bluuebunny/crossref_metadata_2025 huggingface dataset:
Regression‐based convolutional 3D pose estimation from single image
Authors: Ershadi‐Nasab S. , Kasaei S. , Sanaei E.
Published: January 2018

Estimation of 3D human pose from a single image is a challenging task because of ambiguities in projection from 3D space to the 2D image plane. A new two‐stage deep convolutional neural network‐based method is proposed for regressing the distance and angular difference matrices among body joints. Using the angular difference between body joints in addition to the distance between them in articulated objects such as human body can better model the structure of the shapes and increases the modelling capability of the learning method. Experimental results on HumanEva I and Human3.6M datasets show that the proposed method has substantial improvement in the mean per joint position error measure over the state‐of‐the‐art methods.
Multiple‐port reader antenna with three modes for UHF RFID applications
Authors: Zheng Jingming , Yang Yang , He Xiaoxiang , Mao Chenyang , Gao Jin , Zhou Chun
Published: January 2018

A multiple‐port reader antenna for ultra‐high frequency (UHF) radio‐frequency identification (RFID) near‐field and far‐field applications which has three modes is proposed and studied. Three fed‐ports are designed into the structure, which provide different radiation properties. Specially, far‐field radiation for two orthogonal polarisations and near‐field operation based on magnetic field coupling can be modified by feeding different corresponding port. The RFID reader antenna can work at three different operations within 820–880 MHz, including European UHF (865–868 MHz) and Chinese UHF (840–845 MHz) bands. Design details, simulation, and measured results are also presented.
High‐efficiency self‐powered oscillator for capacitive neural stimulation
Authors: Hong G. , Han G.
Published: January 2018

Implantable neural stimulation devices have drawn attention for various clinical purposes. Capacitor‐coupled stimulation inherently maintains charge‐balance, allowing the use of less complex pulse‐generating circuits. This Letter proposes a self‐powered relaxation oscillator, which allows direct charge transfer from the energy harvester to the capacitive stimulation electrode. As the proposed circuit does not require power supply to operate the oscillator itself, it achieves high power efficiency by eliminating wasted current from the power supply to the ground. A prototype of the proposed oscillator was fabricated with a 0.35 μm standard CMOS process. The prototype chip demonstrates power efficiency of up to 94.1% at 520 Hz for 1.4 V signal swing.
Improved rotor structures for increasing flux per pole of permanent magnet synchronous motor
Authors: Kim Hae‐Joong , Moon Jae‐Won
Published: January 2018

This study proposes an improved rotor structure that can increase the flux per pole of apermanent magnet synchronous motor. The air‐gap flux density of the improvedrotor‐type motor is calculated using an equivalent magnetic circuit and comparedwith the calculation result that is obtained using finite element analysis(FEA). In addition, the no‐load fundamental air‐gap flux density of thesurface‐mounted permanent magnet motor, interior permanent magnet motor,spoke‐type motor, and improved rotor‐type motor are compared using FEA. Changesin the no‐load fundamental air‐gap flux density according to changes in therotor diameter and permanent magnet usage are examined for each rotor type. Acomparison of the fundamental air‐gap flux densities of the five rotor types,including the improved rotor‐type conducted using FEA demonstrated that theair‐gap flux density of the improved rotor‐type was highest. A comparison of theno‐load phase back EMF of the five types was conducted after designing them inthe four‐pole six‐slot structure. Each rotor type is applied to 80 W‐grade fanmotors, and the torque ripple and iron loss are compared. A prototype of theimproved rotor‐type motor is developed, and the no‐load phase back EMF and loadtest result are verified through experiments.
Integrated optimal active and reactive power control scheme for grid connected permanent magnet synchronous generator wind turbines
Authors: Mahmoud Tawfek , Dong Zhao Yang , Ma Jin
Published: January 2018

This research presents a novel approach for optimal active and reactive power control using permanent magnet synchronous generator with fully rated converter (PMSG‐FRC). The power output variations and wind energy intermittent performance create significant challenges for power system integration, operation, and control. A fast and reliable sensorless optimal wind speed (WS) control system‐based extreme learning machines and complete ensemble empirical mode decomposition with adaptive noise is developed. Also, an approximate entropy‐based complexity measure is used for online WS estimation. The fuzzy controller system is used for calculating the optimal wind turbine (WT) speed, power, and torque, and then adjusts WT by the optimal speed value. Moreover, the wind farm (WF) active and reactive power controller is utilised for obtaining the active and reactive power reference values for every region/feeder. The system is applied and integrated to power system grid by using IEEE standard models, and the speed of WT is adjusted by the required active power level and the estimated WS value to increase the maximum power capture from WF. The simulations results using different cases studies and power system voltage levels have confirmed the validity and accuracy of the proposed control algorithms for practical applications and demonstrated excellent performance for power system integration.
High‐speed solid rotor induction motor design with improved efficiency and decreased harmonic effect
Authors: Gulbahce Mehmet Onur , Kocabas Derya Ahmet
Published: January 2018

Depending on its mechanical and thermal advantages, solid rotor induction motors (SRIMs) are widely used in demanding high‐speed applications. Since eddy currents are set free in SRIMs, great part of rotor losses is caused by space harmonics created in the air‐gap. Rotor losses are increased tremendously in high‐speed applications with the remarkable increase in driving frequency. Here, an innovative design representing a novel stator and rotor combination that is not achieved in previous studies is proposed by structural changes to stator to eliminate major effective space harmonics. An unconventional stator slotting pattern and winding distribution is calculated by nature‐inspired numerical optimisation techniques while keeping the fundamental winding factor relatively high. An example design where novel concepts are implemented is presented and a comparison is given in terms of important operational quantities with that of a standard SRIM.
Multitarget tracking performance metric: deficiency aware subpattern assignment
Authors: Oksuz Kemal , Cemgil Ali Taylan
Published: January 2018

Multitarget tracking is a sequential estimation problem where conditioned on noisy sensor measurements, state variables of several targets need to be estimated recursively. In this study, the authors propose a novel performance measure for multitarget tracking named as Deficiency Aware Subpattern Assignment (DASA), that can be used to consistently compare algorithms in a broad spectrum of formulations ranging from conventional data association methods to random finite set based multitarget tracking algorithms. The DASA metric combines three components (localisation, type 1 and type 2 errors) in order to represent the behaviour of the tracking filter coherently. Furthermore, a Monte Carlo method is proposed in order to set the cut‐off parameter for the case that the measurement model is known. They illustrate in their simulations that DASA improves upon the previously proposed Optimal Subpattern Assignment metric.
Effect of charge accumulated at oil–paper interface on parameters considered for power transformer insulation diagnosis
Authors: Mishra Deepak , Haque Nasirul , Baral Arijit , Chakravorti Sivaji
Published: January 2018

Polarisation and depolarisation current (PDC) measurement and analysis is one of the popular tools for effective diagnosis of power transformer insulation. Normally, it is assumed that polarisation current is the combination of the current due to dipole movement and conduction current. Similarly, the depolarisation current is only due to the relaxation of dipoles. However, it is found that after eliminating the effect of dc conduction from polarisation current the resulting current is not similar to that of measured depolarisation current. This shows some non‐linearity is present in the system. This non‐linearity occurs due to movement of trapped charge that resides in the interfacial region of oil–paper insulation. This study shows the effect of de‐trapping charge on various performance parameters that are used for insulation diagnosis like paper moisture and dielectric dissipation factor (tanδ).
Enhanced morphological stability of silver nanoparticles supported on rough substrates at high temperatures
Authors: Scherzer Ryan D. , Gasparov Lev V. , Stagon Stephen P.
Published: January 2018

Noble metal nanostructures serve as excellent substrates for the detection of trace amounts of substances in surface enhanced Raman spectroscopy, but they have not found widespread commercial use due to their instability and short shelf lives. This work demonstrates that silver nanoparticles grown onto substrates with nanoscale roughness, using glancing angle physical vapour deposition and subsequently thermally annealed at 500°C to generate a stable lower energy configuration, exhibit Raman enhancements that are strong and remain stable with no drop over 30 days. These nanoparticle arrays may serve as time stable substrates for commercial scale Raman spectroscopy or may be employed in harsh environments.
Perfection of leakage and ferroelectric properties of Ni‐doped BiFeO3 thin films
Authors: Wang Lingxu , Yang Shiju , Zhang Fengqing , Fan Suhua
Published: January 2018

BiFe1−x Nix O3 (x = 0%, 1, 2 and 3%) films were deposited on ITO/glass substrate using sol–gel process. The work reports the impacts of Ni doped on the crystal microstructure, leakage current, conduction mechanism and ferroelectric behaviour systematically. From the XRD analysis, all samples match well with the perovskite structure without impurity phase. Polarisation‐electric filed hysteresis loop demonstrates that the optimal Ni‐doped content of BiFeO3 films is x = 2%, of which the remnant double polarisation (2Pr) is 141.4 μC/cm2 at the test electric field of 1067 kV/cm. Leakage current density curves show that Ni doping has a great contribution in reducing leakage. The value of leakage is 4.79 × 10−7 A/cm2 at tested electric field of 300 kV/cm. In addition, the leakage conduction mechanism transforms from the Ohmic conduction under the low electric field into the space charge limited conduction under high electric field. Ni doped does not cause significant change in the conduction mechanism.
M ‐ary Poisson reception in molecular communication
Authors: Ankit  , Bhatnagar Manav R.
Published: January 2018

In this work, a mathematical modelling of M ‐ary Poisson reception processes in molecular communication (MC) environment is performed. A lower bound of the capacity of MC system is derived using maxentropic capacity‐approaching distributions; and the variation of the capacity with distance, drift velocity, and diffusion coefficient is analytically studied. Average symbol error probability (ASEP) of the considered system is analysed using maximum likelihood (ML) detection criterion. In order to improve on the error performance, an ML sequence detector employing hard decision Viterbi decoding is proposed. The proposed detection allows for a significant improvement in ASEP with some increase in system complexity.
Facile preparation of Ag nanocubes at 30°C under light irradiation
Authors: Li Danli , Shan Yangyang , Liu Ruiyi , Wu Qian , Zheng Tingting , Li Kai
Published: January 2018

Preparation of silver nanocubes (Ag NCs) with low temperature and controlled shapes is challenging in an aqueous solution because of its anticipated low embodied energy and experiment controllability. In this work, Ag NCs have been successfully synthesised under facile reaction conditions (at 30°C oil bath and under daylight illumination) by coordination effects of thermal reduction and photoinduced reduction. The obtained Ag NCs were characterised by transmission electron microscopy, UV–visible spectrophotometer and X‐ray diffractometer. It turned out that, Ag NCs were prepared by using trifluoroacetic acid silver, cetyltrimethyl ammonium chloride, ascorbic acid, ferric chloride and sodium hydrosulphide as raw materials, and their sizes around 35 nm. Besides, as‐synthesised Ag NCs with uniform size and high yield would serve as outstanding substrates for surface‐enhanced Raman scattering detection, and as sacrificial templates to fabricate Au nanocages.
A new compact young moving group around V1062 Scorpii
Authors: Röser Siegfried , Schilbach Elena , Goldman Bertrand , Henning Thomas , Moor Attila , Derekas Aliz
Published: January 2018

Aims.We are searching for new open clusters or moving groups in the solar neighbourhood.

Methods.We used theGaia-TGAS catalogue, cut it into narrow proper motion and parallax slices and searched for significant spatial over-densities of stars in each slice. We then examined stars forming over-densities in optical and near-infrared colour-magnitude diagrams to determine if they are compatible with isochrones of a cluster.

Results.We detected a hitherto unknown moving group or cluster in the Upper Centaurus Lupus (UCL) section of the Scorpius-Centaurus OB association (Sco-Cen) at a distance of 175 pc from the Sun. It is a group of 63 comoving stars of less than 10 to about 25 Myr in age. For the brightest stars that are present in theGaia-TGAS catalogue, the mean difference between kinematic and trigonometric distance moduli is − 0.01 mag with a standard deviation of 0.11 mag. Fainter cluster candidates are found in the HSOY catalogue, where no trigonometric parallaxes are available. For a subset of our candidate stars, we obtained radial velocity measurements at the MPG/ESO 2.2 m telescope in La Silla. Altogether we found 12 members with confirmed radial velocities and parallaxes, 31 with parallaxes or radial velocities, and 20 candidates from the convergent point method. The isochrone masses of our 63 members range from 2.6 to 0.7M⊙.
Preoperative FIBTEM Predicts Postoperative Hemorrhage in Total Knee Arthroplasty
Authors: Kim Seong-Hyop , Oh Chung-Sik , Kim Tae-Hoon , Park Sewon , Rhee Ka Young
Published: January 2018

FIBTEM parameters might predict the amount of postoperative hemorrhage following total knee arthroplasty (TKA), because fibrin polymerization and fibrinolysis have a central role in postoperative hemorrhage following TKA. This study retrospectively evaluated 54 patients who had undergone unilateral primary TKA. Laboratory coagulation parameters, including FIBTEM, were recorded before anesthesia induction and after admission to the postanesthetic care unit. The decrease in hemoglobin (Hb), amount of hemorrhage via closed suction drainage, fluid administration, and amount transfused were reviewed postoperatively. The preoperative FIBTEM amplitudes 10 (A10) and 20 (A20) minutes after clotting time and maximum clot firmness (MCF) had the highest correlations with the postoperative decrease in Hb (p = 0.001, p = 0.002, and p = 0.003, respectively). The preoperative FIBTEM A10 <19 mm, A20 <20 mm, and MCF < 21 mm predicted > 3.0 g/dL postoperative Hb decrement from the postanesthetic Hb value (p = 0.004, p = 0.007, and p = 0.012, respectively). Preoperative FIBTEM can predict the amount of postoperative hemorrhage following TKA.
A Statewide Medication Management System: Health Information Exchange to Support Drug Therapy Optimization by Pharmacists across the Continuum of Care
Authors: Pellegrin Karen , Chan Francis , Pagoria Natalie , Jolson-Oakes Sheena , Uyeno Reece , Levin Andrew
Published: January 2018

Background While evidence generally supports the use of medication management technology, systems are typically implemented and evaluated piecemeal rather than as part of a comprehensive model for medication management. Systems to support drug therapy optimization, increasingly a key role of pharmacists in our healthcare system, have not yet been reported.

Objective Our objective is to describe the design, implementation, and use of health information technology to support the hospital and community pharmacists' management of medications for high-risk patients statewide in the “Pharm2Pharm” model of care. Our aims were to make it easier for the pharmacists to access information needed to identify and resolve drug therapy problems using best practices for medication management and communicate with other members of the care team.

Methods The pharmacist's roles and the medication management processes guided the design of the supporting technology, which was implemented after the Pharm2Pharm model was launched and the pharmacists' technology needs were assessed. Priorities for technology included sending care transition documents from hospital to community pharmacist securely and efficiently, access to medical records, including medications and laboratory results, documentation, and patient tracking. Implementation and use of the technology were documented.

Results Communications, medication management, and population management solutions were implemented to support the Pharm2Pharm model. The pharmacists delivering services through this model adopted and meaningfully used this technology to support their work.

Conclusion Implementing technology with value outside of the Pharm2Pharm model was a strategic approach to investment. This work emphasizes the importance of shifting the focus of technology from supporting a specific piece of the medication management process to supporting the goal of optimizing medication regimens. Health information exchange systems can provide important technology needed to integrate pharmacists into care teams as they are deployed to improve patient outcomes.
Low Vitamin D Blood Levels with Significant Differences Between the Sexes in Viennese School Children – the EDDY Study
Authors: Mehany Sarah , Pöppelmeyer Christina , Helk Oliver , Pachinger Otmar , Widhalm Kurt
Published: January 2018

Hintergrund Die Bestimmung des Serumspiegels von 25(OH)-Vitamin D wird für die Erfassung des Vitamin-D-Status einer Person empfohlen. Vitamin-D-Mangel ist weit verbreitet unter europäischen Jugendlichen. Die Bedeutung von Vitamin D für die Mineralisierung der Knochen und für die Risikoreduktion von Atemwegsinfekten ist gesichert.

Material und Methodik Im Rahmen der EDDY-Studie wurden 25(OH) Vitamin-D-Spiegel bei 138 Kindern (47,8 % weiblich) im Alter von 11 – 13 Jahren in 4 verschiedenen Wiener Schulen bestimmt. Drei Blutabnahmen wurden zu verschiedenen Jahreszeiten durchgeführt. 25(OH)-Vitamin D wurde im Serum mittels CLIA (Chemiluminescent Immunoassay) bestimmt. Dieselben Vitamin-D-Kategorien wie in der HELENA-Studie wurden verwendet.

Ergebnisse Im September und Oktober 2013 hatten lediglich 36,9 % der Kinder 25(OH)-Vitamin-D-Spiegel > 50 nmol/l (untere Grenze für eine adäquate Vitamin-D-Versorgung) und nur 9,4 % wiesen Werte ≥ 75 nmol/l auf. Von den Kindern mit unzureichender Versorgung wiesen 20,3 % 25(OH)-Vitamin-D-Spiegel < 27,5 nmol/l auf. Es bestand ein signifikanter Unterschied in mittleren Vitamin-D-Spiegeln zwischen Mädchen und Jungen (♀ 40,9 ± 20,2 nmol/l versus ♂ 49,9 ± 22,1 nmol/l, p = 0,015), welcher sich auch in den Ergebnissen der zweiten und dritten Blutabnahme präsentierte. In den Wintermonaten hatten nur 0,9 % der Kinder Vitamin-D-Werte > 75 nmol/l.

Schlussfolgerung Vitamin-D-Mangel scheint unter Wiener Jugendlichen im Alter zwischen 11 und 13 Jahren weit verbreitet zu sein. 9,4 % der Kinder hatten im Herbst „optimale“ 25(OH)-Vitamin-D-Spiegel ≥ 75 nmol/l, in den Wintermonaten nur noch 0,9 %.
Design of a facility for thein situmeasurement of catalytic reaction by neutron scattering spectroscopy
Authors: Tan Shuai , Cheng Yongqiang , Daemen Luke L. , Lutterman Daniel A.
Published: January 2018

Catalysis is a critical enabling science for future energy needs. The next frontier of catalysis is to evolve from catalyst discovery to catalyst design, and for this next step to be realized, we must develop new techniques to better understand reaction mechanisms. To do this, we must connect catalytic reaction rates and selectivities to the kinetics, energetics, and dynamics of individual elementary steps and relate these to the structure and dynamics of the catalytic sites involved. Neutron scattering spectroscopies offer unique capabilities that are difficult or impossible to match by other techniques. The current study presents the development of a compact and portable instrumental design that enables the in situ investigation of catalytic samples by neutron scattering techniques. The developed apparatus was tested at the Spallation Neutron Source (SNS) in Oak Ridge National Laboratory and includes a gas handling panel that allows for computer hookups to control the panel externally and online measurement equipment such as coupled GC-FID/TCD (Gas Chromatography-Flame Ionization Detector/Thermal Conductivity Detector) and MS (Mass Spectrometry) to characterize offgassing while the sample is in the neutron scattering spectrometer. This system is flexible, modular, compact, and portable enabling its use for many types of gas-solid and liquid-solid reactions at the various beamlines housed at the SNS.
Carrier polarity engineering in carbon nanotube field-effect transistors by induced charges in polymer insulator
Authors: Aikawa Shinya , Kim Sungjin , Thurakitseree Theerapol , Einarsson Erik , Inoue Taiki , Chiashi Shohei , Tsukagoshi Kazuhito , Maruyama Shigeo
Published: January 2018

We present that the electrical conduction type in carbon nanotube field-effect transistors (CNT-FETs) can be converted by induced charges in a polyvinyl alcohol (PVA) insulator. When the CNT channels are covered with pure PVA, the FET characteristics clearly change from unipolar p-type to ambipolar. The addition of ammonium ions (NH4+) in the PVA leads to further conversion to unipolar n-type conduction. The capacitance − voltage characteristics indicate that a high density of positive charges is induced at the PVA/SiO2 interface and within the bulk PVA. Electrons are electrostatically accumulated in the CNT channels due to the presence of the positive charges, and thus, stable n-type conduction of PVA-coated CNT-FETs is observed, even under ambient conditions. The mechanism for conversion of the conduction type is considered to be electrostatic doping due to the large amount of positive charges in the PVA. A blue-shift of the Raman G-band peak was observed for CNTs coated with NH4+-doped PVA, which corresponds to unipolar n-type CNT-FET behavior. These results confirm that carrier polarity engineering in CNT-FETs can be achieved with a charged PVA passivation layer.
Optimum-wavelength forcing of a bluff body wake
Authors: Bhattacharya Samik , Gregory James W.
Published: January 2018

Three-dimensional forcing of the wake of a circular cylinder was studied experimentally to determine the optimal spatial-forcing-wavelength for drag reduction. Dielectric-barrier-discharge plasma actuators were mounted on a cylinder in a square-wave pattern to create the three-dimensional forcing. Six spatial wavelengths (1d–6d) and two blowing ratios (Uj/U∞ = 0.2 and 0.6) were tested at a Reynolds number of 4700. For most spatial wavelengths and blowing ratios, the segmented plasma actuators produced streamwise vorticity that altered the wake development, formation length, and drag. A spatial wavelength of 4d emerged as the optimum wavelength for the high-blowing-ratio case. Forcing with this optimum wavelength significantly attenuated vortex shedding, leading to maximum drag reduction in the high-blowing-ratio case. This optimum wavelength of 4d exists because longer wavelengths reduce the spatial extent of induced velocity and shorter wavelengths inhibit the development of streamwise vorticity.
Nonadiabatic electron wavepacket dynamics behind molecular autoionization
Authors: Matsuoka Takahide , Takatsuka Kazuo
Published: January 2018

A theoretical method for real-time dynamics of nonadiabatic reorganization of electronic configurations in molecules is developed, with dual aim that the intramolecular electron dynamics can be probed by means of direct and/or indirect photoionizations and that the physical origins behind photoionization signals attained in the time domain can be identified in terms of the language of time-dependent quantum chemistry. In doing so, we first formulate and implement a new computational scheme for nonadiabatic electron dynamics associated with molecular ionization, which well fits in the general theory of nonadiabatic electron dynamics. In this method, the total nonadiabatic electron wavepackets are propagated in time directly with complex natural orbitals without referring to Hartree-Fock molecular orbitals, and the amount of electron flux from a molecular region leading to ionization is evaluated in terms of the relevant complex natural orbitals. In the second half of this paper, we apply the method to electron dynamics in the elementary processes consisting of the Auger decay to demonstrate the methodological significance. An illustrative example is taken from an Auger decay starting from the 2a1 orbital hole-state of H2O+. The roles of nuclear momentum (kinetic) couplings in electronic-state mixing during the decay process are analyzed in terms of complex natural orbitals, which are schematically represented in the conventional language of molecular symmetry of the Hartree-Fock orbitals.
Dynamic exit-channel pathways of the microsolvated HOO−(H2O) + CH3Cl SN2 reaction: Reaction mechanisms at the atomic level from direct chemical dynamics simulations
Authors: Yu Feng
Published: January 2018

Microsolvated bimolecular nucleophilic substitution (SN2) reaction of monohydrated hydrogen peroxide anion [HOO−(H2O)] with methyl chloride (CH3Cl) has been investigated with direct chemical dynamics simulations at the M06-2X/6-31+G(d,p) level of theory. Dynamic exit-channel pathways and corresponding reaction mechanisms at the atomic level are revealed in detail. Accordingly, a product distribution of 0.85:0.15 is obtained for Cl−:Cl−(H2O), which is consistent with a previous experiment [D. L. Thomsen et al. J. Am. Chem. Soc. 135, 15508 (2013)]. Compared with the HOO− + CH3Cl SN2 reaction, indirect dynamic reaction mechanisms are enhanced by microsolvation for the HOO−(H2O) + CH3Cl SN2 reaction. On the basis of our simulations, further crossed molecular beam imaging experiments are highly suggested for the SN2 reactions of HOO− + CH3Cl and HOO−(H2O) + CH3Cl.
Role of hydrogen on the incipient crack tip deformation behavior in α-Fe: An atomistic perspective
Authors: Adlakha I. , Solanki K. N.
Published: January 2018

A crack tip in α-Fe presents a preferential trap site for hydrogen, and sufficient concentration of hydrogen can change the incipient crack tip deformation response, causing a transition from a ductile to a brittle failure mechanism for inherently ductile alloys. In this work, the effect of hydrogen segregation around the crack tip on deformation in α-Fe was examined using atomistic simulations and the continuum based Rice-Thompson criterion for various modes of fracture (I, II, and III). The presence of a hydrogen rich region ahead of the crack tip was found to cause a decrease in the critical stress intensity factor required for incipient deformation for various crack orientations and modes of fracture examined here. Furthermore, the triaxial stress state ahead of the crack tip was found to play a crucial role in determining the effect of hydrogen on the deformation behavior. Overall, the segregation of hydrogen atoms around the crack tip enhanced both dislocation emission and cleavage behavior suggesting that hydrogen has a dual role during the deformation in α-Fe.
Suppression of interfacial voids formation during silane (SiH4)-based silicon oxide bonding with a thin silicon nitride capping layer
Authors: Lee Kwang Hong , Bao Shuyu , Wang Yue , Fitzgerald Eugene A. , Seng Tan Chuan
Published: January 2018

The material properties and bonding behavior of silane-based silicon oxide layers deposited by plasma-enhanced chemical vapor deposition were investigated. Fourier transform infrared spectroscopy was employed to determine the chemical composition of the silicon oxide films. The incorporation of hydroxyl (–OH) groups and moisture absorption demonstrates a strong correlation with the storage duration for both as-deposited and annealed silicon oxide films. It is observed that moisture absorption is prevalent in the silane-based silicon oxide film due to its porous nature. The incorporation of –OH groups and moisture absorption in the silicon oxide films increase with the storage time (even in clean-room environments) for both as-deposited and annealed silicon oxide films. Due to silanol condensation and silicon oxidation reactions that take place at the bonding interface and in the bulk silicon, hydrogen (a byproduct of these reactions) is released and diffused towards the bonding interface. The trapped hydrogen forms voids over time. Additionally, the absorbed moisture could evaporate during the post-bond annealing of the bonded wafer pair. As a consequence, defects, such as voids, form at the bonding interface. To address the problem, a thin silicon nitride capping film was deposited on the silicon oxide layer before bonding to serve as a diffusion barrier to prevent moisture absorption and incorporation of –OH groups from the ambient. This process results in defect-free bonded wafers.
Application of time-resolved shadowgraph imaging and computer analysis to study micrometer-scale response of superfluid helium
Authors: Sajjadi Seyed , Buelna Xavier , Eloranta Jussi
Published: January 2018

Application of inexpensive light emitting diodes as backlight sources for time-resolved shadowgraph imaging is demonstrated. The two light sources tested are able to produce light pulse sequences in the nanosecond and microsecond time regimes. After determining their time response characteristics, the diodes were applied to study the gas bubble formation around laser-heated copper nanoparticles in superfluid helium at 1.7 K and to determine the local cavitation bubble dynamics around fast moving metal micro-particles in the liquid. A convolutional neural network algorithm for analyzing the shadowgraph images by a computer is presented and the method is validated against the results from manual image analysis. The second application employed the red-green-blue light emitting diode source that produces light pulse sequences of the individual colors such that three separate shadowgraph frames can be recorded onto the color pixels of a charge-coupled device camera. Such an image sequence can be used to determine the moving object geometry, local velocity, and acceleration/deceleration. These data can be used to calculate, for example, the instantaneous Reynolds number for the liquid flow around the particle. Although specifically demonstrated for superfluid helium, the technique can be used to study the dynamic response of any medium that exhibits spatial variations in the index of refraction.
Electric field control of magnetic properties in FeRh/PMN-PT heterostructures
Authors: Xie Yali , Zhan Qingfeng , Shang Tian , Yang Huali , Liu Yiwei , Wang Baomin , Li Run-Wei
Published: January 2018

We investigated electric control of magnetic properties in FeRh/PMN-PT heterostructures. An electric field of 1 kV/cm applied on the PMN-PT substrate could increase the coercivity of FeRh film from 60 to 161 Oe at 360 K where the FeRh antiferromagnetic to ferromagnetic phase transition occurs. The electric field dependent coercive field reveals a butterfly shape, indicating a strain-mediated magnetoelectric coupling across the FeRh/PMN-PT interface. However, the uniaxial magnetic anisotropy of FeRh is almost unchanged with the applied electric field on the PMN-PT substrate, which suggests the change of coercivity in FeRh films is mainly due to the shift of the magnetic transition temperature under the electric field.
Performance of the hybrid MLPNN based VE (hMLPNN-VE) for the nonlinear PMR channels
Authors: Wongsathan Rati , Phakphisut Watid , Supnithi Pornchai
Published: January 2018

This paper proposes a hybrid of multilayer perceptron neural network (MLPNN) and Volterra equalizer (VE) denoted hMLPNN-VE in nonlinear perpendicular magnetic recording (PMR) channels. The proposed detector integrates the nonlinear product terms of the delayed readback signals generated from the VE into the nonlinear processing of the MLPNN. The detection performance comparison is evaluated in terms of the tradeoff between the bit error rate (BER), complexity and reliability for a nonlinear Volterra channel at high normalized recording density. The proposed hMLPNN-VE outperforms MLPNN based equalizer (MLPNNE), VE and the conventional partial response maximum likelihood (PRML) detector.
Thermal investigation of nanostructured bulk thermoelectric materials with hierarchical structures: An effective medium approach
Authors: Hao Qing , Zhao Hongbo , Xiao Yue , Xu Dongchao
Published: January 2018

In recent years, hierarchical structures have been intensively studied as an effective approach to tailor the electron and phonon transport inside a bulk material for thermoelectric applications. With atomic defects and nano- to micro-scale structures in a bulk material, the lattice thermal conductivity can be effectively suppressed across the whole phonon spectrum, while maintaining or somewhat enhancing the electrical properties. For general materials with superior electrical properties, high thermoelectric performance can be achieved using hierarchical structures to minimize the lattice thermal conductivity. Despite many encouraging experimental results, accurate lattice thermal conductivity predictions are still challenging for a bulk material with hierarchical structures. In this work, an effective medium formulation is developed for nanograined bulk materials with embedded nanostructures for frequency-dependent phonon transport analysis. This new formulation is validated with frequency-dependent phonon Monte Carlo simulations. For high-temperature thermoelectric applications, nanograined bulk ZnO with embedded GaN nanoparticles is studied with the formulation.
Symmetry and structure of carbon-nitrogen complexes in gallium arsenide from infrared spectroscopy and first-principles calculations
Authors: Künneth Christopher , Kölbl Simon , Wagner Hans Edwin , Häublein Volker , Kersch Alfred , Alt Hans Christian
Published: January 2018

Molecular-like carbon-nitrogen complexes in GaAs are investigated both experimentally and theoretically. Two characteristic high-frequency stretching modes at 1973 and 2060 cm−1, detected by Fourier transform infrared absorption (FTIR) spectroscopy, appear in carbon- and nitrogen-implanted and annealed layers. From isotopic substitution, it is deduced that the chemical composition of the underlying complexes is CN2 and C2N, respectively. Piezospectroscopic FTIR measurements reveal that both centers have tetragonal symmetry. For density functional theory (DFT) calculations, linear entities are substituted for the As anion, with the axis oriented along the 〈1  0  0〉 direction, in accordance with the experimentally ascertained symmetry. The DFT calculations support the stability of linear N-C-N and C-C-N complexes in the GaAs host crystal in the charge states ranging from + 3 to –3. The valence bonds of the complexes are analyzed using molecular-like orbitals from DFT. It turns out that internal bonds and bonds to the lattice are essentially independent of the charge state. The calculated vibrational mode frequencies are close to the experimental values and reproduce precisely the isotopic mass splitting from FTIR experiments. Finally, the formation energies show that under thermodynamic equilibrium CN2 is more stable than C2N.
A miniature implantable coil that can be wrapped around a tubular organ within the human body
Authors: Mao Shitong , Wang Hao , Mao Zhi-Hong , Sun Mingui
Published: January 2018

There are many tubular or rod-shaped organs and tissues within the human body. A miniature medical implant that wraps around such a biological structure can monitor or modulate its function. In order to provide the wrap-around implant with power, a solenoidal coil coupled wirelessly with a planar coil outside the human body can be used. Unfortunately, there is a serious practical problem that this configuration cannot be realized easily because the implantable solenoidal coil cannot be positioned around the tubular biological structure unless either the structure or the coil is cut and reconnected, which is impermissible in most cases. In addition, when a planner exterior coil is used for wireless power transfer and communication, its maximum magnetic coupling with the implanted solenoidal coil is achieved when the tubular structure is perpendicular to the surface of the body. However, in human anatomy, most tubular/rod structures are oriented horizontally. In order to solve these problems, we present a new flexible coil for the class of wrapped-around implantable devices. Our multilayer coil has specially designed windings in cross patterns. The new coil can be made conveniently in high precision at low cost on a flat substrate using the same technology for making the flexible multilayer printed circuit boards along with miniature sensors and electronic circuits. This allows the implant to be made in a flat form and then wrapped around the biostructure during surgery. We present the design of this new coil, perform theoretical analysis with respect to its wireless power transfer efficiency, discuss the effects of coil parameters, and conduct experiments using constructed miniature prototypes. Our results confirm the validity of the new coil.
Spatial dependence of the super-exchange interactions for transition-metal trimers in graphene
Authors: Crook Charles B. , Houchins Gregory , Zhu Jian-Xin , Balatsky Alexander V. , Constantin Costel , Haraldsen Jason T.
Published: January 2018

This study examines the magnetic interactions between spatially variable manganese and chromium trimers substituted into a graphene superlattice. Using density functional theory, we calculate the electronic band structure and magnetic populations for the determination of the electronic and magnetic properties of the system. To explore the super-exchange coupling between the transition-metal atoms, we establish the magnetic ground states through a comparison of multiple magnetic and spatial configurations. Through an analysis of the electronic and magnetic properties, we conclude that the presence of transition-metal atoms can induce a distinct magnetic moment in the surrounding carbon atoms as well as produce a Ruderman-Kittel-Kasuya-Yosida-like super-exchange coupling. It is hoped that these simulations can lead to the realization of spintronic applications in graphene through electronic control of the magnetic clusters.
A stochastic vortex structure method for interacting particles in turbulent shear flows
Authors: Dizaji Farzad F. , Marshall Jeffrey S. , Grant John R.
Published: January 2018

In a recent study, we have proposed a new synthetic turbulence method based on stochastic vortex structures (SVSs), and we have demonstrated that this method can accurately predict particle transport, collision, and agglomeration in homogeneous, isotropic turbulence in comparison to direct numerical simulation results. The current paper extends the SVS method to non-homogeneous, anisotropic turbulence. The key element of this extension is a new inversion procedure, by which the vortex initial orientation can be set so as to generate a prescribed Reynolds stress field. After validating this inversion procedure for simple problems, we apply the SVS method to the problem of interacting particle transport by a turbulent planar jet. Measures of the turbulent flow and of particle dispersion, clustering, and collision obtained by the new SVS simulations are shown to compare well with direct numerical simulation results. The influence of different numerical parameters, such as number of vortices and vortex lifetime, on the accuracy of the SVS predictions is also examined.
Negative impact of surface Ti3+ defects on the photocatalytic hydrogen evolution activity of SrTiO3
Authors: Chen Haidong , Zhang Feng , Zhang Weifeng , Du Yingge , Li Guoqiang
Published: January 2018

Defects play an important and in many cases dominant role in the physical and chemical properties of many oxide materials. In this work, we show that the surface Ti3+ defects in SrTiO3 (STO), characterized by electron paramagnetic resonance and X-ray photoelectron spectroscopy, directly impact the photocatalytic activity of STO. O2 species are found to absorb preferentially on Ti3+ defect sites. Hydrogen evolution under ambient air diminishes with the increase in the concentration of surface Ti3+. This is explained by the over-accumulation of Pt cocatalysts on the site of surface Ti3+ defects after the removal of adsorbed O2.
Detection of kinetic change points in piece-wise linear single molecule motion
Authors: Hill Flynn R. , van Oijen Antoine M. , Duderstadt Karl E.
Published: January 2018

Single-molecule approaches present a powerful way to obtain detailed kinetic information at the molecular level. However, the identification of small rate changes is often hindered by the considerable noise present in such single-molecule kinetic data. We present a general method to detect such kinetic change points in trajectories of motion of processive single molecules having Gaussian noise, with a minimum number of parameters and without the need of an assumed kinetic model beyond piece-wise linearity of motion. Kinetic change points are detected using a likelihood ratio test in which the probability of no change is compared to the probability of a change occurring, given the experimental noise. A predetermined confidence interval minimizes the occurrence of false detections. Applying the method recursively to all sub-regions of a single molecule trajectory ensures that all kinetic change points are located. The algorithm presented allows rigorous and quantitative determination of kinetic change points in noisy single molecule observations without the need for filtering or binning, which reduce temporal resolution and obscure dynamics. The statistical framework for the approach and implementation details are discussed. The detection power of the algorithm is assessed using simulations with both single kinetic changes and multiple kinetic changes that typically arise in observations of single-molecule DNA-replication reactions. Implementations of the algorithm are provided in ImageJ plugin format written in Java and in the Julia language for numeric computing, with accompanying Jupyter Notebooks to allow reproduction of the analysis presented here.
Entropy generation in magnetohydrodynamic radiative flow due to rotating disk in presence of viscous dissipation and Joule heating
Authors: Hayat Tasawar , Qayyum Sumaira , Khan Muhammad Ijaz , Alsaedi Ahmed
Published: January 2018

Simultaneous effects of viscous dissipation and Joule heating in flow by rotating disk of variable thickness are examined. Radiative flow saturating porous space is considered. Much attention is given to entropy generation outcome. Developed nonlinear ordinary differential systems are computed for the convergent series solutions. Specifically, the results of velocity, temperature, entropy generation, Bejan number, coefficient of skin friction, and local Nusselt number are discussed. Clearly the entropy generation rate depends on velocity and temperature distributions. Moreover the entropy generation rate is a decreasing function of Hartmann number, Eckert number, and Reynolds number, while they gave opposite behavior for Bejan numbers.
Optimized plasma actuation on asymmetric vortex over a slender body
Authors: Long Yuexiao , Li Huaxing , Meng Xuanshi , Hu Haiyang
Published: January 2018

Detailed particle-image-velocimetry and surface pressure measurements are conducted to study asymmetric vortex control over a slender body at high angles of attack by using a pair of optimized alternating current surface-dielectric-barrier discharge plasma actuators. The Reynolds number based on the base diameter of the model is ReD = 3.8 × 105. Steady and duty-cycle manipulations are employed. The results demonstrate the effectiveness of the optimized actuator with a thick Teflon barrier at a high free-stream speed. Perfect linear proportional control is also achieved under duty-cycle control with a reduced frequency of f+ = 0.17.
Electron effective mass in Sn-doped monoclinic single crystal β-gallium oxide determined by mid-infrared optical Hall effect
Authors: Knight Sean , Mock Alyssa , Korlacki Rafał , Darakchieva Vanya , Monemar Bo , Kumagai Yoshinao , Goto Ken , Higashiwaki Masataka , Schubert Mathias
Published: January 2018

The isotropic average conduction band minimum electron effective mass in Sn-doped monoclinic single crystal β-Ga2O3 is experimentally determined by the mid-infrared optical Hall effect to be (0.284 ± 0.013)m0 combining investigations on (010) and (2¯01) surface cuts. This result falls within the broad range of values predicted by theoretical calculations for undoped β-Ga2O3. The result is also comparable to recent density functional calculations using the Gaussian-attenuation-Perdew-Burke-Ernzerhof hybrid density functional, which predict an average effective mass of 0.267m0. Within our uncertainty limits, we detect no anisotropy for the electron effective mass, which is consistent with most previous theoretical calculations. We discuss upper limits for possible anisotropy of the electron effective mass parameter from our experimental uncertainty limits, and we compare our findings with recent theoretical results.
Synthesis and Raman spectroscopy of a layered SiS2 phase at high pressures
Authors: Wang Yu , Jiang Shu-Qing , Goncharov Alexander F. , Gorelli Federico A. , Chen Xiao-Jia , Plašienka Dušan , Martoňák Roman , Tosatti Erio , Santoro Mario
Published: January 2018

Dichalcogenides are known to exhibit layered solid phases, at ambient and high pressures, where 2D layers of chemically bonded formula units are held together by van der Waals forces. These materials are of great interest for solid-state sciences and technology, along with other 2D systems such as graphene and phosphorene. SiS2 is an archetypal model system of the most fundamental interest within this ensemble. Recently, high pressure (GPa) phases with Si in octahedral coordination by S have been theoretically predicted and also experimentally found to occur in this compound. At variance with stishovite in SiO2, which is a 3D network of SiO6 octahedra, the phases with octahedral coordination in SiS2 are 2D layered. Very importantly, this type of semiconducting material was theoretically predicted to exhibit continuous bandgap closing with pressure to a poor metallic state at tens of GPa. We synthesized layered SiS2 with octahedral coordination in a diamond anvil cell at 7.5-9 GPa, by laser heating together elemental S and Si at 1300-1700 K. Indeed, Raman spectroscopy up to 64.4 GPa is compatible with continuous bandgap closing in this material with the onset of either weak metallicity or of a narrow bandgap semiconductor state with a large density of defect-induced, intra-gap energy levels, at about 57 GPa. Importantly, our investigation adds up to the fundamental knowledge of layered dichalcogenides.