bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reference dosimetry of modulated and dynamic photon beams
Authors: Bouchard Hugo 
Published: January 2021

Abstract
In the late 1980s, a new technique was proposed that would revolutionize radiotherapy. Now referred to as intensity-modulated radiotherapy, it is at the core of state-of-the-art photon beam delivery techniques, such as helical tomotherapy and volumetric modulated arc therapy. Despite over two decades of clinical application, there are still no established guidelines on the calibration of dynamic modulated photon beams. In 2008, the IAEA-AAPM work group on nonstandard photon beam dosimetry published a formalism to support the development of a new generation of protocols applicable to nonstandard beam reference dosimetry (Alfonso et al 2008 Med. Phys.
35 5179–86). The recent IAEA Code of Practice TRS-483 was published as a result of this initiative and addresses exclusively small static beams. But the plan-class specific reference calibration route proposed by Alfonso et al (2008 Med. Phys.
35 5179–86) is a change of paradigm that is yet to be implemented in radiotherapy clinics. The main goals of this paper are to provide a literature review on the dosimetry of nonstandard photon beams, including dynamic deliveries, and to discuss anticipated benefits and challenges in a future implementation of the IAEA-AAPM formalism on dynamic photon beams.
Inverse treatment planning for an electronic brachytherapy system delivering anisotropic radiation therapy
Authors: Badali Daniel S , Vainer Yonatan , Ellenor Christopher W , Mitchell Christopher R , Fishman Kalman , Soro Nicolas , Price Russ , Funk Tobias 
Published: January 2021

Abstract
An inverse radiation treatment planning algorithm for Sensus Healthcare’s SculpturaTM electronic brachytherapy system has been designed. The algorithm makes use of simulated annealing to optimize the conformation number (CN) of the treatment plan. The highly anisotropic dose distributions produced by the SculpturaTM x-ray source empower the inverse treatment planning algorithm to achieve highly conformal treatment plans for a wide range of prescribed planning target volumes. Over a set of 10 datasets the algorithm achieved an average CN of 0.79 ± 0.08 and an average gamma passing rate of 0.90 ± 0.10 at 5%/5 mm. A regularization term that encouraged short treatment plans was used, and it was found that the total treatment time could be reduced by 20% with only a nominal reduction in the CN and gamma passing rate. It was also found that downsampling the voxelized volume (from 3203 to 643 voxels) prior to optimization resulted in a 150× speedup in the optimization time (from 2 + minutes to < 1 s) without affecting the quality of the treatment plan.
Video-based sleep detection using ocular signals under the standard conditions of the maintenance of wakefulness test in patients with sleep disorders
Authors: Kratzel Lucas , Glos Martin , Veauthier Christian , Rekow Sven , François Clémentine , Fietze Ingo , Penzel Thomas 
Published: January 2021

Abstract

Objective. Excessive sleepiness is a physiological reaction to sleep deficiency but can also be caused by underlying medical conditions. Detecting sleep is essential in preventing accidents and for medical diagnostics. Polysomnography (PSG) is considered the gold standard for the detection of sleep. More convenient video-based methods for detecting sleepiness have recently emerged. Approach. The possibility of detecting sleep using video-based ocular signals will be assessed using PSG for reference. Ocular signals and EEG are recorded in parallel under the conditions of the maintenance of wakefulness test (MWT) in 30 patients with sleep disorders. Main results. In detecting sleep, the ocular signal percentage of eyelid closure (PERCLOS) is superior to other ocular signals, resulting in an area under the curve of 0.88. Using a PERCLOS cutoff value of 0.76, sleep is correctly detected with a sensitivity of 89%, a specificity of 76%, the sleep latency is moderately correlated to the reference (rho = 0.66, p < 0.05) and the 95% confidence interval is ±21.1 min. Significance. Ocular signals can facilitate the detection of sleep under the conditions of the MWT but sleep detection should not solely rely on ocular signals. If PSG recordings are not practicable or if a signal is needed that responds relatively early in the wake/sleep transition, the use of PERCLOS for the detection of sleep is reasonable.
Phase relation between rotating phase locked (2, 1) and (3, 1) tearing modes in ASDEX Upgrade
Authors: Gude A , Maraschek M , Igochine V , Sieglin B , Willensdorfer M , Zohm H 
Published: January 2021

Abstract
Tearing modes are a major concern for large tokamak devices. Therefore their detection and characterization is of importance for timely countermeasures to avoid significant impact on the discharge or at least prevent possible machine damage. In case of phase-locked tearing modes, the poloidal variation of induced magnetic field fluctuation depends on the amplitudes of and the phase difference between the individual modes. This affects mode detection and identification when not considered appropriately. The phase between phase-locked (2, 1) and (3, 1) tearing modes in ASDEX Upgrade has been determined from local electron temperature and magnetic measurements independently. It is shown that the modes can be in phase at any poloidal position starting from the low field side plasma midplane over the plasma top to the high field side midplane. This observation invalidates the widespread assumption that phase-locked tearing modes are in phase near the low field side midplane. Dependence of the in-phase position on both, the plasma pressure and the plasma rotation velocity, is observed.
Estimation of plasma parameters in a pre-breakdown ionization wave at the glow discharge ignition in argon
Authors: Dyatko N A , Ionikh Y Z , Meshchanov A V 
Published: January 2021

Abstract
The results of an experimental study of a pre-breakdown (slow) ionization wave (IW) in argon-filled discharge tubes of 15 mm i.d. and 80 and 100 cm length at a pressure of 1 and 4 Torr are presented. The breakdown and the IW were initiated by a positive voltage pulse with an amplitude of 2 and 4 kV. The IW was detected by the light emitted from its front. The IW emission spectrum consisted of the argon atomic and ion lines. The Ar(763.5 nm) and Ar+(488.0 nm) lines were used to retrieve the electric field strength value in the IW front. For this, the intensity ratio of these lines was measured. The upper levels for these lines are excited by electron impact, and, due to a large difference between their excitation energies, this ratio strongly depends on the reduced electric field strength E/N (E is the electric field strength, N is the atom number density). Theoretical modeling makes it possible to find a relation between the line intensity ratio and the E/N value. In the model, the axial profile of the IW electric field is approximated by a rectangle with a width determined from the measured emission intensity waveform and the wave velocity. As a result, the E/N magnitude in the IW front was found for various positions along the tube. Emission intensity of the DC discharge was also measured, which allowed us to estimate the emitting level population and electron number density in the IW front. The density of seed electrons ahead of the wave is also evaluated and processes responsible for the appearance of these electrons are discussed.
Local electron and ion density control using passive resonant coils in inductively coupled plasma
Authors: Kim Tae-Woo , Lee Moo-Young , Hong Young-Hun , Lee Moo-Hyun , Kim Ju-Ho , Chung Chin-Wook 
Published: January 2021

Abstract
Control of local electron and ion density using passive resonant coils is experimentally investigated in an inductive argon discharge. Four passive resonant coils are installed under a powered coil; each coil has a fan shape and good azimuthal symmetry. Electron energy probability functions and two-dimensional ion density profiles were measured under both resonant and non-resonant regimes. At non-resonance, almost all of the current flows through the powered coil located in the center of the reactor, and the profiles of the electron and ion density are convex. However, at resonance, a large current flows through the passive resonant coil, and dramatic changes are observed in the electron and ion density profiles. At resonance, the electron and ion densities near the passive resonant coil are increased by 300% compared to the non-resonant condition, and radial distributions become almost flat. Experimental results show that the electron and ion density profiles can be effectively controlled by a passive resonant coil at both low pressure (5 mTorr) and high pressure (50 mTorr). These changes in electron and ion density profiles can be understood by the changes of the electron heating and ionization regions.
Effects of RF bias frequency and power on the plasma parameters and ash rate in a remote plasma source
Authors: Zhang Aixian , Lee Moo-Young , Lee Ho-Won , Moon Ho-Jun , Chung Chin-Wook 
Published: January 2021

Abstract
The effects of the RF bias frequency (2–27.12 MHz) and power (0–50 W) on plasma parameters, i.e., effective electron temperatures, electron densities, and electron energy probability functions (EEPFs), were investigated in a remote plasma source. A small cylindrical Langmuir probe based on the Druyvesteyn method was used for the measurements. When the bias power was changed from 0 W to 10 W for each bias frequency, the electron density decreased and the effective electron temperature increased at a given antenna power. As the 2 MHz bias power increased to 50 W, the electron density increased remarkably, whereas the effective electron temperature decreased. Simultaneously, the EEPF evolved from a Druyvesteyn-like distribution to a nearly Maxwellian distribution. In contrast to 2 MHz, when increasing the bias power of 12.5 MHz or 27.12 MHz, there was no distinct change in the effective electron temperature by the bias power and the electron density increased slightly or barely changed. Moreover, the EEPFs retained a Druyvesteyn-like distribution during the bias power increase. These results reveal that the plasma parameters are more controllable at lower bias frequencies, and the analysis is presented in relation to the electron heating mechanism. Therewithal, the ash rate for a 2 MHz bias power was observed to be the highest among the three frequencies when the discharge was operated with pure oxygen.
Cantilever-based micro thrust measurement and pressure field distribution of biomimetic robot fish actuated by macro fiber composites (MFCs) actuators
Authors: Meng Haofeng , Lou Junqiang , Chen Tehuan , Xu Chao , Chen Hairong , Yang Yiling , Cui Yuguo 
Published: January 2021

Abstract
Underwater autonomous vehicles (UAVs) actuated by smart actuators have attracted increasing attention. A miniature macro fiber composite (MFC)-actuated robot fish inspired by koi fish is developed. A cantilever mechanism is designed to transfer the dynamic micro thrust of the robot fish. Three design indexes, namely the bending stiffness, the ratio of the bending stiffness to the torsional stiffness, and the natural frequency of the cantilever transducer are proposed. Thus, a simple and effective method to determine the structural parameters of the cantilever-based micro thrust force measurement system is presented. Calibration results demonstrated that the parameters of the proposed cantilever transducer match well with the designed indexes. Dynamic variation mechanisms of the micro thrust force associated with the swimming behaviors of the robot fish are well captured using the proposed measurement system. Experimental results show that the MFC-actuated robot fish obtains the biggest mean thrust of 1.73 mN in the case of the largest oscillating velocity. The maximum instant thrust grows with the increment of the oscillating frequency, and achieves its maximum of 7.35 mN in the case of 10 Hz. While the maximum instant drag first decreases then increases as the actuation frequency increases, and obtains its minimum of −2.62 mN in the case of the maximum oscillating velocity. On the contrary, variations of the thrust pattern/oscillating period are reversed to those of the maximum instant drag. Computational fluid dynamics results demonstrate that variations of the instant thrust are fully determined by the distribution and intensity of the concentrated pressure regions induced by the oscillating caudal fin. The cycle-averaged velocity fields are closely related to the mean thrust generated by the MFC-actuated robot fish. As a result, the fluid–structure interaction mechanisms associated with the thrust variations of the MFC-actuated robot fish are revealed. This study may be useful for the design and realization of UAVs actuated by smart actuators.
Electromagnetic-thermal-mechanical behaviors of a no-insulation double-pancake coil induced by a quench in the self field and the high field
Authors: Liu Donghui , Li Dongke , Zhang Weiwei , Yong Huadong , Zhou Youhe 
Published: January 2021

Abstract
High-temperature superconducting double-pancake (DP) coils wound by the no-insulation (NI) approach have been proved to have a high thermal stability and a self-protecting ability. This paper mainly studies the effect of a quench of one pancake coil on the electromagnetic-thermal-mechanical behaviors of an NI DP coil in the self field and the high field. An electromagnetic-thermal coupling quench model is used to calculate the distributions of current, temperature and electromagnetic field in the coil, and then a three-dimensional homogeneous mechanical model is built to analyze the changes in strain and stress during a quench by considering the distributions of thermal strain and Lorentz force of the coil. The results indicate that the obvious increase in circumferential current and radial current density in the bottom pancake coil is induced by a quench of the top pancake coil due to the electromagnetic coupling effect in the self field and the high field, and that the DP coil still has a negative coil voltage during a quench in different fields. Although the bottom pancake coil has a large circumferential current, the mechanical deformation of the DP coil during a quench is mainly caused by the temperature rise in the self field. The thermal expansion of the top pancake coil has a remarkable effect on the mechanical behaviors of the bottom pancake coil. Moreover, the DP coil has the same temperature rise and mechanisms of bypass current in the self field and the high field. However, the mechanical deformation of the DP coil is based on the combined effects of temperature rise and Lorentz force in the high field. It can be found that the values of the hoop and axial stresses are affected by a large electromagnetic stress.
Thermal response of the iron-based Ba122 superconductor to in situ and ex situ processes
Authors: Tokuta Shinnosuke , Yamamoto Akiyasu 
Published: January 2021

Abstract
The thermal properties are one of the key parameters to control phase purity and microstructure of polycrystalline materials. The melting point of the iron-based BaFe2As2 superconductor (Ba122), which foresees high-field applications, remains controversial. In this work, thermogravimetry-differential scanning calorimetry measurements (TG-DSC) of undoped and Co-doped Ba122 were carried out. Mixtures of elemental metals and pre-reacted Ba122 powders were prepared to investigate the thermal responses during in situ and ex situ synthesis routes, respectively. In addition, the phases and microstructures of the quenched samples were evaluated to elucidate the observed exothermic/endothermic peaks. Our results suggest that the melting point of Ba122 is ∼1300 °C.
Enhancing the performance of superconducting nanowire-based detectors with high-filling factor by using variable thickness
Authors: Baghdadi Reza , Schmidt Ekkehart , Jahani Saman , Charaev Ilya , Müller Michael G W , Colangelo Marco , Zhu Di , Ilin Konstantin , Semenov Alexej D , Jacob Zubin , Siegel Michael , Berggren Karl K 
Published: January 2021

Abstract
Current crowding at bends of superconducting nanowire single-photon detector (SNSPD) is one of the main factors limiting the performance of meander-style detectors with large filling factors. In this paper, we propose a new concept to reduce the influence of the current crowding effect, a so-called variable thickness SNSPD, which is composed of two regions with different thicknesses. A larger thickness of bends in comparison to the thickness of straight nanowire sections locally reduces the current density and reduces the suppression of the critical current caused by current crowding. This allows variable thickness SNSPD to have a higher critical current, an improved detection efficiency, and decreased dark count rate in comparison with a standard uniform thickness SNSPD with an identical geometry and film quality.
Fiber optic quench detection for large-scale HTS magnets demonstrated on VIPER cable during high-fidelity testing at the SULTAN facility
Authors: Salazar Erica E , Badcock Rodney A , Bajko Marta , Castaldo Bernardo , Davies Mike , Estrada Jose , Fry Vincent , Gonzales Jofferson T , Michael Philip C , Segal Michael , Vieira Rui F , Hartwig Zachary S 
Published: January 2021

Abstract
Fiber-optic thermometry has the potential to provide rapid and reliable quench detection for emerging large-scale, high-field superconducting magnets fabricated with high-temperature-superconductor (HTS) cables. Developing non-voltage-based quench detection schemes, such as fiber Bragg grating (FBG) technology, are particularly important for applications such as magnetic fusion devices where a high degree of induced electromagnetic noise impose significant challenges on traditional voltage-based quench detection methods. To this end, two fiber optic quench detection techniques—FBG and ultra-long FBG (ULFBG)—were incorporated into two vacuum pressure impregnated, insulated, partially transposed, extruded, and roll-formed (VIPER) high-current HTS cables and tested in the SULTAN facility, which provides high-fidelity operating conditions to large-scale superconducting magnets. During surface heater induced quench-like events under a variety of operating conditions, FBG and ULFBG demonstrated strong signal-to-noise ratios (SNRs) ranging from 4 to 32 and measured single-digit temperature excursions; both the SNR and temperature sensitivity increase with temperature. Fiber thermal response times ranged between effectively instantaneous to a few seconds depending on the operating temperature. Strain sensitivity dominates the thermal sensitivity in the conditions achievable at SULTAN; however, measurements at higher quench evolution temperatures, coupled to future work to increase the thermal-to-strain signal, show promise for quench detection capability in full-scale magnets where temperature and strain may occur simultaneously. Overall, FBG and ULFBG were proven capable to quickly and reliably detect small temperature disturbances which induced quench initiation events for high current VIPER HTS conductors in realistic operating conditions, motivating further work to develop FBG and ULFGB quench detection systems for full-scale HTS magnets.
Uniform analysis of electronic sputtering in amorphizable and non-amorphizable insulators and semiconductors
Authors: Szenes G 
Published: January 2021

Abstract
Published experimental data on the variation of the Y sputtering yield with the Se electronic stopping power are analyzed. Systematic results for amorphizable (SiO2, SrCeO3, SrTiO3, CeO2) and non- amorphizable (LiF, KBr) insulators and semiconducting TiO2, ZnO, SiC, UO2 are used. Thermal activation mechanism of electronic sputtering is assumed. The ion-induced temperature is estimated applying the Analytical Thermal Spike Model. A highly accurate description of the experimental Y-Se data is given in the whole range of Se without the application of individual materials parameters apart the U activation energy. The values of U for SiO2 and UO2, are considerably lower than the Us sublimation energies. Sputtering proceeds without threshold of Se.
Green synthesis of zinc oxide nanostructure using Azadirachta Indica leaf extract and its structural and microstructural study
Authors: Barman Kanailal , Chakraborty Pinaki , Samanta Pijus K 
Published: January 2021

Abstract
A green synthesis method using Azadirachta Indica leaf extract has been used to synthesized ZnO nanostructures. TEM image confirmed the formation of nanoparticles of size in the range of ∼50–100 nm. The stochiometry was also confirmed from the EDX spectroscopy. The structural analysis of the synthesized material was performed using the x-ray diffraction (XRD) data. The ZnO nanocrystals exhibit wurtzite unit cell structure as revealed from the XRD pattern. The calculation of lattice parameters shows that the distortion in the structure is very small. The material is highly crystalline with crystallite size of 20.05 nm and microstrain of 5.926 × 10−4. In this context crystallinity index is also calculated. The growth of the crystal is anisotropic as observed from the intensity of the diffraction and was quantified through the parameter degree of orientation. The synthesized ZnO nanostructure has large specific surface area. Other crystal parameters like Zn–O bond length, u-parameter, crystal volume were also calculated form the XRD pattern and show the structural perfection of the grown nanocrystal with a good figure of merit. Raman-shift measurements showed the existence of various phonon vibrational modes of the ZnO lattice. The material being synthesized by green approach is non-toxic in nature and may have potential applications in nanomaterials based medicinal and therapeutic applications.
Ground state of ultracold atoms in a hexagonal ring lattice with synthetic magnetic field
Authors: Meng Hong-Juan , Wang Wen-Yuan , Shi Yu-Ren 
Published: January 2021

Abstract
Ultracold atoms with an artificial gauge field provide a powerful platform for studying physical problems in various fields. We investigate the ground state of ultracold atoms in a hexagonal ring lattice with a synthetic magnetic field. The system undergoes a quantum phase transition characterized by degenerate and nondegenerate ground states. The phase transition depends on the atomic interaction and magnetic flux. With the quantum phase transition, a very interesting quantum odd–even parity effect emerges. The parity effects depend on a repulsive or attractive atomic interaction regime.
Minimum variance control of chaos in a hyperchaotic memristor based oscillator using online particle swarm optimization
Authors: Setoudeh Farbod , Khaki Sedigh Ali 
Published: January 2021

Abstract
This paper introduces a new hyperchaotic oscillator base on a new boundary-restricted Hewlett-Packard memristor model. Firstly, the complex system is designed based on a memristor-based hyperchaotic real system, and its properties are analyzed by means of Lyapunov exponents, Lyapunov dimension and phase portraits diagrams. Secondly, a simple feedback control based on the minimum variance control technique is designed to stabilize the hyperchaotic oscillator system, which is one of the new developed approaches for controlling the chaos in high-dimensional hyperchaotic systems. In this method, the time series variance is considered for designing and calculating the state feedback control gain. Furthermore, the state feedback control is designed so that to minimize the variance as a cost function, followed by developing an online optimization technique using the particle swarm optimization method in order to calculate the state feedback control based on the minimum variance strategy. Then, the application of this method is examined on a hyperchaotic memristor-based oscillator. Finally, the sensitivity of the proposed method is evaluated in different initial conditions that greatly influence the hyperchaotic dynamics. Considering that the optimization is online, simulation results show highly good effectiveness of the presented technique in controlling the chaos in high-dimensional hyperchaotic oscillators