bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictive current control method for dual three‐phase PMSM drives with reduced switching frequency and low‐computation burden
Authors: Xu Zhixian , Wang Zheng , Wang Xueqing , Cheng Ming
Published: December 2019

The multiphase motor drives have attracted more and more attention during the last decade since they offer advantages of high‐power rating, lower voltage and current stresses in semiconductor switches, and high‐fault‐tolerant ability, compared to the conventional three‐phase drives. This study presents a novel two‐step model predictive control (MPC) method for currents in two‐level voltage‐source inverters fed dual three‐phase permanent magnet synchronous motor drives, aiming at reducing the switching frequency and computation burden of the system. In the first step, the proposed method searches the phase having the maximum phase current error among six phases, and then changes the switching signal of that phase depending on the requirement of current change. Thus, overlarge error in the hysteresis‐based predictive control is avoided. In the second step, switching signals are changed in two phases at most and only six voltage vector candidates are evaluated with MPC within one sampling period. So, the switching frequency is reduced and the computation burden is released compared to the conventional finite‐control‐set ‐MPC method. Finally, the experimental results are given to verify the validation of the proposed scheme and compare the performance to the other classical MPC methods.
Low‐torque ripple control of SRM based on current vector
Authors: Kuai Songyan , Xia Xinxiang , Zhang He , Hu Kun
Published: December 2019

To reduce torque ripple of switched reluctance motor (SRM), a low‐torque ripple control method based on current vector is proposed in this study. In which, control strategy is adopted. Then, is decomposed into the vector sum of two‐phase currents in different positions. A Fourier series model about and is established and this model satisfies the magnetic saturation condition. According to the established Fourier series model, the change rule of based on constant reference torque is obtained. In this study, torque models of SRM under traditional unipolar sinusoidal excitation control method, constant unipolar excitation control method and variable unipolar excitation control method are analysed. Finally, experimental platform of SRM control system based on TMS320F2812 is built. Experimental results show that the variable unipolar excitation method based on current vector decomposition can effectively reduce the torque ripple of SRM.
Novel MTPA control strategy for IPMSM based on multiple virtual signals injection
Authors: Chen Bao , Shen Anwen , Luo Xin , Dou Zhaolei , Luo Pan
Published: December 2019

Virtual signal injection‐based maximum torque per ampere (MTPA) control method is widely employed for increasing the efficiency of the interior permanent magnet synchronous machine (IPMSM) due to its simple implementation. However, the conventional method utilises the filters to extract MTPA indicator, which limits the dynamic tracking performance of MTPA operating point. In order to improve the dynamic tracking performance, a novel strategy to use multiple virtual signals injection is proposed in this study. With the proposed method, four small virtual high‐frequency signals are constructed to extract the MTPA indicator information. The MTPA indicator can be calculated directly by solving multiple acquired equations instead of any filters. Due to the absence of filters which are essential in the conventional method, this proposed method shows good dynamic response. The feasibility of the proposed method is verified under various operating conditions with a 1.2 kW IPMSM drive system.
Hybrid DA‐PSO approach for optimal location and parameter settings for TCSC controller in power system
Authors: Kulkarni Pooja Prasad , Ghawghawe Nitin D.
Published: December 2019

Thyrist or controlled series compensator (TCSC) configuration in power system comprises of controlled reactors in parallel with sections of a capacitor bank. This combination offers smooth control of basic frequency capacitive reactance over a wide range. Its benefits include eradication of resonance risks, stability improvements and so on, offering dynamic power flow control. However, the TCSC controllers face issues, while determining their optimal locations and parameter settings (sizing). Hence, this study intends to solve these problems by considering three objectives, namely, congestion minimisation, investment cost minimisation and increased transient stability. The objectives are achieved by optimising various locations of the bus system, where the TCSC has to be placed, and its sizing. From the optimised results, the best solution is chosen to attain the abovementioned objectives. The presented scheme obtains the best solution by a hybridised model, exploiting the dragonfly algorithm (DA) and the particle swarm optimisation (PSO), called PSO‐dependent step vector for DA. Finally, the proposed approach is compared with the conventional schemes by analysing the outcomes for two benchmark systems, namely, IEEE 24 and IEEE 9 test bus systems.
Design for independent and self‐adequate microgrids in distribution systems considering optimal allocation of DG units
Authors: Daryani Narges , Zare Kazem , Tohidi Sajjad
Published: December 2019

Introducing the concept of distributed generations (DGs) and local demand supply have led to significant changes in distribution networks. The idea of aggregating loads and DGs in an appropriate way have resulted in microgrids' (MGs) appearance. Considering the economic and environmental concerns, MGs will play important roles in future distribution systems. However, it is necessary to implement an efficient procedure for the optimal design of MGs. This study proposes optimised methods in order to construct a set of independent, self‐sufficient MGs in distribution networks. Increasing self‐adequacy of constructed MGs is obtained by minimising the power imbalance within them or minimising transferred power between them. The stochastic nature of DGs and consumed loads are also considered. In this regard, optimal allocating and sizing of distributed resources are also studied. In this study, the optimal DG placement is considered with the aim of improving system load factor and decreasing system losses. The presented strategy facilitates controlling strategies of smart distribution systems, such as self‐healing, by using virtual MGs in the future distribution systems. The related formulation and solution algorithms are presented in this study. Moreover, the proposed strategy is studied in the PG&E 69‐bus distribution system.
Synthesis of quaternary nano‐intermetallic LaTi2Ni5Al4 with its hydrogen encapsulation and inspection using lithium‐hydride cell
Authors: Jaafar Hassen , Dhiab Arij , Slama Chiheb , Sahli Ines , Abdellaoui Mohieddine
Published: December 2019

A novel alloy LaTi2Ni5Al4 is investigated in this work. This quaternary composite belongs to the new generation of AB3 intermetallics elaborated using the mechano‐milling method. Several analytical techniques are operated in order to verify and confirm the crystallographic patterns following the growth progression of this nanoalloy. Starting from elemental metals, the authors show that they have basically LaTi2Ni5Al4 major pattern corresponding to the symmetry crystal system (Trigonal R‐3 m SG: 166). Structure refinement simulation demonstrates that performing this preparation with a laboratory grinding and milling benchtop, they obtain a maximum proportion of AB3 intermetallic alloy after 20 h of metallurgy work processing. The proposition of useful stabilised solid‐hydrogen encapsulation is highlighted and tested using a specific lithium‐hydride cell.
Impact of ion irradiation, elemental doping and coating cycles on structural characteristic parameters of nanocrystalline VO2 thin films
Authors: Khan G.R.
Published: December 2019

The origin of the structural phase transition in vanadium dioxide (VO2) has been the subject of immense disagreement in spite of decades of research carried out to comprehend this intriguing phenomenon. Diverse models have been developed to elucidate the obscure theory in order to corroborate assorted experimental results. Herein, the influence of swift heavy ion irradiation, elemental doping and coating cycles on the structural properties of thin films synthesised by sol–gel technique and deposited by spin coater on alumina and glass substrates is investigated. The thin films were characterised by X‐ray diffractometry and the XRD spectra obtained at 1E11, 5E11, 1E12 ion beam fluances of 200 MeV Ag9+ ‐ion irradiation; at 1, 3, 5% of Mo6+ ‐ion doping and at different spin coating cycles were analysed to probe the influence of these effects on the structural characteristic parameters of nanocrystallites in VO2 thin films. This aspect of VO2 thin films has not been investigated to its full capacity and consequently, not reported in the scientific literature.
The single star path to Be stars
Authors: Hastings Ben , Wang Chen , Langer Norbert
Published: December 2019

Context. Be stars are rapidly rotating B main sequence stars that show line emission due to an outflowing disc. By studying the evolution of rotating single star models, we can assess their contribution to the observed Be star populations.

Aims. We identify the main effects that cause single stars to approach critical rotation as functions of initial mass and metallicity, and predict the properties of populations of rotating single stars.

Methods. We perform population synthesis with single-star models of initial masses ranging between 3 and 30 M⊙ and initial equatorial rotation velocities between 0 and 600 km s−1 at compositions representing the Milky Way and the Large and Small Magellanic Clouds. These models include efficient core–envelope coupling mediated by internal magnetic fields and correspond to the maximum efficiency of Be star production. We predict Be star fractions and the positions of fast-rotating stars in the colour–magnitude diagram.

Results. We identify stellar wind mass-loss and the convective core mass fraction as the key parameters determining the time dependance of the stellar rotation rates. Using empirical distributions of initial rotational velocities, our single-star models can reproduce the trends observed in Be star fractions with mass and metallicity. However, they fail to produce a significant number of stars rotating very close to the critical velocity. We also find that rapidly rotating Be stars in the Magellanic Clouds should have significant surface nitrogen enrichment, which may be in conflict with abundance determinations of Be stars.

Conclusions. Single-star evolution might explain the high number of Be stars if 70 to 80% of critical rotation would be sufficient to produce the Be phenomenon. However, even in this case, the unexplained presence of many Be stars far below the cluster turn-off indicates the importance of the binary channel for Be star production.
Synthesis of the neural coordinated control algorithm for the model of CNC machine
Authors: Lyubich Valeriy , Frolov Vladimir , Beliaev Vladimir
Published: December 2019

Objectives: Increase quality factor of the CNC machine model in comparison with the Uncoupled System by synthesizing Neural Coordinated Control. Synthesis: We synthesized the Neural Coordinated Control algorithm based on the coordinated control algorithm and neural control. Experiment: Using mathematical modeling we compared the synthesized algo-rithms and the uncoupled system using the following criteria: contour error, contour speed error, and score function. Results: The four NCC algorithms were synthesized and trained. The experiment shows that synthesized algorithms have better score function values and better quality factor values in comparison to the reference Uncoupled System. Conclusion: The quality factor of the CNC machine model was successfully in-creased by using the synthesized Neural Coordinated Control algorithm.
Gradient heat flux measurement during condensation at the surfaces of pipes
Authors: Sapozhnikov Sergey , Mityakov Vladimir , Babich Alexander , Zainullina Elza
Published: December 2019

Gradient heat flux measurement was used to study steam condensation at the inner and outer surfaces of pipes. Experimental setups were developed, manufactured and tested. The setups were able to incline the pipes for different angles relative to vertical and to rotate them around their main axes. Local heat transfer coefficients (HTC) along the pipe length and perimeter were determined. Formation and motion of condensate film were studied. The results are corresponding to classical ideas and give us some new information.
Free-stream turbine start-up under load
Authors: Khorobrov Svyatoslav , Nemova Daria , Gorbatov Daniil , Kalaev Vladimir , Kotov Eugene
Published: December 2019

Free-stream turbine is an alternative to classical high-head turbines. On one hand, it produces less power, on the other hand, it requires less ser-vice and construction and might be an eco-friendlier option. We have modelled the start-up of a free-stream turbine, which consists of a wheel and a generator, using CFD methods. Unsteady RANS method with k-ω SST model was employed to describe turbulence. We have used finite-volume solver Ansys FLUENT on unstructured mesh. Moving mesh approach was applied for the wheel rotation. We have based the blade sys-tem design on several simple assumptions. Wheel inertia and generator load were taken into account through simple moment equations. Velocity fields during different moments of time were obtained. We have obtained both momentum and power of the wheel curves over time and reviewed cases with generator presence and absence. Angular velocity curves comparison over time is presented for two cases.
Forecasting of an output of eco toxicants at thermal decomposition of chemical fuel
Authors: Barysheva Olga , Sadykov Renat , Khabibullin Yuri , Zheltukhina Elizaveta
Published: December 2019

Combustion of high-energy chemical fuels containing chlorine in the element structure can lead to formation in the particles of smoke of super eco toxicants—the polychlorinated dioxins and furans. The numerical experiment conducted was based on solution of the equations of chemical kinetics. The computational and theoretical researches directed to the solution of a problem of determination of parameters of combustion products of chemical fuels taking into account formation of harbingers of the polychlorinated dioxins were executed. The main data on the accepted method of determination of disequilibrium structures of products of burning the chlorine-containing chemical fuels were represented. Based on the analysis of references about mechanisms and speeds of chemical reactions of transformations of chlorine-containing connections, the kinetic model of formation of predecessors of dioxins is constructed. The carried-out calculations showed (assuming chemical balance) that process of formation of dioxins is significantly disequilibrious. The results of kinetic researches on emission of harbingers of dioxins showed the nature of the influence of different components of combustion products of chemical fuels on time for the different levels of temperatures.
Innovative approach to the problem of preventing the formation of icing on the roofs of buildings in the spring and winter
Authors: Khlobystin Nikolay , Kingasheva Anastasia , Brenchaninov Dmitry
Published: December 2019

Only during 2010 – 2019 more than 100 people have suffered from falling of icicles from roofs. In most cases people get slight injuries, but sometimes it reaches lethal outcome. Also damage is sustained by cars, pavements, shops that are in commercial rooms on the first floors of houses, etc. In the conditions of continuous modernization of design of houses, construction companies do not resolve the matter. In this article the problem of formation of frost during the spring and winter period is studied. We have assessed the probabilities of suffering damage from icicles falling from various heights. The innovative device that does not have analogy around the world and eliminates defects of already existing patents is presented.
Development of measures to protect the population and prevent pollution based on the study of the radiation background of the object
Authors: Antonova Margarita , Yakovlev Vyacheslav , Scorokhodova Anastasia
Published: December 2019

In the modern world, the energy of the atom is used in industry, medicine and other spheres of human activity. However, the usage of radioactive substances can have a negative impact on the environment, the health of workers and the public. Therefore, it is important to keep a close watch on the radiation situation in the immediate vicinity of facilities where radioactive substances are used or stored. These can be nuclear power plants and industrial enterprises, as well as areas with a naturally elevated background radiation level. In this paper, a study of the background radiation of the object of possible radioactive contamination – Gatchina Palace in Gatchina, Leningrad region was carried out. On the basis of measurements made, we have performed the calculation of the annual radiation doses of staff and tourists, as well as issued recommendations to ensure the radiation safety of employees and visitors of the Gatchina Palace.
Inkontinenz beim Hund chiropraktisch behandeln – 3 Fallberichte
Authors: Körner Ute
Published: December 2019

Der Leidensdruck bei Harninkontinenz ist auf beiden Seiten hoch – sowohl natürlich auf der Seite des Tieres als auch auf der des Besitzers. Die Behandlung ist nicht immer einfach, doch es gibt Möglichkeiten, zumindest Linderung zu verschaffen. Dafür sollte man die Hintergründe kennen und verstehen und wissen, wie und wo man ganzheitlich manualtherapeutisch ansetzen kann. Bei inkontinenten Patienten ist außerdem die richtige Kommunikation mit dem Patientenbesitzer von großer Bedeutung.
Exploring Patient Motivations and Impact of Asian Blepharoplasty
Authors: Huynh Pauline P. , Ishii Masaru , Juarez Michelle , Fung Nicholas , Bater Kristin , Darrach Halley , Nellis Jason C. , Bonham Luke W. , Lay P. Chase , Ishii Lisa E.
Published: December 2019

To date, patient motivations for Asian blepharoplasty and the surgery's impact on quality of life have not been quantified. Here, we employed structured interviews and a web-based survey to better characterize patient motivations for Asian blepharoplasty and the impact of Asian blepharoplasty on self-reported domains of happiness, self-esteem, attractiveness, social life, and professional life. Structured interviews were conducted to inform a web-based survey regarding Asian blepharoplasty. Survey respondents used visual analog scales to rate their satisfaction with their eye shape, motivations for undergoing Asian blepharoplasty, and perceived outcomes after surgery. A total of 315 participants (mean 25.7 [18–58] years) of East or Southeast Asian descent were included. 185 participants expressed no desire for Asian blepharoplasty, 76 expressed some desire, and 54 had already undergone surgery. There were statistically significant differences regarding baseline satisfaction, perceived social limitation, and perceived professional limitations regarding eye shape (p < 0.0001). The Looking Glass Self index (comprised of media exposure, low self-esteem, and negative stereotypes related to eye shape) is negatively associated with preoperative satisfaction with eye shape (rho = −0.29, p < 0.01). The desire for social-professional advancement and the Looking Glass Self index significantly predict self-reported improvements in professional and social life, respectively (both p < 0.01). Asian blepharoplasty may be driven by functional, social, or economic patient motivations. Some patients may see Asian blepharoplasty as a potential solution for sociological concerns. These expectations should be further explored in physician–patient discussions regarding candidacy for surgery and establishing expectations for postoperative outcomes.
Beyond solid-state lighting: Miniaturization, hybrid integration, and applications of GaN nano- and micro-LEDs
Authors: Wasisto Hutomo Suryo , Prades Joan Daniel , Gülink Jan , Waag Andreas
Published: December 2019

Gallium nitride (GaN) light-emitting-diode (LED) technology has been the revolution in modern lighting. In the last decade, a huge global market of efficient, long-lasting, and ubiquitous white light sources has developed around the inception of the Nobel-prize-winning blue GaN LEDs. Today, GaN optoelectronics is developing beyond solid-state lighting, leading to new and innovative devices, e.g., for microdisplays, being the core technology for future augmented reality and visualization, as well as point light sources for optical excitation in communications, imaging, and sensing. This explosion of applications is driven by two main directions: the ability to produce very small GaN LEDs (micro-LEDs and nano-LEDs) with high efficiency and across large areas, in combination with the possibility to merge optoelectronic-grade GaN micro-LEDs with silicon microelectronics in a hybrid approach. GaN LED technology is now even spreading into the realm of display technology, which has been occupied by organic LEDs and liquid crystal displays for decades. In this review, the technological transition toward GaN micro- and nanodevices beyond lighting is discussed including an up-to-date overview on the state of the art.
Laws of large numbers for the frog model on the complete graph
Authors: Lebensztayn Elcio , Estrada Mario Andrés
Published: December 2019

The frog model is a stochastic model for the spreading of an epidemic on a graph in which a dormant particle starts to perform a simple random walk on the graph and to awaken other particles once it becomes active. We study two versions of the frog model on the complete graph with N + 1 vertices. In the first version that we consider, active particles have geometrically distributed lifetimes. In the second version, the displacement of each awakened particle lasts until it hits a vertex already visited by the process. For each model, we prove that as N → ∞, the trajectory of the process is well approximated by a three-dimensional discrete-time dynamical system. We also study the long-term behavior of the corresponding deterministic systems.
Thermal annealing effects in polycrystalline EuTiO3 and Eu2Ti2O7
Authors: Schell Juliana , Kamba Stanislav , Kachlik Martin , Maca Karel , Drahokoupil Jan , Rano B. Rahman , Nuno Gonçalves João , Thanh Dang Thien , Costa Angelo , Noll Cornelia , Vianden Reiner , Lupascu Doru C.
Published: December 2019

Using time-differential perturbed angular correlation of γ rays, we investigated the electric-field gradient of polycrystalline EuTiO3 and Eu2Ti2O7, with 181Hf(181Ta) as a probe, following different thermal treatments. The measurements were performed at ISOLDE-CERN following 80 keV implantation at the Bonn Radioisotope Separator. The experimental results indicated successful induction of different phases in the implantation recovery process at 1273 and 1373 K. These observations were combined with ab initio calculations and X-ray diffraction measurements. A comparison of ab initio calculated electric-field gradients with the measured values discriminates between different structures and defects and rules out many possible cases. The Ta probe at the Ti site in the Eu2Ti2O7 phase is found to be the most probable case of site occupation after annealing at 1373 K, while annealing at 1273 K keeps EuTiO3 in the vicinity of the Ta probe. A discussion of the hyperfine interactions that promote variation in the interaction strength at the 181Ta site is presented.
Proton acceleration by collisionless shocks using a supersonic H2 gas-jet target and high-power infrared laser pulses
Authors: Puyuelo-Valdes P. , Henares J. L. , Hannachi F. , Ceccotti T. , Domange J. , Ehret M. , d'Humieres E. , Lancia L. , Marquès J.-R. , Ribeyre X. , Santos J. J. , Tikhonchuk V. , Tarisien M.
Published: December 2019

For most laser-driven ion acceleration applications, a well-characterized intense ion beam with a low divergence and a controllable energy spectrum produced at a high repetition rate is needed. Gas-jet targets have given promising results in simulations, and they have several technical advantages for high-repetition-rate lasers. In this work, we report on proton acceleration to energies up to 6 MeV using a supersonic H2 gas-jet target at the LULI PICO2000 laser facility. The experimental results are compared with the plasma hydrodynamics and the particle-in-cell simulations to identify the acceleration mechanisms at play.
A robust optimization model for prosumer microgrids considering uncertainties in prosumer generation
Authors: Damisa Uyikumhe , Nwulu Nnamdi I. , Sun Yanxia
Published: December 2019

Recent times have seen the emergence of prosumers with undispatchable renewable onsite generators, which can complicate operational planning of grids. The complication can be exacerbated when prosumers have the leeway to export excess generation to the grid, which may necessitate the development of a new paradigm for the operational planning of prosumer grids. In this paper, a computationally tractable robust microgrid operational dispatch model that uses diesel generators, a battery, and interruptible loads to handle uncertainty in prosumer generation is proposed. Using the modified version of a microgrid in Guangdong Province, China, the CPLEX solver in the Advanced Interactive Multidimensional Modeling System environment is used to validate the effectiveness of the proposed model. The proposed robust model yields a higher objective function value than its deterministic counterpart; however, it guarantees system reliability under any realization of prosumer generation within specified bounds, which the deterministic model cannot guarantee. Further analysis shows that the optimal objective function value increases with the uncertainty level of prosumer generation.
The characteristic analysis of a nuclear magnetic resonance oscillator coupled with the phase-locked loop
Authors: Jiang Qiyuan , Wang Zhiguo , Zhan Xiang , Luo Hui , Zhang Yi , Li Jiajia
Published: December 2019

We analyze the scale factor linearity, steady-state, transient, and noise characteristics of a nuclear magnetic resonance oscillator coupled with the phase-locked loop, which makes its performance improvement possible by a balanced strategy in optimizing parameters based on the proposed model. The numerical simulation indicates that the simple oscillator system gives a better scale factor linearity and transient response than the coupled system, while the steady-state solution is similar between the two with experimental validation. The phase and magnetic noise suppression is necessary to ensure the dynamic response of the coupled system. The characteristic analysis not only facilitates the rapid-response optimization of the coupled oscillator system under a dynamic environment but also enlightens corresponding steady-state tracking precision.
Scattering for the 5D quadratic NLS system without mass-resonance
Authors: Wang Hua , Yang Qixiang
Published: December 2019

In this paper, we consider a 5D quadratic nonlinear Schrödinger system: iut + Δu = −2vū, ivt + kΔv = −u2, and (t, x) ∈ R × R5, k > 0. If k=12, we say the system satisfies the mass-resonance condition. Using the argument of Dodson and Murphy [Math. Res. Lett. 25, 1805 (2018)], we prove that the solution (u·v) scatters if initial data (u0, v0) ∈ H1(R5) × H1(R5) satisfy E(u0, v0)M(u0, v0) < E(Q1, Q2)M(Q1, Q2) and K(u0, v0)M(u0, v0) < K(Q1, Q2)M(Q1, Q2) and k lies in some small neighborhood of 12. Under the condition of radial initial data, the range of k can be extended to k > 0 based on the idea of Dodson and Murphy [Proc. Am. Math. Soc. 145, 4859 (2017)].
First principles calculation of interfacial stability, energy, and elemental diffusional stability of Fe (111)/Al2O3 (0001) interface
Authors: Wang Yu , Liu Xiaona , Yang Qiang , Liu Yaxin , Li Zhonghua , Guo Bingxin , Mao Hongkui , Misra R. D. K. , Xu Hong
Published: December 2019

First-principles calculation is widely used to study solid-solid interfaces, which provides insights into the atomic and electronic structure of an interface including the interfacial stability and adhesion strength. In general, the interface of the Fe/Al2O3 composite material is hardly wetted, and the aluminum oxide layer is firm and thin. It is difficult to observe the interface via an electron microscope. Thus, the changes at the interface were studied by first-principles calculations. Interfacial stability, energy of the Fe (111) surface, the Al2O3 (0001) surface, and Fe (111)/Al2O3 (0001) interfaces were studied using the first-principles calculation method. The work of adhesion (Wad), interface energy (γint), and the electronic structure of Fe (111)/Al2O3 (0001) interfaces were studied. The results indicated that Wad of the O-terminated interface was significantly larger than that of the Al-terminated interface. The O-terminated interface was the most stable interface. Furthermore, the O-terminated interface consisted of strong polar covalent bonds and weak metallic bonds, while the Al-terminated interface primarily consisted of covalent and metallic bonds. Furthermore, the segregation of Al atoms at the interface enhanced the stability of the interface structure, and interfacial bonding ability was increased with the increase in aluminum atoms. Only aluminum atoms diffused through the initial oxide layer forming intermetallic compounds on the iron side. The inclusion of Al2O3 significantly impacts the mechanical properties of steel, such as toughness and fatigue, underscoring that it is important to predict and control the inclusions in steel to obtain desired mechanical properties. The insights obtained from the study described here provide fundamental insights and guidelines into tailoring the steel/aluminum composite interface.
Cryogenic ion vibrational predissociation (CIVP) spectroscopy of a gas-phase molecular torsion balance to probe London dispersion forces in large molecules
Authors: Tsybizova Alexandra , Fritsche Lukas , Gorbachev Vladimir , Miloglyadova Larisa , Chen Peter
Published: December 2019

We report a gas-phase molecular torsion balance that uses a conformational equilibrium to “weigh” London dispersion against a competing cation-π interaction, for which the readout is the shift in an N–H stretching frequency measured by cryogenic ion vibrational predissociation (CIVP) spectroscopy of electrosprayed pyridinium cations in a Fourier-transform ion cyclotron resonance trap. While frequency calculations with DFT, within the harmonic approximation, assist in the interpretation of the spectra, the observed complex spectrum most likely comes from a Fermi resonance of the N–H stretch with otherwise “dark” overtones of in-plane C–H wagging modes, as argued on the basis of comparison of the spectrum to those for a range of related cations with systematically varied substitution. An equilibrium in favor of the asymmetric conformer would suggest that the dispersion-corrected DFT calculations tested in this work appear to overestimate significantly the stability of the compact conformations favored by London dispersion in the gas phase, which would then pertain to the use of dispersion energy donors in the design of stereoselective reactions.
Long-range corrected exchange-correlation kernels to describe excitons in second-harmonic generation
Authors: Gauriot Nicolas , Véniard Valérie , Luppi Eleonora
Published: December 2019

We investigate the role of excitons in second-harmonic generation (SHG) through the long-range corrected (LRC) exchange-correlation kernels: empirical LRC, Bootstrap, and jellium-with-a-gap model. We calculate the macroscopic second-order frequency-dependent susceptibility χ(2). We also present the frequency-dependent macroscopic dielectric function ϵM which is a fundamental quantity in the theoretical derivation of χ(2). We assess the role of the long-range kernels in describing excitons in materials with different symmetry types: cubic zincblende, hexagonal wurtzite, and tetragonal symmetry. Our studies indicate that excitons play an important role in χ(2) bringing a strong enhancement of the SHG signal. Moreover, we found that the SHG enhancement follows a simple trend determined by the magnitude of the long-range corrected α-parameter. This trend is material dependent.
Polymer physics across scales: Modeling the multiscale behavior of functional soft materials and biological systems
Authors: Spakowitz Andrew J.
Published: December 2019

Polymeric materials are ubiquitous in our daily lives, and they play a significant role in many technological applications. The general predictive framework for the behavior of soft polymeric materials can be divided into two vastly different approaches. Highly coarse-grained models capture polymers as flexible random walks, resulting in general predictions of physical behavior but lack chemical specificity. Detailed atomistic models contain molecular detail but are frequently computationally intractable for exhaustive materials discovery. In this perspective, we discuss theoretical models that successfully bridge these disparate approaches. We identify intermediate-scale physical models that are amenable to theoretical analyses while containing sufficient granular detail to capture a range of molecular-level processes. We then provide several problems in materials engineering and biological physics where multiscale physics is essential in their behavior.
Broadband vibration energy harvesting for wireless sensor node power supply in train container
Authors: Wang Lu , Luo Guoxi , Jiang Zhuangde , Zhang Fuzheng , Zhao Libo , Yang Ping , Lin Qijing , Maeda Ryutaro
Published: December 2019

Wireless sensor nodes (WSNs) for temperature and humidity monitoring are commonly used in a cold chain logistics container. Energy harvesting technology is expected to realize the sustainable self-power supply for the WSN. Low amplitude and broadband vibration energy harvesting performance are the key points in train application. In this study, two piezoelectric vibration energy harvesters (PVEHs) are designed and simulated via COMSOL. Their low resonant frequencies and high electromechanical sensitivities are realized by big L-shaped mass blocks with different material densities. Their broadband vibration energy harvesting performance is achieved by the stopper and series connection. Experimental data are shown at an acceleration of 0.5 m/s2; PVEH-1 and PVEH-2 have maximum powers of 0.24 mW and 0.1 mW when excited at the resonant frequencies of 13.1 Hz and 18.8 Hz, respectively, and they both have the optimal load resistance of 40 kΩ. Two circuit design styles of two PVEHs, independent and series styles, are proposed for broadband vibration energy harvesting. Experimental results show that the series style has a wider operating frequency bandwidth and shorter charging time. Two PVEHs in series style can be effectively used for power supply of the temperature and humidity WSN in the broadband frequency range of 8.7–22.0 Hz above charging root mean square voltage of 5 V at the acceleration of 3.0 m/s2. This scheme is promised to be applied to the cold chain logistics train container.
Methods for reducing write error rate in voltage-induced switching having prolonged tolerance of voltage-pulse duration
Authors: Matsumoto R. , Imamura H.
Published: December 2019

Simulating the magnetization dynamics in a perpendicularly-magnetized free layer with Langevin equation, we investigated methods for reducing write error rate (WER) in voltage-induced switching with long tolerance of voltage-pulse duration (tp). The simulation results show that WER can be reduced by increasing the perpendicular anisotropy (Ku) before and after the application of voltage or by increasing both Ku and the in-plane external magnetic field.
Nanoscale structural evaluation of 0-3 magnetic nanocomposites fabricated by electro-infiltration
Authors: Smith Connor S. , Mills Sara C. , Savliwala Shehaab , Rinaldi Carlos , Andrew Jennifer , Arnold David P.
Published: December 2019

Magnetic nanocomposites with 0-3 connectivity, whereby a 0D magnetic nanoparticle phase is embedded into a 3D magnetic metal matrix phase, have gained increased interest for use in applications ranging from integrated power inductor cores to exchange-spring magnets. The electro-infiltration process, in which a metal phase is electroplated through a nanoparticle film phase, is an inexpensive approach compatible with semiconductor fabrication methods for the formation of these nanocomposites. Past demonstrations of electro-infiltrated nanocomposites have relied on scanning electron microscopy and energy dispersive x-ray spectroscopy to evaluate the 0-3 composite structure. However, a detailed investigation of the boundary between the particle and metal matrix phases cannot be performed with these tools, and it is unknown whether the particle/matrix interfaces are dense and void-free. This detail is critical, as the presence of even nanoscale voids would affect any potential magnetic exchange coupling and hence the overall electromagnetic properties of the material. This work seeks to explore the phase boundary of 0-3 magnetic nanocomposite fabricated by electro-infiltration by using scanning transmission electron microscopy and energy-dispersive x-ray spectroscopy to analyze the nanostructure of two different composites—a nickel/iron-oxide composite and a permalloy/iron-oxide composite. High-resolution imaging indicates that the interface between the particle phase and matrix phase is dense and void-free. These results will help guide future studies on the design and implementation of these magnetic nanocomposites for end applications.
Fabrication of micro lens array on diamond surface
Authors: Liu Zongchen , Abbasi Haris Naeem , Zhu Tian-Fei , Wang Yan-Feng , Fu Jiao , Wen Feng , Wang Wei , Fan Shuwei , Wang Kaiyue , Wang Hong-Xing
Published: December 2019

Fabrication of microlenses on a diamond surface is an important way to enhance the performance of the embedded nitrogen vacancy (NV) center which is a promising single light source for quantum communication and quantum-based detection. In this work, lenses with a micrometer diameter were fabricated on a diamond surface by using the inductively coupled plasma (ICP) etching technique with a mask of polystyrene (PS) balls. First, 1 µm diameter PS balls were dispersed on the surface of deionized water. Then, the balls were transferred onto a diamond surface. Third, the sample was treated using the ICP technique to form microlenses. By increasing ICP etching time, the surface of fabricated microlenses became smoother. The simulation results demonstrate that the microlenses can greatly improve the photon collection efficiency of the embedded NV center and focus more excitation light to the NV center than bulk diamond.
Diatomic Rovibronic Transitions as Potential Probes for Proton-to-Electron Mass Ratio Across Cosmological Time
Authors: Syme Anna-Maree , Mousley Adam , Cunningham Maria , McKemmish Laura K.
Published: December 2019

Astrophysical molecular spectroscopy is an important method of searching for new physics through probing the variation of the proton-to-electron mass ratio, μ, with existing constraints limiting variation to a fractional change of less than 10−17per year. To improve on this constraint and therefore provide better guidance to theories of new physics, new molecular probes will be useful. These probes must have spectral transitions that are observable astrophysically and have different sensitivities to variation in the proton-to-electron mass ratio. Here, we concisely detail how the set of potential molecular probes and promising sensitive transitions is constrained based on how the frequency and intensity of these transitions align with available telescopes. Our detailed investigation focuses on rovibronic transitions in astrophysical diatomic molecules, using the spectroscopic models of 11 diatomics to identify sensitive transitions and probe how they generally arise in real complex molecules with many electronic states and fine structure. While none of the 11 diatomics investigated have sensitive transitions likely to be astrophysically observable, we have found that at high temperatures (1000K) five of these diatomics have a significant number of low intensity sensitive transitions arising from an accidental near-degeneracy between vibrational levels in the ground and excited electronic states. This insight enables screening of all astrophysical diatomics as potential probes of proton-to-electron mass variation, with CN, CP, SiN and SiC being the most promising candidates for further investigation for sensitivity in rovibronic transitions.
An integrated framework for predicting the risk of experiencing temperature conditions that may trigger late-maturity alpha-amylase in wheat across Australia
Authors: Armstrong Robert N. , Potgieter Andries B. , Mares Daryl J. , Mrva Kolumbina , Brider Jason , Hammer Graeme L.
Published: December 2019

Late-maturity alpha-amylase (LMA) is a key concern for Australia’s wheat industry because affected grain may not meet receival standards or market specifications, resulting in significant economic losses for producers and industry. The risk of LMA incidence across Australia’s wheatbelt is not well understood; therefore, a predictive model was developed to help to characterise likely LMA incidence. Preliminary development work is presented here based on diagnostic simulations for estimating the likelihood of experiencing environmental conditions similar to a potential triggering criterion currently used to phenotype wheat lines in a semi-controlled environment. Simulation inputs included crop phenology and long-term weather data (1901–2016) for >1750 stations across Australia’s wheatbelt. Frequency estimates for the likelihood of target conditions on a yearly basis were derived from scenarios using either: (i) weather-driven sowing dates each year and three reference maturity types, mimicking traditional cropping practices; or (ii) monthly fixed sowing dates for each year. Putative-risk ‘footprint’ maps were then generated at regional shire scale to highlight regions with a low (<33%), moderate (33–66%) or high (>66%) likelihood of experiencing temperatures similar to a cool-shock regime occurring in the field. Results suggested low risks for wheat regions across Queensland and relatively low risks for most regions across New South Wales, except for earlier planting with quick-maturing varieties. However, for fixed sowing dates of 1 May and 1 June and varying maturity types, the combined footprints for moderate-risk and high-risk categories ranged from 34% to 99% of the broad wheat region for South Australia, from 12% to 97% for Victoria, and from 9% to 59% for Western Australia. A further research component aims to conduct a field validation to improve quantification of the range of LMA triggering conditions; this would improve the predictive LMA framework and could assist industry with future decision-making based on a quantifiable LMA field risk.
Time allocation to resources by three species of rats (Rattus spp.) in a radial arm maze
Authors: Witmer Gary W. , Snow Nathan P. , Moulton Rachael S.
Published: December 2019

Abstract ContextIntroduced rats (Rattus spp.) can pose a serious threat to native flora and fauna, especially on islands where most species have evolved in the absence of terrestrial predators. Effective detection and eradication methods for introduced rats are essential to the maintenance of insular ecosystem integrity. Thus, it is important to better understand the behaviour of rats when they first arrive in a new setting. AimsTo determine whether rats would find some novel stimuli to be significantly more attractive than other novel stimuli. MethodsAn eight-arm radial maze was used to study the behaviour of three species of Rattus finding themselves in a novel environment with various familiar and unfamiliar stimuli. Key resultsAlthough there were some differences in responses by species and by sex, most rats sought out and spent considerable time in the den box, suggesting an immediate need for security when in an unfamiliar setting. Rats also sought out faeces of conspecifics, suggesting the need for social contact or reproduction. The rats, which had not been food deprived, did not seem interested in food sources, although there was some attraction to the water source. ImplicationsThe management implications of the present study’s results are two-fold. First, appears that detection of newly arriving rats on islands would be aided by strategic placement of den boxes that are highly acceptable to rats. Managers could then inspect the den boxes periodically (or use a remote sensing system) for evidence of rat presence. Second, the den boxes could be scented with the faeces of other rats to further attract invading rats to the den boxes. This protocol might also hold the rats near the invasion site for a longer period of time before they begin seeking other shelter, food sources or mates. These protocols could give managers increased opportunities to detect any newly invading rats, and potentially increase the available time to deploy a rapid response to the invasion, before the animals begin to widely disperse. Of course, the rats will ultimately seek a source of palatable food, so placing durable, yet palatable, rodenticide bait in the den boxes might further decrease the probability of the invaders establishing a self-sustaining population.
Quality of the early childhood education environment and interactions, and their relationship with time dedicated to free play (Calidad del entorno y de las interacciones en educación infantil y su relación con el tiempo dedicado al juego libre)
Authors: Morales-Murillo Catalina-Patricia , Grau-Sevilla María-Dolores , McWilliam R. A. , García-Grau Pau
Published: December 2019

This study evaluated the quality of early childhood education (ECE) environments, the quality of teacher-child interactions and the duration of free play in 22 ECE classrooms in the Valencian Community, Spain. Twenty-two ECE teachers of four- and five-year-old preschoolers participated in the study. The quality of ECE environments and teacher-child interactions were evaluated using the ECERS-3 and TSRS, respectively. The time children spent in free play and non-free play was also registered. The study concluded that the quality of ECE environments was minimal. The scores of teachers on emotional support were in the medium-high range and scores in instructional support were low, with direct instruction as the predominant teaching style. Indoor free play was positively related to the overall quality of ECE environments and the quality of teacher-child interactions. The findings of this study are discussed in relation to the results of other studies in the Spanish context.
Quantum empathy: an alternative narrative for global transcendence
Authors: Pavlovich Kathryn
Published: December 2019

This paper proposes an alternative narrative for global transcendence that has spirituality at the core of shaping society. It draws on contemplative practices such as mindfulness, reflexivity and empathy that may contribute to closing the gap between self and other. From these practices, I argue that we have the ability to tap into the harmonic frequency of the universe (quantum empathy) that may bridge across, through and beyond boundaries to link our human experience. At this quantum level, empathy is an entangled, interconnected and indeterminate shared existence that may support the ethical shift in human consciousness. This view of spirituality as a macrolevel organizing mechanism does not present a tool-kit for organizational change, but rather offers a provocation of future system-level possibilities abducted from leading-edge science.