bluuebunny/crossref_metadata_2025 huggingface dataset:
Enantioselective Synthesis of α-Hydroxyamino Ketones by a Chiral Phosphine–Silver Complex Catalyzed N-Nitroso Aldol Reaction
Authors: Yanagisawa Akira , Kasahara Shiho , Takeishi Akihiro , Marui Tomoki
Published: October 2022

A catalytic asymmetric N-nitroso aldol reaction of alkenyl trifluoroacetates with nitrosoarenes was achieved using a DTBM-SEGPHOS·AgOTf complex as the chiral precatalyst and KHMDS as the base precatalyst in the presence of methanol. Optically active α-hydroxyamino ketones with up to 89% ee were regioselectively obtained in moderate to high yields not only from acyclic alkenyl esters but also from cyclic ones through the in situ generated chiral silver enolates.
TEMPus VoLA: The timed Epstein multi-pressure vessel at low accelerations
Authors: Capelo H. L. , Kühn J. , Pommerol A. , Piazza D. , Brändli M. , Cerubini R. , Jost B. , Bodénan J.-D. , Planchet T. , Spadaccia S. , Schräpler R. , Blum J. , Schönbächler M. , Mayer L. , Thomas N.
Published: October 2022

The field of planetary system formation relies extensively on our understanding of the aerodynamic interaction between gas and dust in protoplanetary disks. Of particular importance are the mechanisms triggering fluid instabilities and clumping of dust particles into aggregates, and their subsequent inclusion into planetesimals. We introduce the timed Epstein multi-pressure vessel at low accelerations, which is an experimental apparatus for the study of particle dynamics and rarefied gas under micro-gravity conditions. This facility contains three experiments dedicated to studying aerodynamic processes: (i) the development of pressure gradients due to collective particle–gas interaction, (ii) the drag coefficients of dust aggregates with variable particle–gas velocity, and (iii) the effect of dust on the profile of a shear flow and resultant onset of turbulence. The approach is innovative with respect to previous experiments because we access an untouched parameter space in terms of dust particle packing fraction, and Knudsen, Stokes, and Reynolds numbers. The mechanisms investigated are also relevant for our understanding of the emission of dust from active surfaces, such as cometary nuclei, and new experimental data will help interpreting previous datasets (Rosetta) and prepare future spacecraft observations (Comet Interceptor). We report on the performance of the experiments, which has been tested over the course of multiple flight campaigns. The project is now ready to benefit from additional flight campaigns, to cover a wide parameter space. The outcome will be a comprehensive framework to test models and numerical recipes for studying collective dust particle aerodynamics under space-like conditions.
Scattering properties of acoustic beams off spinning objects: Induced radiation force and torque
Authors: Farhat Mohamed , Guenneau Sebastien , Chen Pai-Yen , Wu Ying
Published: October 2022

Understanding the acoustic scattering and radiation force and torque of an object is important in various fields, such as underwater communication, acoustic imaging, and noninvasive characterization, as well as biomedical ultrasound. Generally, acoustic scattering is considered for static (non-moving) objects and the impinging signal is typically a plane wave. Here, we consider scattering off cylindrical objects in spinning motion around the axis of rotational symmetry. We investigate the radiation force and torque induced by various incident signals, e.g., cylindrical diverging and converging beams as well as quasi-Gaussian beams of different orders. It is assumed in this study (unless otherwise stated) that the acoustic parameters of the objects (density and compressibility) are identical to those of the surrounding medium, in order to isolate the effects purely attributed to rotation. The scenario of a spinning inhomogeneous object is also shown to play a prominent role for generating torque with single plane waves. Our findings may add to the current interest in time-varying and moving metamaterials and open vistas in manipulation of movement and position of ultra-small objects via acoustic beams.
Measurements of low-mode asymmetries in the areal density of laser-direct-drive deuterium–tritium cryogenic implosions on OMEGA using neutron spectroscopy
Authors: Forrest C. J. , Crilly A. , Schwemmlein A. , Gatu-Johnson M. , Mannion O. M. , Appelbe B. , Betti R. , Glebov V. Yu. , Gopalaswamy V. , Knauer J. P. , Mohamed Z. L. , Radha P. B. , Regan S. P. , Stoeckl C. , Theobald W.
Published: October 2022

Areal density is one of the key parameters that determines the confinement time in inertial confinement fusion experiments, and low-mode asymmetries in the compressed fuel are detrimental to the implosion performance. The energy spectra from the scattering of the primary deuterium–tritium (DT) neutrons off the compressed cold fuel assembly are used to investigate low-mode nonuniformities in direct-drive cryogenic DT implosions at the Omega Laser Facility. For spherically symmetric implosions, the shape of the energy spectrum is primarily determined by the elastic and inelastic scattering cross sections for both neutron-deuterium and neutron-tritium kinematic interactions. Two highly collimated lines of sight, which are positioned at nearly orthogonal locations around the OMEGA target chamber, record the neutron time-of-flight signal in the current mode. An evolutionary algorithm is being used to extract a model-independent energy spectrum of the scattered neutrons from the experimental neutron time-of-flight data and is used to infer the modal spatial variations (l = 1) in the areal density. Experimental observations of the low-mode variations of the cold-fuel assembly (ρL0 + ρL1) show good agreement with a recently developed model, indicating a departure from the spherical symmetry of the compressed DT fuel assembly. Another key signature that has been observed in the presence of a low-mode variation is the broadening of the kinematic end-point due to the anisotropy of the dense fuel conditions.
Spin filtering effect in intrinsic 2D magnetic semiconductor Cr2Ge2Te6
Authors: Feng Honglei , Shi Gang , Yan Dayu , Li Yong , Shi Youguo , Xu Yang , Xiong Peng , Li Yongqing
Published: October 2022

All van der Waals Fe3GeTe2/Cr2Ge2Te6/graphite magnetic heterojunctions have been fabricated via mechanical exfoliation and stacking, and their magnetotransport properties are studied in detail. At low bias voltages, large negative junction magnetoresistances have been observed and are attributed to spin-conserving tunneling transport across an insulating Cr2Ge2Te6 layer. With increasing bias, a crossover to Fowler–Nordheim tunneling takes place. The negative sign of the tunneling magnetoresistance suggests that the bottom of a conduction band in Cr2Ge2Te6 belongs to minority spins, opposite to the findings of some first-principles calculations. This work shows that the vdW heterostructures based on 2D magnetic insulators are a valuable platform to gain further insight into spin polarized tunneling transport, which is the basis for pursuing high performance spintronic devices and a large variety of quantum phenomena.
A high-performance quasi-vertical MoSe2 photodiode with ultra-low dark current
Authors: Zhu Xiaoxiao , Lu Wei , Ning Jing , Zhang Jincheng , Wang Dong , Zhang Chi , Wang Yanbo , Cui Xuan , Zhou Yu , Guo Haibin , Wang Yong , Hao Yue
Published: October 2022

Van der Waals heterostructure based on 2D materials is a promising technology for high-performance optoelectronic devices because of its tunable bandgaps and optical properties. However, photodetectors with a low dark current and a fast response speed commonly lose their photoresponsivity. The recovery current induced by the Schottky barrier height variation cancels out the device's reverse bias current in this paper, resulting in a quasi-vertical MoSe2 photodiode with ultralow dark current (<1 pA). Simultaneously, rapid electron–hole pair separation occurs at the interface due to the large heterojunction area and the strong interlayer coupling of MoSe2/graphene heterojunction, resulting in a fast response time of 1.5 ms and a high photoresponsivity of 19.72 A/W. Furthermore, the Au/MoSe2 forms a Schottky contact, which is asymmetrical to the Ohmic contact formed by the MoSe2/graphene, enabling the proposed device to achieve high-performance self-powered photodetection. Our work shows an alternative approach to improve the performance of future electronic and optoelectronic applications.
High-resolution time-resolved spectroscopy based on hybrid asynchronous optical sampling
Authors: Hu Hao , Yang Ningning , Liao Zichun , Chen Liao , Zhang Chi , Wang Weiqiang , Zhang Wenfu , Zhang Xinliang
Published: October 2022

The capability of characterizing arbitrary and non-repetitive emission spectra with a high resolution in real-time is of great merit in various research fields. Optical frequency combs provide precise and stable frequency grids for the measurement of a single spectral line with high accuracy. Particularly, dual-comb spectroscopy enables spectral measurement with a large bandwidth spanning tens of nanometers, but it is limited to measuring absorption spectra and has to trade-off spectral resolution vs the acquisition frame rate set by the repetition rate. Here, to alleviate these restrictions, we propose and demonstrate time-resolved spectroscopy for an emission spectrum based on hybrid asynchronous optical sampling, which features a spectral resolution of 0.63 pm, a frame rate of 1 MHz, and a measurement bandwidth of 13.6 nm, simultaneously. A mode-locked fiber comb with a repetition frequency of f1 is harnessed to interrogate emission spectral features with high resolution via optical Fourier transform achieved using a time-lens. Subsequently, a soliton microcomb of repetition frequency f2s ≈ 1000f1 serving as a probe pulse implements hybrid asynchronous optical sampling, thus significantly increasing the acquisition rate by nearly 3 orders of magnitude. As a proof-of-concept demonstration, the frequency trajectory of a rapidly scanning laser with a linear chirp of 6.2 THz/s is tracked. We believe that chip-scale microcombs will make the fast and high-resolution emission spectroscopy presented here a powerful tool for widespread applications.
“Genes” for material tailoring: Begin with the electron work function for MoC carbide modification—A first-principles study
Authors: Zhang Dong , Tang Y. Q. , Liu R. L. , Li D. Y. , Li Q. Y. , Li Wei
Published: October 2022

This article reports a study on the modification of bulk and Young's moduli of MoC carbide by partially substituting Mo with selected metallic elements, which influence the strengths and contributions of covalent, ionic, and metallic bond components to the overall atomic bonding of the carbide and thus its mechanical properties. Electron work function (EWF) analysis demonstrates that this parameter plays a promising role as an indicator similar to an encoded parameter with material “genetic” information for guiding the substitute selection. The higher the carbide's EWF, the higher are its bulk and Young's moduli. A substitute having a higher EWF generally enhances the covalent bonding at the expense of ionic bonding. The covalent bond plays a primary role in determining the carbide's strength, while the ionic bonding also contributes to the strength to some degree. A substitute having a higher EWF enhances the metallic bonding, which improves the carbide's strength as well, although such a contribution is minor.
Dependence of tip and hub vortices shed by a propeller with winglets on its load conditions
Authors: Posa A.
Published: October 2022

Large-eddy simulation on a cylindrical grid consisting of about 5 × 109 points is utilized to reproduce the wake of a five-bladed propeller with pressure side winglets. Computations are conducted across five values of the advance coefficient, to capture the dependence of the tip and hub vortices on the rotational speed of the propeller. The results demonstrate that the pressure minima at the core of all vortices grow more quickly than the rotational speed of the propeller, making them more problematic in terms of cavitation phenomena, acoustic signature, and stresses. Also, the instability of both tip and hub vortices is captured. It develops more quickly for increasing rotational speeds and is faster for the tip vortices than for the hub vortex, as demonstrated by the streamwise evolution of turbulent kinetic energy at the their core, which is non-monotonic: the initial decline of turbulence after the onset of both tip and hub vortices is followed by a rise, due to instability. This switch occurs faster at the core of the tip vortices than within the hub vortex.
Oxygen functionalized interface enables high MnO2 electrolysis kinetics for high energy aqueous Zn-MnO2 decoupled battery
Authors: Shi Xin , Liu Xinyue , Cao Xianshuo , Cheng Xiaoning , Lu Xihong
Published: October 2022

Aqueous Zn-based batteries show great potential in large scale energy storage system due to their low-cost and high-safety merits. However, the practical application of Zn-based batteries is restricted by their inferior energy and power densities, which is resulted from the low output voltage and poor reaction kinetics of cathode materials. To address the above issues, we propose a decoupled aqueous Zn–Mn battery with high-rate and high-voltage by using oxygen functionalized carbon nanotubes (OCNTs) substrate. The functional interface can greatly improve the wettability of the electrode, promote the ion transport capability, and facilitate the rapid deposition/dissolution of MnO2/Mn2+. Consequently, the OCNTs/MnO2 electrode can deliver a high capacity of 9.2 mA h cm−2 and superior capacity retention of 86.6% at an ultrahigh current density of 200 mA cm−2. When coupled with Zn anode, the Zn//OCNTs/MnO2 decoupled full battery exhibits a high discharge plateau (∼2.45 V) and area specific capacity (1.96 mA h cm−2) at a current density of 2 mA cm−2. Moreover, the outstanding peak power density of 13.4 kW kg−1 and peak energy density of 564.4 W h kg−1 can be achieved for Zn//OCNTs/MnO2 battery (based on the mass of active material involved in the reaction on the positive and negative electrodes during charge and discharge), far beyond currently reported aqueous electrochemical energy storage devices. This work provides a train of thoughts for the development of high energy and power density aqueous batteries.
Impedance response of electrochemical interfaces. III. Fingerprints of couplings between interfacial electron transfer reaction and electrolyte-phase ion transport
Authors: Li Chen Kun , Zhang Jianbo , Huang Jun
Published: October 2022

Electron transfer (ET), electric double layer (EDL) charging, and ion transport (IT) are three elementary physicochemical processes in electrochemistry. These processes are coupled with each other in the way that the local reaction environment for the ET is shaped by EDL charging, which is nothing but IT in a nanoscale nonelectroneutral region. Herein, we investigate fingerprints of the coupling between these processes in electrochemical impedance spectroscopy. EDL charging and IT are described uniformly using the Poisson–Nernst–Planck theory, and interfacial ET is described using the Frumkin–Butler–Volmer theory. Different diffusion coefficients for cations and anions (D+ ≠ D−) are considered. Exact analytical expressions are obtained when the potential of zero charge (Epzc), the equilibrium potential of the reaction (Eeq), and electrode potential (EM) are equal. The analytical solution shows that a decoupling treatment is valid only for the case of D+ = D−. Using a new scheme of calculating impedance response at any electrode potential, we observe an inductive loop in the low frequency range, which is a clear impedance fingerprint of the coupling effects.
A 44-y perspective on the influence of cash on Ju/‘hoansi Bushman networks of sharing and gifting
Authors: Wiessner Polly , Huang Cindy Hsin-yee
Published: October 2022

Money has been portrayed by major theorists as an agent of individualism, an instrument of freedom, a currency that removes personal values attached to things, and a generator of avarice. Regardless, the impact of money varies greatly with the cultural turf of the recipient societies. For traditional subsistence economies based on gifting and sharing, surplus perishable resources foraged from the environment carry low costs to the giver compared with the benefits to the receiver. With cash, costs to the giver are usually the same as benefits to the receiver, making sharing expensive and introducing new choices. Using quantitative data on possessions and expenditures collected over a 44-y period from 1974 to 2018 among the Ju/’hoansi (!Kung) in southern Africa, former hunter-gatherers, we look at how individuals spend monetary income, how a partial monetary economy alters traditional norms and institutions (egalitarianism, gifting, and sharing), and how institutions from the past steer change. Results show that gifting declines as cash is spent to increase the well-being of individual families and that gifting and sharing decrease and networks narrow. The sharing of meals and casual gifting hold fast. Substantial material inequalities develop, even between neighbors, but social, gender, and political equalities persist. A strong tradition for individual autonomy combined with monetary income allows individuals to spend their money as they choose, adapt to modern conditions, and pursue new options. However, new challenges are emerging to develop greater community cooperation and build substantial and sustainable economies in the face of such centrifugal forces.
The insubordinated infinitive in Makhuwa-Enahara and the expression of feelings
Authors: Kruijsdijk Iris , van der Vlugt Nina , van der Wal Jenneke
Published: October 2022

This study sets out to investigate the insubordinated infinitive in the Bantu language Makhuwa-Enahara (P31, northern Mozambique), which is used with feeling predicates that have passive experiencers. The expression of bodily feelings and emotions in Makhuwa serves as a foundation, highlighting the unique formal and interpretational properties of the insubordinated infinitive within the domain of feelings.
A table named James or a table named Maya?
Authors: Kurz Pia I. , Gonner Coleen , Bartnicka Monika Magdalena , De Mulder Hannah N. M.
Published: October 2022

In French, the noun apple (la pomme) is grammatically feminine, in German (der Apfel) it is masculine. Does this entail that French speakers perceive apples to be feminine whereas German speakers attribute masculine characteristics to them? Various studies suggest that grammatical gender does indeed influence object perception (Haertlé 2017; Boroditsky & Schmidt 2000), although findings are not always replicated (Bender et al. 2011). The current study investigates this phenomenon for Polish, an understudied language in this domain, and German, a language for which contradictory results have been obtained. We investigated whether Polish (N = 21) and German (N = 27) speakers follow the grammatical gender of an object when providing a first name for it (e.g. James or Maya). Results suggest that while Polish speakers provided names that were in accordance with the object’s grammatical gender, German speakers did not. Cross-linguistic differences between these two languages (regarding noun transparency) may explain these findings.
Addition, restriction, iteration
Authors: Reuneker Alex
Published: October 2022

Conditional clauses in Dutch can be accompanied by focus particles, as in zelfs als ‘even if’ and
alleen als ‘only if’. The literature focuses on these additive and restrictive particles, because they may
influence the truth-conditional meaning of the sentence, which is uncommon for particles. Most of these studies are not based on
empirical language data, or draw largely from formal written texts in English. This study investigates which focus particles occur
in Dutch conditionals, and to which extent their uses are associated with spoken and written modes and with formal and informal
registers. It is shown that restrictive and additive particles are most frequent in formal written texts, and that a third type of
particle exists, which adds iterative meaning to the conditional, as in telkens als ‘everytime if [when]’. The
results show this type of particles to be associated with informal spoken texts.
Mutations within the selectivity filter reveal that Kv1 channels have distinct propensities to slow inactivate
Authors: Wu Xiaosa , Gupta Kanchan , Swartz Kenton J.
Published: October 2022

Voltage-activated potassium (Kv) channels open in response to membrane depolarization and subsequently inactivate through distinct mechanisms. For the model Shaker Kv channel from Drosophila, fast N-type inactivation is thought to occur by a mechanism involving blockade of the internal pore by the N-terminus, whereas slow C-type inactivation results from conformational changes in the ion selectivity filter in the external pore. Kv channel inactivation plays critical roles in shaping the action potential and regulating firing frequency, and has been implicated in a range of diseases including episodic ataxia and arrhythmias. Although structures of the closely related Shaker and Kv1.2 channels containing mutations that promote slow inactivation both support a mechanism involving dilation of the outer selectivity filter, mutations in the outer pores of these two Kv channels have been reported to have markedly distinct effects on slow inactivation, raising questions about the extent to which slow inactivation is related in both channels. In this study, we characterized the influence of a series of mutations within the external pore of Shaker and Kv1.2 channels and observed many distinct mutant phenotypes. We find that mutations at four positions near the selectivity filter promote inactivation less dramatically in Kv1.2 when compared to Shaker, and they identify one key variable position (T449 in Shaker and V381 in Kv1.2) underlying the different phenotypes in the two channels. Collectively, our results suggest that Kv1.2 is less prone to inactivate compared to Shaker, yet support a common mechanism of inactivation in the two channels.
A simple linear algebra approach to Pauli spinors
Authors: Chamizo Fernando
Published: October 2022

The transformation law of the Pauli spinors under rotations, linked to 1/2-spin particles, leads to a mathematical problem that can be rephrased and solved in purely linear algebraic terms. We present it as a possible approach to be incorporated in a first course of quantum mechanics when introducing the concept of the spin. This concept was very elusive at early times and had an intricate development commonly overlooked in modern texts. We also take the opportunity to make some historical comments.
An advanced plasma current tomography method based on Bayesian inference and neural networks for real-time application
Authors: Liu Zijie , Luo Zhengping , Wang Tianbo , Huang Yao , Wang Yuehang , Yu Qingze , Rui Wangyi , Yuan Qiping , Xiao Bingjia , Li Jiangang
Published: October 2022

An advanced plasma current tomography method is established for the Experimental Advanced Superconducting Tokamak (EAST), which combines Bayesian probability theory and neural networks. It is different from the existing current tomography method based on a conditional autoregressive (CAR) prior. Specifically, the CAR prior is replaced with an advanced squared exponential (ASE) kernel function prior. Therefore, the proposed method can overcome the deficiencies of the CAR prior, where the calculated core current is lower than the reference current and the uncertainty becomes severe after introducing noise in the diagnostics. The ASE kernel prior is developed from the squared exponential kernel function by integrating the useful information from the reference discharge. The ASE kernel prior adopts nonstationary hyperparameters and introduces the current profile into the hyperparameters, which can make the shape of the current profile more flexible in space. To provide a suitable reference discharge, a neural network model is also trained. The execution time is less than 1 ms for each time slice, which indicates its potential for application in future real-time plasma feedback control.
Development of an electron cyclotron resonance heating and electron Bernstein wave current drive system on ST40
Authors: du Toit E J , Shevchenko V F
Published: October 2022

A mutli-frequency electron cyclotron resonance heating and current drive system is currently under construction at the ST40 spherical tokamak. The system employs two gyrotrons with a maximum output power of 1 MW each. Both gyrotrons can be tuned to operate at either 105 GHz or 140 GHz. The system is designed to study a non-inductive plasma start-up, current ramp-up and sustainment. Detailed modelling of the system capabilities has been conducted for various RF launch configurations in ST40.
Research on probe fault detection of EAST magnetic diagnostic system
Authors: Li Tingyu , Shen Biao , Shi Tonghui , Chen Dalong , Guo Bihao , Luo Zhengping , Huang Yao , Chen Ming , Xiao Bingjia
Published: October 2022

The magnetic diagnostic system provides input signals for equilibrium reconstruction and plays a key role in plasma feedback control. Real-time monitoring and abnormal signal detection in the magnetic diagnostic system are of significance for the operation of a tokamak. In this paper, a general fault detection algorithm is proposed, based on the spatial autocorrelation of the probes. This algorithm first obtains a linear mapping between the expected value of each probe and the measured values of its adjacent probe combination through regression fitting, and then sets the fault detection threshold initially based on the fitting result of the absolute error distribution. In addition, the fault probe location is realized through a voting mechanism. The algorithm can simultaneously realize the fault detection of multiple non-adjacent probes. Based on the experimental data from the EAST, the method described here shows good performance and potential for use in long-pulsed operation.
Thermoelastic characteristics of moving viscoelastic nanobeams based on the nonlocal couple stress theory and dual-phase lag model
Authors: Abouelregal Ahmed E , Sedighi Hamid M
Published: October 2022

Thermal behavior of a moving viscoelastic nanobeam under the influence of periodic thermal load is considered in the framework of Kelvin-Voigt viscoelastic model with fractional operators. The equation of motion for axially moving nanobeam is modeled by employing the Eringen’s nonlocal elastic theory in conjunction with the couple stress hypothesis and the conventional Euler–Bernoulli beam model. The thermoelastic features is then established by employing the generalized dual phase-lag heat conduction model. After utilizing the Laplace transform, the thermomechanical equations are coupled and solved. The current results are validated by presenting numerical examples and comparing with previous solutions obtained by traditional theories in the literature. According to the provided numerical simulations, the deflection of the axially moving nanobeam as well as its temperature change reduce with the axial velocity and the influences of small scale and nonlocal parameters are also revealed and discussed.
Three-state resistive switching effect in BiFeO3 thin films
Authors: Yang Ying , Zhang Yuelin , Yang Liang , Lu Jingdi , Deng Gongxun , Wang Yinshu , Zhu Hui , Wang Aiji
Published: October 2022

Resistive switching (RS) memristor has been widely used in the in-memory computation systems. Due to the strong information processing capability and low area cost of the ternary logic, the development of the three-state RS memristor was promoted. Here, we demonstrate a three-state RS phenomenon on Pt/BiFeO3/SrRuO3 structure. After applying a positive voltage to the thin film for a period, an abrupt RS effect occurs, where the three-state RS behavior can be obtained. By analyzing the conduction mechanisms of the current-voltage curves and the behavior of the capacitance-voltage curves, the three-state storage capability of the memristor can be ascribed to the movement of oxygen vacancies and the trapping/detrapping of charge carriers at the interface. The ternary OR logic gate was also designed with three steps by using only one memristor.
Strong dissipation induced coupling interaction between photons
Authors: Chen Bin , Zhang Hao , Chen Qi-Ze , Bian Yu-Xiang , Xia Yan
Published: October 2022

Dissipation is used to achieve the coupling interaction between different cavities connected by a low-Q cavity. When the dissipative rate of the central cavity is enough large, vacuum Rabi oscillation can be found. We obtain the noise spectrum which may show the unique dynamics character of the investigated system. Under the condition of strong dissipation, non-zero entanglement between photons may be observed. We also discuss the effect of thermal noise on the dynamic evolution. The work will be helpful for manipulating photonic state in noisy environment.
Nonlinear wave propagation in acoustic metamaterials with bilinear nonlinearity
Authors: Liang Shiqi , Liu Jiehui , Lai Yun , Liu Xiaozhou
Published: October 2022

Nonlinear phononic crystals have attracted great interest because of their unique properties absent in linear phononic crystals. However, few researches have considered the bilinear nonlinearity as well as its consequences in acoustic metamaterials. Hence, we introduce bilinear nonlinearity into acoustic metamaterials, and investigate the propagation behaviors of the fundamental and the second harmonic waves in the nonlinear acoustic metamaterials by discretization method, revealing the influence of the system parameters. Furthermore, we investigate the influence of partially periodic nonlinear acoustic metamaterials on the second harmonic wave propagation, and the results suggest that pass-band and band-gap can be transformed into each other under certain conditions. Our findings could be beneficial to the band gap control in nonlinear acoustic metamaterials.
Series connection of quantum Hall resistance array and programmable Josephson voltage standard for current generation at one microampere
Authors: Chae Dong-Hun , Kim Mun-Seog , Oe Takehiko , Kaneko Nobu-Hisa
Published: October 2022

An accurate current can be realized by a series connection of an invariant voltage and resistance with zero interconnection resistance in the framework of Ohm’s law. In practice, however, accurate current realization is limited by the temporal drift and instability of employed resistors, solid-state voltage sources and interconnection wires against environmental fluctuations, such as temperature or atmospheric pressure. Here, we generated a current of 1 μA, determined by the Josephson voltage and quantized Hall resistance array (QHRA). A programmable Josephson voltage standard (PJVS), 1 MΩ QHRA and ultrastable low noise current amplifier (ULCA) are connected in series to generate and measure a current of 1 μA. The expected current is calculated as the ratio of the Josephson voltage to the QHRA plus the output resistance of the PJVS. The relative difference between the current measured by the ULCA and the calculated current is as small as 40 nA A−1 with a combined measurement uncertainty (k = 1) of 0.13 μA A−1.
E × B flow driven electron temperature bifurcation in a closed slot divertor with ion B × ∇B away from the X-point in the DIII-D tokamak
Authors: Ma X. , Wang H.Q. , Guo H.Y. , Leonard A. , Maurizio R. , Meier E.T. , Ren J. , Stangeby P.C. , Sinclair G. , Thomas D.M. , Wilcox R.S. , Yu J.H. , Watkins J.
Published: October 2022

An electron temperature bifurcation is observed in the small angle slot divertor, which has been developed to enhance neutral cooling across the divertor target by coupling a closed slot structure with appropriate target shaping. Experiments in the DIII-D tokamak and associated SOLPS-ITER modeling with full drifts find a strong interplay between drifts and divertor geometry on divertor dissipation. The coupling of divertor geometry and drift flows can strongly affect the path towards divertor detachment onset as the plasma density is raised. With the strike point on the inner slanted surface and ion B × ∇B away from the magnetic X-point, bifurcative transitions were observed with sharp decrease of T
e towards detachment onset both experimentally and computationally. This differs from the situation for the open divertor where the T
e cliff was only observed for ion B × ∇B towards the X-point. SOLPS-ITER modeling with full drifts demonstrates that the magnitude of the E × B drift flow is comparable with the main plasma flow. The reversal of both the poloidal and radial E × B flows near the strike point leads to rapid density accumulation right near the separatrix, which results in bifurcative step transition of divertor conditions with cold plasma across the entire divertor target plate. These results indicate that the interplay between geometry and drifts should be fully taken into account in future fusion reactor divertor designs.
Secondary ion emission from C2H6:H2O ice by fission fragments
Authors: Oliveira P. R. B. , Martinez R. , Silveira E. F. da
Published: October 2022

Water (H2O) ice is a common constituent of several astrophysical object surfaces; other condensed gases (e.g., CH4, CO2, NH3, and C2H6) also occur in specific bodies. Bombarded by cosmic rays, these molecules react among them, generating new molecular species, which are partially ejected to the gas phase via a process called sputtering. In the current work, C2H6:H2O ice is irradiated at an averaged temperature of 100 K by energetic multicharged ions (252Cf fission fragments of ∼ 65 MeV). The sputtered positive and negative secondary ions are detected and analyzed by time-of-flight mass spectrometry (PDMS-TOF). The projectile-surface collision induces the formation of ionic cluster series (H2O)nX (X = H2O+, H3O+, O− and OH−), and their yield distribution can be represented by the sum of two decreasing exponentials, suggesting the presence of a two distinct formation processes, one for the low cluster masses and another for the larger ones.
Holographic thermodynamics and transport for the hot and baryon dense quark-gluon plasma
Authors: Rougemont Romulo
Published: October 2022

This is a contribution to the Proceedings of the XLIV Brazilian Workshop on Nuclear Physics, held in virtual format during 9-11 November, 2021. In this contribution I briefly review some of the main results obtained with collaborators regarding quantitative predictions from an Einstein-Maxwell-Dilaton holographic model for the thermodynamics and some of the transport coefficients of the hot and baryon dense quark-gluon plasma produced in relativistic heavy ion collisions.
Regularization issues for a cold and dense quark matter with a chiral imbalance
Authors: Pasqualotto Arthur E. B. , Farias Ricardo L. S. , Tavares William R. , Avancini Sidney S.
Published: October 2022

In this work we investigate the effects of the chiral chemical potential, μ
5, in the two flavor cold and dense quark matter with two different regularization procedures within the Nambu–Jona-Lasinio (NJL SU(2)) model: the Traditional Regularization Scheme (TRS) and the Medium Separation Scheme (MSS). We study the effects of different choices for the parametrization of the model for both regularization schemes. More specifically we were interested in the behavior of the effective quark masses as a function of chiral and quark chemical potentials.
Effects of the quark anomalous magnetic moment in the thermodynamical properties of the magnetized two flavor Nambu–Jona-Lasinio model
Authors: Farias Ricardo L. S. , Nunes Rodrigo M. , Tavares William R. , Avancini Sidney S.
Published: October 2022

The influence of the anomalous magnetic moment (AMM) of quarks in the chiral phase transition is studied in the context of the hot and magnetized two flavor Nambu–Jona-Lasinio model. Making use of the mean field approximation (MFA) and the vacuum magnetic regularization (VMR) scheme, we obtain the effective quark masses as a function of the magnetic field for the two usual different sets of AMM. Basic thermodynamical properties are explored and compared with the zero AMM-case, as the pressure, entropy, energy density, interaction measure and the specific heat. The main differences are present in the thermodynamical quantities when one consider a sizable value of AMM, in which an underestimation over the transition region is observed.
Finite-size and temperature effects up to all orders : effective scalar models
Authors: Cavalcanti Erich
Published: October 2022

We discuss some general behaviors up to all orders in a perturbative expansion investigating a parametric representation of the model under interest. To consider finite-size and temperature effects we build two extensions of the usual Schwinger parametric representation: one suited for small characteristic lengths (and high temperatures) and another suited for large lengths (and low temperatures). As a first step, we consider scalar fields with periodic boundary conditions in the spatial directions and discuss both the asymptotic limits of very small lengths (and very high temperatures) and the asymptotic limit of very large lengths (and zero temperature).
Towards a Predictive HFB+QRPA Framework for Deformed Nuclei: Selected Tools and Techniques
Authors: Chimanski Emanuel V. , In Eun Jin , Escher Jutta E. , Péru Sophie , Younes Walid
Published: October 2022

Reliable predictions of the static and dynamic properties of a nucleus require a fully microscopic description of both ground and excited states of this complicated many-body quantum system. Predictive calculations are key to understanding such systems and are important ingredients for simulating stellar environments and for enabling a variety of contemporary nuclear applications. Challenges that theory has to address include accounting for nuclear deformation and the ability to describe medium-mass and heavy nuclei. Here, we perform a study of nuclear states in an Hartree-Fock-Bogoliubov (HFB) and Quasiparticle Random Phase Approximation (QRPA) framework that utilizes an axially-symmetric deformed basis. We present some useful techniques for testing the consistency of such calculations and for interpreting the results.
Modelling inclusive breakup: application to incomplete fusion
Authors: Moro Antonio M. , Lei Jin , Simpson Edward C.
Published: October 2022

We propose an extension of the inclusive breakup model of Ichimura, Austern and Vincent [Phys. Rev. C 32, 431 (1985)] for the evaluation of incomplete fusion (ICF) cross sections in nuclear reactions induced by two-body projectiles. The main idea, adopted in other methods, consists in the separation of the participant-target optical potential into its direct reaction and compound reaction components, the latter being responsible for the ICF contribution of the total nonelastic breakup cross section. Preliminary comparison with experimental data shows encouraging results.
Distance analysis of elastic scattering data of light projectiles on 27Al target
Authors: Nistal P C , Guimarães V , Lubian J
Published: October 2022

The strong synergy between nuclear structure and reactions mechanism has allowed the observation of cluster effects in the elastic scattering process. In this work we present an alternative phenomenological analysis on the angular distributions for elastic scattering induced by tightly-bound (12C, 16O), weakly-bound (6Li, 7Li, 9Be), and exotic (6He) nuclei on light 27Al target at energies close to the Coulomb barrier. The reported and published angular distributions for these systems were converted from cross sections as a function of angle to cross sections as a function of the distance of closest approach. From these new plots, it is now possible to extract the critical-interaction and strong-absorption distances. Larger values for the critical distances were obtained for the exotic and weakly-bound nuclei as compared to those corresponding to tightly-bound 12C and 16O nuclei.
Optimization design and analysis of permanent magnet synchronous generator based on Motor-CAD
Authors: Li X X , Liu Z S
Published: October 2022

With the development of the automotive industry, the demand for electricity for automotive equipment increases, which puts forward higher requirements for automotive generators. Compared with the traditional electric excitation generator, the permanent magnet synchronous generator (PMSG) has the characteristics of high efficiency, high power density, stable and controllable output voltage, and good heat dissipation performance, and is especially suitable for automotive applications. According to its characteristics, this paper makes an in-depth study on its design theory and main performance parameters. A high-efficiency rotor magnetic steel built-in vehicle permanent magnet synchronous generator is designed by using motor CAD, which eliminates the easily damaged collector ring and brush, improves the reliability of the motor, opens a ventilation hole in the rotor, enhances the heat dissipation effect, and adopts a skewed stator to effectively reduce the sinusoidal distortion rate of the output voltage waveform. The prototype has the characteristics of high power, small size and high reliability. The various performances of the prototype are analysed and verified on the simulation software. The results show that the performance of the prototype meets the design requirements, and the simulation results prove the rationality of the prototype design.
Study on the printing quality of fused deposition modeling using Taguchi method
Authors: Teng H M , Fan S K , Jiang C H , Yang Q W , Liu F H , Tsao C C
Published: October 2022

Fused deposition modeling (FDM) in 3D printing is a very promising technology and one of the focuses of scientific research. The main reason is that it has the advantages of simple structure, relatively low price and convenient operation, which has made its development more and more rapid in recent years. However, due to the fact that the FDM products are susceptible to the operating environment, the printing quality is not stable enough and the development is restricted. In addition, this research uses Taguchi method to explore FDM to optimize a long and thin desired volume of the workpiece under different printing parameters (printing temperature, printing speed ratio, and printing layer thickness). From the experimental results, the size of the factors that affect the FDM’s expected volume of the workpiece is, in order, the printing temperature is the most important, the printing speed ratio is the second, and the printing layer thickness is the smallest. The optimal parameter combination for the desired workpiece volume is A1B1C1, that is, the printing temperature is 190°C, the printing speed ratio is 0.286 (20 mm/s on the outer side, 70 mm/s on the inner side), and the printing layer thickness is 0.1 mm. Finally confirmed the experimental results and found that the volume error of the finished product using the best printing parameters is less than 0.3 %, which proves that the optimized printing parameters obtained by Taguchi method are indeed effective and feasible.
Dieless drawing wire with a given end geometry by realizing temperature distribution evolution
Authors: Fann K J , Hsu H Y
Published: October 2022

Dieless drawing that has been widely used to produce metal tubes, wires, and rods has more potential for the future, especially in manufacturing high performance screws and nails with specific points. Because there are no dies but heating and cooling system along with drawing platform needed, it is highly flexible and meets the requirements of the steadily asked manufacturing on-demand. Under this trend, this study attempts to propose a heat transfer model that can achieve the required temperature evolution for dieless drawing a wire to form a specific end geometry as a nail point by obtaining the required evolution of heat transfer coefficient and the correspondingly approximated cooling fluid rate. After it is validated with tests on a dieless drawing platform implemented with a cooling system, whose cooling flow rate is controllable, the results show that for a linear end geometry of a stainless steel wire, there is no significant difference between the temperature distribution evolution required and obtained from the experiment. Furthermore, the end geometry of the drawn wire falls within the current industry standard tolerances as well.
Research on the influence of different machining parameters and cooling and lubrication methods on the change of chip color on tool life
Authors: Chen S H , Liao T H , Chen J Y , Li Y J , Yang Z W , Lai H W
Published: October 2022

Cutting fluid has always been a commonly used cooling and lubrication method in machining. However, the traditional flood cooling method is not environmentally friendly, and the purchase of cutting fluid and disposal of waste fluid also create a lot of costs for employers. The emergence of MQL and air cooling can provide Due to the advantages of environmental protection and cost, this study uses three cutting conditions, dry, cold air gun and MQL, and two high and low cutting speeds to conduct experiments to record tool wear and analyze chip chromaticity. The results show that the two cooling methods are better than dry cutting. It can improve the tool life by about 40%, and with the increase of tool wear, the chip chromaticity also has a clear trend of change. The chip chromaticity data is predicted by the back-transmission neural network (BPNN), and the average absolute error percentage of the model is 11.12%. According to the prediction ability of the mean absolute percentage error (MAPE), this model has good prediction ability, and the relevant color and tool wear data will help to establish a tool wear prediction model for related materials and cooling methods in the future.
Study on friction properties of different abrasive materials and polylactic acid materials
Authors: Liu C T , Chang Y P , Yeh J W
Published: October 2022

In recent years, 3D printing technology is often used in various fields such as industry, medical care, and academia, because it can produce components with complex shapes at a lower cost than traditional processing. However, the size of 3D products is often limited by the printable range of printing equipment, so large objects often need to be disassembled and printed before joining. Friction stir welding is used to join different thermoplastics and has considerable potential for industrial applications, and the influence of the design of the welding tool on the formation of the welding zone is an important key. In this study, different abrasive materials and polylactic acid materials were used for friction, and the changes of friction coefficient and friction temperature during the friction process were discussed. The experimental results show the surface roughness of the abrasive tool has a significant effect on the coefficient of friction and temperature rise. As increasing the roughness of the abrasive tool, the wear scars, the cracks below the wear scar are both significant. It can be inferred from the crack shape that the PLA softens at high temperatures and then solidifies again, so the cracks are seen with a streamlined appearance, which means that the softened PLA can be carried by the abrasives tool with highly rough surfaces.