bluuebunny/crossref_metadata_2025 huggingface dataset:
That which is not form: The practical challenges in using functional concepts in design
Authors: Eckert Claudia
Published: July 2013

Functional modeling is a very significant part of many different well-known design methodologies. This paper investigates the questions of what functional modeling approaches people use in industry and how they conceptualize functions. Using interviews and the findings from an experiment where 20 individual designers were asked to generate a functional model of a product, the paper highlights the different notions designers associate with the wordfunction. Difficulties associated with functional modeling arise from varied and inconsistent notions of functions as well as wider challenges associated with modeling and the introduction of methods in industry.
Toward a scientific ontology based concept of function
Authors: Chen Yong , Zhang Zhinan , Huang Jian , Xie Youbai
Published: July 2013

Function is an ambiguous concept, whereas having explicit and precise concepts is critical for building a systematic science of engineering design. Based on Bunge's scientific ontology, this paper is devoted to developing an explicit and precise concept of function for design science. First, we attempt to clarify the concept of behavior, which is closely related to function and is also shown as an ambiguous concept in engineering. Second, the concept of action is imported from scientific ontology into design science. Third, a scientific ontology based concept of function is proposed, together with an ontology-based functional taxonomy. A case of a function definition of a civil aircraft type demonstrates that the proposed concept of function is more explicit and precise than previous ones, and it can lead to better functional design results.
Linking assumptions in amblyopia
Authors: LEVI DENNIS M.
Published: July 2013

Over the last 35 years or so, there has been substantial progress in revealing and characterizing the many interesting and sometimes mysterious sensory abnormalities that accompany amblyopia. A goal of many of the studies has been to try to make the link between the sensory losses and the underlying neural losses, resulting in several hypotheses about the site, nature, and cause of amblyopia. This article reviews some of these hypotheses, and the assumptions that link the sensory losses to specific physiological alterations in the brain. Despite intensive study, it turns out to be quite difficult to make a simple linking hypothesis, at least at the level of single neurons, and the locus of the sensory loss remains elusive. It is now clear that the simplest notion—that reduced contrast sensitivity of neurons in cortical area V1 explains the reduction in contrast sensitivity—is too simplistic. Considerations of noise, noise correlations, pooling, and the weighting of information also play a critically important role in making perceptual decisions, and our current models of amblyopia do not adequately take these into account. Indeed, although the reduction of contrast sensitivity is generally considered to reflect “early” neural changes, it seems plausible that it reflects changes at many stages of visual processing.
Linking perception to neural activity as measured by visual evoked potentials
Authors: NORCIA ANTHONY M.
Published: July 2013

Linking propositions have played an important role in refining our understanding of the relationship between neural activity and perception. Over the last 40 years, visual evoked potentials (VEPs) have been used in many different ways to address questions of the relationship between neural activity and perception. This review organizes and discusses this research within the linking proposition framework developed by Davida Teller, and her colleagues. A series of examples from the VEP literature illustrates each of the five classes of linking propositions originally proposed by Davida Teller. The related concept of the bridge locus—the site at which neural activity can be said to first be proscriptive of perception—is discussed and a suggestion is made that the concept be expanded to include an evolution over time and cortical area.
Are flatter diurnal cortisol rhythms associated with major depression and anxiety disorders in late adolescence? The role of life stress and daily negative emotion
Authors: Doane Leah D. , Mineka Susan , Zinbarg Richard E. , Craske Michelle , Griffith James W. , Adam Emma K.
Published: July 2013

Alterations in hypothalamic–pituitary–adrenal (HPA) axis functioning have been associated with major depression disorder (MDD) and some anxiety disorders. Few researchers have tested the possibility that high levels of recent life stress or elevations in negative emotion may partially account for the HPA axis alterations observed in these disorders. In a sample of 300 adolescents from the Youth Emotion Project, we examined associations between MDD and anxiety disorders, dimensional measures of internalizing symptomatology, life stress, mood on the days of cortisol testing, and HPA axis functioning. Adolescents with a past MDD episode and those with a recent MDD episode comorbid with an anxiety disorder had flatter diurnal cortisol slopes than adolescents without a history of internalizing disorders. Higher reports of general distress, a dimension of internalizing symptomatology, were also associated with flatter slopes. Negative emotion, specifically sadness and loneliness, was associated with flatter slopes and partially accounted for the associations between comorbid MDD and anxiety disorders and cortisol. The associations between past MDD and cortisol slopes were not accounted for by negative emotion, dimensional variation in internalizing symptomatology, or levels of life stress, indicating that flatter cortisol slopes may also be a “scar” marker of past experiences of MDD.
Strategic objectives for improving understanding of informant discrepancies in developmental psychopathology research
Authors: De Los Reyes Andres
Published: July 2013

Developmental psychopathology researchers and practitioners commonly conduct behavioral assessments using multiple informants' reports (e.g., parents, teachers, practitioners, children, and laboratory observers). These assessments often yield inconsistent conclusions about important questions in developmental psychopathology research, depending on the informant (e.g., psychiatric diagnoses and risk factors of disorder). Researchers have theorized why informant discrepancies exist and advanced methodological models of informant discrepancies. However, over 50 years of empirical data has uncovered little knowledge about these discrepancies beyond that they exist, complicate interpretations of research findings and assessment outcomes in practice, and correlate with some characteristics of the informants providing reports (e.g., demographics and mood levels). Further, recent studies often yield take-home messages about the importance of taking a multi-informant approach to clinical and developmental assessments. Researchers draw these conclusions from their work, despite multi-informant approaches to assessment long being a part of best practices in clinical and developmental assessments. Consequently, developmental psychopathology researchers and practitioners are in dire need of a focused set of research priorities with the key goal of rapidly advancing knowledge about informant discrepancies. In this paper, I discuss these research priorities, review work indicating the feasibility of conducting research addressing these priorities, and specify what researchers and practitioners would gain from studies advancing knowledge about informant discrepancies in developmental psychopathology research.
Effects of family cohesion and heart rate reactivity on aggressive/rule-breaking behavior and prosocial behavior in adolescence: The Tracking Adolescents' Individual Lives Survey study
Authors: Sijtsema Jelle Jurrit , Nederhof Esther , Veenstra Rene , Ormel Johan , Oldehinkel Albertine J. , Ellis Bruce J.
Published: July 2013

The biological sensitivity to context hypothesis posits that high physiological reactivity (i.e., increases in arousal from baseline) constitutes heightened sensitivity to environmental influences, for better or worse. To test this hypothesis, we examined the interactive effects of family cohesion and heart rate reactivity to a public speaking task on aggressive/rule-breaking and prosocial behavior in a large sample of adolescents (N = 679; M age = 16.14). Multivariate analyses revealed small- to medium-sized main effects of lower family cohesion and lower heart rate reactivity on higher levels of aggressive/rule-breaking and lower levels of prosocial behavior. Although there was some evidence of three-way interactions among family cohesion, heart rate reactivity, and sex in predicting these outcome variables, these interactions were not in the direction predicted by the biological sensitivity to context hypothesis. Instead, heightened reactivity appeared to operate as a protective factor against family adversity, rather than as a susceptibility factor. The results of the present study raise the possibility that stress reactivity may no longer operate as a mechanism of differential susceptibility in adolescence.
A theoretical model of continuity in anxiety and links to academic achievement in disaster-exposed school children
Authors: Weems Carl F. , Scott Brandon G. , Taylor Leslie K. , Cannon Melinda F. , Romano Dawn M. , Perry Andre M.
Published: July 2013

This study tested a theoretical model of continuity in anxious emotion and its links to academic achievement in disaster-exposed youth. An urban school based sample of youths (n = 191; Grades 4–8) exposed to Hurricane Katrina were assessed at 24 months (Time 1) and then again at 30 months (Time 2) postdisaster. Academic achievement was assessed through end of the school year standardized test scores (~31 months after Katrina). The results suggest that the association of traumatic stress to academic achievement was indirect via linkages from earlier (Time 1) posttraumatic stress disorder symptoms that predicted later (Time 2) test anxiety. Time 2 test anxiety was then negatively associated with academic achievement. Age and gender invariance testing suggested strong consistency across gender and minor developmental variation in the age range examined. The model presented advances the developmental understanding of the expression of anxious emotion and its links to student achievement among disaster-exposed urban school children. The findings highlight the importance of identifying heterotypic continuity in anxiety and suggest potential applied and policy directions for disaster-exposed youth. Avenues for future theoretical refinement are also discussed.
Contextual risk and promotive processes in Puerto Rican youths' internalizing trajectories in Puerto Rico and New York
Authors: Ramos-Olazagasti María A. , Shrout Patrick E. , Yoshikawa Hirokazu , Canino Glorisa J. , Bird Héctor R.
Published: July 2013

Research on ethnic-minority youths' mental health has rarely examined developmental trajectories for the same ethnic group in contexts where they are a minority versus where they are the majority or mechanisms accounting for differences in trajectories across such contexts. This study examines Puerto Rican youth residing in two contexts, one in which they are in their home culture of Puerto Rico and one in which they are a minority group, in New York. We explore the relationship among social context, minority status, risk, resilience, and trajectories of internalizing symptoms after adjusting for factors related to migration. We found that youths' reports of internalizing symptoms declined over time. Youths in New York had higher levels of internalizing symptoms than did youths in Puerto Rico, but they had similar trajectories. Differences in internalizing symptoms across the two social contexts were accounted for by experiences of discrimination and exposure to violence. Parental monitoring was associated with fewer internalizing symptoms across the two sites, although this effect diminished over time. Contrary to what was expected, family religiosity was associated with higher levels of internalizing symptoms. This association was stronger in New York than in the Puerto Rico site.
Restricted and repetitive behaviors in autism spectrum disorders: The relationship of attention and motor deficits
Authors: Ravizza Susan M. , Solomon Marjorie , Ivry Richard B. , Carter Cameron S.
Published: July 2013

Restricted and repetitive behaviors (RRBs) are hallmark symptoms of autism spectrum disorders (ASDs); however, it has proven difficult to understand the mechanisms underlying these behaviors. One hypothesis suggests that RRBs are the result of a core deficit in attention. Alternatively, abnormalities of the motor system may constitute the central mechanism underlying RRBs, given motor deficits observed in ASDs. In this experiment, we investigated the etiology of RRBs and the relationship between attention and motor deficits. Movement impairments (a) may be indirectly related to attention deficits, (b) may result from a shared compromised process, or (c) may be independent. Twenty-two adolescents with ASD and 20 typically developing participants performed a spatial attention task. Movement impairments were assessed with a rhythmic tapping task. Attentional orienting and motor control were found to be related and supported the hypothesis that these impairments in ASD arise from a shared process. In contrast, measures of attention switching and motor control were found to be independent. Stereotyped behaviors, as assessed by parental ratings, were related more to the degree of motor impairment than to deficits of attention. These results suggest that both attentional orienting deficits and stereotyped RRBs are related to a compromised motor system.
THE ARGUMENT FROM IGNORANCE AND ITS CRITICS IN MEDIEVAL ARABIC THOUGHT
Authors: Shihadeh Ayman
Published: July 2013

The earliest debate on the argument from ignorance emerged in Islamic rational theology around the fourth/tenth century, approximately seven centuries before John Locke identified it as a distinct type of argument. The most influential defences of the epistemological principle that ‘that for which there is no evidence must be negated’ are encountered in Muʿtazilī sources, particularly ʿAbd al-Jabbār and al-Malāḥimī who argue that without this principle scepticism will follow. The principle was defended on different grounds by some earlier Ashʿarīs, but was then rejected by al-Juwaynī, and was eventually classed as a fallacy by Fakhr al-Dīn al-Rāzī whoseNihāyat al-ʿuqūlcontains the most definitive and comprehensive refutation of classical kalām epistemology and the first ever defence of Aristotelian logic in a kalām summa. According to the eighth/fourteenth-century historian Ibn Khaldūn, this debate provided the main impetus for the philosophical turn that Ashʿarism took during the sixth/twelfth century.
Cardiomyopathy in young adults with classic mitral valve prolapse
Authors: Malev Eduard , Reeva Svetlana , Vasina Lyubov , Timofeev Eugeny , Pshepiy Asiyet , Korshunova Alexandra , Prokudina Maria , Zemtsovsky Eduard
Published: July 2013

Background: In some inherited connective tissue diseases with involvement of the cardiovascular system, for example, Marfan syndrome, early impairment of left ventricular function, which have been described as Marfan-related cardiomyopathy has been reported. Our aim was to evaluate the left ventricular function in young adults with mitral valve prolapse without significant mitral regurgitation using two-dimensional strain imaging and to determine the possible role of the transforming growth factor-β pathway in its deterioration. Methods: We studied 78 young adults with mitral valve prolapse without mitral regurgitation in comparison with 80 sex-matched and age-matched healthy individuals. Longitudinal strain and strain rates were defined using spackle tracking. Concentrations of transforming growth factor-β1 and β2 in serum were determined by enzyme-linked immunosorbent assays. Results: In 29 patients, classic relapse was identified with a leaflet thickness of ≥ 5 mm; 49 patients had a non-classic mitral valve prolapse. Despite the similar global systolic function, a significant reduction in global strain was found in the classic group (−15.5 ± 2.9%) compared with the non-classic group (−18.7 ± 3.8; p = 0.0002) and the control group (−19.6 ± 3.4%; p < 0.0001). In young adults with non-classic prolapse, a reduction in longitudinal deformation was detected only in septal segments. Transforming growth factor-β1 and β2 serum levels were elevated in patients with classic prolapse as compared with the control group and the non-classic mitral valve prolapse group. Conclusions: These changes in the deformations may be the first signs of deterioration of the left ventricular function and the existence of primary cardiomyopathy in young adults with mitral valve prolapse, which may be caused by increased transforming growth factor-β signalling.
A Small Chance of Disaster
Authors: Broome John
Published: July 2013

Expected utility theory tells us how we should make decisions under uncertainty: we should choose the option that leads to the greatest expectation of utility. This may, however, not be the option that is likely to produce the best result – that may be the wrong choice if it also creates a small chance of a great disaster. A small chance of disaster may be the most important consideration in decision making. Climate change creates a small chance of disaster, and some authors believe this to be the most important consideration in deciding our response to climate change. To know whether they are right, we need to make a moral judgement about just how bad the disaster would be.
Science, Technology and Preservation of the Life-world
Authors: Moran Dermot
Published: July 2013

The opposition between rationality and irrationality is often portrayed as a struggle between rational evidence-based science and irrational, ungrounded myth. I shall argue that this is too simplistic and that different forms of rationality need to be recognised – in particular, the rationality of everyday life. All scientific inquiry and reasoning is based and depends upon the practices, activities and antecedent beliefs of human knowers, who are embedded in cultural life-worlds in ways that science has hitherto ignored. Progress in civilisational rationality requires that the rationality of the life-world be understood.
THE -SINGULAR DICHOTOMY FOR EXCEPTIONAL LIE GROUPS AND ALGEBRAS
Authors: HARE K. E. , JOHNSTONE D. L. , SHI F. , YEUNG W.-K.
Published: July 2013

We show that every orbital measure, ${\mu }_{x} $, on a compact exceptional Lie group or algebra has the property that for every positive integer either ${ \mu }_{x}^{k} \in {L}^{2} $ and the support of ${ \mu }_{x}^{k} $ has non-empty interior, or ${ \mu }_{x}^{k} $ is singular to Haar measure and the support of ${ \mu }_{x}^{k} $ has Haar measure zero. We also determine the index $k$ where the change occurs; it depends on properties of the set of annihilating roots of $x$. This result was previously established for the classical Lie groups and algebras. To prove this dichotomy result we combinatorially characterize the subroot systems that are kernels of certain homomorphisms.
Development and Evaluation of New Coupling System for Lower Limb Prostheses with Acoustic Alarm System
Authors: Eshraghi Arezoo , Osman Noor Azuan Abu , Gholizadeh Hossein , Ahmadian Jalil , Rahmati Bizhan , Abas Wan Abu Bakar Wan
Published: July 2013

Individuals with lower limb amputation need a secure suspension system for their prosthetic devices. A new coupling system was developed that is capable of suspending the prosthesis. The system's safety is ensured through an acoustic alarm system. This article explains how the system works and provides an in vivo evaluation of the device with regard to pistoning during walking. The system was designed to be used with silicone liners and is based on the requirements of prosthetic suspension systems. Mechanical testing was performed using a universal testing machine. The pistoning during walking was measured using a motion analysis system. The new coupling device produced significantly less pistoning compared to a common suspension system (pin/lock). The safety alarm system would buzz if the suspension was going to fail. The new coupling system could securely suspend the prostheses in transtibial amputees and produced less vertical movement than the pin/lock system.
Identification of Specific Language Impairment in Bilingual Children: I. Assessment in English
Authors: Gillam Ronald B. , Peña Elizabeth D. , Bedore Lisa M. , Bohman Thomas M. , Mendez-Perez Anita
Published: July 2013

Purpose

This study was designed to derive cut scores for English testing for use in identifying specific language impairment (SLI) in bilingual children who were learning English as a second language.

Method

In a 1-gate design, 167 children received comprehensive language assessments in English and Spanish during their first-grade year. The reference standard was identification by a team of expert bilingual speech-language pathologists. Receiver operating curve (ROC) analyses were used to identify the optimal prediction model for SLI.

Results

The original, English EpiSLI criteria (Tomblin, Records, & Zhang, 1996) yielded a sensitivity of .95 and a specificity of .45 (LR+ = 1.73, LR− = 0.11, and AUC = .79) for our bilinguals. Revised cutoff scores yielded a sensitivity of .86 and a specificity of .68 (LR+ = 2.67, LR− = 0.21, and AUC = .77). An optimal prediction model yielded a sensitivity of .81 and a specificity of .81 (LR+ = 4.37, LR− = 0.23 and AUC = .85).

Conclusion

The results of English testing could be used to make a reasonably accurate diagnostic decision for bilingual children who had attended public school for at least 1 year and were using English at least 30% of the time.
Intelligent controller for managing power flow within standalone hybrid power systems
Authors: Natsheh Emad Maher , Natsheh Abdel Razzak , Albarbar Alhussein
Published: July 2013

This study presents a novel adaptive management strategy for power flow in standalone hybrid power systems. The method introduces an on‐line energy management by using a hierarchical controller between three energy sources: photovoltaic (PV) panels, battery storage and proton exchange membrane fuel cell. The proposed method includes a feed‐forward, back‐propagation neural network controller in the first layer, which is added in order to achieve the maximum power point for the different types of PV panels. In the second layer, a fuzzy logic controller has been developed to optimise performance by distributing the power inside the hybrid system and by managing the charge and discharge of the current flow. Finally, and in the third layer, local controllers are presented to regulate the fuel cell/battery set points in order to reach to best performance. Moreover, perturb and observe algorithm with two different controller techniques – the linear proportional‐integral (PI) and the non‐linear passivity‐based controller – are provided for a comparison with the proposed maximum power point tracking controller system. The comparison revealed the robustness of the proposed PV control system for solar irradiance and load resistance changes. Real‐time measured parameters and practical load profiles are used as inputs for the developed management system. The proposed model and its control strategy offer a proper tool for optimising the hybrid power system performance, such as the one used in smart‐house applications.
Passive runaway electron suppression in tokamak disruptions
Authors: Smith H. M. , Boozer A. H. , Helander P.
Published: July 2013

Runaway electrons created in disruptions pose a serious problem for tokamaks with large current. It would be desirable to have a runaway electron suppression method which is passive, i.e., a method that does not rely on an uncertain disruption prediction system. One option is to let the large electric field inherent in the disruption drive helical currents in the wall. This would create ergodic regions in the plasma and increase the runaway losses. Whether these regions appear at a suitable time and place to affect the formation of the runaway beam depends on disruption parameters, such as electron temperature and density. We find that it is difficult to ergodize the central plasma before a beam of runaway current has formed. However, the ergodic outer region will make the Ohmic current profile contract, which can lead to instabilities that yield large runaway electron losses.
Depth estimation of surface cracks on metallic components by means of lock-in thermography
Authors: Streza M. , Dadarlat D. , Fedala Y. , Longuemart S.
Published: July 2013

In this work, a new method to characterize vertical cracks by lock-in thermography is presented. The heat transfer process induced by a modulated thermal excitation located in the vicinity of the crack is simulated using a finite element method computer package. The propagation of heat flow along the solid surface is disturbed when crossing an inhomogeneity. The disturbance of the thermal-wave allows a quantitative analysis of the crack. The main idea consists of exploiting the second derivative of the amplitude image in order to highlight the useful signal. In addition, an image analysis procedure based on the use of Laplacian calculations is proposed. To support this approach, experimental tests were performed and compared with mathematical simulations. The results demonstrate the potential of active lock-in thermography as a contactless tool for crack-depth estimation.
An induction reactor for studying crude-oil oxidation relevant to in situ combustion
Authors: Bazargan Mohammad , Lapene Alexandre , Chen Bo , Castanier Louis M. , Kovscek Anthony R.
Published: July 2013

In a conventional ramped temperature oxidation kinetics cell experiment, an electrical furnace is used to ramp temperature at a prescribed rate. Thus, the heating rate of a kinetics cell experiment is limited by furnace performance to heating rates of about 0.5–3 °C/min. A new reactor has been designed to overcome this limit. It uses an induction heating method to ramp temperature. Induction heating is fast and easily controlled. The new reactor covers heating rates from 1 to 30 °C/min. This is the first time that the oxidation profiles of a crude oil are available over such a wide range of heating rate. The results from an induction reactor and a conventional kinetics cell at roughly 2 °C/min are compared to illustrate consistency between the two reactors. The results at low heating rate are the same as the conventional kinetics cell. As presented in the paper, the new reactor couples well with the isoconversional method for interpretation of reaction kinetics.
Investigations of protons passing through the CR-39/PM-355 type of solid state nuclear track detectors
Authors: Malinowska A. , Szydłowski A. , Jaskóła M. , Korman A. , Sartowska B. , Kuehn T. , Kuk M.
Published: July 2013

Solid State Nuclear Track Detectors of the CR-39/PM-355 type were irradiated with protons with energies in the range from 0.2 to 8.5 MeV. Their intensities and energies were controlled by a Si surface barrier detector located in an accelerator scattering chamber. The ranges of protons with energies of 6–7 MeV were comparable to the thickness of the PM-355 track detectors. Latent tracks in the polymeric detectors were chemically etched under standard conditions to develop the tracks. Standard optical microscope and scanning electron microscopy techniques were used for surface morphology characterization.
Study of 2G high temperature superconducting coils: Influence of anisotropic characteristics
Authors: Zhang Min , Kvitkovic J. , Kim C. H. , Pamidi S. V. , Combs T. A.
Published: July 2013

This paper focuses on the study of anisotropic characteristic of second generation high-temperature superconductors (HTS), and how it influences the performance of HTS coils. The critical current of 4 sections of a HTS coil is measured and compared. The sectional difference of critical current exists due to an HTS anisotropy. A numerical method is introduced to consider the HTS anisotropy using finite element method. The model shows good consistency with experimental results. The model demonstrates that the anisotropy changes the current distribution inside the coil, and the discrepancy of critical current in different sections is the joint-effect of the anisotropy and shielding current. The paper discusses the possibility to optimize the performance of HTS coils by changing the anisotropic characteristic. Based on the study, strategies to improve the performance of HTS coils are provided.
SURFRESIDE2: An ultrahigh vacuum system for the investigation of surface reaction routes of interstellar interest
Authors: Ioppolo S. , Fedoseev G. , Lamberts T. , Romanzin C. , Linnartz H.
Published: July 2013

A new ultrahigh vacuum experiment is described to study atom and radical addition reactions in interstellar ice analogues for astronomically relevant temperatures. The new setup – SURFace REaction SImulation DEvice (SURFRESIDE2) – allows a systematic investigation of solid state pathways resulting in the formation of molecules of astrophysical interest. The implementation of a double beam line makes it possible to expose deposited ice molecules to different atoms and/or radicals sequentially or at the same time. Special efforts are made to perform experiments under fully controlled laboratory conditions, including precise atom flux determinations, in order to characterize reaction channels quantitatively. In this way, we can compare and combine different surface reaction channels with the aim to unravel the solid state processes at play in space. Results are constrained in situ by means of a Fourier transform infrared spectrometer and a quadrupole mass spectrometer using reflection absorption infrared spectroscopy and temperature programmed desorption, respectively. The performance of the new setup is demonstrated on the example of carbon dioxide formation by comparing the efficiency through two different solid state channels (CO + OH → CO2 + H and CO + O → CO2) for which different addition products are needed. The potential of SURFRESIDE2 to study complex molecule formation, including nitrogen containing (prebiotic) compounds, is discussed.
Continuous wave solid phase laser annealing of single-pot electrodeposited CuInSe2 thin films: Effects of Cu/In stoichiometry
Authors: Bhatia A. , Meadows H. , Crossay A. , Dale P. J. , Scarpulla M. A.
Published: July 2013

CuInSe2 (CISe) is a prototype material for the I–III–VI chalcopyrites such as Cu(In,Ga)(S,Se)2 (CIGSSe) used as absorber layers in thin film photovoltaic cells. These thin film photovoltaic absorber layers are primarily synthesized by vacuum-based techniques in manufacturing. In this work, we investigate non-vacuum film synthesis by electrochemical deposition of CISe from a single bath followed by continuous wave laser annealing (CWLA) using a 1064 nm laser. We find that parameters exist for near-infrared CWLA which result in structural changes without melting and dewetting of the films. While Cu-poor samples show only about 40% reduction in the full width at half maximum (FWHM) of the respective x-ray diffraction (XRD) peaks, identically treated Cu-rich samples indicate a FWHM reduction of more than 70% in the XRD and Raman scattering data for irradiation at 50 W/cm2. This study demonstrates that an entirely solid-phase annealing path driven by intense illumination exists for chalopyrite phase formation and crystallization from electrodeposited CISe thin films.
Loss mechanisms and back surface field effect in photon enhanced thermionic emission converters
Authors: Segev Gideon , Rosenwaks Yossi , Kribus Abraham
Published: July 2013

Photon Enhanced Thermionic Emission (PETE) solar converters are based on emission of energetic electrons from a semiconductor cathode that is illuminated and heated with solar radiation. By using a semiconductor cathode, photo generated electrons enable high electron emission at temperatures much lower than the common range for thermionic emitters. Simple models show that PETE conversion can theoretically reach high efficiency, for example, above 40% at concentration of 1000 suns. In this work, we present a detailed one-dimensional model of PETE conversion, accounting for recombination mechanisms, surface effects, and spatial distribution of potential and carrier concentration. As in the previous PETE models, negative space charge effects, photon recycling, and temperature gradients are not considered. The conversion efficiency was calculated for Si and GaAs based cathodes under a wide range of operating conditions. The calculated efficiencies are lower than predictions of previous zero-dimensional models. We analyze the loss mechanisms and show that electron recombination at the cathode contact is a significant loss. An electron-blocking junction at the cathode back contact is therefore essential for achieving high efficiency. The predicted efficiencies for Si and GaAs cathodes with homo-junction back surface field layers are both around 31%, but with more favorable assumptions on the contact structure, it may be near 40%. The analysis leads to important conclusions regarding the selection of cathode material and back surface junction configuration.
In situ Raman monitoring of He2+ irradiation induced damage in a UO2 ceramic
Authors: Guimbretière G. , Desgranges L. , Canizarès A. , Caraballo R. , Duval F. , Raimboux N. , Omnée R. , Ammar M. R. , Jégou C. , Simon P.
Published: July 2013

The in situ Raman probing of a UO2 ceramic in [Ar/H2, 95/5] gas atmosphere followed by exposure to He2+ ionic irradiation coming from a cyclotron accelerator was implemented. It was observed that the growth of Raman defect bands exhibits a unique kinetic nicely modelized by a simple direct impact model, and with an annealing rate constant of 5.6 × 10−4 ± 4 × 10−5 s−1 for an ionic flow of 50 nA and an ions-beam induced sample heating of 170 ± 10 °C. Also, it was observed that the Ar plasma induced by the ions-beam is a sensitive probe of the presence of the ions-beam.
Generation of an atmospheric plasmoid from a water discharge: An analysis of the dissipated energy
Authors: Fantz U. , Kalafat S. , Friedl R. , Briefi S.
Published: July 2013

A plasmoid in air at atmospheric pressure of about 20 cm in diameter and up to 500 ms duration is generated from a water discharge which is powered for a short time period by a capacitor bank. The analysis of the electrical circuit and the comparison with experimental values show that the energy dissipated into the system is given by the conventional equation for discharging capacitors. The resistance of the system is governed by the resistances of the water reservoir, the plasma, and the plasma-water transition, which are represented as one time-averaged resistance in the equation. Thus, the dissipated energy can be influenced by the energy available (capacitance and voltage), the voltage-on time, the conductivity of the water, the electrode gap and the size of the container (plate electrode) within the experimental boundaries. An estimation of the energy channels for a discharge at standard conditions revealed that the dominant part of the energy is dissipated into the water reservoir. About 25% of the energy is dissipated directly into the plasmoid and is available for plasma formation, plasma kinetics and chemical processes.
Investigations of the disorder in the TaxN thin films: On the first order Raman spectrum of the rock salt crystal structure
Authors: Očko M. , Žonja S. , Salamon K. , Ivanda M. , Yu L. , Newman N.
Published: July 2013

First order Raman absorption in materials with the rock salt crystal structure is forbidden. Its appearance in real crystals results from the presence of vacancies and other defects. For TaxN polycrystalline thin films, we found that imperfections that reduce the coherence length contribute to the appearance of the first order Raman spectrum. This investigation enables us to better understand the anomalous concentration dependence of the resistivity of TaxN polycrystalline thin films fabricated using reactive sputtering at 450 °C and 4.9 mTorr nitrogen pressures on amorphous substrates.
Enhancement of giant magnetoresistance by L21 ordering in Co2Fe(Ge0.5Ga0.5) Heusler alloy current-perpendicular-to-plane pseudo spin valves
Authors: Li S. , Takahashi Y. K. , Furubayashi T. , Hono K.
Published: July 2013

We report large magnetoresistance (MR) output in fully epitaxial Co2Fe(Ge0.5Ga0.5)/Ag/Co2Fe(Ge0.5Ga0.5) current-perpendicular-to-plane pseudo spin valves. The resistance-area product change (ΔRA) of 12 mΩμm2 at room temperature (RT), equivalent to MR ratio of 57%, and ΔRA = 33 mΩμm2 at 10 K, equivalent to MR ratio of 183%, were obtained by using L21-ordered Co2Fe(Ge0.5Ga0.5) ferromagnetic electrodes. The bulk spin scattering asymmetry (β) were estimated to be ∼0.83 at RT and ∼0.93 at 10 K for the L21-ordered Co2Fe(Ge0.5Ga0.5) films by the Valet-Fert model, indicating that the L21-ordered Co2FeGe0.5Ga0.5 Heusler alloy is virtually half-metal at 10 K, but its half-metallicity is degraded at RT.
Giant low-field magnetostriction of epoxy/TbxDy1−x(Fe0.8Co0.2)2 composites (0.20 ≤ x ≤ 0.40)
Authors: Liu J. J. , Pan Z. B. , Si P. Z. , Du J.
Published: July 2013

Spin configuration, magnetocrystalline anisotropy compensation, and magnetostriction of TbxDy1−x(Fe0.8Co0.2)2 (0.20 ≤ x ≤ 0.40) compounds have been investigated. Experimental evidence for the anisotropy compensation has been observed directly by performing x-ray diffraction on magnetic-field aligned powders and by evaluating the Mössbauer spectra. The easy magnetization direction (EMD) at room temperature rotates from the ⟨100⟩ (x ≤ 0.27) to the ⟨111⟩ axis (x ≥ 0.32), subjected to the anisotropy compensation between Tb3+ and Dy3+ ions. The strong grain-⟨111⟩-oriented pseudo-1–3 epoxy/composite has been fabricated by curing under a moderate magnetic field. A giant low-field magnetostriction, longitudinal λ|| and linear anisotropic λa (=λ|| − λ⊥) up to 550 and 760 ppm at 3 kOe, respectively, is obtained for Tb0.32Dy0.68(Fe0.8Co0.2)2 composite, which can be attributed to anisotropy compensation, a large magnetostriction coefficients λ111, EMD lying along ⟨111⟩ direction, the strong ⟨111⟩-textured orientation, and the chain structure. The good magnetoelastic properties, besides only containing 27 vol. % alloy particles in the insulating epoxy, make it a promising candidate for magnetostriction applications.
Unusual 90° domain structure in (2/3)Bi(Zn1/2Ti1/2)O3-(1/3)BiFeO3 epitaxial films with giant 22% tetragonal distortion
Authors: Yasui Shintaro , Yazawa Keisuke , Matsushima Masaaki , Yamada Tomoaki , Morioka Hitoshi , Uchida Hiroshi , Iijima Takashi , You Lu , Wang Junling , Yamamoto Takahisa , Ikuhara Yuichi , Funakubo Hiroshi
Published: July 2013

Epitaxial films of tetragonal (001)/(100)-oriented (2/3)Bi(Zn1/2Ti1/2)O3-(1/3)BiFeO3 were grown on (100)cSrRuO3//(100)SrTiO3 substrates by metalorganic chemical vapor deposition. 93% of the film is occupied by c-domain [(001) orientation], and the out-of-plane (c-axis) and in-plane (a-axis) lattice parameters are 0.465 nm and 0.381 nm, respectively. The tetragonal distortion, (c/a)-1, is 22% which is 3.5 times larger than that of PbTiO3 (6.3%). High-angle annular dark-field-scanning transmission electron microscopy images show clear c-/a-domain structures with unusual boundary angles of 51°/39° due to the large c/a ratio of tetragonal phase. High temperature X-ray diffraction measurements reveal that the Curie temperature of this film is above 800 °C.
Microresonator-enhanced electroluminescence of an organic light emitting diode based on a columnar liquid crystal
Authors: Vollbrecht Joachim , Kasdorf Olga , Quiring Viktor , Suche Hubertus , Bock Harald , Kitzerow Heinz-S.
Published: July 2013

The liquid crystalline organic semiconductor perylene-3,4,9,10-tetracarboxylic-tetraethylester is used to create resonant cavity enhanced organic light emitting diodes. The results indicate that the emitted intensity can be increased and the emission spectrum narrowed by embedding a suitable sequence of several organic layers, including the discotic liquid crystal, with appropriate thicknesses in a microresonator consisting of a highly reflecting metal electrode and a Bragg reflector. The experimental data are in good agreement with theoretical calculations. Resonant cavity enhancement revealed to be suitable for improving the performance of liquid crystal-based electroluminescent devices.
Microwave radiation power of relativistic electron beam with virtual cathode in the external magnetic field
Authors: Kurkin S. A. , Hramov A. E. , Koronovskii A. A.
Published: July 2013

The study of the output power of the electromagnetic radiation of the relativistic electron beam (REB) with virtual cathode in the presence of external magnetic field has been found out. The typical dependencies of the output microwave power of the vircator versus external magnetic field have been analyzed by means of 3D electromagnetic simulation. It has been shown that the power of vircator demonstrates several maxima with external magnetic field growth. The characteristic features of the power behavior are determined by the conditions of the virtual cathode formation in the presence of the external transversal magnetic field and the REB self-magnetic fields.
Room temperature spontaneous exchange bias in (La,Sr)MnO3/PbZr0.8Ti0.2O3/(La,Sr)MnO3 sandwich structure
Authors: Mao H. J. , Song C. , Cui B. , Wang G. Y. , Xiao L. R. , Pan F.
Published: July 2013

We report on a room temperature spontaneous exchange bias (SEB) effect in La0.67Sr0.33MnO3/PbZr0.8Ti0.2O3/La0.67Sr0.33MnO3 (LSMO/PZT/LSMO) sandwich structure, where PZT is a discontinuous film producing somewhat the direct touch of two LSMO layers. The exchange coupling between the top and bottom LSMO, which, respectively, behaves as the antiferromagnetic and ferromagnetic layer, is demonstrated to be responsible for the SEB effect. The formation of antiferromagnetic LSMO is ascribed to the large strain imposed through the PZT seed layer, whose thickness profoundly affects the SEB behavior. Thus, our finding provides an appealing alternative way to generate exchange bias by strain engineering.
Lift and drag characteristics of a cascade of flat plates in a configuration of interest for a tidal current energy converter: Numerical simulations analysis
Authors: Cebrián D. , Ortega-Casanova J. , Fernandez-Feria R.
Published: July 2013

Numerical simulations of the three-dimensional flow through a cascade of flat plates are conducted to analyze its lift and drag characteristics in a configuration of interest for a particular type of tidal hydrokinetic energy converter. To that end, the turbulent model parameters in the computational fluid dynamics code are validated against experimental data for the flow around an isolated plate at different angles of incidence and the same Reynolds number used in the cascade. The lift and drag coefficients of a plate in the cascade, as well as the effective nondimensional power extracted from the tidal current, are compared to the corresponding values for an isolated plate. These results are used as a guide for the design of the optimum configuration of the cascade (angle of attack, blade speed, and solidity) which extracts the maximum power from a tidal current for a given reference value of the Reynolds number.
Low dark current small molecule organic photodetectors with selective response to green light
Authors: Leem Dong-Seok , Lee Kwang-Hee , Park Kyung-Bae , Lim Seon-Jeong , Kim Kyu-Sik , Wan Jin Yong , Lee Sangyoon
Published: July 2013

We report green-sensitive organic photodetectors consisting of a bulk heterojunction blend of N,N-dimethylquinacridone and dicyanovinyl-terthiophene. Devices incorporating a triphenylamine derivative-based electron blocking layer and a molybdenum oxide hole extracting layer lead to significantly low dark currents (Jd) ∼ 6.41 nA/cm2 at −3 V and high external quantum efficiency of 55.2% at 540 nm wavelength with a narrow full width at half maximum of 146 nm, which is likely to be applicable for full colour organic image sensors. Based on the interfacial energy barrier and temperature dependent current-voltage characteristics, possible origins of the reverse Jd of devices are further described.
Finite size effect on the phase transition of vanadium dioxide
Authors: Nazari M. , Zhao Y. , Hallum V. , Bernussi A. A. , Fan Z. Y. , Holtz M.
Published: July 2013

Raman studies are reported of vanadium dioxide grown on sapphire substrates with morphology ranging from island to continuous layer. Temperatures corresponding to the onset of the structural phase transition and the insulator to metal transition are estimated based on the shifts and disappearance of the phonons, respectively. Minimum dimension h, corresponding to island height or layer thickness, plays a critical role in the transformation. The transition temperature and width exhibit 1/h dependence consistent with finite-size effects related to martensitic nucleation. The length scale below which the finite size effects are important is found to be ∼300 nm.
La-doped BaSnO3—Degenerate perovskite transparent conducting oxide: Evidence from synchrotron x-ray spectroscopy
Authors: Sallis S. , Scanlon D. O. , Chae S. C. , Quackenbush N. F. , Fischer D. A. , Woicik J. C. , Guo J.-H. , Cheong S. W. , Piper L. F. J.
Published: July 2013

We report direct evidence of conduction band filling in 3% La-doped BaSnO3 using hard x-ray photoelectron spectroscopy. Direct comparisons with hybrid density functional theory calculations support a 3.2 eV indirect band gap. The use of hybrid DFT is verified by excellent agreement between our photoelectron spectra and O K-edge x-ray emission and absorption spectra. Our experimental and computational results demonstrate that the conduction band is primarily of Sn 5s orbital character with little O 2p contribution, which is a prerequisite for designing a perovskite-based transparent conducting oxide.
Highly efficient reddish orange emission in Mn2+/Eu3+ co-doped phosphate glasses for greenhouse
Authors: Ming Chengguo , Song Feng , Ren Xiaobin , An Liqun
Published: July 2013

A series of phosphate glasses doped with Mn2+/Eu3+ ions were prepared by high temperature melting method to explore reddish orange luminescent materials for greenhouse. The absorption, emission, and excitation spectra of the samples were studied in detail. A wide excitation band at 300-550 nm in the Mn2+/Eu3+ co-doped phosphate glasses was observed. Under the illumination of sunlight, the Mn2+/Eu3+ co-doped phosphate glasses can emit strong red emission. Our materials will be helpful to improve the utilization of solar for glass greenhouses.
Lattice constant and substitutional composition of GeSn alloys grown by molecular beam epitaxy
Authors: Bhargava Nupur , Coppinger Matthew , Prakash Gupta Jay , Wielunski Leszek , Kolodzey James
Published: July 2013

Single crystal epitaxial Ge1−xSnx alloys with atomic fractions of tin up to x = 0.145 were grown by solid source molecular beam epitaxy on Ge (001) substrates. The Ge1−xSnx alloys formed high quality, coherent, strained layers at growth temperatures below 250 °C, as shown by high resolution X-ray diffraction. The amount of Sn that was on lattice sites, as determined by Rutherford backscattering spectrometry channeling, was found to be above 90% substitutional in all alloys. The degree of strain and the dependence of the effective unstrained bulk lattice constant of Ge1−xSnx alloys versus the composition of Sn have been determined.
High thermal stability of zero-field ferromagnetic resonance above 5 GHz in ferrite-doped CoFe thin films
Authors: Chai Guozhi , Phuoc Nguyen N. , Ong C. K.
Published: July 2013

Ferrite doped CoFe films with stripe domains are demonstrated to possess zero-field ferromagnetic resonance frequency above 5 GHz. The high resonance frequency is driven by the rotatable magnetic anisotropy propagated from the stripe domain structure and exchange coupling between rotatable ferrimagnetic spins and the ferromagnetic grains. The high temperature results show that these films have excellent thermal stability, which may have a great implication for microwave applications.