bluuebunny/crossref_metadata_2025 huggingface dataset:
Robust nonlinear H ∞  control based on the incremental gain
Authors: Beikzadeh Hossein , Marquez Horacio J.
Published: January 2014

The incremental gain is proposed as an alternative to the usual gain for designing nonlinear H ∞  controllers. Considering a class of plants with Lipschitz nonlinearities and using linear matrix inequalities, a state feedback controller is designed such that the closed‐loop system is exponentially stable in the absence of disturbance inputs and has incremental gain less than or equal to a minimized number in the presence of disturbances as well as model uncertainties. Moreover, a norm‐wise robustness analysis of the proposed technique against nonlinear uncertainties has been accomplished. Our result is verified through stabilization of both certain and uncertain systems in an incremental sense and also input tracking of a chaotic plant. Copyright © 2014 John Wiley & Sons, Ltd.
A mobile phone‐based physical‐social location proof system for mobile social network service
Authors: Ni Xudong , Luo Junzhou , Zhang Boying , Teng Jin , Bai Xiaole , Liu Bo , Xuan Dong
Published: January 2014

Location‐related mobile social network services are popular nowadays, and their methods to obtain end users’ location information are based on people's self‐report location claims, using mobile devices to check positions and send them back to the service providers. However, this mechanism has a serious vulnerability that makes malicious users be able to access restricted resource by transmitting fake locations. Both academic and industrial researchers are recently aware of this problem's importance since the commercialized trend of location‐related mobile social network services. To address this issue, we propose mobile phone‐based physical‐social location, a mobile phone‐based location proof system to verify users’ location claims and defend various fake location information. Our core idea is that a user's location claim can be proved by a set of selective physical encountered people serving as “witnesses” who are co‐located with him/her in that area. The system is composed of proof generation and verification. In the proof generation phase, we leverage a certain number of co‐located people to generate certificates as location proofs during their encounters via bluetooth interface. In the verification phase, we propose an efficient verification scheme to make our system accurate and adaptive. We have implemented the MPSL system using real world Nokia N82 (Nokia, Espoo, Finland) phones. Our experimental results show that our mobile phone‐based system can achieve high verification accuracy and good performance. Copyright © 2014 John Wiley & Sons, Ltd.
Comparison of urine and self‐collected vaginal samples for detecting human papillomavirus DNA in pregnant women
Authors: Franciscatto Laura G. , Silva Cláudia M.D. , Barcellos Regina B. , Angeli Suelen , Silva Márcia S.N. , Almeida Sabrina E.M. , Rossetti Maria L.R.
Published: January 2014

Objective

To investigate the utility of urine sampling for detecting human papillomavirus (HPV) DNA among pregnant women and to compare HPV DNA detection in urine with detection in vaginal samples.

Methods

In a cross‐sectional study, urine and vaginal samples were self‐collected from pregnant women attending prenatal care at Hospital Divina Providencia, Frederico Westphalen, Brazil, between October 2006 and August 2007. Part of the L1 region of the HPV genome was amplified via GP5+/bioGP6+ primers. Positive urine was genotyped for high‐risk HPV genotypes (HPV16, HPV18, HPV31, HPV33, HPV39, HPV45, and HPV59).

Results

During the study period, urine samples were obtained from 133 pregnant women, 63 of whom also self‐collected vaginal samples. HPV DNA was detected in 54.0% (34/63) and 61.9% (39/63) of urine and vaginal samples, respectively. HPV infection was significantly associated with first intercourse at younger than 20 years of age (P = 0.008). There was substantial agreement in HPV DNA test results between the urine and vaginal samples (κ value, 77.3%; P < 0.0001). HPV31 and HPV16 accounted for 80.7% of the oncogenic types identified.

Conclusion

Detection of HPV DNA in urine showed good agreement with detection in self‐collected vaginal samples, indicating that urine might be a reliable sample for HPV testing among pregnant women.
Obstetric complications and cesarean delivery in Nepal
Authors: Karkee Rajendra , Lee Andy H. , Khanal Vishnu , Pokharel Paras K. , Binns Colin W.
Published: January 2014

Objective

To determine the incidence of obstetric complications, the stillbirth rate, and the factors associated with cesarean delivery in central Nepal.

Methods

A community‐based prospective cohort study was undertaken in the Kaski district during 2011–2012. In total, 701 women who were at least 5 months pregnant were recruited and interviewed. Participants were followed‐up and interviewed again within 45 days after delivery.

Results

Of the 658 women who remained in the cohort after 43 were lost to follow‐up, 12 (1.8%) had stillbirths. Cesareans accounted for 13.3% of the total deliveries. Age, urban residency, college‐level education, and particularly presence of intrapartum symptoms significantly increased the likelihood of cesarean delivery. Prepartum, intrapartum, and postpartum symptoms were reported by 21.1%, 24.4%, and 10.2% of women, respectively. Common danger signs included prolonged labor, severe abdominal pain, swollen hand and body, and heavy bleeding.

Conclusion

Obstetric complications and stillbirth rates were relatively high in central Nepal. Cesarean delivery appeared to meet obstetric need and was performed with medical indication, particularly after the onset of labor.
Idols in the Archive
Authors: Asif Manan Ahmed
Published: January 2014

Is a circumcision, for example, an exterior mark? Is it an archive?

Let me begin at the beginning.

My left eyebrow has a scar. It is jagged, and usually the droop of the eyebrow hides it from view. I see it sometimes when I look in the mirror. When I see it, I am reminded instantly of my father. He was sitting, reading a newspaper, on the lawn of our Lahore house. It was near to 6:00 p.m.—late evening to dusk. I had recently conquered the art of biking and I was eager to show him how well I rode. I kept going past him on the bike, but he was engrossed in the paper. Finally I decided that to really get his attention, I would need to go really, really fast. I went a ways, and began to pedal furiously. Right as I gathered full speed and came up to him, I looked at him to see if he was watching me. He wasn't. That split second, however, was enough for me to lose control of the bike, which swerved radically to the left, and I went face-first into a column of bricks. He looked up as I stumbled up, my eye covered in blood. I have no memory of this, except for when I “see” my scar.
On the Importance of Golden Parachutes
Authors: Fich Eliezer M. , Tran Anh L. , Walkling Ralph A.
Published: January 2014

In acquisitions, target chief executive officers (CEOs) face a moral hazard: Any personal gain from the deal could be offset by the loss of the future compensation stream associated with their jobs. Larger, more important parachutes provide greater relief for these losses. To explicitly measure the moral hazard target CEOs face, we standardize the parachute payment by the expected value of their acquisition-induced lost compensation. We examine 851 acquisitions from 1999–2007, finding that more important parachutes benefit target shareholders through higher completion probabilities. Conversely, as parachute importance increases, target shareholders receive lower takeover premia, while acquirer shareholders capture additional rents from target shareholders.
Disseminating Behavioural Activation for Depression via Online Training: Preliminary Steps
Authors: Hubley Sam , Woodcock Eric A. , Dimeff Linda A. , Dimidjian Sona
Published: January 2014

Background: Despite the availability of evidence-based treatments for depression, large gaps exist between empirical research and clinical practice. Aims: To make preliminary steps toward the dissemination of Behavioural Activation (BA) via online training by examining clinicians’ interest in learning BA via online training and the effects of a preliminary version of BA online training. Method: In study 1, practising clinicians (n = 540) completed a survey that assessed attitudes towards learning BA using an online training format. In study 2, we conducted a small, pilot randomized controlled trial (n = 46) to examine preliminary efficacy of teaching BA principles and treatment strategies with a precursor version of BA online training. Results: Study findings suggest that clinicians have interest in learning about BA via online training and that clinicians participating in BA online training evidence high satisfaction and significant gains in self-efficacy using BA and knowledge of BA terms and concepts. Conclusions: These results support the importance of efforts to disseminate BA and the viability of online training as an easily accessible and affordable training option.
Productive Welfare, the East Asian ‘Model’ and Beyond: Placing Welfare Types in Greater China into Context
Authors: Hudson John , Kühner Stefan , Yang Nan
Published: January 2014

This article rounds off the themed section by reviewing broader debates within welfare state modelling relevant to Greater China. More specifically, it examines the now well-established literature around the East Asian ‘model’ of welfare, and related debates on the notion of a ‘productive welfare’ model. In so doing, it challenges simplistic classifications that present the region as representing a single model of welfare and, instead, highlights the diversity of welfare provision found within both Greater China and East Asia more generally. Building on the authors’ earlier published work comparing East Asian welfare systems with those found across the OECD, it also challenges claims that the region is home to a distinct ‘productive’ model of welfare. The article ends by highlighting some key drivers that will shape future debates.
Colorimetric sensing of copper based on its suppressive effect on cloud point extraction of label free silver nanoparticles
Authors: Pourreza Nahid , Golmohammadi Hamed
Published: January 2014

Method based on SPR and cloud point extraction of AgNPs for the determination of copper.
Ultrasensitive online SERS detection of structural isomers separated by capillary zone electrophoresis
Authors: Negri Pierre , Flaherty Ryan J. , Dada Oluwatosin O. , Schultz Zachary D.
Published: January 2014

On line SERS detection of nanomolar concentrations of rhodamine structural isomers separated by capillary zone electrophoresis is reported.
The kinetics and product state distributions from gas-phase reactions of small atomic and molecular cations with C2H4, C2H3F, 1,1-C2H2F2, C2HF3and C2F4
Authors: Parkes Michael A. , Simpson Matthew J. , Mikhailov Victor , Tuckett Richard P.
Published: January 2014

Reactions between atomic and small molecular ions with a series of fluorinated ethenes are studied in a selected ion flow tube. Kinetics and product state distributions are measured. The latter are compared with those from photoionisation.
Efficient and selective nitrile hydration reactions in water catalyzed by an unexpected dimethylsulfinyl anion generated in situ from CsOH and DMSO
Authors: Chen Haonan , Dai Wujie , Chen Yi , Xu Qing , Chen Jianhui , Yu Lei , Zhao Yajuan , Ye Mingde , Pan Yuanjiang
Published: January 2014

Dimethylsulfinyl anions derived from CsOH–DMSO catalyzed nitrile hydration reactions in water to give the versatile amidesviainteresting DMSO-participating mechanisms.
A carbon-based photocatalyst efficiently converts CO2 to CH4 and C2H2 under visible light
Authors: Wu Tongshun , Zou Luyi , Han Dongxue , Li Fenghua , Zhang Qixian , Niu Li
Published: January 2014

Photocatalysts consisting of porphyrin and graphene have been designed and applied to reduce CO2 to C2H2 under visible light, which is an excellent simulator of natural photosynthesis.
Metallic influence on the atomic structure and optical activity of ligand-protected nanoparticles: a comparison between Ag and Au
Authors: Hidalgo Francisco , Noguez Cecilia , Olvera de la Cruz Monica
Published: January 2014

The metallic influence on the atomic structure and optical activity was studied for Au and Ag NPs upon adsorption of SCH3.
NIR electrochemical fluorescence switching from polymethine dyes
Authors: Seo Seogjae , Pascal Simon , Park Chihyun , Shin Kyoungsoon , Yang Xu , Maury Olivier , Sarwade Bhimrao D. , Andraud Chantal , Kim Eunkyoung
Published: January 2014

Reversible electrochemical fluorescence switching in the NIR region is achieved by the reversible redox reaction of an NIR emissive polymethine dye.
Observation of the rare chrysene excimer
Authors: Khorev Oleg , Bösch Caroline D. , Probst Markus , Häner Robert
Published: January 2014

Formation of the so far elusive chrysene excimer in solution is achieved by using DNA as a supramolecular scaffold.
Efficient spectral conversion from visible to near-infrared in transparent glass ceramics containing Ce3+–Yb3+codoped Y3Al5O12nanocrystals
Authors: Fang Zaijin , Cao Renping , Zhang Fangteng , Ma Zhijun , Dong Guoping , Qiu Jianrong
Published: January 2014

Transparent glass ceramics containing Ce3+–Yb3+codoped Y3Al5O12nanocrystals were prepared, and demonstrated to be promising materials for spectral conversion of visible sunlight to near-infrared emission.
Mechanistic insight into the reaction catalysed by bacterial type II dehydroquinases
Authors: Coderch Claire , Lence Emilio , Peón Antonio , Lamb Heather , Hawkins Alastair R. , Gago Federico , González-Bello Concepción
Published: January 2014

DHQ2 (type II dehydroquinase), which is an essential enzyme in Helicobacter pylori and Mycobacterium tuberculosis and does not have any counterpart in humans, is recognized to be an attractive target for the development of new antibacterial agents. Computational and biochemical studies that help understand in atomic detail the catalytic mechanism of these bacterial enzymes are reported in the present paper. A previously unknown key role of certain conserved residues of these enzymes, as well as the structural changes responsible for triggering the release of the product from the active site, were identified. Asp89*/Asp88* from a neighbouring enzyme subunit proved to be the residue responsible for the deprotonation of the essential tyrosine to afford the catalytic tyrosinate, which triggers the enzymatic process. The essentiality of this residue is supported by results from site-directed mutagenesis. For H. pylori DHQ2, this reaction takes place through the assistance of a water molecule, whereas for M. tuberculosis DHQ2, the tyrosine is directly deprotonated by the aspartate residue. The participation of a water molecule in this deprotonation reaction is supported by solvent isotope effects and proton inventory studies. MD simulation studies provide details of the required motions for the catalytic turnover, which provides a complete overview of the catalytic cycle. The product is expelled from the active site by the essential arginine residue and after a large conformational change of a loop containing two conserved arginine residues (Arg109/Arg108 and Arg113/Arg112), which reveals a previously unknown key role for these residues. The present study highlights the key role of the aspartate residue whose blockage could be useful in the rational design of inhibitors and the mechanistic differences between both enzymes.
Note: A compact three-axis optical force/torque sensor using photo-interrupters
Authors: Kim Ji-Chul , Kim Kyung-Soo , Kim Soohyun
Published: January 2014

By integrating four photo-interrupters in a cross-shaped structure, we developed a compact three-axis optical force/torque (F/T) sensor. The developed sensor has a diameter of 28 mm and a thickness of 7 mm. Despite simplicity and compactness, the experiments with a prototype of the proposed sensor demonstrate notably high accuracy. The RMS errors are 0.5% ± 0.1% of the maximum vertical force in z-axis, 1.9% ± 0.2% of the maximum torque in x-axis, and 2.0% ± 0.3% of the maximum torque in y-axis. It is expected that the proposed sensor allows cost-effective integration of robot systems requiring compact and multi-axis F/T sensors such as a walking assist robot.
Two-dimensional semiconductor alloys: Monolayer Mo1−xWxSe2
Authors: Tongay Sefaattin , Narang Deepa S. , Kang Jun , Fan Wen , Ko Changhyun , Luce Alexander V. , Wang Kevin X. , Suh Joonki , Patel K. D. , Pathak V. M. , Li Jingbo , Wu Junqiao
Published: January 2014

Monolayer Mo1−xWxSe2 (x = 0, 0.14, 0.75, and 1) alloys were experimentally realized from synthesized crystals. Mo1−xWxSe2 monolayers are direct bandgap semiconductors displaying high luminescence and are stable in ambient. The bandgap values can be tuned by varying the W composition. Interestingly, the bandgap values do not scale linearly with composition. Such non-linearity is attributed to localization of conduction band minimum states around Mo d orbitals, whereas the valence band maximum states are uniformly distributed among W and Mo d orbitals. Results introduce monolayer Mo1−xWxSe2 alloys with different gap values, and open a venue for broadening the materials library and applications of two-dimensional semiconductors.
Contrasting the experimental properties of hydrogen in SnO2, In2O3, and TiO2
Authors: Stavola Michael , Bekisli Figen , Yin Weikai , Smithe Kirby , Beall Fowler W. , Boatner Lynn A.
Published: January 2014

IR spectroscopy has been used to investigate the properties of H and D in single crystals of the transparent conducting oxides, SnO2, and In2O3. H introduces several O-H stretching lines and also the broad absorption arising from free carriers. IR spectroscopy has been used to identify the sources of n-type conductivity, its thermal stability, and the reactions of H-containing defects. The properties of OH and OD centers in TiO2, while studied for decades, reveal new surprises and properties that are in sharp contrast to the shallow, H-related donors seen in SnO2 and In2O3. Recent theory and EPR experiments find that electrons in TiO2 become self-trapped at Ti sites to form small polarons. The OD center in TiO2 shows a multiline vibrational spectrum with an unusual temperature dependence that can be explained by a small polaron model with the donor electron self-trapped at different Ti sites near the OD oscillator.
Formation of carbon vacancy in 4H silicon carbide during high-temperature processing
Authors: Ayedh H. M. , Bobal V. , Nipoti R. , Hallén A. , Svensson B. G.
Published: January 2014

As-grown and pre-oxidized silicon carbide (SiC) samples of polytype 4H have been annealed at temperatures up to 1950 °C for 10 min duration using inductive heating, or at 2000 °C for 30 s using microwave heating. The samples consisted of a n-type high-purity epitaxial layer grown on 4° off-axis ⟨0001⟩ n+-substrate and the evolution of the carbon vacancy (VC) concentration in the epitaxial layer was monitored by deep level transient spectroscopy via the characteristic Z1/2 peak. Z1/2 appears at ∼0.7 eV below the conduction band edge and arises from the doubly negative charge state of VC. The concentration of VC increases strongly after treatment at temperatures ≥ 1600 °C and it reaches almost 1015 cm−3 after the inductive heating at 1950 °C. A formation enthalpy of ∼5.0 eV is deduced for VC, in close agreement with recent theoretical predictions in the literature, and the entropy factor is found to be ∼5 k (k denotes Boltzmann's constant). The latter value indicates substantial lattice relaxation around VC, consistent with VC being a negative-U system exhibiting considerable Jahn-Teller distortion. The microwave heated samples show evidence of non-equilibrium conditions due to the short duration used and display a lower content of VC than the inductively heated ones. Finally, concentration-versus-depth profiles of VC favour formation in the “bulk” of the epitaxial layer as the prevailing process and not a Schottky type process at the surface.
On the low carrier lifetime edge zone in multicrystalline silicon ingots
Authors: Jiang Tingting , Yu Xuegong , Wang Lei , Gu Xin , Yang Deren
Published: January 2014

We have demonstrated the cause of low minority carrier lifetime corresponding to the edge zone of casting multicrystalline silicon ingots and its influence on the performance of solar cells. It is found that the concentration of substitutional carbon, interstitial oxygen, and dislocation density have no direct correlation with the low minority carrier lifetime in the edge zone. However, the distribution of interstitial iron exactly coincides with the minority carrier lifetime, indicating that iron contamination is mainly responsible for the lifetime degradation. After phosphorus diffusion gettering process, the low carrier lifetime region became narrower, and the concentration of interstitial iron is reduced by almost one order of magnitude. However, the carrier lifetime in the edge zone cannot be raised to average level. After celling process, the internal quantum efficiency map of the edge zone has a lower response to the long wavelength light, in accordance with the minority carrier lifetime distribution in this region. Therefore, the solar cells based on edge zones exhibit slightly lower efficiency than those conventional ones.
Temperature dependence of defect-related photoluminescence in III-V and II-VI semiconductors
Authors: Reshchikov Michael A.
Published: January 2014

Mechanisms of thermal quenching of photoluminescence (PL) related to defects in semiconductors are analyzed. We conclude that the Schön-Klasens (multi-center) mechanism of the thermal quenching of PL is much more common for defects in III–V and II–VI semiconductors as compared to the Seitz-Mott (one-center) mechanism. The temperature dependencies of PL are simulated with a phenomenological model. In its simplest version, three types of defects are included: a shallow donor, an acceptor responsible for the PL, and a nonradiative center that has the highest recombination efficiency. The case of abrupt and tunable thermal quenching of PL is considered in more detail. This phenomenon is predicted to occur in high-resistivity semiconductors. It is caused by a sudden redirection of the recombination flow from a radiative acceptor to a nonradiative defect.
Linac4 low energy beam measurements with negative hydrogen ions
Authors: Scrivens R. , Bellodi G. , Crettiez O. , Dimov V. , Gerard D. , Granemann Souza E. , Guida R. , Hansen J. , Lallement J.-B. , Lettry J. , Lombardi A. , Midttun Ø. , Pasquino C. , Raich U. , Riffaud B. , Roncarolo F. , Valerio-Lizarraga C. A. , Wallner J. , Yarmohammadi Satri M. , Zickler T.
Published: January 2014

Linac4, a 160 MeV normal-conducting H− linear accelerator, is the first step in the upgrade of the beam intensity available from the LHC proton injectors at CERN. The Linac4 Low Energy Beam Transport (LEBT) line from the pulsed 2 MHz RF driven ion source, to the 352 MHz RFQ (Radiofrequency Quadrupole) has been built and installed at a test stand, and has been used to transport and match to the RFQ a pulsed 14 mA H− beam at 45 keV. A temporary slit-and-grid emittance measurement system has been put in place to characterize the beam delivered to the RFQ. In this paper a description of the LEBT and its beam diagnostics is given, and the results of beam emittance measurements and beam transmission measurements through the RFQ are compared with the expectation from simulations.
pn-homojunction organic solar cells formed in phase-separated co-deposited films
Authors: Kubo Masayuki , Kaji Toshihiko , Hiramoto Masahiro
Published: January 2014

Simultaneous control of the doping and phase-separation in organic co-deposited films consisting of metal-free phthalocyanine and fullerene was performed. The doping was used to form pn-homojunctions in the phase-separated co-deposited films. The diffusion length of the minority carriers reached 0.3 μm allowing the fabrication of very thick cells up to 0.5 μm thick. It was shown that suppression of the interfacial recombination processes is crucial for obtaining cells with high performance.
Finite element method analysis of surface acoustic wave devices with microcavities for detection of liquids
Authors: Senveli Sukru U. , Tigli Onur
Published: January 2014

This paper introduces the use of finite element method analysis tools to investigate the use of a Rayleigh type surface acoustic wave (SAW) sensor to interrogate minute amounts of liquids trapped in microcavities placed on the delay line. Launched surface waves in the ST-X quartz substrate couple to the liquid and emit compressional waves. These waves form a resonant cavity condition and interfere with the surface waves in the substrate. Simulations show that the platform operates in a different mechanism than the conventional mass loading of SAW devices. Based on the proposed detection mechanism, it is able to distinguish between variations of 40% and 90% glycerin based on phase relations while using liquid volumes smaller than 10 pl. Results from shallow microcavities show high correlation with sound velocity parameter of the liquid whereas deeper microcavities display high sensitivities with respect to glycerin concentration. Simulated devices yield a maximum sensitivity of −0.77°/(% glycerin) for 16 μm wavelength operation with 8 μm deep, 24 μm wide, and 24 μm long microcavities.
Optimal multivariate method for Raman spectroscopy based diagnosis of nasopharyngeal carcinoma
Authors: Chen Bingling , Li Shaoxin , Li Jianghua , Guo Zhouyi , Chen Qiuyan , Mai Haiqiang
Published: January 2014

In this paper, we evaluated four kinds of classification algorithms on Raman spectra for nasopharyngeal carcinoma (NPC) diagnosis: Bayesian classification (BC), Linear discriminate analysis (LDA), Mahalanobis distance after the principal component analysis (PCA); as well the Genetic algorithm-LDA. A total of 225 Raman spectra were acquired from 120 tissue sites of 63 patients, in which 56 Raman spectra were from normal tissue, whereas 171 Raman spectra were from cancer nasopharyngeal tissue. The averaged Raman spectrum of NPC could be distinguished from that of the control group by the above multivariate analysis. Discrimination analysis of PCA-BC revealed that the highest sensitivity, specificity and overall accuracy of cancer diagnosis were 98% (1/56), 99% (1/171), and 99%, respectively. The results showed that Raman spectroscopy in combination with Bayesian classification had high enough sensitivity and specificity to accurately detect and diagnose NPC.
Voltage-dependent resistance of undoped rutile, TiO2, ceramics
Authors: Liu Yang , West Anthony R.
Published: January 2014

Lightly reduced rutile ceramics are n-type semiconductors whose resistance increases reversibly by 1–2 orders of magnitude, depending on temperature, on application of a small dc bias of 10–100 V cm−1. A similar effect is seen on changing the oxygen partial pressure surrounding the sample during impedance measurements and the bias dependence is attributed to changes in the equilibria between various ionised oxygen species adsorbed on sample surfaces, leading to changes in the mobile electron concentration in the sample bulk. The increase in resistance of n-type TiO2 with dc bias mirrors the decrease in resistance seen with p-type semiconductors such as acceptor-doped BaTiO3 and represents an effect, which has certain memristive characteristics but also significant differences.
Radiofrequency hydrogen ion source with permanent magnets providing axial magnetic field
Authors: Oikawa Kohei , Saito Yuta , Komizunai Shota , Takahashi Kazunori , Ando Akira
Published: January 2014

Uniform axial magnetic field of about 70 G is applied to a radiofrequency (rf) hydrogen ion source by arrays of permanent magnets. The plasma density and electron temperature downstream of the source and near the magnetic filter are compared with those in the previously described ion source, where the axial field has been applied by two solenoids. The source is operated at ∼350 kHz and above 10 kW rf power with a field-effect-transistor-based invertor power supply in 1.5 Pa hydrogen. The results show that the plasma density of ∼1019 m−3 near the source exit and ∼1018 m−3 near the magnetic filter can be obtained, which are higher than those with the solenoids.
A microNewton thrust stand for average thrust measurement of pulsed microthruster
Authors: Zhou Wei-Jing , Hong Yan-Ji , Chang Hao
Published: January 2014

A torsional thrust stand has been developed for the study of the average thrust for microNewton pulsed thrusters. The main body of the thrust stand mainly consists of a torsional balance, a pair of flexural pivots, a capacitive displacement sensor, a calibration assembly, and an eddy current damper. The behavior of the stand was thoroughly studied. The principle of thrust measurement was analyzed. The average thrust is determined as a function of the average equilibrium angle displacement of the balance and the spring stiffness. The thrust stand has a load capacity up to 10 kg, and it can theoretically measure the force up to 609.6 μN with a resolution of 24.4 nN. The static calibrations were performed based on the calibration assembly composed of the multiturn coil and the permanent magnet. The calibration results demonstrated good repeatability (less than 0.68% FSO) and good linearity (less than 0.88% FSO). The assembly of the multiturn coil and the permanent magnet was also used as an exciter to simulate the microthruster to further research the performance of the thrust stand. Three sets of force pulses at 17, 33.5, and 55 Hz with the same amplitude and pulse width were tested. The repeatability error at each frequency was 7.04%, 1.78%, and 5.08%, respectively.
An image filtering technique for SPIDER visible tomography
Authors: Fonnesu N. , Agostini M. , Brombin M. , Pasqualotto R. , Serianni G.
Published: January 2014

The tomographic diagnostic developed for the beam generated in the SPIDER facility (100 keV, 50 A prototype negative ion source of ITER neutral beam injector) will characterize the two-dimensional particle density distribution of the beam. The simulations described in the paper show that instrumental noise has a large influence on the maximum achievable resolution of the diagnostic. To reduce its impact on beam pattern reconstruction, a filtering technique has been adapted and implemented in the tomography code. This technique is applied to the simulated tomographic reconstruction of the SPIDER beam, and the main results are reported.
Effect of the parameters of traveling waves created by blowing and suction on the relaminarization phenomena in fully developed turbulent channel flow
Authors: Mamori H. , Iwamoto K. , Murata A.
Published: January 2014

A series of direct numerical simulations of a fully developed turbulent channel flow controlled by traveling waves induced by blowing and suction is performed. Relaminarization, i.e., the transition from turbulent flow to laminar flow, is observed for some sets of parameter when the wave is traveling in the downstream direction. Since the downstream traveling wave produces the drag, the drag of the flow is slightly larger than the corresponding laminar flow. A parametric study is performed, and reveals that the range of control parameters that produce relaminarization are the wave speed and amplitude of the wave which scale with the mean bulk flow rate corresponding to laminar flow and the wavelength which scales with the viscous scale. When relaminarization occurs, the amplitude of the wave, wavelength, and wave speed are in the range of \documentclass[12pt]{minimal}\begin{document}$a/\overline{u}_{\rm lam}>0.1$\end{document}a/u¯ lam >0.1, 200 < λ+ < 500, and \documentclass[12pt]{minimal}\begin{document}$c/\overline{u}_{\rm lam}>1.5$\end{document}c/u¯ lam >1.5, respectively. These ranges are organized by displacement thickness and are between 3 and 10 wall units when the relaminarization occurs. A three-component decomposition is used to observe the effects of the control parameters. The periodic component has the effect of decreasing the random component, resulting in relaminarization. When the displacement thickness is smaller, the periodic component does not have the effect of decreasing the random component, and the drag is virtually unchanged. When the displacement thickness is larger, the periodic component produces large drag, and the drag increases despite the decrease in the random component.
Towards a specific reaction parameter density functional for reactive scattering of H2 from Pd(111)
Authors: Boereboom J. M. , Wijzenbroek M. , Somers M. F. , Kroes G. J.
Published: January 2014

Recently, an implementation of the specific reaction parameter (SRP) approach to density functional theory (DFT) was used to study several reactive scattering experiments of H2 on Cu(111). It was possible to obtain chemical accuracy (1 kcal/mol ≈ 4.2 kJ/mol), and therefore, accurately model this paradigmatic example of activated H2 dissociation on a metal surface. In this work, the SRP-DFT methodology is applied to the dissociation of hydrogen on a Pd(111) surface, in order to test whether the SRP-DFT approach is also applicable to non-activated H2-metal systems. In the calculations, the Born–Oppenheimer static surface approximations are used. A comparison to molecular beam sticking experiments, performed at incidence energies ⩾125 meV, on H2 + Pd(111) suggested the PBE-vdW [where the Perdew, Burke, and Ernzerhof (PBE) correlation is replaced by van der Waals correlation] functional as a candidate SRP density functional describing the reactive scattering of H2 on Pd(111). Unfortunately, quantum dynamics calculations are not able to reproduce the molecular beam sticking results for incidence energies <125 meV. From a comparison to initial state-resolved (degeneracy averaged) sticking probabilities it seems clear that for H2 + Pd(111) dynamic trapping and steering effects are important, and that these effects are not yet well modeled with the potential energy surfaces considered here. Applying the SRP-DFT method to systems where H2 dissociation is non-activated remains difficult. It is suggested that a density functional that yields a broader barrier distribution and has more non-activated pathways than PBE-vdW (i.e., non-activated dissociation at some sites but similarly high barriers at the high energy end of the spectrum) should allow a more accurate description of the available experiments. Finally, it is suggested that new and better characterized molecular beam sticking experiments be done on H2 + Pd(111), to facilitate the development of a more accurate theoretical description of this system.
Spectroscopic observation of higher vibrational levels of C2 through visible band systems
Authors: Nakajima Masakazu , Endo Yasuki
Published: January 2014

Higher vibrational levels of the C2 molecule than those observed so far were investigated for the $X{}^1\Sigma _g^ +$XΣg+1, A1Πu, a3Πu, $c{}^3\Sigma _u^ +$cΣu+3, and d3Πg states through the Phillips, Swan, and $d{}^3\Pi _g - c{}^3\Sigma _u^ +$dΠg3−cΣu+3 band systems under a jet-cooled condition. The term values and the molecular constants for 21 new vibronic levels were determined from rotationally resolved excitation spectra. The determined term values and rotational constants were compared to those derived from high-level ab initio potential curves. Perturbations identified in low J levels of the d3Πg(v = 8) state are most likely to be caused by the 15Πg(v = 3) state.
Multi-photon ionization and fragmentation of uracil: Neutral excited-state ring opening and hydration effects
Authors: Barc B. , Ryszka M. , Spurrell J. , Dampc M. , Limão-Vieira P. , Parajuli R. , Mason N. J. , Eden S.
Published: January 2014

Multi-photon ionization (MPI) of the RNA base uracil has been studied in the wavelength range 220–270 nm, coinciding with excitation to the S2(ππ*) state. A fragment ion at m/z = 84 was produced by 2-photon absorption at wavelengths ≤232 nm and assigned to C3H4N2O+ following CO abstraction. This ion has not been observed in alternative dissociative ionization processes (notably electron impact) and its threshold is close to recent calculations of the minimum activation energy for a ring opening conical intersection to a σ(n-π)π* closed shell state. Moreover, the predicted ring opening transition leaves a CO group at one end of the isomer, apparently vulnerable to abstraction. An MPI mass spectrum of uracil-water clusters is presented for the first time and compared with an equivalent dry measurement. Hydration enhances certain fragment ion pathways (particularly C3H3NO+) but represses C3H4N2O+ production. This indicates that hydrogen bonding to water stabilizes uracil with respect to neutral excited-state ring opening.
Effect of attractive interactions on the water-like anomalies of a core-softened model potential
Authors: Pant Shashank , Gera Tarun , Choudhury Niharendu
Published: January 2014

It is now well established that water-like anomalies can be reproduced by a spherically symmetric potential with two length scales, popularly known as core-softened potential. In the present study we aim to investigate the effect of attractive interactions among the particles in a model fluid interacting with core-softened potential on the existence and location of various water-like anomalies in the temperature-pressure plane. We employ extensive molecular dynamic simulations to study anomalous nature of various order parameters and properties under isothermal compression. Order map analyses have also been done for all the potentials. We observe that all the systems with varying depth of attractive wells show structural, dynamic, and thermodynamic anomalies. As many of the previous studies involving model water and a class of core softened potentials have concluded that the structural anomaly region encloses the diffusion anomaly region, which in turn, encloses the density anomaly region, the same pattern has also been observed in the present study for the systems with less depth of attractive well. For the systems with deeper attractive well, we observe that the diffusion anomaly region shifts toward higher densities and is not always enclosed by the structural anomaly region. Also, density anomaly region is not completely enclosed by diffusion anomaly region in this case.
Characterization of Cu doping on GeTe for phase change memory application
Authors: Zhang Zhonghua , Peng Cheng , Song Sannian , Song Zhitang , Cheng Yan , Ren Kun , Li Xiaoyun , Rao Feng , Liu Bo , Feng Songlin
Published: January 2014

In this paper, Cu-doped GeTe materials have been investigated for high-temperature phase change memory (PCM) application. Cu incorporated in GeTe increases the crystallization temperature, crystallization active energy, and band gap significantly. The incorporated Cu has effect on refining the crystal growth and brings more number of bonds in GeTe, and has remarkable effect on improving the thermal stability of GeTe. The 10-year data retention of Cu0.06(GeTe)0.94 and Cu0.13(GeTe)0.87 are 151 °C and 185 °C, which is higher than that of GeTe. PCM device based on Cu0.06(GeTe)0.94 exhibits faster switching speed than that of GeTe. In addition, Cu0.06(GeTe)0.94 shows endurance up to 2.8 × 103 cycles with an on/off ratio of two orders of magnitude.
Structure, stability, and electronic property of carbon-doped gold clusters AunC− (n = 1–10): A density functional theory study
Authors: Yan Li-Li , Liu Yi-Rong , Huang Teng , Jiang Shuai , Wen Hui , Gai Yan-Bo , Zhang Wei-Jun , Huang Wei
Published: January 2014

The equilibrium geometric structures, relative stabilities, and electronic properties of AunC− and Aun+1− (n = 1–10) clusters are systematically investigated using density functional theory with hyper-generalized gradient approximation. The optimized geometries show that one Au atom capped on Aun−1C− clusters is a dominant growth pattern for AunC− clusters. In contrast to Aun+1− clusters, AunC− clusters are most stable in a quasi-planar or three-dimensional structure because C doping induces the local non-planarity while the rest of the structure continues to grow in a planar mode, resulting in an overall non-2D configuration. The relative stability calculations show that the impurity C atom can significantly enhance the thermodynamic stability of pure gold clusters. Moreover, the effect of C atom on the Aun− host decreases with the increase of cluster size. The HOMO-LUMO gap curves show that the interaction of the C atom with Aun− clusters improves the chemical stability of pure gold clusters, except for Au3− and Au4− clusters. In addition, a natural population analysis shows that the charges in corresponding AunC− clusters transfer from the Aun− host to the C atom. Meanwhile, a natural electronic configuration analysis also shows that the charges mainly transfer between the 2s and 2p orbitals within the C atom.
In-layer stacking competition during ice growth
Authors: Choi Saehyun , Jang Eunseon , Kim Jun Soo
Published: January 2014

When ice grows, the growth rates are unequal along different growth directions and some layers contain planar defective regions. With the aim of helping to understand these phenomena, we report the molecular dynamics simulations of ice growth on the basal and prismatic faces of initial hexagonal ice, using the TIP5P-E water model. By presenting the time evolution of the two-dimensional density profiles of water molecules in each layer and the kinetics of layer formation during ice growth at the temperature of 11 K supercooling, we show that two forms of ice arrangements, hexagonal and cubic, develop competitively within the same ice layer on the basal face, whereas such in-layer stacking-competition is insignificant on the prismatic face. It is shown that, on the basal face, the occurrence of significant in-layer stacking competition in one of the layers significantly delays the layer formation in several overlying layers and explains the overall delay in ice growth on the basal face compared to that on the prismatic face. In addition, it is observed that large planar defects form on the basal face, as a consequence of the long-lasting in-layer stacking competition when the overlying layer grows rapidly.
Pair correlation functions of two- and three-dimensional hard-core fluids confined into narrow pores: Exact results from transfer-matrix method
Authors: Gurin Péter , Varga Szabolcs
Published: January 2014

The effect of confinement is studied on the local structure of two- and three-dimensional hard-core fluids. The hard disks are confined between two parallel lines, while the hard spheres are in a cylindrical hard pore. In both cases only nearest neighbour interactions are allowed between the particles. The vertical and longitudinal pair correlation functions are determined by means of the exact transfer-matrix method. The vertical pair correlation function indicates that the wall induced packing constraint gives rise to a zigzag (up-down sequence) shaped close packing structure in both two- and three-dimensional systems. The longitudinal pair correlation function shows that both systems transform continuously from a one-dimensional gas-like behaviour to a zigzag solid-like structure with increasing density.
Angular-divergence calculation for Experimental Advanced Superconducting Tokamak neutral beam injection ion source based on spectroscopic measurements
Authors: Chi Yuan , Hu Chundong , Zhuang Ge
Published: January 2014

Calorimetric method has been primarily applied for several experimental campaigns to determine the angular divergence of high-current ion source for the neutral beam injection system on the Experimental Advanced Superconducting Tokamak (EAST). A Doppler shift spectroscopy has been developed to provide the secondary measurement of the angular divergence to improve the divergence measurement accuracy and for real-time and non-perturbing measurement. The modified calculation model based on the W7AS neutral beam injectors is adopted to accommodate the slot-type accelerating grids used in the EAST's ion source. Preliminary spectroscopic experimental results are presented comparable to the calorimetrically determined value of theoretical calculation.
Investigation of hole injection enhancement by MoO3 buffer layer in organic light emitting diodes
Authors: Haitao Xu , Xiang Zhou
Published: January 2014

An MoO3 buffer layer prepared by thermal evaporation as hole injection layer was investigated in organic light emitting diodes. The MoO3 film inserted between the anode and hole transport layer decreased the operating voltage and enhanced power efficiency. Introduction of 1 nm MoO3 film, which was found to be the optimum layer thickness, resulted in 45% increase in efficiency compared with traditional ITO anode. Results from atomic force microscopy and photoemission spectroscopy showed that smooth surface morphology and suitable energy level alignment of ITO/MoO3 interface facilitated hole injection and transport. The hole injection and transport mechanism at the ITO/MoO3 interface in thin and thick buffer layers were analyzed.
A simple and reliable sensor for accurate measurement of angular speed for low speed rotating machinery
Authors: Kuosheng Jiang , Guanghua Xu , Tangfei Tao , Lin Liang , Yi Wang , Sicong Zhang , Ailing Luo
Published: January 2014

This paper presents the theory and implementation of a novel sensor system for measuring the angular speed (AS) of a shaft rotating at a very low speed range, nearly zero speed. The sensor system consists mainly of an eccentric sleeve rotating with the shaft on which the angular speed to be measured, and an eddy current displacement sensor to obtain the profile of the sleeve for AS calculation. When the shaft rotates at constant speed the profile will be a pure sinusoidal trace. However, the profile will be a phase modulated signal when the shaft speed is varied. By applying a demodulating procedure, the AS can be obtained in a straightforward manner. The sensor system was validated experimentally based on a gearbox test rig and the result shows that the AS obtained are consistent with that obtained by a conventional encoder. However, the new sensor gives very smooth and stable traces of the AS, demonstrating its higher accuracy and reliability in obtaining the AS of the low speed operations with speed-up and down transients. In addition, the experiment also shows that it is easy and cost-effective to be realised in different applications such as condition monitoring and process control.
Frequency-domain multiscale quantum mechanics/electromagnetics simulation method
Authors: Meng Lingyi , Yin Zhenyu , Yam ChiYung , Koo SiuKong , Chen Quan , Wong Ngai , Chen GuanHua
Published: January 2014

A frequency-domain quantum mechanics and electromagnetics (QM/EM) method is developed. Compared with the time-domain QM/EM method [Meng et al., J. Chem. Theory Comput. 8, 1190–1199 (2012)], the newly developed frequency-domain QM/EM method could effectively capture the dynamic properties of electronic devices over a broader range of operating frequencies. The system is divided into QM and EM regions and solved in a self-consistent manner via updating the boundary conditions at the QM and EM interface. The calculated potential distributions and current densities at the interface are taken as the boundary conditions for the QM and EM calculations, respectively, which facilitate the information exchange between the QM and EM calculations and ensure that the potential, charge, and current distributions are continuous across the QM/EM interface. Via Fourier transformation, the dynamic admittance calculated from the time-domain and frequency-domain QM/EM methods is compared for a carbon nanotube based molecular device.