bluuebunny/crossref_metadata_2025 huggingface dataset:
Asteroseismology of evolved stars to constrain the internal transport of angular momentum
Authors: Eggenberger P. , den Hartogh J. W. , Buldgen G. , Meynet G. , Salmon S. J. A. J. , Deheuvels S.
Published: October 2019

Context. Asteroseismic observations enable the characterisation of the internal rotation of evolved stars. These measurements reveal that an unknown efficient angular momentum (AM) transport mechanism is needed for subgiant and red giant stars in addition to hydrodynamic transport processes. A revised prescription for AM transport by the magnetic Tayler instability has been recently proposed as a possible candidate for such a missing mechanism.

Aims. We compare the rotational properties predicted by this magnetic AM transport to asteroseismic constraints obtained for evolved stars with a particular focus on the subgiant phase.

Methods. We computed models accounting for the recent prescription for AM transport by the Tayler instability with the Geneva stellar evolution code for subgiant and red giant stars, for which an asteroseismic determination of both core and surface rotation rates is available.

Results. The revised prescription for the transport by the Tayler instability leads to low core rotation rates after the main sequence that are in better global agreement with asteroseismic measurements than those predicted by models with purely hydrodynamic processes or with the original Tayler-Spruit dynamo. A detailed comparison with asteroseismic data shows that the rotational properties of at most two of the six subgiants can be correctly reproduced by models accounting for this revised magnetic transport process. This result is obtained independently of the value adopted for the calibration parameter in this prescription. We also find that this transport by the Tayler instability faces difficulties in simultaneously reproducing asteroseismic measurements available for subgiant and red giant stars. The low values of the calibration parameter needed to correctly reproduce the rotational properties of two of the six subgiants lead to core rotation rates during the red giant phase that are too high. Inversely, the higher values of this parameter needed to reproduce the core rotation rates of red giants lead to a very low degree of radial differential rotation before the red giant phase, which is in contradiction with the internal rotation of subgiant stars.

Conclusions. In its present form, the revised prescription for the transport by the Tayler instability does not provide a complete solution to the missing AM transport revealed by asteroseismology of evolved stars.
Surface vs diffusion in TDS of hydrogen
Authors: Alekseeva Ekaterina L. , Belyaev Alexander K. , Polyanskiy Anatoly M. , Polyanskiy Vladimir A. , Varshavchik Evgeniy A. , Yakovlev Yuri A.
Published: October 2019

The paper addresses the numerical simulation of conditions in which the measurement of thermal desorption spectra of hydrogen (TDS) is carried out. Plane steel samples of 10 mm thickness were used as the specimens for simulation. The skin effect which is observed with standard hydrogen charging of samples was accounted for the initial conditions. The standard diffusion of hydrogen was simulated according to Fick’s law. Solution of the Fick’s equation is obtained by finite element methods using the developed code. The resulting solutions show that standard hydrogen charging can lead to the appearance of an additional TDS peak, even without taking into account the traps. New interpretation of the TDS method for hydrogen dissolved in a solid was suggested.
Correlation of acoustoelasticity with hydrogen saturation during destruction
Authors: Tretyakov Dmitry , Belyaev Alexander , Polyanskiy Vladimir , Stepanov Aleksey , Yakovlev Yuri
Published: October 2019

The surface effect of acoustic anisotropy in steel and aluminum industrial alloys was experimentally detected. Changes in the integral value of acoustic anisotropy in 10–15 times were observed after removing the surface layer with a thickness of 100 microns in steel specimens and 250 microns in aluminum specimens. The correlation between distributions of acoustic anisotropy and hydrogen concentrations in surface layer of specimens was found. It was suggested that the surface effect of acoustic anisotropy occurs due to the influence of microcrack systems localized in a surface layer of metal. This result can be used to improve existing approaches to estimating of corrosion damage, fatigue, mechanical stresses and plastic deformations of technical structures by using acoustic anisotropy.
Application of vapor phase corrosion inhibitors for contaminated environments
Authors: Bavarian Behzad , Avanessian Aline B. , Yekani Reza , Reiner Lisa , Radic Borsic Ivana , Miksic Boris
Published: October 2019

Availability and accessibility to clean water for industrial applications such as hydrotesting and hydrostatic testing of pipelines, vessels, and plumbing distribution systems has been a challenging task especially when the job sites are in remote locations. When contaminated water is used in these tests, corrosion of the metallic components of the systems, during and after testing become a major concern. Vapor-phase corrosion inhibitors (VCI), can be added to water in small concentrations to prevent corrosion during testing, during wet storage and after testing. These inhibitors are to prevent corrosion of metallic components in three phases, within the solution, at the water line, and above the water line. Three commercially available corrosion inhibitors were evaluated in this investigation. Laboratory studies are presented in this paper, showed the effectiveness of VCI products in both fresh and salt water applications. Average corrosion rate dropped from ~10 mpy for salt solution to less than 1-1.6 mpy when various inhibitors was added. The effectiveness of these inhibitors is remarkable in the fresh water (less than 0.4 mpy). Exposure of the steel samples to these inhibitors did not show any loss in mechanical properties. Both strength and ductility of the low carbon steel samples was maintained.
Protection of materials from hydrogen accumulation
Authors: Yakovlev Yuri A. , Zumberov Petr A.
Published: October 2019

The article is concerned with possible accidents caused by high concentrations of hydrogen in metals. The problem of using recycled metal is considered. The mechanisms of hydrogen accumulation are described. Among other things, we propose an introduction to the output control of hydrogen concentrations. The results of reducing the concentration of diffuse-mobile hydrogen in steels after ultrasonic treatment are described.
The corrosion damage mechanisms of the gas pipelines in the Republic of Sakha (Yakutia)
Authors: Ivanov Alexander , Bolshev Konstantin , Bolshakov Alexander , Syromyatnikova Aytalina , Alexeev Anisiy , Burnashev Afanassiy , Andreev Yakov , Prokopiev Leonid , Grigoriev Albert , Cheremkin Maxim , Efimov Vasiliy , Golikov Nikolay , Makharova Susanna , Zhirkov Aysen
Published: October 2019

The article provides examples of critical damage to a long-running gas pipeline on the territory of the Republic of Sakha (Yakutia), which arose as a result of the development of corrosion processes, discusses the mechanisms and scenarios for the development of corrosion damage in the cryolithozone conditions. Considering the processes and mechanisms, they continue for a long period of time., an increase in the number of damages to a gas main pipeline due to corrosive degradation is expected in the near future. The stage of diffuse damage during long-term operation is confirmed by the increasing loss of working capacity due to corrosion damage in the last 25 years of the pipeline operation.
Silver braze corrosion in H2S environment: life assessment and methods of preventing
Authors: Shakhmatov Aleksey , Badrak Robert , Howie William , Kolesov Sergey
Published: October 2019

Issues of using silver as the braze material in H2S environment are discussed due to environment related sulfidation which cause corrosion penetration and risk of compromising seals. To explore risk and mitigation techniques, static H2S high temperature silver braze corrosion tests were conducted. The results are presented and interpreted by Arrhenius equation approach. The corrosion rate decreased with time due to the formation of Ag2S corrosion product layer. This corrosion product changed the chemical reaction type from mass transfer controlled to diffusion controlled. The environment temperature vs braze joint thickness vs guarantee period relationships are shown and discussed. Additionally, possible protection options connected with metallic and non-metallic coating were investigated.
Calculating the activation energies of nickel, manufactured using 3D printing technology, with multichannel hydrogen diffusion model
Authors: Zumberov Petr , Kolesov Sergey , Polyansky Vladimir , Varshavchik Evgeniy
Published: October 2019

In modern world more and more materials with extreme properties are being used: high alloys, high-entropy alloys, nanostructured materials, etc. The extreme properties of these materials make them especially sensitive to hydrogen diffusion. Hydrogen can severely impair their properties and cause failures in structures and machines the material is used in. Nowadays, when structures and components are becoming increasingly complex, the use of 3D printing technology is becoming more widespread. Components made using 3D printing technologies are usually layered, which increase the amount of hydrogen that can diffuse into the material. The amount of hydrogen concentration in 3D printed nickel samples has been determined using vacuum heating method in hydrogen analyzer AV-1. The samples were held at different constant temperatures and the total amount of hydrogen extracted at those temperatures was calculated. A mathematic model was developed to evaluate the amount of hydrogen extracted at a given temperature. The evaluation was then compared to the experiment results, and the validity of the mathematical model and the selected hydrogen activation energies was verified.
Experiences with Sandvik grades in oil refinery applications
Authors: Höwing Jonas , Philipp Angela
Published: October 2019

A modern refinery can have more than a thousand of heat exchangers, of which the clear majority comprises tubes made of carbon or low alloyed steel. In some special applications severe conditions can occur where the use of low alloyed steels does not give enough life time and in the worst cases causes unplanned shutdowns. Among the most problematic heat exchangers in a refinery are the overhead condensers in atmospheric and vacuum distillation units, but also others within the refineries can have highly corrosive conditions. The most common problems are condensation of hydrochloric acid, diluted chlorides in acidic water phases, deposits and formation of chloride salts such as ammonium chloride. These conditions can induce general and under deposit corrosion, pitting and stress corrosion cracking. Other units in the refineries where high alloyed stainless steel or nickel base alloys are commonly encountered are in hydrotreaters and reactor effluent air coolers (REACs). In this paper experiences from installations of high alloyed stainless steels tubes in critical refinery heat exchangers will be discussed. Comparisons of different grades, their performances and limitations depending on the environments, will also be addressed.
A comparative study regarding to physical and calorific properties of briquettes from vegetable biomass
Authors: Spirchez Cosmin , Lunguleasa Aurel , Croitoru Cātālin
Published: October 2019

The paper makes a comparison between four types of briquettes: first was wheat and rapeseed briquettes, second was wheat briquettes (batch 2018), third was wheat briquettes (batch 2017), and fourth was lucernes briquettes, from the point of view of the physical and energetic characteristics, in order to choose the best ones and their corresponding market. The main properties studied are the density and moisture of the briquettes, physical properties, and also calorific power and ash content as energetic properties. Research results show that wheat and rape briquettes have had high calorific value but low density, compared to other types of briquettes. A general conclusion rise from whole paper, respectively the vegetable biomass is a renewable material and briquettes from it remains the best option of combustible materials.
Economic feasibility of developing large scale solar photovoltaic power plants in Spain
Authors: Menéndez Javier , Loredo Jorge
Published: October 2019

In 2017, electricity generation from renewable sources contributed more than one quarter (30.7%) to total EU-28 gross electricity consumption. Wind power is for the first time the most important source, followed closely by hydro power. The growth in electricity from photovoltaic energy has been dramatic, rising from just 3.8 TWh in 2007, reaching a level of 119.5 TWh in 2017. Over this period, the contribution of photovoltaic energy to all electricity generated in the EU-28 from renewable energy sources increased from 0.7% to 12.3%. During this period the investment cost of a photovoltaic power plant has decreased considerably. Fundamentally, the cost of solar panels and inverters has decreased by more than 50%. The solar photovoltaic energy potential depends on two parameters: global solar irradiation and photovoltaic panel efficiency. The average solar irradiation in Spain is 1,600 kWh m-2. This paper analyzes the economic feasibility of developing large scale solar photovoltaic power plants in Spain. Equivalent hours between 800-1,800 h year-1 and output power between 100-400 MW have been considered. The profitability analysis has been carried out considering different prices of the electricity produced in the daily market (50-60 € MWh-1). Net Present Value (NPV) and Internal Rate of Return (IRR) were estimated for all scenarios analyzed. A solar PV power plant with 400 MW of power and 1,800 h year-1, reaches a NPV of 196 M€ and the IRR is 11.01%.
Wind and wave energy resource of Germany reported by ERA-Interim reanalysis data
Authors: Rusu Eugen , Onea Florin
Published: October 2019

The aim of this work is to identify the most suitable offshore wind farms from Germany that present relevant wave conditions, suitable for the development of a wave energy project. By using the ERA-Interim data (wind and waves) reported for the time interval from 1999 and 2018, was possible to identify the more important areas, by taking also into account the seasonal distributions. Several wave energy converters were considered for assessment, for which a capacity factor located between 2.5% and 14% was reported, better results being accounted by the Seabased system (rated at 15 kW). Finally, we canconcluded that the North Sea represent an important area in terms of the marine energy and since at this moment there are operational wave projects, this will represent a suitable area for the development of a mixed wind-wave project.
Nasale mukoziliäre Clearance und
Vitamin-D-Mangel
Authors: Haxel Boris
Published: October 2019

Akcan FA et al. Evaluation of nasal mucociliary clearance time in patients with
Vitamin-D deficiency. Eur Arch Otorhinolaryngol 2019; doi:
10.1007/s00405–019–05286-y

HNO-Ärzte aus der Türkei untersuchten die Zeitdauer der nasalen mukoziliären
Clearance (NMC) bei Patienten mit Vitamin-D-Mangel.
Ausbildungscurriculum zum Zertifikat „Diagnostik und
Therapie oropharyngealer Dysphagien, inklusive FEES“ der Deutschen Gesellschaft
für Phoniatrie und Pädaudiologie und der Deutschen Gesellschaft für
Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie
Authors: Graf Simone , Keilmann Annerose , Dazert Stefan , Deitmer Thomas , Stasche Norbert , Arnold Barbara , Löhler Jan , Arens Christoph , Pflug Christina
Published: October 2019

Hintergrund In Deutschland leiden ca. 5 Millionen Menschen jeden
Lebensalters an einer Dysphagie. Durch den demografischen Wandel und die
verbesserte medizinische Versorgung ist mit einer Zunahme der Inzidenz von
Schluckstörungen zu rechnen. Die Dysphagie ist mit einer erhöhten Morbiditäts-
und Mortalitätsrate assoziiert und führt zu einer erheblichen finanziellen
Belastung der Gesundheitssysteme. Die zwei häufigsten Ursachen einer
Schluckstörung sind neurologische Erkrankungen und Kopf-Hals-Tumore. Die
Diagnostik und Therapie haben sich in den letzten Jahrzehnten kontinuierlich
weiterentwickelt. Insbesondere die flexibel-endoskopische Beurteilung des
Schluckaktes (FEES) ist zu einem festen Bestand in der Abklärung von
Schluckstörungen geworden.

Ergebnisse Das Zertifikat „Diagnostik und Therapie oropharyngealer
Dysphagien, inkl. FEES“ wurde von der Deutschen Gesellschaft für Phoniatrie und
Pädaudiologie (DGPP) und der Deutschen Gesellschaft für
Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie (DGHNO KHC) in
Zusammenarbeit mit dem Deutschen Berufsverband für Phoniatrie und Pädaudiologie
und dem Deutschen Berufsverband der Hals-Nasen-Ohrenärzte entwickelt.

Es besteht aus drei Teilen: den Modulen (A, B und C), der indirekten Supervision
und einer praktischen Prüfung. Aufbau, detaillierte Inhalte und die
Anforderungen zur Erlangung des Zertifikates werden im folgenden Artikel
beschrieben. Ebenso werden die Qualifikationen der Dozenten und Prüfer
festgesetzt.

Fazit Die systematische Ausbildung dient der Qualitätssicherung und
Etablierung von Standards in der Diagnostik und Therapie von oropharyngealen
Dysphagien in der Phoniatrie und Pädaudiologie und in der Hals-, Nasen-
Ohrenheilkunde.
Rheumatologische Rehabilitation und Begutachtung aus Patientensicht
Authors: Schmidt-Ohlemann Matthias
Published: October 2019

In der modernen Medizin spielt die Einbeziehung der Patientenperspektive eine zunehmende Rolle. Dies gilt in besonderem Maße für das System der Rehabilitation, in dem im SGB IX umfassende Patientenbeteiligungen und eine stärkere Personorientierung vorgesehen sind. Zur Praxis der medizinischen Rehabilitation werden Erwartungen, Hoffnungen und Erfahrungen von Patientinnen und Patienten mit entzündlich-rheumatischen Erkrankungen berichtet und Vorschläge zur Weiterentwicklung der medizinischen Rehabilitation für Rheumakranke unterbreitet. Im sozialrechtlichen Kontext werden im Rahmen der Verwaltungsverfahren häufig medizinische Unterlagen, Stellungnahmen und Gutachten benötigt. Probleme in den verschiedenen Verwaltungsverfahren werden aufgezeigt und die spezifisch rheumatologis chen Fragestellungen dargestellt. Vorschläge für eine sachgerechte und patientenorienterte Befunderstellung, sozialmedizinische Beurteilung und Begutachtung werden vorgestellt.
Newborn Screening for Congenital Hypothyroidism, Congenital Adrenal Hyperplasia, and Glucose-6-Phosphate Dehydrogenase Deficiency for Improving Health Care in India
Authors: Verma Jyotsna , Roy Papai , Thomas Divya C. , Jhingan Geetu , Singh Azad , Bijarnia-Mahay Sunita , Verma Ishwar C.
Published: October 2019

Newborn screening (NBS) aims toward early detection of treatable congenital disorders. From January 2008 through December 2017, 13,376 newborns were screened for congenital hypothyroidism (CH), congenital adrenal hyperplasia (CAH), and glucose-6-phosphate dehydrogenase (G6PD) deficiency at Sir Ganga Ram Hospital, India, by measuring G6PD activity, thyroid-stimulating hormone, and 17-hydroxyprogesterone on dried blood specimens. The birth prevalence of 1:2,000 for CH, 1:2,500 for CAH, and 1:125 for G6PD deficiency indicates the latter as the most prevalent. Performance evaluation of testing reveals a robust screening program with 100% sensitivity and >99% specificity. Hence, we recommend NBS for early diagnosis and treatment to prevent adverse outcomes.
A multiscale materials-to-systems modeling of polycrystalline PbSe photodetectors
Authors: Ganguly Samiran , Jang Moon-Hyung , Tan Yaohua , Yoo Sung-Shik , Gupta Mool C. , Ghosh Avik W.
Published: October 2019

We present a physics based multiscale materials-to-systems model for polycrystalline PbSe photodetectors that connects fundamental material properties to circuit level performance metrics. From experimentally observed film structures and electrical characterization, we first develop a band structure model that explains carrier-type inversion and large carrier lifetimes in sensitized films. The unique band structure of the photosensitive film causes separation of generated carriers with holes migrating to the inverted PbSe|PbI2 interface, while electrons are trapped in the bulk of the film intergrain regions. These flows together form the 2-current theory of photoconduction that quantitatively captures the I−V relationship in these films. To capture the effect of pixel scaling and trapped carrier blocking, we develop a model for the metallic contacts with the detector films based on the relative workfunction differences. We also develop detailed models for various physical parameters such as mobility, lifetime, quantum efficiency, noise, etc. that connect the detector performance metrics such as responsivity R and specific detectivity D∗ intimately with material properties and operating conditions. A compact Verilog-A based SPICE model is developed which can be directly combined with advanced digital Read-Out Integrated Circuit cell designs to simulate and optimize high performance Focal Plane Arrays which form a critical component in the rapidly expanding market of self-driven automotive, internet of things security, and embedded applications.
Non-invasive evaluation of microcirculation and metabolic regulation using flow mediated skin fluorescence (FMSF): Technical aspects and methodology
Authors: Katarzynska Joanna , Lipinski Zbigniew , Cholewinski Tomasz , Piotrowski Lukasz , Dworzynski Wojciech , Urbaniak Malgorzata , Borkowska Anna , Cypryk Katarzyna , Purgal Radoslaw , Marcinek Andrzej , Gebicki Jerzy
Published: October 2019

This paper describes a new technique for noninvasive diagnostic analysis of metabolic regulation and the microcirculation. Flow Mediated Skin Fluorescence (FMSF) is based on monitoring the intensity of NADH fluorescence emitted from skin tissue on the forearm. The principles of the technique are discussed, in particular, concerning experimental procedures and the definition and interpretation of the measured parameters. The unique features and potential avenues for development of the FMSF technique are also outlined.
Electronic control of ultrafast field emission in carbon nanotube gaps
Authors: Son B. H. , Park D. J. , Ahn Y. H.
Published: October 2019

The electronic control of an ultrafast tunneling electron emission was demonstrated in the nanogap of a single-walled nanotube (SWNT) when irradiated by a femtosecond laser pulse. The SWNT apex possesses a nanoscale morphology with a large damage threshold and thus enabled the achievement of a large emission rate. More importantly, the DC field-emission characteristics varied when the gate bias was changed. This was analyzed in terms of the change in the effective barrier height and enhancement factors. Photoinduced electron emission was observed when the gap area was illuminated with a femtosecond laser centered at a wavelength of 800 nm. As the laser power was increased, a saturated tunneling current was observed, reaching more than 10 electrons per pulse. Finally, the photoelectron emission yield was tuned with the help of gate-induced variations in the electronic band structures of the SWNTs.
A multi-term spherical harmonic expansion of the Boltzmann equation for application to low-temperature collisional plasmas
Authors: Swanekamp S. B. , Ottinger P. F. , Adamson P. E. , Giuliani J. L. , Petrova Tz. B. , Richardson A. S. , Rittersdorf I. M.
Published: October 2019

The Boltzmann equation describes the evolution of the electron and ion distributions in a plasma over time through a six-dimensional phase space. For highly collisional plasmas, scattering collisions keep the distribution function nearly isotropic in velocity space with small perturbations created by the hydrodynamic and electromagnetic forces. For these plasmas, a spherical-harmonic expansion of the velocity-space distribution function is an effective technique for solving the Boltzmann equation. This paper examines each of the terms in the Boltzmann equation in detail to derive conditions where a spherical harmonic expansion is useful. Expressions for the matrix elements are presented which represent the projection of the various operators in the Boltzmann equation onto the spherical harmonics basis set. The resulting multiple-term spherical-harmonic expansion makes no assumptions about either the direction of the electric and magnetic fields or the magnitude of the spatial gradients and is appropriate for coupling with a Maxwell equation solver for the time- and spatially-dependent electromagnetic fields. When only the first two lowest-order terms are kept, it is shown that the resulting equations are very similar in form to the continuity and force-balance fluid equations. Additional kinetic terms appear in the continuity-like equation which are related to the changes in the energy distribution due to the electric field and collisions, including Ohmic heating. Two additional kinetic terms also appear in the force-balance-like equation. The collision term accounts for momentum-transfer during scattering collisions and the other accounts for the flow of energy in velocity space and is proportional to the derivative with respect to energy of the energy density.
POLED displays: Robust printing of pixels
Authors: Kant Pallav , Hazel Andrew L. , Dowling Mark , Thompson Alice B. , Juel Anne
Published: October 2019

The fabrication of a high-quality polymeric organic light emitting diode display requires the deposition of identical, uniform fluid films into a large number of shallow recessed regions that form a regular array of pixels on a display backplane. We determine the protocols required to achieve continuous liquid coverage of the entire pixel area for the case where equally spaced fluid droplets are sequentially printed along a straight line within a stadium-shaped pixel and explore how these protocols depend on the wetting properties of the pixel surface. Our investigation uses a combination of experiments and numerical modeling, based on the assumption of fluid redistribution via capillary spreading according to a Cox-Voinov law. We show that the model is able to predict quantitatively the evolution of the liquid deposited in a pixel and provides a computationally inexpensive design tool to determine efficient printing strategies that account for uncertainties arising from imperfect substrate preparation or printhead dysfunction.
Nano-shaped hot-wire for ultra-high resolution anemometry in cryogenic helium
Authors: Diribarne Pantxo , Thibault Pierre , Roche Philippe-Emmanuel
Published: October 2019

We present the principle, modeling, and the first implementation of a new type of high resolution hot-wire anemometer designed to operate at cryogenic temperatures and very high Reynolds numbers. Its spatial resolution of a few micrometers is comparable to the most spatially resolved hot-wires reported in the literature. Compared to existing designs, its fabrication involves a limited number of steps, essentially the shaping at nanoscales of a superconducting NbTi wire of submicron diameter. The velocity spectra in the far wake of a centimeter-sized grid are measured as a proof of concept in stringent flow conditions.
Laser induced cavitation: Plasma generation and breakdown shockwave
Authors: Sinibaldi G. , Occhicone A. , Alves Pereira F. , Caprini D. , Marino L. , Michelotti F. , Casciola C. M.
Published: October 2019

Laser induced cavitation is one of the effective techniques to generate controlled cavitation bubbles, both for basic study and for applications in different fields of engineering and medicine. Unfortunately, control of bubble formation and symmetry is hardly achieved due to a series of concurrent causes. In particular, the need to focus the laser beam at the bubble formation spot leads, in general, to a conical region proximal to the light source where conditions are met for plasma breakdown. A finite sized region then exists where the electric field may fluctuate depending on several disturbing agents, leading to possible plasma fragmentation and plasma intensity variation. Such irregularities may induce asymmetry in the successive bubble dynamics, a mostly undesired effect if reproducible conditions are sought for. In the present paper, the structure of the breakdown plasma and the ensuing bubble dynamics are analyzed by means of high speed imaging and intensity measurements of the shockwave system launched at breakdown. It is found that the parameters of the system can be tuned to optimize repeatability and sphericity. In particular, symmetric rebound dynamics is achieved almost deterministically when a pointlike plasma is generated at the breakdown threshold energy. Spherical symmetry is also favored by a large focusing angle combined with a relatively large pulse energy, a process which, however, retains a significant level of stochasticity. Outside these special conditions, the elongated and often fragmented conical plasma shape is found to be correlated with anisotropic and multiple breakdown shockwave emission.
The length error compensation method of articulated arm coordinate measuring machine
Authors: Feng Xugang , Zhu Jiaqi , Zhang Jiayan
Published: October 2019

It is difficult to establish the error model of an articulated arm coordinate measuring machine by using the traditional mathematical modeling because there are many error factors between which the relationship is nonlinear. Taking the angle coding, thermal deformation, probe system, and coordinate values as the research object on the basis of parameter calibration, this paper establishes the compensation model to reduce length error through the Back Propagation (BP) neural network. The connection weights are optimized by the modified simulated annealing (MSA) algorithm so as to solve the issues of neural networks easily falling into a local minimum value and poor anti-interference ability. The data samples obtained through experiments are utilized to train the error model, while the model built compensates test data. It is indicated in the experiment that the average of length measurement after the compensation decreases from −0.0946 mm to −0.0046 mm, and the length measurement deviation at eight different locations is reduced by 0.1352 mm with respect to the MSA-BP model.
Two novel superhard carbon allotropes with honeycomb structures
Authors: Zhang Wei , Chai Changchun , Fan Qingyang , Song Yanxing , Yang Yintang
Published: October 2019

Two novel superhard 3D sp3 hybridized carbon allotropes (Cmmm-C32 and P6/mmm-C54) are proposed in this work through first-principles calculations. Both Cmmm-C32 and P6/mmm-C54 have a honeycomb structure. P6/mmm-C54 shows a wide direct bandgap (3.564 eV), while Cmmm-C32 shows an ultrawide indirect bandgap (5.051 eV), as determined using the HSE06 hybrid functional. The hardnesses of Cmmm-C32 and P6/mmm-C54 are 83.72 and 54.01 GPa, respectively, and their calculated ideal strengths further confirm their superhardness characteristics. P6/mmm-C54 is isotropic in the (001) plane. The minimum thermal conductivities of Cmmm-C32 and P6/mmm-C54 are larger than those of diamond-C, illustrating that Cmmm-C32 and P6/mmm-C54 are potential semiconductor device materials.
In situ and selective area etching of GaN by tertiarybutylchloride (TBCl)
Authors: Li Bingjun , Nami Mohsen , Wang Sizhen , Han Jung
Published: October 2019

In situ etching (ISE) of gallium nitride (GaN) can enable lateral and vertical junctions through selective area etching (SAE) and regrowth. We report the study of ISE and SAE of GaN using an organometallic precursor, tertiarybutylchloride (TBCl), in a metal-organic chemical vapor deposition reactor. Compared to the conventional etching in hydrogen, the use of TBCl allows in situ etching at a much lower temperature (<850 °C), likely due to a more reactive etchant and a more efficient desorption rate of the etching products. The TBCl etching is near equilibrium and can be significantly changed with the change of the NH3 flow rate. We also report initial results of SAE on SiO2 patterned GaN samples. An important finding is the need to control the desorption of the reaction products in order to achieve smooth surfaces. TBCl etching is crystallographically anisotropic with low etch rates on N-terminated facets. The use of TBCl and possibly other organometallic halogen precursors is expected to enable the design and implementation of III-nitride lateral junction devices that have not been possible.
Temperature-dependent spin Hall effect tunneling spectroscopy in platinum
Authors: Nakagawara Keita , Kasai Shinya , Ryu Jeongchun , Mitani Seiji , Liu Luqiao , Kohda Makoto , Nitta Junsaku
Published: October 2019

We evaluate the spin Hall angle (SHA) for Pt by using spin Hall effect tunneling spectroscopy (SHT) in combination with weak antilocalization analysis. From the angular dependence of the SHT signal, we confirm that the effects of the anomalous Hall effect and anisotropic magnetoresistance are negligible in the SHT signal. Temperature dependence of the obtained SHA indicates that the intrinsic and/or side jump contributions evaluated for Pt in the present study are in good agreement with those reported in previous studies using other methods. On the other hand, there is no correlation in the extrinsic skew scattering contributions associated with the residual resistance of Pt in each study, implying the presence of unveiled impurity and interface effects.
Multi-level quantum Rabi model for anharmonic vibrational polaritons
Authors: Hernández Federico J. , Herrera Felipe
Published: October 2019

We propose a cavity QED approach to describe light-matter interaction of an infrared cavity field with an anharmonic vibration of a single nonpolar molecule. Starting from a generic Morse oscillator potential with quantized nuclear motion, we derive a multilevel quantum Rabi model to study vibrational polaritons beyond the rotating-wave approximation. We analyze the spectrum of vibrational polaritons in detail and compare it with available experiments. For high excitation energies, the system exhibits a dense manifold of polariton level crossings and avoided crossings as the light-matter coupling strength and cavity frequency are tuned. We also analyze polariton eigenstates in nuclear coordinate space. We show that the bond length of a vibrational polariton at a given energy is never greater than the bond length of a Morse oscillator with the same energy. This type of polariton bond strengthening occurs at the expense of the creation of virtual infrared cavity photons and may have implications in chemical reactivity of polariton states.
A smoothed particle hydrodynamics (SPH) formulation of a two-phase mixture model and its application to turbulent sediment transport
Authors: Bertevas Erwan , Tran-Duc Thien , Le-Cao Khoa , Khoo Boo Cheong , Phan-Thien Nhan
Published: October 2019

A Smoothed Particle Hydrodynamics (SPH) formulation and implementation of the classical two-phase mixture model are reported, with a particular focus on the turbulent sediment transport and the sediment disturbances generated by moving equipment operating near or on the seabed. In the mixture model, the fluid-particle system is considered to be an equivalent medium whose evolution is described by a set of equations for the mixture continuity and momentum conservation, with the particle volume fraction being tracked by a transport equation. The governing equations are adapted to a Lagrangian, weakly-compressible SPH framework, the turbulence is modeled by a Reynolds-averaged Navier-Stokes approach, and adaptive boundary conditions for shear stress and turbulent quantities are implemented to account for laminar or turbulent local flow conditions. The complex rheological behavior of clay sediment/water mixtures is modeled using a volume fraction, shear rate-dependent viscosity which accounts for the existence of a yield stress. Hence, the proposed work encompasses several challenging modeling aspects: turbulence, non-Newtonian fluid behavior, sediment transport, and fluid-structure interactions. It is then illustrated on diverse cases of interest: a fluid-particle mixture column release, its subsequent turbulent transport and return to a hydrostatic equilibrium, the settling of particle clouds and two cases of particle-driven gravity currents, and their comparisons with available results. Finally, SPH simulation results for the disturbance of a bed of clay sediment/water mixture induced by a moving plate are reported and compared with experiments performed in our laboratory. The proposed SPH two-phase mixture model agrees well with the existing results considered in this study.
Separated boundary layer transition under pressure gradient in the presence of free-stream turbulence
Authors: Li Hua J. , Yang Zhiyin
Published: October 2019

Large-eddy simulation (LES) has been carried out to investigate the transition process of a separated boundary layer on a flat plate. A streamwise pressure distribution is imposed to mimic the suction surface of a low-pressure turbine blade, and the free-stream turbulence intensity at the plate leading edge is 2.9%. A dynamic subgrid scale model is employed in the study, and the current LES results compare well with available experimental data and previous LES results. The transition process has been thoroughly analyzed, and streamwise streaky structures, known as the Klebanoff streaks, have been observed much further upstream of the separation. However, transition occurs in the separated shear layer and is caused by two mechanisms: streamwise streaks and the inviscid K-H instability. Analysis suggests that streamwise streaks play a dominant role in the transition process as those streaks severely disrupt and break up the K-H rolls once they are formed, leading to significant three-dimensional (3D) motions very rapidly. It is also demonstrated in the present study that the usual secondary instability stage under low free-stream turbulence intensity where coherent two-dimensional (2D) spanwise rolls get distorted gradually and eventually broken up into 3D structures has been bypassed.
Time-dependent optimization of laser-produced molecular plasmas through high-order harmonic generation
Authors: Boltaev Ganjaboy S. , Ganeev Rashid A. , Kim Vyacheslav V. , Zhang Ke , Venkatesh Mottamchetty , Guo Chunlei
Published: October 2019

Analysis and characterization of laser-produced plasmas (LPPs) require the advanced methods for determination of different multiparticle component formation and spreading. Time-resolved high-order harmonic generation (HHG) in spreading LPPs allows determining optimal conditions for this process. One of the most important parameters of HHG in LPP is the delay between the heating and driving pulses. We demonstrate that the optimization of delays allows achieving the maximal harmonic yields in LPP created on the surfaces of the solid targets possessing different molar masses (m). The optimal delays (t) for B4C, ZnO, GaP, GaAs, and Ag2S plasmas were determined to be approximately 200, 300, 350, 500, and 700 ns, respectively. These variations of delays correspond to the t∞(m)0.5 dependence for different materials. We demonstrate the applicability of the proposed method for analysis of the resonance-enhanced harmonics in atomic and molecular plasmas (Mo and MoS2) and for studies of large perovskite aggregates as potential emitters of harmonics. This diagnostic technique can also be applied to the analysis of the presence of different nanostructures in LPPs through HHG with a high spatiotemporal resolution.
Stacked quantum cascade laser and detector structure for a monolithic mid-infrared sensing device
Authors: Hitaka Masahiro , Dougakiuchi Tatsuo , Ito Akio , Fujita Kazuue , Edamura Tadataka
Published: October 2019

We report the stacked quantum cascade laser and detector structures for a monolithic midinfrared sensing device. In the fabricated quantum cascade device, the layer structures for the detector are grown directly on the quantum cascade laser structure. The laser and detector structures thereby are flexibly designed to operate at the same wavelength, without any compensation needed in the way that the active region is designed in the laser and detector. The fabricated monolithic quantum cascade devices exhibit a low threshold current density at the midinfrared wavelength of 5.7 μm. As a result, light emission and detection on the same chip are demonstrated in continuous wave operation at room temperature.
Work estimation and work fluctuations in the presence of non-ideal measurements
Authors: Debarba Tiago , Manzano Gonzalo , Guryanova Yelena , Huber Marcus , Friis Nicolai
Published: October 2019

From the perspective of quantum thermodynamics, realisable measurements cost work and result in measurement devices that are not perfectly correlated with the measured systems. We investigate the consequences for the estimation of work in non-equilibrium processes and for the fundamental structure of the work fluctuations when one assumes that the measurements are non-ideal. We show that obtaining work estimates and their statistical moments at finite work cost implies an imperfection of the estimates themselves: more accurate estimates incur higher costs. Our results provide a qualitative relation between the cost of obtaining information about work and the trustworthiness of this information. Moreover, we show that Jarzynski’s equality can be maintained exactly at the expense of a correction that depends only on the system’s energy scale, while the more general fluctuation relation due to Crooks no longer holds when the cost of the work estimation procedure is finite. We show that precise links between dissipation and irreversibility can be extended to the non-ideal situation.
Theoretical and experimental study on frequency pushing effect of magnetron*
Authors: Li Kang , Zhang Yi , Zhu Hua-Cheng , Huang Ka-Ma , Yang Yang
Published: October 2019

The applications of magnetrons are greatly limited because of the poor output spectrum of the free-running magnetron. Currently, one of the best ways to solve this problem is injection locking. However, the injection locking theory which is widely used nowadays is based on the simplified oscillator, which does not include the frequency pushing effect of the magnetron. In this paper, the theory of injection locking magnetrons with frequency pushing effect is systematically studied. Analytical analysis shows that the locking bandwidth turns larger with the consideration of the pushing parameter (α), and the increase of locking bandwidth is expanded with α increasing. Experimental results show that the locking bandwidth is expanded by 0.3 MHz, 1 MHz, and 1.6 MHz compared with the locking bandwidth from the conventional locking theory under an injection ratio (ρ) of 0.05, 0.075, and 0.1, respectively. This research provides a more accurate prediction of the properties of the injection-locked magnetron.
Self-starting all-fiber PM Er:laser mode locked by a biased nonlinear amplifying loop mirror*
Authors: Yin Ke , Li Yi-Ming , Wang Yan-Bin , Zheng Xin , Jiang Tian
Published: October 2019

A compact all-fiber polarization-maintaining Er:laser using a nonlinear amplifying loop mirror is reported. Fundamental single-pulse mode-locking operation can always self start, with a cavity round-trip decreased from ∼ 4.7 m to ∼ 1.7 m. When the pulse repetition rate is 121.0328 MHz, output pulse is measured to have a center wavelength/3-dB spectral bandwidth/radio frequency signal to noise ratio (SNR)/pulse width of 1571.65 nm/18.70 nm/80 dB/477 fs, respectively. Besides, three states including the exponential growth, damping state, and steady state are investigated through the build-up process both experimentally and numerically. Excellent stability of this compact Er:laser is further evaluated, demonstrating that it can be an easy-fabrication maintenance-free ultrafast candidate for the scientific area of this kind.
Selective synthesis of three-dimensional ZnO@Ag/SiO2@Ag nanorod arrays as surface-enhanced Raman scattering substrates with tunable interior dielectric layer*
Authors: Mu Jia-Jia , He Chang-Yi , Sun Wei-Jie , Guan Yue
Published: October 2019

We describe the synthesis of three-dimensional (3D) multilayer ZnO@Ag/SiO2@Ag nanorod arrays by the physico–chemical method. The surface-enhanced Raman scattering (SERS) performance of the 3D multilayer ZnO@Ag/SiO2@Ag nanorod arrays is studied by varying the thickness of dielectric layer SiO2 and outer-layer noble Ag. The 3D ZnO@Ag/SiO2@Ag nanorod arrays create a huge number of SERS “hot spots” that mainly contribute to the high SERS sensitivity. The great enhancement of SERS results from the electron transfer between ZnO and Ag and different electromagnetic enhancements of Ag nanoparticles (NPs) with different thicknesses. Through the finite-difference time-domain (FDTD) theoretical simulation, the enhancement of SERS signal can be ascribed to a strong electric field enhancement produced in the 3D framework. The simplicity and generality of our method offer great advantages for further understanding the SERS mechanism induced by the surface plasmon resonance (SPR) effect.
Effect of growth temperature of GaAsx Sb1–x metamorphic buffer layer on electron mobility of InAs/AlSb heterostructures grown on Si substrate*
Authors: Zhang Jing , Lv Hong-Liang , Ni Hai-Qiao , Yang Shi-Zheng , Cui Xiao-Ran , Niu Zhi-Chuan , Zhang Yi-Men , Zhang Yu-Ming
Published: October 2019

The InAs/AlSb heterostructures with step-graded GaAs
x
Sb1 − x
metamorphic buffer layers grown on Si substrates by molecular beam epitaxy are studied. The step-graded GaAs
x
Sb1 − x
metamorphic buffer layers are used to relax the strain and block defects at each interface of the layers. Meanwhile, adding Sb to GaAs is also beneficial to suppressing the formation of dislocations in the subsequent materials. The influences of the growth temperature of the step-graded GaAs
x
Sb1 − x
metamorphic buffer layer on the electron mobility and surface topography are investigated for a series of samples. Based on the atomic force microscopy (AFM), high resolution x-ray diffraction (HRXRD), reciprocal space map (RSM), and Hall measurements, the crystal quality and composition of GaAs
x
Sb1 − x
layer are seen to strongly depend on growth temperature while keeping the Ga growth rate and V/III ratio constant. The results show that the highest electron mobility is 10270 cm2/V·s and the roughness is 4.3 nm for the step-graded GaAs
x
Sb1 − x
metamorphic buffer layer grown at a temperature of 410 °C.
Slaughtering of entire male pigs seen from the slaughterhouse perspective
Authors: Aaslyng M D , Støier S , Lund B W , Nielsen D B
Published: October 2019

Several challenges need to be taken into account before a full transition to slaughtering entire male pigs. To optimize welfare, entire male pigs should spend as short a time as possible in the pick-up facilities at the farm. At the slaughterhouse, there is no need to control the ratio between genders in the pens, as this has only minor effects on welfare. Boar taint detection must be performed, and an analytical on-line method is being developed. Rejection limits for skatole and androstenone must be set as a balance between the risk of consumers getting a negative experience on consuming the meat and the number of carcasses discarded. Smoking is a promising strategy for use of the discarded carcasses, and as much smoke as possible is recommended. Using spices and serving the meat in complex meals can also be a strategy to utilize boar tainted meat. In addition to boar taint, meat from entire male pigs is less tender and the protein content is lower than meat from castrates. In addition, the weight distribution of the carcass is different, with entire males having approximately 500g more weight at the fore-end and less at the ham. However, the meat percentages are higher in the entire males, and this can somewhat counteract the weight distribution.