bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scientific literacy, PISA, and socioscientific discourse: Assessment for progressive aims of science education
Authors: Sadler Troy D. , Zeidler Dana L. 
Published: September 2009

AbstractIn this article, we explore the Programme for International Student Assessment (PISA) with a lens informed by the socioscientific issues (SSI) movement. We consider the PISA definition of scientific literacy and how it is situated with respect to broader discussions of the aims of science education. We also present an overview of the SSI framework that has emerged in the science education community as a guide for research and practice. We then use this framework to support analysis of the PISA approach to assessment. The PISA and SSI approaches are seemingly well aligned when considering general aims. Both approaches emphasize preparing students for life and citizenship, complex reasoning and reflective practices, and robust understandings of the nature of science particularly as it is practiced in society. However, as the focus of comparison moves from the conceptual to more specific, the connections between PISA and the SSI movement become more tenuous. For instance, many of the PISA test items, at least those that have been released publicly, seem quite removed from the intent of the SSI movement. The article concludes with a discussion of recent trends in research associated with SSI, which may provide alternative avenues for assessing progressive aims of science education. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 909–921, 2009
Context of teaching and learning school science in Finland: Reflections on PISA 2006 results
Authors: Lavonen Jari , Laaksonen Seppo 
Published: August 2009

AbstractFinnish students' opinions about the frequency of learning activities and communication in the Finnish science classroom, their interest in science and science studies and careers, their sense of self‐efficacy, and their beliefs about their own competence as well as their performance in science are analyzed based on PISA 2006 Scientific Literacy Assessment data. Students' success on PISA is explained by these context variables and by the national education policy in Finland. The regression analysis revealed that positive student level predictors for PISA science performance were science‐related self‐efficacy and self‐concept, interest in physics and chemistry, and a view of the usefulness of science studies in preparing students for future jobs in science. From the point of view of science teaching, one of the most robust predictors of the high results in Finland were frequent use of teacher demonstrations, practical work in the classroom, and the possibility for students to draw conclusions. Knowledge based society, educational equality, and devolution of decision power at the local level, and teacher education are named as most important educational policy issues behind students' high performance in PISA 2006 science. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 922–944, 2009
Estimation of Dynamic Parameters of a Synchronous Generator using Genetic Algorithm
Authors: Hassannia Amir , Darabi Ahmad , Alshamali Mustafa 
Published: August 2009

AbstractDynamic modeling of synchronous generators is of great importance in power system studies. Three‐phase sudden short circuit test is the basic conventional method applied for determining the parameters of synchronous generators. The conventional curve fitting yields to non‐unique and inaccurate solutions depending on the initial guesses and nature of the numerical methods. In this paper, a genetic algorithm based method is developed for curve fitting process and identifying uniquely the dynamic parameters through a new fitness function. Owing to the problems associated with sudden short circuit test and unavailability of experimental results, the test is performed on an exact model of the generator with harmonics content space dependent inductances gathered from finite elements analysis. The parameters of a 31.5 kVA alternator are evaluated by use of the proposed method and compared with measured parameters available for this machine by manufacturer showing a good approximation. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
New Research on AC–AC Converters without Intermediate Storage and Their Applications in Power‐Electronic Transformers and AC Drives
Authors: Mohapatra Krushna Keshab , Gupta Ranjan , Thuta Satish , Somani Apurva , Umarikar Amod , Basu Kaushik , Mohan Ned 
Published: August 2009

AbstractAC‐AC converters (e.g. matrix converters) are mostly semiconductor solutions for applications where intermediate energy storage is eliminated. This paper summarizes the research done and being carried out at the University of Minnesota for applications in motor drives and power‐electronic transformers with advanced features. This paper presents a carrier‐based modulation method for matrix converters and its application during for both input unbalance and output over‐modulation. Various topologies of matrix converter are described for both drives and power‐electronic transformers. These topologies have some inherent benefits like common‐mode voltage elimination across the bearings of the motor/generator and controllable power factor at the input side. Some of the described technologies require open‐ended machines as load and thereby some advantages like enhanced output voltage (1.5 times the output of normal three terminal load) are achieved. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Controller‐Switching Strategy for HDD Servo Systems with Measurement Errors and Constraints on State and Control Variables
Authors: Okuyama Atsushi , Kobayashi Masahito 
Published: August 2009

AbstractThe head‐positioning control system of a hard disk drive (HDD) must enable precise positioning and high‐speed access. Mode switching control (MSC) has widely been used to meet these control requirements. One of the issues with MSC is how to determine the controller‐switching strategy, which needs decisions on the controller's switching conditions and its initialization. We propose a method that utilizes initial value compensation (IVC) to determine the initial state of the controller. Although mode switching is non‐linear, transient responses can be improved if the control system takes the initial state response after mode switching into consideration. IVC, which is based on this, can improve the transient response after mode switching. We also propose a method, which is based on the concept of a maximal output admissible set, of determining the switching conditions. It takes pointwise‐in‐time constraints and measurement errors in the plant's initial state into consideration. Experimental evaluations of the switching‐control strategy we propose were undertaken with a 2.5‐inch form‐factor HDD. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Electrical Insulation Performance of Paper–Ice Composite Insulation System at Cryogenic Temperature
Authors: Murakami Yoshinobu , Nagao Masayuki , Kosaki Masamitsu 
Published: August 2009

AbstractIn recent years, research on the development of high‐temperature superconducting cables has advanced. The application of a composite insulating system made of insulating paper‐liquid nitrogen has been studied as an electrical insulating system for high‐temperature superconducting cables. In paper‐liquid nitrogen composite insulating systems developed on the basis of conventional techniques, microscopic bubbles easily remain inside the paper, and the partial discharge are supposed to occur easily. In order to overcome this drawback, we formulated a paper‐ice composite insulating system as a substitute for the paper‐LN2 of the cryogenic electrical insulating system in high‐temperature superconducting cables. In this study, the breakdown strength, partial discharge, V‐t characteristics, effect of pressure on breakdown characteristics, and the self‐healing breakdown characteristics of a paper‐ice composite insulating system were investigated in order to understand the basic properties of new insulating materials for applications to high‐temperature superconducting cables. As a result, it was clarified that the AC breakdown strength of paper‐ice composite insulating system was higher than that of paper‐liquid nitrogen insulating system, and that of paper‐ice composite insulating system exhibited a self‐healing type. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Modular Modeling of Turbo‐Expander Driven Generators for Power System Studies
Authors: Turkemani Mehdi Babaei , Rastegar Hassan 
Published: August 2009

AbstractOne application of turbo‐expanders is in the natural gas pressure reduction at city gates gas regulating stations, in place of mechanical valves. Besides, they can drive electrical generators, but, because of instantaneous varying of domestic consumptions, environment temperature and other effective parameters, turbo‐expander inlet gas pressure and mass flow‐rate vary with time and consequently extracted power has time variant specification. These variations are transferred by coupled generator to the power distribution network and cause some power quality issues such as voltage flicker, voltage sag, etc. So, we need to assess the amount of flicker and voltage sag at the point of common coupling (PCC). Moreover, it is essential to investigate turbo‐expander‐gearbox‐generator stability behavior when a fault has occurred in the power network. Thus, this paper presents a modular model for turbo‐expander driven generators in power system studies. Using this model, we show the produced power quality is dependant on inlet gas specifications. Also it is proven that proper modeling of shaft is critical to transient stability study of this system. In addition, the inlet mass flow‐rate and inlet pressure variation can produce torsional oscillation on the shaft. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
General Nature of Luminous Body Transition Produced by Pulsed Discharge on an Electrolyte Solution in the Atmosphere
Authors: Hayashi Noriyuki , Satomi Hiroko , Mohri Takahiro , Kajiwara Toshinori , Tanabe Tetsuo 
Published: August 2009

AbstractA luminous body (LB) was produced by a pulsed electric discharge that initiated at the tip of the cathode and widely propagated on the surface of an electrolyte in the atmosphere. Entire images of the LB transition taken by a high‐speed camera are visually demonstrated for the first time. It is indicated that the entire phenomenon of the LB transition can be classified into three sequential processes, regardless of the experimental conditions. It is estimated that the bright and octopus‐like discharge, which may act as a source of high‐energy ions and atoms, plays an essential role to make the mechanism of LB phenomena clear. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Exploiting Context‐Awareness in Cluster‐Based Wireless Sensor Networks
Authors: Haque Md Enamul , Matsumoto Noriko , Yoshida Norihiko 
Published: August 2009

AbstractMost of the wireless sensor network's (WSN's) applications require getting accurate information as well as uninterrupted, prolonged service life. Among the constituting elements of WSN, an efficient routing protocol plays a significant role in attaining such service requirements. In this article, an energy efficient routing protocol, context‐aware clustering hierarchy (CACH), is proposed where cluster formation is based on the context of the environment. Moreover, a technique is utilized to avoid similar data traffic across the network. The performance in the simulation shows energy saving which ensures prolonged service life. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
A New Light‐Path Setup Scheme for Dynamic Traffic in Ring‐based Optical Networks
Authors: Sato Yusuke , Iwakawa Nobuyuki , Park Mirang , Okazaki Naonobu 
Published: August 2009

AbstractA simple and fast ring management token (RMT) wavelength reservation method for dynamic traffic in multi‐ring wavelength‐routed networks is proposed. The RMT is an agent that can control and manage the used wavelength in the network efficiently. We show that the proposed scheme achieves a high performance in terms of setup delay and loss probability. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Running Test of VVVF Inverter Type Railcar Using Lithium Ion Battery
Authors: Ogihara Takashi , Yamanaka Shigenobu 
Published: August 2009

AbstractLithium ion battery was applied to the running of variable voltage variable frequency (VVVF) inverter‐type railcar. A 15 kWh of Mn‐type lithium ion battery was used. The relation between running time and voltage, current and integrating watt was investigated. The running test was also carried out using VVVF inverter‐type railcar to investigate charge performance due to regenerative energy. Lithium ion battery module was quickly charged for three times at rate of 4.68 C by regenerative braking system. It was estimated that the effect of energy saving was about 22% by the charge of lithium ion battery from regenerative energy. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Structure and Properties of Hydrogenated Ca, Sr, Ba, and Eu Silicides
Authors: Armbruster Markus , Wörle Michael , Krumeich Frank , Nesper Reinhard 
Published: August 2009

AbstractThe binary metal silicides CaSi, BaSi, SrSi, and EuSi that crystallize in the CrB type absorb reversibly hydrogen. Hydrogen contents of the products were measured by the carrier gas hot extraction method (CaSiHx: 1.56 wt %, x ≈︁ 1.06; SrSiHx: 1.35 wt %, x ≈︁ 1.6; BaSiHx: 2.08 wt %, x ≈︁ 3.4; EuSiHx: 0.99 wt %, x ≈︁ 1.8). According to simultaneous thermogravimetric, DTA and mass‐spectroscopic analyses, the dehydrogenation for the different hydrides starts at 610 K for BaSiHx, at 675 K for CaSiHx and SrSiHx, and at 640 K for EuSiHx. BaSiHx releases further hydrogen at 765 K and 1000 K, respectively, CaSiHx at 760 K. Fundamental morphological and structural changes caused by the hydrogenation of the silicides were detected and comprehensively characterized by SEM and X‐ray diffraction. According to XRD results, the crystal structures of the phases MSiHx (M = Ca, Ba, Sr, Eu) are all orthorhombic (space group Pnma). The lattice parameters change from a = 4.559(1) Å, b = 10.731(1) Å, c = 3.890(1) Å (space group Cmcm, Z = 1) in CaSi to a = 14.4884(9) Å, b = 3.8247(1) Å, c = 11.2509(5) Å (Z = 3) in CaSiHx caused by the hydrogen uptake that induces the formation of a threefold superstructure along the a axis. In CaSiHx, the planes of the [Sin]2– zigzag chains are tilted and inter‐chain Si–Si contacts are formed formally corresponding to an oxidation to Si–. The hydrogen desorption process was investigated by in situ X‐ray diffraction studies which revealed the presence of two different hydrogen species in CaSiHx. The new phase SrSiHx crystallizes in a related structure comprising tilted [Sin]2– chains (a = 15.1051(5) Å, b = 3.95400(8) Å, c = 12.3431(3) Å, space group Pnma). The lattice parameters of BaSiHx are a = 15.7(2) Å, b = 4.13(3) Å, c = 13.43(8); that of EuSiHx a = 15.17 Å, b = 3.95 Å, c = 11.56 Å (Z = 3).
Ternary Rare Earth Rhodium Antimonides Ln6Rh30Sb19 with Ln = La–Nd, Sm, and Eu
Authors: Jeitschko Wolfgang , Altmeyer Rainer O. , Rodewald Ute Ch. 
Published: August 2009

AbstractThe six title compounds were prepared by annealing cold‐pressed pellets consisting of stoichiometric mixtures of binary rare earth and rhodium antimonides with additional elemental rhodium in evacuated silica tubes. Their crystal structure was determined from four‐circle X‐ray diffractometer data of a Eu6Rh30Sb19 single crystal, which was isolated from an arc‐melted sample annealed just below the melting temperature in a high‐frequency furnace. It is hexagonal: P63/m, a = 1693.2(2) pm, c = 408.11(4) pm, Z = 1. The least‐squares refinement resulted in a residual of R = 0.034 for 1259 structure factors and 62 variable parameters. The structure shows some disorder around the 63 axis but otherwise is very similar to the structures of Sc6Co30Si19 and Yb6Co30P19, but different from that of U6Co30Si19. The plot of the cell volumes of the new series Ln6Rh30Sb19 indicates the europium atoms in Eu6Rh30Sb19 to be at least partially divalent.
Stabilizing the Boat Conformation of Piperazines Coordinated to Iron(II): iso‐Butyl Substituents Lead to Robust Oxidation Catalysts via Hyperconjugation
Authors: Ostermeier Marc , Limberg Christian , Herwig Christian , Ziemer Burkhard 
Published: August 2009

AbstractA known route to diastereomerically pure diketopiperazines starting from natural amino acids was utilized for the preparation of a chiral, 2,5‐di‐iso‐butyl‐substituted 1,4‐bis(2‐pyridyl‐methyl)piperazine, which can serve as a ligand in metal complexes. Whereas it should be possible to extend the procedure described also to derivatives with other amino acid‐derived substituents in the 2,5 positions, here two bulky iso‐butyl residues were chosen with the aim of stabilizing a tetradentate coordination mode at FeII atoms thus avoiding coordination polymers. Reaction of the corresponding ligand 2iBuBPMP with FeCl2 and Fe(OTf)2 indeed led to the desired complexes(2iBuBPMP)FeX2 (X = Cl, OTf) with the piperazine ring in a boat conformation, as confirmed by single‐crystal X‐ray diffraction analysis. However, unexpectedly the bulky iso‐butyl residues were found in the axial positions. To explain this phenomenon DFT calculations were carried out. The results showed that the most stable conformations of the free ligand contain the piperazine ring in a boat conformation with carbon atoms at the tips of the boat since repulsive interactions between the lone‐pairs at the nitrogen atoms are avoided thereby. This way the ligand is preorganized to adopt the observed conformation with the axial iso‐butyl residues after complexation with iron(II). Moreover, it turned out that the resulting complex structures are also favoured thermodynamically over the corresponding ones with the residues in equatorial positions. Having thus stabilized the tetrapodal binding of a BPMP ligand to single iron atoms, the potential of the complexes as catalysts for the oxidation of hydrocarbons with H2O2 was tested employing cyclooctene as a representative example. It turned out that the two complexes mentioned above show similar (moderate) activities, which are comparable to those displayed by corresponding complexes of other polydentate pyridylmethyl‐amino ligands. Interestingly, the two complexes described herein are superior to an Fe(OTf)2 complex of the unsubstituted ligand.
An Unusual Linear Trinuclear NiII‐based MOF with an Unprecedented μ4‐κ2N1,N5:κ1N2:κ1N6 Binding Mode by 5‐(Pyrazinyl)tetrazolate Ligand
Authors: Feng Yan , Yang En‐Cui , Fu Min , Zhao Xiao‐Jun 
Published: August 2009

AbstractA photofluorescent linear trinuclear NiII‐based three‐dimensional (3D) metal‐organic framework (MOF) with tfz‐d topology, {[Ni3(H2O)4(ptz)2(btec)]·4H2O}n (1) (ptz– = 5‐(pyrazinyl)tetrazolate, btec4– = 1,2,4,5‐benzenetetracarboxylate), was achieved by in situ hydrothermal reaction of 2‐cyanopyrazine with NaN3 in the presence of Ni2+ as Lewis acid and aromatic H4btec as coligand. Interestingly, the ptz– ligand in 1 represents an unprecedented tetradentate μ4‐κ2N1,N5:κ1N2:κ1N6 chelating‐bridging mode and contributes to the extension of the 1D ribbons into a 3D framework.
Crystal Structures of Ternary Ruthenium Ferrites SrM2±xRu4∓xO11 with M = Fe, Co and Magnetic and Transport Properties of Al‐doped Single Crystals
Authors: Niewa Rainer , Shlyk Larysa , Schüpp‐Niewa Barbara , De Long Lance E. 
Published: August 2009

AbstractSingle crystals of SrM2±xRu4∓xO11 with M = Fe, Co with maximum width of 2 mm and a thickness around 0.05 mm were grown from a chloride flux. Sample compositions were determined from refinements of X‐ray diffraction data and microprobe analysis. The hexagonal crystal structure (space group P63/mmc, Z = 2) consists of basal‐plane layers of edge‐sharing octahedra (M,Ru)O6, which are connected along [001] by face‐sharing pairs of octahedra (M,Ru)2O9 and trigonal bipyramids MO5. A significant homogeneity range is generated by variable occupation of the octahedral sites by 3d and 4d elements. Aluminum is also found to substitute for transition elements in the octahedral sites. The title compounds are narrow‐gap semiconductors and soft ferromagnets with Curie temperatures that can substantially exceed room‐temperature, depending on composition. Aluminum doping significantly modifies the transport properties, but magnetic properties such as the Curie temperature, magnetization and anisotropy are less affected. Hall coefficient measurements reveal the predominant charge carriers are holes. The structural, electronic and magnetic properties suggest that these solid solutions are promising candidates for spin‐injection devices.
The influence of feeding, enrichment, and seasonal context on the behavior of Pacific Walruses (Odobenus rosmarus divergens)
Authors: Franks Becca , Lyn Heidi , Klein Lauren , Reiss Diana 
Published: August 2009

AbstractThough some research exists concerning general behavior and activity patterns of Walruses in zoos or aquariums, less is known about how these patterns change in response to various environmental and temporal contexts. This study presents two studies assessing behavioral changes in relation to feeding period, object enrichment (OE), and season in a social group of four Pacific Walruses at the New York Aquarium. Study 1 examined behavior in relation to feeding context (nonfeed, prefeed, postfeed); data were collected over a three‐week period, resulting in 47 observation sessions for each feeding context. Study 2 examined behavior in relation to OE and season; data were collected in two phases resulting in 12 enrichment and 9 no‐enrichment (NE) observation sessions (Phase 1), and 21 enrichment and 18 NE observation sessions (Phase 2). Study 1 showed that after feeding, oral behavior increased while social behavior and total swim frequency decreased. In Study 2, both swim frequency and social behavior were found to interact with OE and phase, while oral behavior remained constant across all conditions. As in the wild, both studies found all animals to be swimming the majority of the time. Though every animal spent much of its swim time engaged in an Individual Swimming Pattern (ISP), both studies showed that the proportion of ISP (in relation to total time swimming) remained stable across all contexts, suggesting a potential functional role of the ISPs. These results are discussed in light of the ongoing debate over the role of stereotypies in welfare assessment. Zoo Biol 29:397–404, 2010. © 2009 Wiley‐Liss, Inc.