallions ofSalernitanoHorseBreed and evaluated for gross appearance, volume, visual motility and membrane integrity withTrypan blue/Giemsa staining and thirty‐five mares were inseminated during the breeding season fromApril toJuly. Differences among stallions were found in volume, sperm concentration (p < 0.05) and visual motility (p < 0.01). A decrease in sperm motility, concentration (p < 0.05) and total sperm number was found in June–July (p < 0.01). Live sperm with intact acrosome (LSIA) and proximal droplets (PD) were lower (p < 0.01) in June–July, while acrosome reacted sperm (ARS) percentage increased (p < 0.05). No fertility differences were found among stallions with an average fertility per cycle of 44.6% and a pregnancy rate of 68.6%. Higher percentages ofLSIAwere found in the ejaculates used to inseminate mares that became pregnant vs those used in mares not pregnant (p < 0.05). The significance ofLSIAas test variable to verify the reliability ofTrypan blue/Giemsa staining was confirmed by Receiver operating characteristicROCanalysis and the sensitivity of the test was 85% at a cut‐off value of 48%LSIA. Trypan blue‐Giemsa showed to be an accurate method that can be applied on field to evaluate sperm membrane integrity and to identify poor‐quality ejaculates.
Pulmonary rehabilitation after an exacerbation of chronic obstructive pulmonary disease – Evidence for the applicability of trial results to practice populations
Authors: Puhan Milo
Published: July 2013

See article, page 1063
An overview of service quality of continuous positive airway pressure services in Australian pharmacies
Authors: Hanes Carissa A. , Wong Keith K.H. , Saini Bandana
Published: July 2013

Background and objective

Little is known about CPAP services offered in the Australian primary care pharmacy setting, despite the potential influence of service quality on patient adherence. The objective of this study was to provide an overview on a nationwide scale of the range and quality of CPAP and sleep apnoea‐related services in Australian pharmacies.

Methods

A paper‐based questionnaire was developed and mailed to all pharmacies in Australia that currently provide CPAP services (as identified by manufacturer's distributor lists or Internet search). A point system was devised to score participants on the quality of their CPAP service. Pharmacies were rated against a list of 23 criteria that were determined by consensus, with one point allocated for each criterion met, allowing for a maximum score of 23.

Results

The study response rate was 55% (110/199), and representation was obtained from all eight Australian states and territories. The mean number of criteria met (total score) for pharmacies was 15.7 ± 3.4 (15.7/23 = 68.3%; score range 2–22). Variability was evident in the range of services offered. Eighty‐seven per cent of respondents believed that pharmacies supplying CPAP should adhere to a formalized set of professional guidelines.

Conclusions

The accessibility of pharmacies may make them a valuable venue for CPAP service provision. However, models of care to guide practice and standardize the variability in services are required. Implementation of such models could improve patient access to quality treatment in the primary care setting.
Multidirectional, synchronously‐triggered seismo‐turbidites and debrites revealed by X‐ray computed tomography (CT)
Authors: Van Daele Maarten , Cnudde Veerle , Duyck Philippe , Pino Mario , Urrutia Roberto , De Batist Marc
Published: July 2013

On 21 April 2007, a Mw 6·2 earthquake struck Aysén fjord (Chilean Patagonia) and caused onshore and offshore mass movements which triggered tsunamis and density flows in the fjord. To better understand the facies successions in, and the intercalation of, the density‐flow deposits, a study was made of the 2007 deposits in 22 short sediment cores taken in the inner Aysén fjord. By combining grain‐size analysis with X‐ray computed tomography scanning, it was possible to demonstrate that the encountered facies correspond to classical divisions of debrites and turbidites. The single‐event deposits consist of a succession of several sub‐deposits deposited under different flow directions and can be interpreted as stacked turbidites. Orientations of: (i) folds; (ii) imbricated mud clasts; (iii) backsets and foresets of climbing ripples; and (iv) asymmetrical convolute lamination were used to determine relative flow directions at the location of the cores. By assigning the basal flow of the stacked debrites and turbidites to the closest principal mass flow, the absolute flow directions of the sub‐deposits were determined which, in combination with multibeam basin‐floor morphology, allowed reconstruction of the 2007 density‐flow successions in Aysén fjord. Furthermore, alternating flow directions provide evidence for a seiche induced by the density flows. It was concluded that X‐ray computed tomography scans provide crucial information for reconstructing palaeoflows and can be a useful tool in marine and lacustrine sedimentology and palaeoseismology. The multidirectionality of sub‐deposits in turbidites is, next to differences in mineralogy, a new criterion to identify stacked turbidites. These multidirectional, stacked turbidites are an indication of simultaneous triggering of density flows and can therefore, in most cases, be attributed to earthquakes, ruling out other triggers, such as floods, storms or other sediment failures.
An Accurate Spatial Discretization and Substructure Method With Application to Moving Elevator Cable-Car Systems—Part I: Methodology
Authors: Zhu W. D. , Ren H.
Published: July 2013

A spatial discretization and substructure method is developed to accurately calculate dynamic responses of one-dimensional structural systems, which consist of length-variant distributed-parameter components, such as strings, rods, and beams, and lumped-parameter components, such as point masses and rigid bodies. The dependent variable of a distributed-parameter component is decomposed into boundary-induced terms and internal terms. The boundary-induced terms are interpolated from boundary motions, and the internal terms are approximated by an expansion of trial functions that satisfy the corresponding homogeneous boundary conditions. All the matching conditions at the interfaces of the components are satisfied, and the expansions of the dependent variables of the distributed-parameter components absolutely and uniformly converge if the dependent variables are smooth enough. Spatial derivatives of the dependent variables, which are related to internal forces/moments of the distributed-parameter components, such as axial forces, bending moments, and shear forces, can be accurately calculated. Combining component equations that are derived from Lagrange's equations and geometric matching conditions that arise from continuity relations leads to a system of differential algebraic equations (DAEs). When the geometric matching conditions are linear, the DAEs can be transformed to a system of ordinary differential equations (ODEs), which can be solved by an ODE solver. The methodology is applied to several moving elevator cable-car systems in Part II of this work.
An Accurate Spatial Discretization and Substructure Method With Application to Moving Elevator Cable-Car Systems—Part II: Application
Authors: Ren H. , Zhu W. D.
Published: July 2013

This paper uses the methodology developed in Part I of this work to study the longitudinal, transverse, and their coupled vibrations of moving elevator cable-car systems. A suspension cable is a one-dimensional length-variant distributed-parameter component. When there is only one suspension cable connected to the car, the car is modeled as a point mass. When there are multiple suspension cables, the car is modeled as a rigid body, and the rotation of the car is considered. There are complicated matching conditions between the cable and car, which cannot be satisfied in the classical assumed modes method but can be satisfied in the current method. Hence, not only the longitudinal and transverse displacements but also the internal forces/moment, such as the axial force, the bending moment, and the shear force, which are related to the spatial derivatives of the longitudinal and transverse displacements, are accurately calculated. The results from different choices of boundary motions and trial functions are essentially the same, and the convergence is much faster than that of the assumed modes method. The longitudinal-transverse coupled vibrations of a moving cable-car system are also studied using the current method, and the results are compared with those from the linear models. While the result from the linear model for the transverse vibration agrees well with that from the nonlinear coupled model, the axial force from the linear model can significantly differ from that from the nonlinear model when the car approaches the top of the hoistway.
Two-Phase Flow Control of Electronics Cooling With Pseudo-CPUs in Parallel Flow Circuits: Dynamic Modeling and Experimental Evaluation
Authors: Lamaison Nicolas , Braz Marcinichen Jackson , Richard Thome John
Published: July 2013

On-chip two-phase cooling of parallel pseudo-CPUs integrated into a liquid pumped cooling cycle is modeled and experimentally verified versus a prototype test loop. The system's dynamic operation is studied since the heat dissipated by microprocessors is continuously changing during their operation and critical heat flux (CHF) conditions in the microevaporator must be avoided by flow control of the pump speed during heat load disturbances. The purpose here is to cool down multiple microprocessors in parallel and their auxiliary electronics (memories, dc/dc converters, etc.) to emulate datacenter servers with multiple CPUs. The dynamic simulation code was benchmarked using the test results obtained in an experimental facility consisting of a liquid pumped cooling cycle assembled in a test loop with two parallel microevaporators, which were evaluated under steady-state and transient conditions of balanced and unbalanced heat fluxes on the two pseudochips. The errors in the model's predictions of mean chip temperature and mixed exit vapor quality at steady state remained within ±10%. Transient comparisons showed that the trends and the time constants were satisfactorily respected. A case study considering four microprocessors cooled in parallel flow was then simulated for different levels of heat flux in the microprocessors (40, 30, 20, and 10 W cm−2), which showed the robustness of the predictive-corrective solver used. For a desired mixed vapor exit quality of 30%, at an inlet pressure and subcooling of 1600 kPa and 3 K, the resulting distribution of mass flow rate in the microevaporators was, respectively, 2.6, 2.9, 4.2, and 6.4 kg h−1 (mass fluxes of 47, 53, 76 and 116 kg m−2 s−1) and yielded approximately uniform chip temperatures (maximum variation of 2.6, 2, 1.7, and 0.7 K). The vapor quality and maximum chip temperature remained below the critical limits during both transient and steady-state regimes.
High-Efficiency Transient Temperature Calculations for Applications in Dynamic Thermal Management of Electronic Devices
Authors: Touzelbaev Maxat N. , Miler Josef , Yang Yizhang , Refai-Ahmed Gamal , Goodson Kenneth E.
Published: July 2013

The highly nonuniform transient power densities in modern semiconductor devices present difficult performance and reliability challenges for circuit components, multiple levels of interconnections and packaging, and adversely impact overall power efficiencies. Runtime temperature calculations would be beneficial to architectures with dynamic thermal management, which control hotspots by effectively optimizing regional power densities. Unfortunately, existing algorithms remain computationally prohibitive for integration within such systems. This work addresses these shortcomings by formulating an efficient method for fast calculations of temperature response in semiconductor devices under a time-dependent dissipation power. A device temperature is represented as output of an infinite-impulse response (IIR) multistage digital filter, processing a stream of sampled power data; this method effectively calculates temperatures by a fast numerical convolution of the sampled power with the modeled system's impulse response. Parameters such as a steady-state thermal resistance or its extension to a transient regime, a thermal transfer function, are typically used with the assumption of a linearity and time-invariance (LTI) to form a basis for device thermal characterization. These modeling tools and the time-discretized estimates of dissipated power make digital filtering a well-suited technique for a run-time temperature calculation. A recursive property of the proposed algorithm allows a highly efficient use of an available computational resource; also, the impact of all of the input power trace is retained when calculating a temperature trace. A network identification by deconvolution (NID) method is used to extract a time-constant spectrum of the device temperature response. We verify this network extraction procedure for a simple geometry with a closed-form solution. In the proposed technique, the amount of microprocessor clock cycles needed for each temperature evaluation remains fixed, which results in a linear relationship between the overall computation time and the number of temperature evaluations. This is in contrast to time-domain convolution, where the number of clock cycles needed for each evaluation increases as the time window expands. The linear dependence is similar to techniques based on FFT algorithms; in this work, however, use of z-transforms significantly decreases the amount of computations needed per temperature evaluation, in addition to much reduced memory requirements. Together, these two features result in vast improvements in computational throughput and allow implementations of sophisticated runtime dynamic thermal management algorithms for all high-power architectures and expand the application range to embedded platforms for use in a pervasive computing environment.
Assessment of Solar Development in Taiwan
Authors: Boehm Robert
Published: July 2013

A study of the state of solar energy development in Taiwan has been performed. In this work, general energy use, solar research issues, and solar manufacturing status and applications were surveyed in late 2011. It was found that there are active research efforts underway in a variety of solar technologies, primarily in photovoltaics, and to a limited extent in solar domestic water heating. Significant manufacturing capabilities in photovoltaic cells have developed within the last decade, and this has grown rapidly, such that Taiwan has edged out Germany for the number two spot in the list of top manufacturers. Very little in the line of photovoltaic installations are found on the island, however. Another characteristic in terms of solar water heating manufacturing and application is that not much is found in Taiwan in contrast to what has taken place on the mainland of China. Some government efforts to stimulate the Taiwanese consumer market both in photovoltaics as well as water heating are outlined, but goals for the PV installations seem overly optimistic based upon recent history.
Flow Distribution in Flat Solar Collectors Systems Interconnected
Authors: Ríos Orozco C. O. , Uzarraga-Rodriguez N. C. , Gallegos-Muñoz A. , Riesco Ávila J. M.
Published: July 2013

In this work the characterization of the water flow through a flat solar collector and solar collectors systems interconnected is presented. This allows analyzing the behavior of flow distribution in the headers pipe and riser tubes of flat solar collectors. The hydraulic analysis allows determining if the water flow inside the risers presents a no-uniform distribution, having that the mass flow rate through riser tubes increases when they are located a greater distance from inlet of header pipe. This effect also occurs at system composed of several solar collectors interconnected, through their own header pipes, which behaves like a simple flat solar collector with header pipe longer and major number of riser tubes.

The hydraulic model of the water flow through a flat solar collector, equipped with different number of riser tubes, is modeled in the FLUENT® software and comparing with theory and methodology knowing for the calculation of pressure drop in pipe sections and accessories. The results show the curves obtained for hydraulic behavior for the cases of study, where is observed that the water flow is no-uniform. This no uniformity provokes that the friction coefficient varies depending of the position of riser tube.
The Impact of Receiver Position Error on Parabolic Trough Collector Optical Performance
Authors: Zhu Guangdong
Published: July 2013

A newly developed analytical optical approach — First-principle OPTical Intercept Calculation (FirstOPTIC) — is employed to study the optical impact of receiver position error on parabolic trough collectors. The FirstOPTIC program performs first-principle treatment system optical error sources. By analyzing a large number of cases with varying system parameters such as the overall system optical error and the collector geometrical parameters, the paper quantitatively examines the difference between the first-principle treatment and probability approximation to receiver position error. In addition, a practical correlation between actual measurement data and its probability approximation for receiver position errors is established from parametric study; the correlation can be used to evaluate the relative importance of receiver position error to the collector’s optical performance. The effective coefficients defining the correlation of receiver position errors are also summarized for some existing trough collectors and make it convenient to conduct error-convolution-based optical analysis, which was not straightforward before. It is also shown that FirstOPTIC is a suitable tool for in-depth optical analysis and fast collector design optimization, which otherwise requires computationally intensive ray-tracing simulations.
Energetic Comparison of Linear Fresnel and Parabolic Trough Collector Systems
Authors: Schenk Heiko , Hirsch Tobias , Feldhoff Jan Fabian , Wittmann Michael
Published: July 2013

Within the last years, Linear Fresnel (LF) collector systems have been developed as a technical alternative to parabolic trough collector (PT) systems. In the past, LF systems focused on low- and medium temperature applications. Nowadays, LF systems equipped with vacuum receivers can be operated at the same temperatures as PT systems. Papers about the technical and economical comparison of specific PT and LF systems have already been published, [1–3]. However, the present paper focuses on the systematic differences in optical and thermodynamic performance and the impact on the economic figures.

In a first step the optical performance of typical PT and LF solar fields has been examined, showing the differences during the course of the day and annually. Furthermore, the thermodynamic performance, depending on the operating temperature, has been compared.

In a second step, the annual electricity yield of typical PT and LF plants are examined. Solar Salt has been chosen as heat transfer fluid. Both systems utilize the same power block and storage type. Solar field size, storage capacity, and power block electrical power are variable, while all examined configurations achieve the same annual electricity yield. As expected for molten salt systems, both systems are the most cost-effective with large storage capacities. The lower thermodynamic performance of the LF system requires a larger solar field and lower specific costs in order to be competitive. Assuming specific PT field costs of 300 €/m2 aperture, the break-even costs of the LF system with Solar Salt range between 202 and 235 €/m2, depending on the site and storage capacity.
Modeling of Gas Turbine-Based Cogeneration System
Authors: Zabihian Farshid , Fung Alan S. , Schuler Fabio
Published: July 2013

Gas turbine-based power plants generate a significant portion of world’s electricity. This paper presents the modeling of a gas turbine-based cogeneration cycle. One of the reasons for the relatively low efficiency of a single gas turbine cycle is the waste of high-grade energy at its exhaust stream. In order to recover this wasted energy, steam and/or hot water can be cogenerated to improve the cycle efficiency. In this work, a cogeneration power plant is introduced to use this wasted energy to produce superheated steam for industrial processes. The cogeneration system model was developed based on the data from the Whitby cogeneration power plant in ASPEN PLUS®. The model was validated against the operational data of the existing power plant. The electrical and total (both electrical and thermal) efficiencies were around 40% and 70% (LHV), respectively. It is shown that cogenerating electricity and steam not only significantly improve the general efficiency of the cycle but it can also recover the output and efficiency losses of the gas turbine as a result of high ambient temperature by generating more superheated steam. Furthermore, this work shows that the model could capture the operation of the systems with an acceptable accuracy.
Three-Dimensional Optical and Thermal Numerical Model of Solar Tubular Receivers in Parabolic Trough Concentrators
Authors: Wirz Men , Roesle Matthew , Steinfeld Aldo
Published: July 2013

Monte Carlo ray tracing, coupled to a finite volume solver, is used to model 3D heat transfer in a parabolic trough solar concentrator system. The non-uniform distribution of the incident solar radiation, the radiative exchange between the various receiver surfaces, and the heat gain/loss around the receiver’s circumference and along the system’s axis are determined for spectral radiative properties of the receiver and concentrator surfaces. The computed heat losses and thermal efficiencies agree well with experimental data. Besides the beneficial information on peak temperatures and heat flux, the 3D model also has a potential to predict glass temperatures more accurately than previous gray models and temperature correlations.
Experimental Validation of Solar Chimney Performance Models and Operational Characteristics for Small Scale Remote Applications
Authors: Raney Stephen M. , Brooks Jeremy R. , Schaffer Jared P. , French Jesse J.
Published: July 2013

Though the Solar Chimney (SC) concept is one that has been around for nearly a century, this technology has regained momentum in recent decades. Several large-scale projects have been constructed, and others are in the process of being constructed. CFD and numerical analysis have allowed research to progress in characterizing the performance of SCs. Previous research has focused primarily on large-scale, high power production designs. The authors have validated these analyses empirically for small-scale, low power production SCs through the design and fabrication of a small-scale SC with adjustable geometries. The performance of the SC was characterized by the primary variable of chimney height. The effects of secondary variables were also measured and characterized: chimney diameter, collector height, and collector slope.

Results are presented showing that, though the numerical analysis and characteristic equations hold for large scale SCs, in small scale applications the reduction in size creates a greater dependence on the secondary variables in the overall performance of the SC. Optimization of both primary and secondary variables is discussed and demonstrated based on empirically gathered data. Though this study does not consider the turbine generator system, charge controller, or their efficiencies, power output as a function of collector geometry is discussed in detail.
Potential of Solar Energy for Power Generation, Heating and Other Applications in Iran
Authors: Yaghoubi Mahmood , Zarrini Saeed
Published: July 2013

Renewable energy continues to grow its share of the energy market during the past few years. This is evident by the fact that in 2010, renewable energy supplied an estimated 16% of global final energy consumption, and that the trend still moves upward despite the overall downturn in global energy consumption in 2009. In Iran, a total of 7797.3 Megawatts renewable energy has been utilized for electricity production during the period between 3/2009 and 3/2010 (i.e. the Iranian official year). This sum yields from four renewables, namely hydro (7704.7 MW), wind (90.6 MW), biogas (1.9 MW) and solar (0.1 MW). During the four year period between 2006 and 2010, the capacities of hydro and wind plants have experienced increases of 27.5% and 90.2%, respectively. In this paper, the current status of the renewable energy in the world in general and in Iran in specific is reviewed and the growth trends are presented with particular emphasis on solar energy. A brief assessment of solar radiation in Iran is then presented and accordingly, the potential locations for each application are identified. These potential locations generally absorb a daily solar irradiation of more than 4.5 kWh/m2, a value that most probably ensures the financial feasibility for a variety of solar thermal applications. A solar radiation map for Iran, indicating appropriate application for each region (based on the average calculated daily radiation for that region), is also presented. Moreover, the relevant researches and investigations conducted in Iran are introduced (including pilot projects and those under development and/or construction).
Reducing Residential and Commercial Energy Consumption in the US: The Role of Water Heaters
Authors: Twomey Kelly M. , Conover Susan , Webber Michael E.
Published: July 2013

Residential and commercial water heating in the United States consumed nearly 3,700 trillion British Thermal Units (BTUs) of primary energy in 2010. Nearly half of this primary energy was lost as waste heat at the point of power generation to provide electricity for electric water heaters. In the residential sector alone, water heating accounted for 17% of total 2010 on-site energy, use or about 1,960 trillion BTUs. Of this amount, about 22%, or 440 trillion BTUs, was consumed by residential electric water heaters. However, 1,380 trillion BTUs of primary energy was required to produce this retail electric power at the power station, indicating that electricity generation is much less efficient than directly burning fuels for water heating.

This study analyzes 2010 baseline primary energy consumption for water heating in the US by considering energy conversions and end-use efficiencies in the residential and commercial sectors. In order to assess more energy and carbon-efficient means of heating water, we defined four additional scenarios in order to quantify potential energy savings by replacing electric water heaters with more efficient, commercially available technologies. The scenarios ranged in scope and technology deployment, and resulted in energy savings of 10–25% and carbon dioxide emission reductions of 10–20%. Although future deployment of water heating technologies is not likely to replicate any specific scenario, the conclusions drawn from this study are useful in guiding policy incentives and consumer behavior in regards to choosing between water heating technologies.