bluuebunny/crossref_metadata_2025 huggingface dataset:
Crisscross cascade multilevel inverter with reduction in number of components
Authors: Toupchi Khosroshahi Mahdi
Published: November 2014

Recently, multilevel converters have received the largest amount of attention because of some advantages such as high quality output waveform, lower harmonic distortion and reduced electromagnetic interference. A novel cascaded multilevel inverter topology is proposed in this study. First basic part of inverter configuration is described and then symmetric and asymmetric form of converter is discussed. Comparison study is done between the proposed topology and cascaded H‐Bridge (CHB) converter. Number of components such as switch number and gate driver has been reduced in the suggested topology compared to multilevel CHB converter. Furthermore, Peak inverse voltage of suggested topology is lower than that of conventional CHB converter. Reduction in number of on‐state switches in introduced topology leads to the reduction of power loss and voltage drop. Moreover, modularity is other characteristic of this configuration. Finally, simulation and experimental results are presented. The presented results show the validity and the effectiveness of the proposed multilevel structure.
Speed sensor‐less maximum power point tracking and constant output power operation of wind‐driven wound rotor induction generators
Authors: Vijayakumar Krishnasamy , Kumaresan Natarajan , Ammasaigounden Nanjappagounder
Published: November 2014

A simple control strategy has been proposed for maximum power point tracking (MPPT) mode and constant output power mode operation of variable speed wind turbine system employing wound rotor induction generators (WRIGs). The control strategy proposed in this paper has been implemented using TMS320LF2407A real time digital signal processor (DSP) and detailed procedure for such implementation is given. The salient feature of the proposed controller is that it employs only a single switch, which is an IGBT chopper and does not require any mechanical sensors or machine parameters. This makes the overall controller simple, flexible and robust. Further, space heating and battery loads are connected at rotor side of the machine through a diode bridge rectifier and the IGBT chopper. A method has been developed for the analysis of such grid connected WRIGs with variable external resistance at the chopper circuit. The successful working of the proposed controller has been amply demonstrated through extensive simulation and experimental results on the WRIG system for MPPT and constant output power operation.
Observer‐based open transistor fault diagnosis and fault‐tolerant control of five‐phase permanent magnet motor drive for application in electric vehicles
Authors: Salehifar Mehdi , Salehi Arashloo Ramin , Moreno‐Eguilaz Manuel , Sala Vicent , Romeral Luis
Published: November 2014

To meet increasing demand for higher reliability in power electronics converters applicable in electric vehicles, fault detection (FD) is an important part of the control algorithm. In this study, a model‐based open transistor fault diagnsosis method is presented for a voltage‐source inverter (VSI) supplying a five‐phase permanent magnet motor drive. To realise this goal, a model‐based observer is designed to estimate model parameters. After that, the estimated parameters are used to design a sliding mode observer in order to estimate the phase current in an ideal model. Subsequently, the proposed FD technique measures the similarity between the estimated current and real current using cross‐correlation factor. This factor is used for the first time in this study to define a FD index in VSI. The presented FD scheme is simple and fast; also, it is able to detect multiple open switch or open phase faults in contrast to conventional methods. On the other side, in order to track reference current of the motor, the estimated parameters are used to design a proportional resonant controller. The FD technique is used to operate a multiphase fault‐tolerant brushless direct current (BLDC) motor drive. Experimental results on a five‐phase BLDC motor with in‐wheel outer rotor applicable in electrical vehicles are conducted to validate the theory.
Efficient circuit modelling of wireless power transfer to multiple devices
Authors: Liu Xiaochang , Wang Gaofeng , Ding Wen
Published: November 2014

Circuit analysis of the wireless power transfer (WPT) system with one source and multiple receiving devices is presented. An equivalent circuit model for the WPT system with one source and multiple receiving devices is proposed and formulae for calculating the maximum power efficiency and the optimal loads of the receiving devices are derived analytically. The tuning scheme for optimising the WPT system is deduced and expressed in terms of empirical equations for load networks. The circuit analysis of the WPT system is validated by the experimental results and circuit simulations. The proposed circuit modelling scheme provides an efficient way for designing and optimising the multiple‐device WPT systems.
Load disturbance suppression for voltage‐controlled three‐phase voltage source inverter with transformer
Authors: Qi Yu , Peng Li , Chen Manlin , Huang Zeyi
Published: November 2014

This study concentrates on the load disturbance in voltage‐controlled three‐phase voltage source inverter (VSI) with transformer. High power density could be obtained when the transformer placed behind the inductor–capacitor (LC) filter, but the voltage drop on transformer leakage impedance may reduce output voltage quality in high power application. Load current feedforward control is applied to reduce output impedance and suppress load disturbance. To avoid the non‐ideal high‐frequency noise introduced by full feedforward strategy, simplified feedforward strategy is proposed to improve dynamic performance. The feedforward strategies implemented in both stationary frame and synchronous frame are derived, and the reduction of output impedance is analysed in detail. The distinct features of the proposed feedforward strategies are error‐free steady‐state fundamental output, fast dynamic response and convenient implementation. Finally, simulation and experimental results are provided to verify feasibility and validity of the proposed control strategy.
Digital control of isolated Cuk power factor correction converter under wide range of load variation
Authors: Dian Songyi , Wen Xuefeng , Deng Xiang , Zhang Shimin
Published: November 2014

This study presents a novel digital double‐loop control method, that is, inner current loop and outer voltage loop, for a single‐stage isolated Cuk power factor correction (PFC) converter in continuous conduction mode (CCM). First, control law of current loop, consisting of a current term and a voltage term, is derived. Considering that inductance value of inductors varies with load change, an adaptive gain scheduling method is applied to change the current term. Second, control law of voltage loop is derived based on proportional‐integral control with introducing linearisation and feedforward compensation. Meanwhile, a moving average filter is utilised to decrease ripple effect of output voltage, and thus smoother input signal for current loop and fast dynamic response for voltage loop are guaranteed. A 1600 W one‐phase isolated Cuk PFC converter controlled by a digital signal processor is developed and achieves power factor higher than 0.99, total harmonic distortion of input current lower than 8.5% with load varying from 25 to 100% and fast dynamic response performance. Finally, a 4800 W three‐phase AC–DC converter based on the above PFC converter is implemented and its performance additionally indicate that current sharing issue can be easy to deal with by using the proposed control method.
Depressurised reservoirs for portable fluid extraction in SU‐8‐based microfluidic systems
Authors: Aracil Carmen , Perdigones Francisco , Moreno J. Miguel , Luque Antonio , Flores Guadalupe , Quero José Manuel
Published: November 2014

A depressurisation method to build SU‐8 chambers as pneumatic energy reservoirs is described. The method consists in a combination of injection/extraction of uncrosslinked SU‐8 and its exposure in different steps, intended to set the pressure of a chamber below atmospheric. These chambers are intended to be integrated with an actuation system to perform the extraction of fluids from the outside to the inside of a microfluidic SU‐8 lab‐on‐a‐chip. This method improves the portability of the platform because external pumps used to impulse the fluids can be avoided.
Stopping power: Effect of the projectile deceleration
Authors: Kompaneets Roman , Ivlev Alexei V. , Morfill Gregor E.
Published: November 2014

The stopping force is the force exerted on the projectile by its wake. Since the wake does not instantly adjust to the projectile velocity, the stopping force should be affected by the projectile deceleration caused by the stopping force itself. We address this effect by deriving the corresponding correction to the stopping force in the cold plasma approximation. By using the derived expression, we estimate that if the projectile is an ion passing through an electron-proton plasma, the correction is small when the stopping force is due to the plasma electrons, but can be significant when the stopping force is due to the protons.
Reduced lattice thermal conductivity in Bi-doped Mg2Si0.4Sn0.6
Authors: Gao Peng , Lu Xu , Berkun Isil , Schmidt Robert D. , Case Eldon D. , Hogan Timothy P.
Published: November 2014

This letter reports the thermoelectric properties of Bi-doped Mg2Si0.4Sn0.6 thermoelectric materials. It was found that the ZTs of this material could be greatly enhanced by Bi-doping. Analyses on the transport properties showed that the power factors of the material were enhanced while the lattice thermal conductivities were reduced by Bi-doping. The reduction of the lattice thermal conductivity was likely caused by the interstitial Bi impurities. A peak ZT ≈ 1.55 at 773 K was obtained.
Ultrafast lattice response of photoexcited thin films studied by X-ray diffraction
Authors: Schick Daniel , Herzog Marc , Bojahr André , Leitenberger Wolfram , Hertwig Andreas , Shayduk Roman , Bargheer Matias
Published: November 2014

Using ultrafast X-ray diffraction, we study the coherent picosecond lattice dynamics of photoexcited thin films in the two limiting cases, where the photoinduced stress profile decays on a length scale larger and smaller than the film thickness. We solve a unifying analytical model of the strain propagation for acoustic impedance-matched opaque films on a semi-infinite transparent substrate, showing that the lattice dynamics essentially depend on two parameters: One for the spatial profile and one for the amplitude of the strain. We illustrate the results by comparison with high-quality ultrafast X-ray diffraction data of SrRuO3 films on SrTiO3 substrates.
Protonic transistors from thin reflectin films
Authors: Ordinario David D. , Phan Long , Jocson Jonah-Micah , Nguyen Tam , Gorodetsky Alon A.
Published: November 2014

Ionic transistors from organic and biological materials hold great promise for bioelectronics applications. Thus, much research effort has focused on optimizing the performance of these devices. Herein, we experimentally validate a straightforward strategy for enhancing the high to low current ratios of protein-based protonic transistors. Upon reducing the thickness of the transistors’ active layers, we increase their high to low current ratios 2-fold while leaving the other figures of merit unchanged. The measured ratio of 3.3 is comparable to the best values found for analogous devices. These findings underscore the importance of the active layer geometry for optimum protonic transistor functionality.
Toughening in electrospun fibrous scaffolds
Authors: Koh C. T. , Oyen M. L.
Published: November 2014

Electrospun scaffolds mimic the microstructure of structural collagenous tissues and have been widely used in tissue engineering applications. Both brittle cracking and ductile failure have been observed in scaffolds with similarly random fibrous morphology. Finite element analysis can be used to qualitatively examine the mechanics of these differing failure mechanisms. The finite element modeling demonstrates that the noncontinuum deformation of the network structure results in fiber bundle formation and material toughening. Such toughening is accommodated by varying fiber properties, including allowing large failure strains and progressive damage of the fibers.
Scattering through a straight quantum waveguide with combined boundary conditions
Authors: Briet Ph. , Dittrich J. , Soccorsi E.
Published: November 2014

Scattering through a straight two-dimensional quantum waveguide \documentclass[12pt]{minimal}\begin{document}$\mathbb {R} \times (0,d)$\end{document}R×(0,d) with Dirichlet boundary conditions on \documentclass[12pt]{minimal}\begin{document}$(\mathbb {R}_-^* \times \lbrace y=0 \rbrace ) \cup (\mathbb {R}_+^* \times \lbrace y=d \rbrace )$\end{document}(R−*×{y=0})∪(R+*×{y=d}) and Neumann boundary condition on \documentclass[12pt]{minimal}\begin{document}$(\mathbb {R}_-^* \times \lbrace y=d \rbrace ) \cup (\mathbb {R}_+^* \times \lbrace y=0 \rbrace )$\end{document}(R−*×{y=d})∪(R+*×{y=0}) is considered using stationary scattering theory. The existence of a matching conditions solution at x = 0 is proved. The use of stationary scattering theory is justified showing its relation to the wave packets motion. As an illustration, the matching conditions are also solved numerically and the transition probabilities are shown.
The high temperature photoluminescence and optical absorption of undoped ZnO single crystals and thin films
Authors: Margueron Samuel , Clarke David R.
Published: November 2014

The photoluminescence of undoped ZnO single crystals up to 1350 °C and the optical absorption of stress-relaxed, epitaxial ZnO thin films up to 1100 °C are reported. The photoluminescence intensity and power dependence with illumination flux are related to the crystal growth methods and stabilize after high temperature annealing. The observation of excitonic recombination at very high temperatures requires high illumination flux. It is found that the zero phonon line model reproduces the shift and the band gap narrowing as well as the free excitonic transition up to the cross-over with a defect level at 2.83 eV that occurs at 800 °C. A phenomenological model of the excitonic recombination band shape, taking account exciton-phonon losses and defect levels provides an excellent fit up to 2.2–2.4 eV (1100 °C). At these cross-over temperatures, an energy transfer is observed between the free exciton transition and defect transitions. However, at temperature above 1100 °C, the decrease of the band gap and the increase of thermal radiation, as well as the restrictions of our experimental set-up and particularly the illumination flux of the exciting laser, limit the analysis of the photoluminescence spectra measurements.
Where does the electron go? The nature of ortho/para and meta group directing in electrophilic aromatic substitution
Authors: Liu Shubin
Published: November 2014

Electrophilic aromatic substitution as one of the most fundamental chemical processes is affected by atoms or groups already attached to the aromatic ring. The groups that promote substitution at the ortho/para or meta positions are, respectively, called ortho/para and meta directing groups, which are often characterized by their capability to donate electrons to or withdraw electrons from the ring. Though resonance and inductive effects have been employed in textbooks to explain this phenomenon, no satisfactory quantitative interpretation is available in the literature. Here, based on the theoretical framework we recently established in density functional reactivity theory (DFRT), where electrophilicity and nucleophilicity are simultaneously quantified by the Hirshfeld charge, the nature of ortho/para and meta group directing is systematically investigated for a total of 85 systems. We find that regioselectivity of electrophilic attacks is determined by the Hirshfeld charge distribution on the aromatic ring. Ortho/para directing groups have most negative charges on the ortho/para positions, while meta directing groups often possess the largest negative charge on the meta position. Our results do not support that ortho/para directing groups are electron donors and meta directing groups are electron acceptors. Most neutral species we studied here are electron withdrawal in nature. Anionic systems are always electron donors. There are also electron donors serving as meta directing groups. We predicted ortho/para and meta group directing behaviors for a list of groups whose regioselectivity is previously unknown. In addition, strong linear correlations between the Hirshfeld charge and the highest occupied molecular orbital have been observed, providing the first link between the frontier molecular orbital theory and DFRT.
Structural and electrical properties of Bi0.5Na0.5 TiO3 based superlattices grown by pulsed laser deposition
Authors: Bousquet M. , Batista L. , Dellis J. L. , Boulle A. , Rabe U. , Durand-Drouhin O. , Gagou Y. , Dupont L. , Viallet V. , Zeinert A. , Hirsekorn S. , Lemée N.
Published: November 2014

Artificial superlattices of ferroelectric Bi0.5Na0.5TiO3 and BaTiO3 have been successfully grown on (001) insulator or conductive SrTiO3 substrates by pulsed laser deposition. In these epitaxial layered structures, the BaTiO3 layers were shown to contribute to an improvement of the two dimensional growth of the Bi0.5Na0.5TiO3 layers. The influence of the superlattice period Λ, between 5 and 20 nm, was investigated. We observe an increase in the in-plane tensile strain as Λ is reduced from 20 nm to 10 nm, accompanied by a decrease in the density of dislocations. A concomitant enhancement of the dielectric permittivity was measured, demonstrating the strain tunability of these superlattices. A significant reduction of the dielectric losses is also obtained with decreasing Λ. Furthermore, a minimum value of the coercive field of less than 70 kV/cm, close to that of Bi0.5Na0.5TiO3 bulk ceramics, was reached by decreasing the period. We demonstrate that the dielectric and ferroelectric properties can be explained as the result of the in-plane tensile strain which contributes to improve the structural properties in the superlattices.
Ab initio study on the effect of structural relaxation on the electronic and optical properties of P-doped Si nanocrystals
Authors: Pi Xiaodong , Ni Zhenyi , Yang Deren , Delerue Christophe
Published: November 2014

In contrast to the conventional doping of bulk silicon (Si), the doping of Si nanocrystals (NCs) that are often smaller than 5 nm in diameter may lead to serious structural changes. Since the electronic and optical properties of Si NCs are intimately associated with their structures, it is critical to understand how doping impacts the structures of Si NCs. By means of ab initio calculation we now compare 1.4 nm phosphorus (P)-doped Si NCs without structural relaxation and those with structural relaxation. Structural changes induced by structural relaxation are manifested by the stretching and compressing of bonds and apparent variations in bond angles. With the increase of the concentration of P structural changes induced by structural relaxation become more serious. It is found that structural relaxation makes differences in the energy-level schemes of P-doped Si NCs. Structural relaxation also causes the binding energy of an electron in a P-doped Si NC to more significantly increase as the concentration of P increases. With the increase of the concentration of P structural relaxation leads to more pronounced changes in the optical absorption of P-doped Si NCs.
Enhanced diffusion of oxygen depending on Fermi level position in heavily boron-doped silicon
Authors: Torigoe Kazuhisa , Fujise Jun , Ono Toshiaki , Nakamura Kozo
Published: November 2014

The enhanced diffusivity of oxygen in heavily boron doped silicon was obtained by analyzing oxygen out-diffusion profile changes found at the interface between a lightly boron-doped silicon epitaxial layer and a heavily boron-doped silicon substrate by secondary ion mass spectrometry. It was found that the diffusivity is proportional to the square root of boron concentration in the range of 1018 cm−3–1019 cm−3 at temperatures from 750 °C to 950 °C. The model based on the diffusion of oxygen dimers in double positive charge state could explain the enhanced diffusion. We have concluded that oxygen diffusion enhanced in heavily boron-doped silicon is attributed to oxygen dimers ionized depending on Fermi level position.
Composition dependent lattice dynamics in MoSxSe(2–x) alloys
Authors: Jadczak J. , Dumcenco D. O. , Huang Y. S. , Lin Y. C. , Suenaga K. , Wu P. H. , Hsu H. P. , Tiong K. K.
Published: November 2014

We report on room temperature, polarization-resolved Raman scattering measurements on layered crystals of the series MoSxSe(2–x) (0 ≤ x ≤ 2) grown by chemical vapor transport technique. The results reveal two distinct sets of features related to the E2g1 and A1g modes of pure members of series. As composition x changes, the in-plane E2g1 mode shows two-mode behavior, whereas the out-of-plane A1g mode presents more complex evolution. The MoSe2-like branch reveals the splitting associated with the altering arrangement of S and Se atoms around Mo and the resulting changes in the dipole moment of the molecule. The X-ray diffraction measurements confirm that the samples are single-phase materials of 2H-type structure over the entire range of the sulfide composition x, while the scanning transmission electron microscopy imaging reveals a random arrangement of the S and Se atoms. Modified random-element-isodisplacement model is adopted to predict the behavior of the individual modes in the alloys. The model successfully confirms the two-mode behavior exhibited by the MoSxSe(2–x) series.
Spin-orbit enhanced demagnetization rate in Co/Pt-multilayers
Authors: Kuiper K. C. , Roth T. , Schellekens A. J. , Schmitt O. , Koopmans B. , Cinchetti M. , Aeschlimann M.
Published: November 2014

In order to explore the role of enhanced spin-orbit interactions on the laser-induced ultrafast magnetization dynamics, we performed a comparative study on cobalt thin films and Co/Pt multilayers. We show that the presence of the Co/Pt interfaces gives rise to a three-fold faster demagnetization upon femtosecond laser heating. Experimental data for a wide range of laser fluences are analyzed using the Microscopic 3-Temperature Model. We find that the Elliott-Yafet spin-flip scattering in the multilayer structure is increased by at least a factor of four with respect to the elementary Co film.
Multiscale tunability of solitary wave dynamics in tensegrity metamaterials
Authors: Fraternali Fernando , Carpentieri Gerardo , Amendola Ada , Skelton Robert E. , Nesterenko Vitali F.
Published: November 2014

A class of strongly nonlinear metamaterials based on tensegrity concepts is proposed, and the solitary wave dynamics under impact loading is investigated. Such systems can be tuned into elastic hardening or elastic softening regimes by adjusting local and global prestress. In the softening regime these metamaterials are able to transform initially compression pulse into a solitary rarefaction wave followed by oscillatory tail with progressively decreasing amplitude. Interaction of a compression solitary pulse with an interface between elastically hardening and softening materials having correspondingly low-high acoustic impedances demonstrates anomalous behavior: a train of reflected compression solitary waves in the low impedance material; and a transmitted solitary rarefaction wave with oscillatory tail in high impedance material. The interaction of a rarefaction solitary wave with an interface between elastically softening and elastically hardening materials with high-low impedances also demonstrates anomalous behavior: a reflected solitary rarefaction wave with oscillatory tail in the high impedance branch; and a delayed train of transmitted compression solitary pulses in the low impedance branch. These anomalous impact transformation properties may allow for the design of ultimate impact mitigation devices without relying on energy dissipation.
Bismuth doping strategies in GeTe nanowires to promote high-temperature phase transition from rhombohedral to face-centered cubic structure
Authors: Zhang Jie , Kong Tao , Huang Rong , Wei Fenfen , Cheng Guosheng
Published: November 2014

The phase transition of Bi-doped (∼3 at. %) GeTe nanowires from a rhombohedral (R) to a face-centered cubic (C) structure was observed in in situ high-temperature X-ray diffraction. The promotion of high-temperature R-C phase transition by a doping approach was revealed. Ab initio energy calculations of doped GeTe at various Bi doping concentrations were performed to interpret the promoted temperature-induced phase transitions. Those results indicated that the total energy differences between R and C structures of doped GeTe decreased as Bi doping concentrations increased, which facilitated R-C phase transitions.
Influence of neutron flux, frequency and temperature to electrical impedance of nano silica particles
Authors: Huseynov Elchin , Garibov Adil , Mehdiyeva Ravan , Andreja Eršte , Rustamov Anar
Published: November 2014

We studied electric impedance of SiO2 nanomaterial at its initial state and after being exposed to continuous neutron irradiation for up to 20 hours. In doing so we employed a flux of neutrons of 2x1013 n⋅cm−2s−1 while the frequency and temperature ranges amounted to 0,09 – 2.3 MHz and 100 – 400 K correspondingly. Analysis in terms of the Cole-Cole expression revealed that with increasing irradiation period the polarization and relaxation times decrease as a result of combination of nanoparticles. Moreover, it is demonstrated that the electric conductivity of samples, on the other hand, increases with the increasing irradiation period. At low temperatures formations of clusters at three distinct states with different energies were resolved.
Experimental verification of a bridge-shaped, nonlinear vibration energy harvester
Authors: Gafforelli Giacomo , Corigliano Alberto , Xu Ruize , Kim Sang-Gook
Published: November 2014

This paper reports a comprehensive modeling and experimental characterization of a bridge shaped nonlinear energy harvester. A doubly clamped beam at large deflection requires stretching strain in addition to the bending strain to be geometrically compatible, which stiffens the beam as the beam deflects and transforms the dynamics to a nonlinear regime. The Duffing mode non-linear resonance widens the frequency bandwidth significantly at higher frequencies than the linear resonant frequency. The modeling includes a nonlinear measure of strain coupled with piezoelectric constitutive equations which end up in nonlinear coupling terms in the equations of motion. The main result supports that the power generation is bounded by the mechanical damping for both linear and nonlinear harvesters. Modeling also shows the power generation is over a wider bandwidth in the nonlinear case. A prototype is manufactured and tested to measure the power generation at different load resistances and acceleration amplitudes. The prototype shows a nonlinear behavior with well-matched experimental data to the modeling.
Depth resolved band alignments of ultrathin TiN/ZrO2 and TiN/ZrO2-Al2O3-ZrO2 dynamic random access memory capacitors
Authors: Lee Sang Yeon , Chang Jaewan , Kim Younsoo , Lim HanJin , Jeon Hyeongtag , Seo Hyungtak
Published: November 2014

In this paper, we investigated the interface band alignment of TiN/ZrO2 and TiN/ZrO2-Al2O3-ZrO2 (TiN/ZAZ) structures by analyzing the conduction band offset (CBO) and valence band offset at the electrode/dielectric interface using depth-resolved spectroscopy techniques. At the center of the interface, which is defined by the chemical composition depth profile, CBO values of 2.03 eV and 2.57 eV for ZrO2 and ZAZ were found, respectively. Subcutaneous TiON, which is induced by the process, was identified at this interface, and it played an important role in creating sub-band states. Based on combined analyses on both intrinsic and sub-band structures, a band alignment model is proposed. It was confirmed that the Al2O3 layer in ZAZ leads to a lowering of the Fermi energy or a p-doping effect, thereby increasing both the CBO and the tunneling barrier height in metal-insulator-metal capacitors.
Sound reduction by metamaterial-based acoustic enclosure
Authors: Yao Shanshan , Li Pei , Zhou Xiaoming , Hu Gengkai
Published: November 2014

In many practical systems, acoustic radiation control on noise sources contained within a finite volume by an acoustic enclosure is of great importance, but difficult to be accomplished at low frequencies due to the enhanced acoustic-structure interaction. In this work, we propose to use acoustic metamaterials as the enclosure to efficiently reduce sound radiation at their negative-mass frequencies. Based on a circularly-shaped metamaterial model, sound radiation properties by either central or eccentric sources are analyzed by numerical simulations for structured metamaterials. The parametric analyses demonstrate that the barrier thickness, the cavity size, the source type, and the eccentricity of the source have a profound effect on the sound reduction. It is found that increasing the thickness of the metamaterial barrier is an efficient approach to achieve large sound reduction over the negative-mass frequencies. These results are helpful in designing highly efficient acoustic enclosures for blockage of sound in low frequencies.
Tailoring characteristic thermal stability of Ni-Au binary nanocrystals via structure and composition engineering: theoretical insights into structural evolution and atomic inter-diffusion
Authors: Li Bangquan , Xing Guozhong , Wang Hailong , Wang Rongming
Published: November 2014

We report on the structural evolution and atomic inter-diffusion characteristics of the bimetallic Ni-Au nanocrystals (NCs) by molecular dynamics simulations studies. Our results reveal that the thermal stability dynamics of Ni-Au NCs strongly depends on the atomic configurations. By engineering the structural construction with Ni:Au = 1:1 atomic composition, compared with core-shell Au@Ni and alloy NCs, the melting point of core-shell Ni@Au NCs is significantly enhanced up to 1215 K. Unexpectedly, with atomic ratio of Au:Ni= 1:9, the melting process initiates from the atoms in the shell of Ni@Au and alloy NCs, while starts from the core of Au@Ni NCs. The corresponding features and evolution process of structural motifs, mixing and segregation are illustrated via a series of dynamic simulations videos. Moreover, our results revealed that the face centered cubic phase Au0.75Ni0.25 favorably stabilizes in NCs form but does not exist in the bulk counterpart, which elucidates the anomalies of previously reported experimental results on such bimetallic NCs.
A systematic study of pool boiling heat transfer on structured porous surfaces: From nanoscale through microscale to macroscale
Authors: Rioux Russell P. , Nolan Eric C. , Li Calvin H.
Published: November 2014

An experimental study has been conducted to examine the effects of macroscale, microscale, and nanoscale surface modifications in water pool boiling heat transfer and to determine the different heat transfer enhancing mechanisms at different scales. Nanostructured surfaces are created by acid etching, while microscale and macroscale structured surfaces are synthesized through a sintering process. Six structures are studied as individual and collectively integrated surfaces from nanoscale through microscale to macroscale: polished plain, flat nanostructured, flat porous, modulated porous, nanostructured flat porous, and nanostructured modulated porous. Boiling performance is measured in terms of critical heat flux (CHF) and heat transfer coefficient (HTC). Both HTC and CHF have been greatly improved on all modified surfaces compared to the polished baseline. Hierarchical multiscale surfaces of integrated nanoscale, microscale, and macroscale structures have been proven to have the most significant improvements on HTC and CHF. The CHF and HTC of the hierarchical multiscale modulated porous surface have achieved the most significant improvements of 350% and 200% over the polished plain surface, respectively. Experimental results are compared to the predictions of a variety of theoretical models with an attempt to reveal the different heat transfer enhancing mechanisms at different scales. It is concluded that models for the structured surfaces at all scales need to be further developed to be able to have good quantitative predictions of CHFs on structured surfaces.
Transforming Macau: Planning as Institutionalized Informality and the Spatial Dynamics of Hypercompetition
Authors: Lee Kah-Wee
Published: November 2014

This paper examines the crucial years between 2002 and 2012 when land enclosures, reclamation works, and architectural production transformed the urban landscape of Macau. Building on the literature on urban informality, I first analyze how planning as institutionalized informality unmapped the city of Macau through a complex medium of neoliberal ethos, technical rationality, and geopolitical calculations. Then, I show how the casino concessionaires remapped the city in a highly competitive milieu by tracing how they maneuvered to secure relative locational advantage. This analysis shows the importance of framing mapping and unmapping as a simultaneous dialectical process so as to render the creative–destructive dynamic of capitalist urban transformation. It also suggests how we can further the analysis of urban planning as an informalized practice and institution.
Europeanizing Territoriality—Towards Soft Spaces?
Authors: Allmendinger Phil , Chilla Tobias , Sielker Franziska
Published: November 2014

This paper explores the coexistence of relational and territorial spaces—soft spaces—through the experiences of EU integration and territorialization. First, we seek a better understanding of EU integration through an engagement with the literature and research on soft spaces. We propose that EU integration is best understood as involving an interplay between territorial and relational understandings and approaches that vary through time, a variation that can be categorized as involving pooled territoriality, supraterritoriality, and nonterritoriality. Second, we seek to add to the current research and literature on soft spaces by focusing upon the changing character of soft spaces and their temporalities. We approach these two dimensions through an exploration of two ex post case studies, the development of which typically shows different stages of softening, hardening, and of differing degrees of Europeanization. With the focus on Europeanization, the paper concludes with three findings: the new spaces of European territoriality are characterized by, first, temporal dynamics, second, their parallel existence with ‘hard’ spaces, and, finally, they can be employed as a political tool.
In Search of Radical Democracy: The Ideological Character of Current Political Advocacies for Culture Change in Planning
Authors: Grange Kristina
Published: November 2014

This paper argues that current attempts to situate the crisis in planning in demoralised or old planning cultures are playing a key role in strengthening the ideological commitment of planning to an advanced liberal social order. In order to provide planners with the means to understand some of the ideological mechanisms at work in such processes, the 2007 Danish structural reform and the parallel advocacy for culture change in planning are analysed. Drawing on post-Marxist theories of Ernesto Laclau and Chantal Mouffe, the analysis draws attention to the need for reflection on whether the current ideological commitment of planning is that which best serves a democratic society.
Kapoorian Geographies of Relationality: The Baroque, Topological Twists, Phase Space in Action
Authors: Jones Martin
Published: November 2014

The Baroque offers architectures of vision that situate the viewer in a distinctly spatial relationship to the representation. Rather than providing a statically ordered perspectival arrangement, the ‘center’ continually shifts, the result being the ongoing articulation of complex spatial conditions where the subject is coextensive with that of the observer. This paper develops a ‘Baroque sensibility’ by offering a geographical perspective on the work of Anish Kapoor—one of the most celebrated and definitional artists of our time, and an expander of the notion of public art—and linking this to ongoing debates on spatializations in human geography. The paper suggests that Kapoor's work of ‘moving narratives’ and ‘processional methods of viewing’ is an example of ‘phase space’ in action—a critique and extension of ‘thinking space relationally’ in human geography. Focusing specifically on Kapoor's 2008 Memory, a commission for the Deutsche Guggenheim, which travelled to New York in 2009, it deploys a Kapoorian geography of the polycentric logic to illustrate this. From the experience of Memory, the paper then discusses two interrelated conceptual perspectives, fractal spatiality and plasticity, to take the human geographies of relationality forward.
Do Suburban Areas Impact House Prices?
Authors: Helbich Marco
Published: November 2014

Urban fringes are frequently occupied by a particular socioeconomic group of households, who have a certain demand on real-estate markets. Consequently, it is advisable to model the suburban housing market in hedonic studies. The operationalization of suburbia is challenged by its inherent vagueness, specifically, its continuous merging with rural areas and its potentially fragmented spatial pattern. Investigating the urban fringe of Vienna, Austria, this research proposes a suburban taxonomy based on fuzzy clustering and a spatially explicit, nonlinear hedonic pricing model to determine the marginal price of suburbia on single-family homes. The clustering result suggests that suburban municipalities are increasingly located next to the main traffic arterials in the immediate proximity of the core city. The hedonic regression confirms a stratification of the housing market. Furthermore, a local intra-submarket in the south of the core city is evident, referring to an additional locational asset. Suburbia has a significant effect on housing prices and reflects a self-contained housing market, albeit one which is economically interrelated with other submarkets. It is concluded that suburbanites implicitly value such neighborhoods and are willing to pay a premium to live in like-minded communities.
Stock‐Specific Migration Pathways of Juvenile Sockeye Salmon in British Columbia Waters and in the Gulf of Alaska
Authors: Beacham Terry D. , Beamish Richard J. , Candy John R. , Wallace Colin , Tucker Strahan , Moss Jamal H. , Trudel Marc
Published: November 2014

We outlined the route and relative timing of juvenile Sockeye Salmon Oncorhynchus nerka migration by analyzing stock composition and relative CPUE in marine sampling conducted in coastal British Columbia and the Gulf of Alaska. Variation at 14 microsatellites was analyzed for 10,500 juvenile Sockeye Salmon obtained from surveys conducted during 1996–2011. Using a 404‐population baseline, we identified the sampled individuals to 47 populations or stocks of origin. Stock compositions of the mixtures increased in diversity in more northerly sampling locations, indicating a general northward movement of juveniles. The primary migration route of Columbia River and Washington stocks was northward along the west coast of Vancouver Island, with a majority of the juveniles subsequently migrating through Queen Charlotte Sound and Dixon Entrance. Fraser River stocks migrated principally through the Strait of Georgia and Johnstone Strait. Some Fraser River populations, such as the Cultus Lake population, appeared to spend little time rearing in the Strait of Georgia, as individuals from this population were primarily observed in July samples from Hecate Strait, Dixon Entrance, and Southeast Alaska. Other Fraser River populations, such as the Chilko Lake and Quesnel Lake populations, were widely distributed during July surveys, as they were observed from the Gulf of Alaska to the Strait of Georgia. For the British Columbia central coast and Owikeno Lake stocks, not all individuals migrated northward in the summer: some individuals were still present in local areas during the fall and winter after spring entry into the marine environment. Juvenile Fraser River Sockeye Salmon dominated the catch of juveniles at the Yakutat, Prince William Sound, Kodiak Island, and Alaska Peninsula sampling locations. There was a wide divergence among stocks in dispersion among sampling locations.

Received September 26, 2013; accepted June 6, 2014
Novel Single‐Nucleotide Polymorphism Markers Confirm Successful Spawning of Endangered Pallid Sturgeon in the Upper Missouri River Basin
Authors: Eichelberger Jennifer S. , Braaten Patrick J. , Fuller David B. , Krampe Matthew S. , Heist Edward J.
Published: November 2014

Spawning of the federally endangered Pallid Sturgeon Scaphirhynchus albus is known to occur in the upper Missouri River basin, but progeny from natural reproductive events have not been observed and recruitment to juvenile or adult life stages has not been documented in recent decades. Identification of Pallid Sturgeon progeny is confounded by the fact that Shovelnose Sturgeon S. platorynchus occurs throughout the entire range of Pallid Sturgeon and the two species are essentially indistinguishable (morphometrically and meristically) during early life stages. Moreover, free embryos of sympatric Paddlefish Polyodon spathula are very similar to the two sturgeon species. In this study, three single‐nucleotide polymorphism (SNP) assays were employed to screen acipenseriform free embryos and larvae collected from the upper Missouri River basin in 2011, 2012, and 2013. A mitochondrial DNA SNP discriminates Paddlefish from sturgeon, and specific multilocus genotypes at two nuclear DNA SNPs occurred in 98.9% of wild adult Pallid Sturgeon but only in 3% of Shovelnose Sturgeon sampled in the upper Missouri River. Individuals identified as potential Pallid Sturgeon based on SNP genotypes were further analyzed at 19 microsatellite loci for species discrimination. Out of 1,423 free embryos collected over 3 years of sampling, 971 Paddlefish, 446 Shovelnose Sturgeon, and 6 Pallid Sturgeon were identified. Additionally, 249 Scaphirhynchus spp. benthic larvae were screened, but no Pallid Sturgeon were detected. These SNP markers provide an efficient method of screening acipenseriform early life stages for the presence of Pallid Sturgeon in the Missouri River basin. Detection of wild Pallid Sturgeon free embryos in the upper Missouri and Yellowstone rivers supports the hypothesis that the failure of wild Pallid Sturgeon to recruit to the juvenile life stage in the upper Missouri River basin is caused by early life stage mortality rather than by lack of successful spawning.

Received January 22, 2014; accepted June 4, 2014
Genetic Mixed-Stock Analysis of American Shad in Two Atlantic Coast Fisheries: Delaware Bay, USA, and Inner Bay of Fundy, Canada
Authors: Waldman John , Hasselman Daniel , Bentzen Paul , Dadswell Michael , Maceda Lorraine , Wirgin Isaac
Published: November 2014

American Shad Alosa sapidissima in the Hudson River, New York, and coastwide have shown major long-term declines. A possible contributing factor is commercial fisheries that harvest this population outside of the Hudson River estuary. Using previously published and new reference microsatellite data from 33 baseline populations, our goals were (1) to estimate the proportion of Hudson River American Shad contributing to the two remaining major mixed-stock fisheries along the Atlantic coast in Delaware Bay and the Bay of Fundy and (2) to estimate the proportions of other American Shad stocks contributing to these two fisheries at the highest level of stock specificity. Stock composition estimates for 2009 and 2010 Delaware Bay collections were made using three models that ranged from the most simple question (Hudson River and Delaware Bay populations) to one with all 33 baseline populations included. In all cases, a Hudson River contribution nearly equal to that of the Delaware Bay contribution was observed, indicating a substantial take on the otherwise protected Hudson River population. When all baseline populations were included for the larger 2010 Delaware Bay collection, 19 showed nonzero contributions, largely drawn from mid-Atlantic U.S. rivers. The 2009 Bay of Fundy collection showed contributions from across most of the species’ range but was dominated by northern populations. Mixed-stock analyses of collections from the two sites together indicate that these estuarine fisheries harvested not only proximal populations but those originating from a wide latitudinal range.

Received April 3, 2014; accepted August 5, 2014
Effects of Appendaged Circle Hook Use on Catch Rates and Deep Hooking of Black Sea Bass in a Recreational Fishery
Authors: Bergmann Charles , Driggers William B. , Hoffmayer Eric R. , Campbell Matthew D. , Pellegrin Gilmore
Published: November 2014

Previous studies have demonstrated that circle hooks modified with an appendage can reduce the occurrence of deep hooking in some fishes. To determine whether this modification affects total catch and deep-hooking rate of Black Sea Bass Centropristis striata in a recreational fishery off the coast of Florida, anglers were provided with standardized gear that included one appendaged and one nonappendaged hook. Both hook types were fished equally, and a greater number of Black Sea Bass were caught on appendaged hooks (n = 301) than on nonappendaged hooks (n = 221). There was no significant difference in the mean TL (P = 0.80) of jaw- or deep-hooked fish during the study. Logistic regression was applied to the data using anatomical hooking location as the dependent variable and angler, hook position, and hook type as categorical factors. Hook type was the only significant variable in the final model (P = 0.03) in which fewer fish were deep hooked on appendaged hooks (0.96%) than on nonappendaged hooks (2.11%). Our findings indicate appendaged hooks are capable of reducing deep hooking of Black Sea Bass without reducing catch rates or altering size composition of the catch.

Received February 3, 2014; accepted August 14, 2014
Virtual experiments in megastudies: A case study of language and emotion
Authors: Kuperman Victor
Published: November 2014

A recent dramatic increase in the number and scope of chronometric and norming lexical megastudies offers the ability to conduct virtual experiments—that is, to draw samples of items with properties that vary in critical linguistic dimensions. This paper introduces a bootstrapping approach, which enables testing of research hypotheses against a range of samples selected in a uniform, principled manner and evaluates how likely a theoretically motivated pattern is in a broad distribution of possible outcome patterns. We apply this approach to conflicting theoretical and empirical accounts of the relationship between the psychological valence (positivity) of a word and its speed of recognition. To this end, we conduct three sets of multiple virtual experiments with a factorial and a regression design, drawing data from two lexical decision megastudies. We discuss the influence that criteria for stimuli selection, statistical power, collinearity, and the choice of dataset have on the efficacy and outcomes of the bootstrapping procedure.