bluuebunny/crossref_metadata_2025_split huggingface dataset:
An adaptive digital processor for power efficiency enhancement in hybrid supply modulators
Authors: Salimi Atefeh , Dehghani Rasoul , Nabavi Abdolreza 
Published: April 2015

SummaryA novel digital envelope modulator for envelope tracking radio frequency power amplifier is presented in this paper. The proposed modulator consists of a parallel combination of linear class AB and switching class D power amplifiers that are controlled digitally. In the previous analog architectures, the requirements needed for the AB operational amplifier such as high‐current driving capability, high bandwidth and large output swing is usually obtainable at high overall static power dissipation. The digitally controlled power opamp presented here not only provides the aforementioned requirements but also reduces power dissipation compared with previous work. Furthermore, the digital control of the modulator makes it adaptive to the input signal variations in comparison with conventional analog parallel hybrid envelope modulators. The digital processor of the modulator is evaluated with a 45‐nm complementary metal oxide semiconductor technology. The overall power consumption of the digital processor is around 142 mW at 1.5‐GHz clock frequency. As an application, the designed digital class AB is incorporated in a complete envelope modulator architecture. The overall efficiency of the modulator, including the digital processor power consumption, is around 82% at an average 32 dBm output power for a 5‐MHz input signal. Copyright © 2015 John Wiley & Sons, Ltd.
PIC/MCC Simulation of Electron and Ion Currents to Spherical Langmuir Probe
Authors: Trunec D. , Bonaventura Z. , Zikin P. , Jánský J. 
Published: April 2015

AbstractThe Particle In Cell/Monte Carlo Collisions (PIC/MCC) simulation was used for the calculation of electron and ion currents to a spherical Langmuir (electrostatic) probe. This simulation took into account the collisions of collected charged particles with neutral gas particles around the probe and it can calculate the probe currents at higher neutral gas pressures. The improvements of usual simulation techniques enabled to speed up the simulation and to calculate the probe current even for neutral gas pressures above 1 kPa. The simulations were carried out for two cases: i) probe with radius of 0.5 mm in non‐thermal plasma with high electron temperature, ii) probe with radius of 10 µm in afterglow plasma with low electron temperature. The influence of probe radius on electron probe current was also studied. The simulations showed that thick sheath limit of OML theory provides incorrect values of probe current for probes with radii larger than 200 µm at plasma parameters considered even at very low neutral gas pressures. The probe characteristics were calculated for probe with 0.5 mm radius for pressures up to 500 Pa and for probe with 10 μm radius for pressures up to 3 kPa. The influence of collisions on electron and ion probe current was demonstrated and the procedure for determination of electron and ion densities from the probe measurement at higher pressures was developed. The results from PIC/MCC simulations were compared with results from continuum theory. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear Fluid Theory for Weakly Inhomogeneous Plasmas with Strong Correlations
Authors: Kählert H. , Kalman G. J. , Bonitz M. 
Published: April 2015

AbstractLinearized fluid equations for the collective modes of weakly inhomogeneous plasmas including strong coupling effects are derived from a recent kinetic theory based on an extended Singwi‐Tosi‐Land‐Sjölander (STLS) ansatz [H. Kählert, G. J. Kalman, and M. Bonitz, Phys. Rev. E 90, 011101(R) (2014)]. The equations are analogous to the equations of linearized elasticity theory with space dependent elastic moduli that correspond to those of a bulk system with the local fluid density. The identification of the latter as infinite‐frequency elastic moduli shows that the present version of the extended STLS theory accounts for the elastic properties of the fluid but does not capture the viscous behavior. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular Dynamics Simulations of Warm Dense Carbon
Authors: Whitley H. D. , Sanchez D. M. , Hamel S. , Correa A. A. , Benedict L. X. 
Published: April 2015

AbstractWe present classical and DFT‐based molecular dynamics (MD) simulations of carbon in the warm dense matter regime (ϱ = 3.7 g/cc, 0.86 eV < T < 8.62 eV [T < 100 eV for classical MD]). Two different classical interatomic potentials are used: 1. LCBOP, designed to simulate condensed (e.g. solid) phases of C, and 2. linearly screened Coulomb (Yukawa) potentials. It is shown that LCBOP over‐predicts minima and maxima in the pair correlation functions of liquid‐C in this regime when compared to the DFT‐MD results. The screened Coulomb model, while under‐correlating at low‐T, seems to produce the correct qualitative features in the static ionic pair distributions at the highest‐T. However, both approaches predict the decay in the ionic contribution of the specific heat as T → ∞ to be much slower than that predicted by a model based on DFT‐MD. These differences in the MD‐derived equations of state in warm dense regimes could have important consequences when using classical inter‐ionic forces such as these in large‐scale MD simulations aimed at studying, for instance, processes of relevance to inertial confinement fusion when C is used as an ablator material. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of Carrier Frequency and Circuit Resistance on Iron Loss of Non‐Oriented Electrical Steel Sheet under Single‐Phase Full‐Bridge PWM Inverter Excitation
Authors: Kaihara Hiroki , Takahashi Norio , Nakano Masanori , Kawabe Morio , Nomiyama Takuma , Shiozaki Akira , Miyagi Daisuke 
Published: April 2015

SUMMARYBecause of the development of power electronics technology, pulse width modulation (PWM) inverters are now being used to drive motors in order to achieve precise and energy‐efficient control. Precise estimation of the increase in iron loss due to the high harmonic components of flux, including the carrier frequency, is important in the design of motors excited by a PWM inverter. We measured the iron losses of non‐oriented electrical steel sheets that were excited using a single‐phase full‐bridge PWM inverter, and examined the influence of the carrier frequency and circuit resistance on the iron loss. We showed that the iron loss increased because of the generation of minor loops when the circuit resistance was high. Therefore, the circuit resistance should be decreased in an actual motor system.
Catalytic Models of Tyrosinase: Reactivity Differences between Systems Based on Mono‐ and Binucleating Ligands
Authors: Schottenheim Julia , Gernert Claus , Herzigkeit Benjamin , Krahmer Jan , Tuczek Felix 
Published: April 2015

AbstractA new tyrosinase model based on the binucleating ligand Lpy2 is synthesized and characterized. The ligand Lpy2 contains a combination of an imine and a pyridine function in the sidearms, which are bridged by a flexible alkyl spacer. As shown by UV/Vis and NMR spectroscopy, the Cu2Lpy2 complex catalyzed the conversion of the monophenol 2,4‐di‐tert‐butylphenol (DTBP‐H) into the o‐quinone 3,5‐di‐tert‐butylquinone (DTBQ) with a turnover number (TON) of 18. The dicopper complex of Lpy2 thus shows monophenolase activity that is comparable to that of the recently developed Lpy1 model of tyrosinase, which is based on a known mononucleating ligand (M. Rolff, J. Schottenheim, G. Peters, F. Tuczek, Angew. Chem. Int. Ed. 2010, 122, 6583). The electron‐poor substrate 4‐hydroxybenzoic acid methyl ester (MeBA‐OH), in contrast, is converted by Cu2Lpy2 into the semiquinone. For both substrates, the oxygenation reactions were also conducted in a stoichiometric fashion to obtain information on the intermediates involved. For the substrate MeBA‐OH, we detected a binuclear μ‐catecholato copper(II) complex by high‐resolution ESI mass spectrometry. These studies were complemented by investigations of deactivation mechanisms that could be invoked to explain the limitation of the TON. To this end, a bis‐μ‐hydroxido Lpy2 dicopper(II) complex as well as a semiquinone Lpy2 complex were prepared. Both complexes may represent decay products of the catalyst.
Phosphaindazole: A Phosphorus–Carbon Aromatic Heterocycle
Authors: Jevtovikj Ivana , Sárosi Menyhárt B. , Adhikari Anup K. , Lönnecke Peter , Hey‐Hawkins Evamarie 
Published: April 2015

AbstractA straightforward synthetic route to a novel phosphorus–carbon heterocycle, namely, phosphaindazole, which is the phosphorus analogue of indazole or indene, was developed from sodium tetraphosphanediide [Na2(P4Mes4)](Mes = 2,4,6‐Me3C6H2) and nBuLi. A proposed intermediate in this reaction, the dimesityldiphosphanide dianion, could be isolated and structurally characterized as [Na8(thf)8(P2Mes2)4]·2THF.
Palladium‐Catalyzed Nucleophilic Substitution of Propargylic Carbonates and Meldrum's Acid Derivatives
Authors: Ambrogio Ilaria , Cacchi Sandro , Fabrizi Giancarlo , Goggiamani Antonella , Iazzetti Antonia 
Published: April 2015

AbstractThe palladium‐catalyzed reaction of propargylic carbonates with Meldrum's acid derivatives proceeds smoothly in the presence of Pd(OAc)2 and P(2‐furyl)3 in THF at 80 °C to give substitution products. The substitution products can be useful intermediates for the stereoselective synthesis of functionalized (Z)‐γ‐alkylidene‐γ‐butyrolactones.
Combining Alkaline Extraction and in Situ Plated Bismuth Film for Reliable Quantification of Zn in Multivitamin Formulations
Authors: Fonseca Wilson T. , Takeuchi Regina M. , Santos André L. 
Published: April 2015

AbstractIn this work a bismuth film electrode (BiFE) plated in situ onto glassy carbon was used to quantify Zn2+ in multivitamin formulation samples by square wave anodic stripping voltammetry. For partially water‐soluble multivitamin tablets, an alkaline extraction with 1.0 mol L−1 NaOH aqueous solution was adopted. This procedure was simple, fast and efficient to extracting Zn from sample matrix. Moreover, this procedure was able to make the method less susceptible to interferences from Cu2+, since it remains at extracting vessel as insoluble Cu(OH)2. For fully water‐soluble effervescent tablets, sample pretreatment was not required.
Seismic design and experiment of single and coupled corner gusset connections in a full‐scale two‐story buckling‐restrained braced frame
Authors: Lin Pao‐Chun , Tsai Keh‐Chyuan , Wu An‐Chien , Chuang Ming‐Chieh , Li Chao‐Hsien , Wang Kung‐Juin 
Published: April 2015

SummaryA gusset plate is subjected to forces induced from a buckling‐restrained brace (BRB) and frame action. In this study, a performance‐based design method of the gusset connections incorporating a BRB and frame actions is investigated. The force demands resulting from the BRB axial force are computed from the generalized uniform force method. The force demands induced from the frame action effects primarily result from beam shear. A conservative method, which considers the beam axial force effect and the thereafter reduced beam flexural capacity possibly developed at the gusset tips, is adopted in estimating the maximum beam shear. An improved equivalent strut model is used to represent the gusset plate subjected to the frame action effect. The total force demands of the gusset connection are combined from the BRB force and the frame actions. For design purposes, the stress distributions on the gusset interfaces are linearized. The maximum von Mises stress combining the normal and shear stresses is considered as the demand for the gusset plate design. In order to verify the effectiveness of the proposed design method, experiments on a two‐story full‐scale buckling‐restrained braced frame (BRBF) were performed. The chevron and single diagonal brace configurations were arranged in the second and the first stories, respectively. Two different corner gusset connection configurations including one single corner gusset and one coupled corner gusset connection, where two braces in adjacent stories joined at the same beam‐to‐column joint, were tested. The BRBF specimen was subjected to cyclically increasing lateral displacements with a maximum frame drift of 0.04 rad. The maximum story drifts reached 0.035 and 0.061 rad. in the first and the second stories, respectively. At the end of the tests, no fractures were observed on any of the gusset interfaces. Along the gusset interfaces, the normal and shear stress distributions computed from the proposed design procedures and the FEM analysis correlated well with the experimental results. This paper concludes with the procedure and recommendations for the performance‐based design of gusset connections. Copyright © 2015 John Wiley & Sons, Ltd.
Preparation and characteristics of nanocapsules containing essential oil for textile application
Authors: Liu Cong , Liang Baijun , Shi Guang , Li Zhicheng , Zheng Xubin , Huang Yang , Lin Li 
Published: April 2015

AbstractMethyl methacrylate (MMA)–styrene (St) copolymer nanocapsules containing cologne essential oil for fragrant fabrics treatment were prepared by miniemulsion polymerization. The morphology, chemical composition and thermal properties were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT‐IR) and thermal gravimetric analysis (TGA). The nanocapsules had relatively small size (ca. 136 nm of mean particle diameter), regular sphericity and uniform particle size distribution. The encapsulation efficiency and loading capacity of the nanocapsules were 85.4% and 42.7%, respectively. The nanocapsules had good thermostability. The release experiments showed that 6.8% cologne essential oil still existed after being washed 15 times in the fabrics treated with nanocapsules, indicating that the fabrics treated with nanocapsules had good washing durability. Copyright © 2015 John Wiley & Sons, Ltd.
Variational modeling and homogenization in dissipative magneto‐mechanics
Authors: Ethiraj Gautam , Sridhar Ashish , Miehe Christian 
Published: April 2015

AbstractThe aim of this work is to present new variational‐based modeling and homogenization approaches in dissipative magneto‐mechanics. On the modeling side, the presented constitutive models are motivated by the underlying physical phenomena at the micro‐ and nano‐scale that are embedded in appropriate variational‐based finite element frameworks. We discuss aspects that are characteristic to magneto‐mechanical problems such as the unity constraint on the magnetization, the inclusion of the surrounding free‐space, the micro‐mechanics of the coupled response etc. Following a hierarchical structure of scales, we present new variational principles for three model scenarios: (i) The modeling of magnetic domains at a micro‐level, (ii) the modeling of magnetorheological elastomers at a macro‐level and (iii) a homogenization‐based scale bridging scenario. Numerical simulations are outlined in each focus area in order to demonstrate the salient features of the variational‐based formulations. From the theoretical and computational standpoint, this work aims to contribute a building block to the ultimate goal of construction of a compatible hierarchy of computational models for magneto‐mechanically coupled materials. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical energy relaxation to model microstructure evolution in functional magnetic materials
Authors: Kiefer Björn , Buckmann Karsten , Bartel Thorsten 
Published: April 2015

AbstractThis paper proposes energy relaxation‐based approaches for the modeling of magnetostriction, with a particular focus on single crystalline magnetic shape memory alloy response. The theoretical development relies on concepts of energy relaxation in the context of nonconvex free energy landscapes whose wells define preferred states of spontaneous straining and magnetization. The constrained theory of magnetoelasticity developed by DeSimone and James [1] represents the point of departure for the model development, and its capabilities, but also limitations, are demonstrated by means of representative numerical examples. The key features that characterize the extended approach are (i) the incorporation of elastic deformations, whose distribution among the individual phases occurs in an energy minimizing fashion, (ii) a finite magnetocrystalline anisotropy energy, that allows magnetization rotations away from easy axes, and (iii) dissipative effects, that are accounted for in an incremental variational setting for standard dissipative materials. In the context of introducing elastic strain energy, two different relaxation concepts, the convexification approach and the rank‐one relaxation with respect to first‐order laminates, are considered. In this manner, important additional response features, e.g. the hysteretic nature, the linear magnetization response in the pre‐variant reorientation regime, and the stress dependence of the maximum field induced strain, can be captured, which are prohibited by the inherent assumptions of the constrained theory. The enhanced modeling capabilities of the extended approach are demonstrated by several representative response simulations and comparison to experimental results taken from literature. These examples particularly focus on the response of single crystals under cyclic magnetic field loading at constant stress and cyclic mechanical loading at constant magnetic field. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐performance conventional tunnelling – The Bibra Tunnel on project VDE 8, Germany / Konventioneller Hochleistungsvortrieb – Der Bibratunnel im Projekt VDE 8, Deutschland
Authors: Gisi Bruno , Schöbel Stefan 
Published: April 2015

AbstractThe 123 km long Erfurt‐Leipzig/Halle high speed train link connects in the north the cities of Berlin and Munich with Verona in the South as part of the EU's Trans‐Europe Network. The project which is designed for a top speed of 300 km/h is being managed by DB Projekt Bau, a subsidiary of Deutsche Bahn. The total cost of this section between Berlin and Munich including tunnels and bridges is estimated at 13 Mrd. Euro. On the project section VDE 8.2 between Erfurt–Leipzig/Halle three tunnels are being built with a total length of 15.4 km, each composed of two single track tubes with centers approx. 25 m apart. One tunnel is being executed by mechanized tunnelling, the two others by conventional drill and blast method. The longer of these two – the Bibra tunnel with a length of 6,466 m was awarded in January 2008 to the by Marti Tunnelbau AG lead J.V. for 209 m. Euro.Concerning the implemented equipment – great emphasis is being put onto machines to increase the efficiency of the production as well as the handling of the muck by crushing the blasted material in the tunnel and transport it by conveyor belt systems with minimal emissions out of the tunnel to the final placement area.Die 123 km lange Hochgeschwindigkeitsstrecke Erfurt‐Leipzig/ Halle verbindet im Norden die Städte Berlin und München mit Verona im Süden, dies als Teil der Trans‐Europa Hochleistungsbahnstrecke. Das Bahnprojekt ist für eine Höchstgeschwindigkeit von 300 km/h ausgelegt und wird durch die DB Projekt Bau, einer Tochtergesellschaft der Deutschen Bahn, umgesetzt. Die Gesamtkosten dieses Abschnitts zwischen Berlin und München mit Tunneln und Brücken betragen ca. 13 Mrd. Euro. Auf dem Projekt‐Abschnitt VDE 8.2 zwischen Erfurt–Leipzig/Halle werden drei Tunnels mit einer Gesamtlänge von 15,4 km gebaut, welche jeweils aus zwei einzelnen Tunnelröhren bestehen, die rund 25 m von einander entfernt sind. Einer dieser Tunnel wird als maschineller Tunnelvortrieb ausgeführt, die beiden anderen im konventionellen Sprengvortrieb. Der längere dieser beiden – der Bibra Tunnel mit einer Länge von 6.466 m wurde im Januar 2008 an die von der Marti Tunnelbau AG geführte Arbeitsgemeinschaft für 209 Mio. Euro vergeben.In Bezug auf den Einsatz des Vortriebsinventars wird großer Wert auf leistungsfähiges Inventar gesetzt ‐ dies um die Effizienz des Vortriebs zu steigern sowie das Handling des gesprengten Ausbruchmaterials mittels installiertem Brecher im Tunnel bandgerecht zu zerkleinern und mit Bandförderungsanlagen emissionsarm durch den Tunnel der Endlagerstelle zu geführt werden kann.
ABS/NBS Karlsruhe‐Basel – Implementation of line section 1 and special features of the Rastatt Tunnel / ABS/NBS Karlsruhe‐Basel – Realisierung des Streckenabschnitts 1 und Besonderheiten beim Bau des Rastatter Tunnels
Authors: Grundhoff Thomas , Klar Sascha Björn 
Published: April 2015

AbstractThe northernmost section 1 (StA 1) of the section of line being upgraded (ABS) and newly built (NBS) between Karlsruhe and Basel runs from Karlsruhe to Rastatt Süd. 16 km of new line is being built, which should be in operation in 2022. The core structure of StA 1 is the 4, 270 m long Rastatt Tunnel, the second largest engineered structure in the overall ABS/NBS Karlsruhe‐Basel project after the Katzenberg Tunnel. The main contract for the construction of the tunnel was awarded in August 2014. The first preparatory construction measures on site started in summer 2013. Due to the prevailing conditions of topography and existing infrastructure and the continuously increasing requirements of approvals and codes, the construction of the Rastatt Tunnel poses great challenges for the engineers, which demand innovative solutions in design and construction as well as a collaborative approach from all those involved in the project.Der nördlichste Streckenabschnitt 1 (StA 1) der Ausbau‐ und Neubaustrecke (ABS/NBS) Karlsruhe‐Basel führt von Karlsruhe bis nach Rastatt Süd. Hier entsteht ein rund 16 km langer Neubaustreckenabschnitt, der 2022 in Betrieb genommen werden soll. Das Herzstück des StA 1 ist der 4.270 m lange Tunnel Rastatt, nach dem Katzenbergtunnel das zweitgrößte Ingenieurbauwerk im Gesamtprojekt ABS/NBS Karlsruhe‐Basel. Die Vergabe für das Hauptgewerk Tunnelrohbau erfolgte im August 2014. Mit den ersten vorlaufenden Baumaßnahmen vor Ort wurde bereits im Sommer 2013 begonnen. Durch die vorherrschenden Verhältnisse aus Topographie und Bestand sowie stetig steigende Genehmigungs‐ und Regelwerksanforderungen stellt die Realisierung des Rastatter Tunnels die Ingenieure vor herausfordernde Aufgaben, die innovative Lösungen in Planung und Bau sowie eine partnerschaftliche Herangehensweise aller Projektbeteiligten erfordern.
Impact of Lean Production on Perceived Job Autonomy and Job Satisfaction: An Experimental Study
Authors: Rodríguez Denise , Buyens Dirk , Van Landeghem Hendrik , Lasio Virginia 
Published: April 2015

AbstractPrevious studies have indicated positive and negative effects of lean production on employees’ perceived work characteristics and job attitudes. The most detrimental consequence of lean production is a decrease in the perceived job autonomy of workshop employees. To reduce these negative consequences, we propose human resource practices for integration with lean production. Drawing on the job characteristics model, we hypothesized that the implementation of lean production combined with human resource practices would enhance perceived job autonomy, job satisfaction, and operational performance. To evaluate our hypotheses, we used an experimental design consisting of a simulation game that mimics a manufacturing company. We implemented lean production combined with human resource practices in this simulated company. The results indicated a significant increase in perceived job autonomy, job satisfaction, and operational performance. Moreover, the results revealed a positive relationship between job satisfaction and operational performance.