bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymmetric propagation of low-frequency acoustic waves in a granular chain using asymmetric intruders
Authors: Jalali Hoda , Rizzo Piervincenzo , Nasrollahi Amir
Published: August 2019

This paper investigates the asymmetric propagation of acoustic waves in a one-dimensional chain of spherical particles coupled with asymmetric intruders. The chain passes acoustic waves along one direction (forward configuration) whereas partially blocks the acoustic energy propagating along the opposite direction (reverse configuration). A numerical analysis is conducted to investigate this asymmetric propagation by simulating a statically compressed chain of particles interacting via Hertzian contact and subjected to small amplitude periodic displacements at one end. The amount of acoustic energy transmitted through the chain in both configurations is studied and quantified in terms of the acoustic energy transfer ratio, defined as the ratio of the acoustic power at the last particle to the acoustic power at the first particle. The effect of the applied frequency and number of particles in the chain on the transfer ratio is investigated. In addition, a parametric study is performed to evaluate the effects of geometric and material properties on the efficiency of asymmetric acoustic wave propagation in the proposed system. The results show that the proposed design supports asymmetric propagation of low frequency acoustic waves.
Capturing magnetic bead-based arrays using perpendicular magnetic anisotropy
Authors: Hsiao Yu-Ching , Khojah Reem , Li Xu , Kundu Auni , Chen Cai , Gopman Daniel B. , Chavez Andres C. , Lee Taehwan , Xiao Zhuyun , Sepulveda Abdon E. , Candler Rob N. , Carman Gregory P. , Di Carlo Dino , Lynch Christopher S.
Published: August 2019

Designing and implementing means of locally trapping magnetic beads and understanding the factors underlying the bead capture force are important steps toward advancing the capture-release process of magnetic particles for biological applications. In particular, capturing magnetically labeled cells using magnetic microstructures with perpendicular magnetic anisotropy (PMA) will enable an approach to cell manipulation for emerging lab-on-a-chip devices. Here, a Co (0.2 nm)/Ni (0.4 nm) multilayered structure was designed to exhibit strong PMA and large saturation magnetization (Ms). Finite element simulations were performed to assess the dependence of the capture force on the value of Ms. The simulated force profile indicated the largest force at the perimeter of the disks. Arrays of Co/Ni disk structures of (4–7) μm diameter were fabricated and tested in a microchannel with suspended fluorescent magnetic beads. The magnetic beads were captured and localized to the edge of the disks as predicted by the simulations. This approach has been demonstrated to enable uniform assembly of magnetic beads without external fields and may provide a pathway toward precise cell manipulation methods.
Reconstruction of IrO2/(Pb, La)(Zr, Ti)O3 (PLZT) interface by optimization of postdeposition annealing and sputtering conditions
Authors: Nomura Kenji , Wang Wensheng , Nakamura Ko , Eshita Takashi , Takai Kazuaki , Ozawa Soichiro , Yamaguchi Hideshi , Mihara Satoru , Hikosaka Yukinobu , Saito Hitoshi , Kataoka Yuji , Kojima Manabu
Published: August 2019

We reconstruct the interface between ferroelectric (FE) lanthanum-doped lead zirconate titanate (PLZT) and an iridium oxide (IrOx) top electrode (TE), taking advantage of the interdiffusion of Ir and Pb during postdeposition annealing. The tetragonal perovskite phase with a low c/a axis ratio at the IrOx/PLZT interface is observed by X-ray diffraction. It is suggested that the low c/a axis ratio in the interfacial layer is due to the effect of diffusion of Ir from the TE-IrOx. It is also considered that the low c/a axis ratio interfacial layer functions as a nucleation layer for reversal of polarization, thereby achieving a low coercive electric field. The formation of the interfacial layer is very sensitive to the O2 content of the Ar/O2 atmosphere during TE-IrOx deposition. Although an optimized Ar/O2 ratio achieves excellent polarization characteristics (high polarization value and low coercive field), the optimum Ar/O2 region is very narrow at around 36% O2. In other Ar/O2 regions, a pyrochlore phase is formed at the interface owing to interdiffusion of the TE and FE films, and polarization characteristics deteriorate.
On the Bargmann-Fock-Fueter and Bergman-Fueter integral transforms
Authors: Diki Kamal , Krausshar Rolf Sören , Sabadini Irene
Published: August 2019

This paper deals with some special integral transforms of Bargmann-Fock type in the setting of quaternionic valued slice hyperholomorphic and Cauchy-Fueter regular functions. The construction is based on the well-known Fueter mapping theorem. In particular, starting with the normalized Hermite functions, we can construct an Appell system of quaternionic regular polynomials. The ranges of such integral transforms are quaternionic reproducing kernel Hilbert spaces of regular functions. New integral representations and generating functions in this quaternionic setting are obtained in both the Fock and Bergman cases.
Detection of alpha particles from 7Li(p,α)4He and 19F(p,α)16O reactions induced by laser-accelerated protons using CR-39 with potassium hydroxide–ethanol–water etching solution
Authors: Nishiura Yosuke , Inoue Shunsuke , Kojima Sadaoki , Teramoto Kensuke , Furukawa Yuki , Hashida Masaki , Sakabe Shuji
Published: August 2019

Alpha particles generated by 7Li(p,α)4He and 19F(p,α)16O reactions are selectively detected in the presence of abundant primary protons by reducing the proton sensitivity of CR-39 using a potassium hydroxide–ethanol–water (PEW) etching solution. These nuclear reactions are induced in a LiF crystal using the laser-accelerated protons (4 × 1011 protons/pulse with a maximum energy of 3.3 MeV) generated and accelerated by the interaction of a 40-fs laser pulse with a polyethylene thin film target at a peak intensity of 5 × 1019 W/cm2. Subsequent etching of the CR-39 in the PEW solution (KOH: 17 wt. %; C2H5OH: 25 wt. %; H2O: 58 wt. %) permits the selective detection of 4.0 MeV alpha particles, which is independently confirmed by an experiment using alpha particles from an 241Am source. The described method is expected to be useful for research into nuclear reactions in laser plasma.
Cavity ring down spectroscopy of cold neutral phenanthrene and phenanthridine in supersonic jets
Authors: Bejaoui Salma , Salama Farid
Published: August 2019

Here we study the effect of nitrogen insertion on the electronic spectra of polycyclic aromatic hydrocarbon (PAH) molecules measured under laboratory conditions that are relevant for comparison with astronomical data. We examine the case of the substitution of carbon atoms by nitrogen atoms in the benzenoid skeleton of phenanthrene (C14H10), a prototype non-compact PAH. The vibronic transitions of the 21A1(S1)⟵X1A1(S0) electronic absorption band system of neutral phenanthrene (C14H10) and phenanthridine (C13H9N) molecules seeded in a supersonic free jet expansion of argon gas are measured in the 315-345 nm region using the cavity ring down spectroscopy (CRDS) technique. Additional measurements of the absorption spectra of the phenanthrene, phenanthridine, and 1,10-phenanthroline (C12H8N2) molecules isolated in 10-K solid argon matrices are also presented. The results obtained confirm that laboratory spectra of cold, isolated molecules obtained under astrophysically relevant conditions are required for a direct, unambiguous comparison with astronomical observations as well as for the understanding of the physical evolution of the interstellar medium.
Fluorine doped tin oxide as an alternative of indium tin oxide for bottom electrode of semi-transparent organic photovoltaic devices
Authors: Way Amirah , Luke Joel , Evans Alex D. , Li Zhe , Kim Ji-Seon , Durrant James R. , Hin Lee Harrison Ka , Tsoi Wing C.
Published: August 2019

Indium tin oxide (ITO) is commonly used as the transparent bottom electrode for organic solar cells. However, it is known that the cost of the ITO is quite high due to the indium element, and in some studies ITO coated glass substrate is found to be the most expensive component of device fabrication. Moreover, indium migration from ITO can cause stability issues in organic solar cells. Nevertheless, the use of ITO as the bottom electrode is still dominating in the field. Here, we explore the possibility of using fluorine doped tin oxide (FTO) as an alternative to ITO for the bottom electrode of organic solar cells particularly on semi-transparent cells. We present side-by-side comparisons on their optical, morphological and device properties and suggest that FTO could be more suitable than ITO as the bottom electrode for glass substrate based organic photovoltaic devices.
Control of flow and suppression of separation for Couette-Poiseuille hydrodynamics of ferrofluids using tunable magnetic fields
Authors: Ghosh Dibyendu , Das Prasanta K.
Published: August 2019

The present study reports unidirectional laminar flow of ferrofluids between parallel plate channels under the action of a homogeneous magnetic field. The applied field is found to uniquely modify the local velocity distribution and to reduce the effect of both adverse and favorable pressure gradients. We find that it is possible to control the flow separation by varying the magnetic field strength within a certain range of adverse pressure gradients. We also discuss the effect of the magnetization relaxation time scale and volume fraction of the solid magnetic particles on the flow phenomenon. Finally, we propose an analytical solution which provides closed form expressions for velocity and spin field that are in good agreement with the numerically obtained results.
Sedimentation of an elliptic rigid particle in a yield-stress fluid: A Lattice-Boltzmann simulation
Authors: Sobhani S. M. J. , Bazargan S. , Sadeghy K.
Published: August 2019

Sedimentation of a single, two-dimensional, rigid, elliptic particle in a biviscous fluid contained in a finite, closed-ended channel is studied in this work using the lattice-Boltzmann method. The main objective of the work is to numerically investigate the role played by a fluid’s yield stress on the trajectory, orientation, and terminal velocity of such a particle for different density and aspect ratios. Numerical results suggest that a new mode of settling might emerge for yield-stress fluids, which is nonexistent for Newtonian fluids. That is, a particle released from the rest state at the midplane with a prescribed, nonzero, inclination angle (with respect to the horizontal line) migrates toward the left side-wall (if the inclination angle is positive) soon after it is released but changes course after a short while and moves back toward the centerline where the voyage started. However, while for Newtonian fluids the particle eventually returns to the centerline and continues its free fall with a horizontal orientation, for yield-stress fluids, the particle might finally lodge at a specific distance away from the centerline and continue its fall assuming a nonhorizontal orientation. The offset position is predicted to be a function of the Bingham number and the density ratio but independent of the initial inclination angle.
Thermally stable electrostrain in BiFeO3-BaTiO3-based high temperature lead-free piezoceramics
Authors: Wang Lei , Liang Ruihong , Zhou Zhiyong , Dong Xianlin
Published: August 2019

BiFeO3-BaTiO3 ceramics possess both high electromechanical properties and a high Curie temperature, which are promising high temperature lead-free piezoactuator materials. However, the poor thermal stability of electrostrain limits their practical exploration. Here, we report a temperature stable electrostrain of 0.18% at 6 kV/mm, with a variation of 13% from 25 °C to 175 °C for (1-x)(0.67BiFeO3-0.33BaTiO3)-xSr0.8Bi0.1◻0.1TiO2.95 solid solutions with x = 0.04. The addition of a relaxor ferroelectric Sr0.8Bi0.1◻0.1TiO2.95 (SBT) breaks the long range ferroelectric order of BiFeO3-BaTiO3 (BFBT) ceramics. More importantly, the combined effect of the negative temperature dependent electrostrain for relaxors and the positive one for the parent BFBT contributes to the superior temperature stability of the electrostrain. This work provides an effective method for designing piezoelectric materials with an enhanced temperature stability for high temperature actuator applications.
Experimental validation of deep-subwavelength diffusion by acoustic metadiffusers
Authors: Ballestero E. , Jiménez N. , Groby J.-P. , Dance S. , Aygun H. , Romero-García V.
Published: August 2019

An acoustic metadiffuser is a subwavelength locally resonant surface relying on slow sound propagation. Its design consists of rigidly backed slotted panels, with each slit being loaded by an array of Helmholtz resonators. Due to the slow sound properties, the effective thickness of the panel can therefore be dramatically reduced when compared to traditional diffusers made of quarter-wavelength resonators. The aim of this work is to experimentally validate the concept of metadiffusers from the scattering measurements of a specific metadiffuser design, i.e., a quadratic residue metadiffuser. The experimental results reported herein are in close agreement with analytical and numerical predictions, therefore showing the potential of metadiffusers for controlling sound diffusion at very low frequencies.
Controlling acoustic waves using magneto-elastic Fano resonances
Authors: Latcham O. S. , Gusieva Y. I. , Shytov A. V. , Gorobets O. Y. , Kruglyak V. V.
Published: August 2019

We propose and analyze theoretically a class of energy-efficient magnetoelastic devices for analog signal processing. The signals are carried by transverse acoustic waves while the bias magnetic field controls their scattering from a magnetoelastic slab. By tuning the bias field, one can alter the resonant frequency at which the propagating acoustic waves hybridize with the magnetic modes, and thereby control transmission and reflection coefficients of the acoustic waves. The scattering coefficients exhibit Breit-Wigner/Fano resonant behavior akin to inelastic scattering in atomic and nuclear physics. Employing oblique incidence geometry, one can effectively enhance the strength of magnetoelastic coupling, and thus countermand the magnetic losses due to the Gilbert damping. We apply our theory to discuss potential benefits and issues in realistic systems and suggest routes to enhance the performance of the proposed devices.
Flow-induced resonant shear-wave instability between a viscoelastic fluid and an elastic solid
Authors: Joshi Parag , Shankar V.
Published: August 2019

Linear stability analysis of plane Couette flow of a viscoelastic, upper-convected Maxwell (UCM) fluid past a deformable elastic solid is carried out in the low Reynolds number limit using both numerical and asymptotic techniques. The UCM fluid is characterized by its viscosity η, density ρ, and relaxation time τR, whereas the deformable solid is considered to be a linear elastic solid of shear modulus G. The asymptotic analysis is performed in the Re ≪ 1 limit, where Re = ρVR/μ is the Reynolds number, V is the top plate velocity, and R is the thickness of the fluid. Both asymptotic and numerical approaches are used to understand the effect of solid elasticity, represented by the dimensionless parameter Γ, and fluid elasticity, characterized by the Weissenberg number W, on the growth rate of a class of modes with high frequencies (compared to the imposed shear rate, termed high-frequency Gorodtsov-Leonov, or “HFGL” modes) in the Re ≪ 1 limit. Here, the dimensionless groups are defined as W = τRV/R and Γ = ηV/GR. The results obtained from the numerical analysis show that there is an interaction between the shear waves in the fluid and the elastic solid, which are coupled via the continuity conditions at the interface. The interaction is particularly pronounced when W = Γ, strongly reminiscent of resonance. The resonance-induced interaction leads to shear waves in the coupled system with a decay rate of ci = −1/[2k(W + Γ)]. In this case, it is not possible to differentiate the fluid and solid shear waves individually and the coupled fluid-solid system behaves as a single composite material. The leading order asymptotic analysis suggests that the growth rate of the HFGL modes is proportional to W2 for W ≪ 1. The asymptotic analysis, up to first correction, shows an oscillating behavior of ci with an increase in Γ, in agreement with the results from our numerical approach. In addition, we also carry out an asymptotic analysis in the no-flow, but nonzero inertia limits to illustrate the role played by the imposed flow in the instability of the shear waves. It is found that, at the leading order, the wave speed for the coupled fluid-solid problem is neutrally stable in the absence of flow. Thus, the unstable resonant modes in the coupled fluid-solid system are shown to be driven by the imposed flow.
Distorted hysteresis loop with normal round
Authors: Xiao Yating , Gao Hui , Liu Yifan
Published: August 2019

Distorted hysteresis loops with normal round may occur when out-of-plane measurements are performed for film samples by using two-coils vibrating sample magnetometer (VSM). A model is proposed to describe the origin of this distortion based on the deviation of measuring field, normal of film plane and vibrating direction from each other.
Dicyandiamide increased ammonia volatilisation and decreased carbon dioxide emission from calcareous soil during wheat–maize rotation on the Loess Plateau
Authors: Raza Sajjad , Li Xuesong , Miao Na , Ahmed Muneer , Liu Zhanjun , Zhou Jianbin
Published: August 2019

Nitrification inhibitors (NIs) have been found to retard the nitrification process, reduce N losses and increase nitrogen use efficiency; however, their effect on carbon dioxide (CO2) emission from calcareous soil has rarely been reported. A 2-year field experiment was conducted to study whether nitrification inhibition by dicyandiamide (DCD) has any effect on CO2 release from calcareous soil. The experiment comprised five treatments: a control (0 kg N ha–1) and two levels of N fertiliser applied on wheat (160 and 220 kg N ha–1) and maize (180 and 280 kg N ha–1) crops, with and without DCD. Compared with the control, a decrease in soil pH (mean 0.21 units in N fertiliser treatments without DCD and 0.11 units with DCD) and increases in cumulative CO2 emission (mean 17% and 23% in wheat and maize respectively) and cumulative ammonia (NH3) volatilisation (mean 28% and 446% in wheat and maize respectively) was recorded under all N fertilised treatments (with and without DCD). The application of DCD with N fertiliser retarded the nitrification process, as indicated by a higher NH4+-N and lower NO3–-N content, as well as a relatively higher soil pH, compared with application of N fertiliser without DCD. In addition, DCD application significantly reduced CO2 emission in both wheat (10–20%) and maize (13–14%) crops compared with crops grown with N fertiliser without DCD. However, the losses from NH3 volatilisation increased when DCD was applied at both N fertiliser levels in both wheat (38–41%) and maize (24–36%) crops. Inhibition of nitrification by DCD was more effective during the wheat than during maize season. Controlling nitrification using DCD is an effective approach to minimise CO2 emission from calcareous soils on the Loess Plateau; however, DCD application increases in NH3 volatilisation.
Soil properties of sugarcane fields controlling triazine leaching potential
Authors: Portocarrero Rocio , Aparicio Virginia , de Gerónimo Eduardo , Costa José Luis
Published: August 2019

Atrazine and ametryn are pre- and post-emergence herbicides widely used in sugarcane fields. Both are characterised by moderate to high mobility in soil and are regarded as a threat to hydrologic systems. Physical and chemical soil properties are highlighted as one of the factors governing the fate of pesticides in hydrologic systems. The aim of our study was to estimate the leaching potential of atrazine and ametryn in soils of the saline alluvial plain of Tucumán cultivated with sugarcane. Miscible displacement experiments were carried out in triplicate using undisturbed topsoil cores from four farm fields. Field 1 was in plant, fields 2 and 3 were in second ratoon, and field 4 was in third ratoon. Experimental breakthrough curves were fitted to the convection–dispersion equation; results showed that hydraulic transport was in equilibrium conditions, meaning that all soil water was involved in solute convective transport. Atrazine had asymmetric breakthrough curves, revealing chemical non-equilibrium conditions, with at least two sorption–desorption sites participating in the process. In contrast, ametryn concentrations in leached samples were low and inconsistent; therefore, no breakthrough curves could be described. Of the total applied, recoveries reached 10% and 2% for leached atrazine and ametryn respectively. For an estimated annual recharge of 100 mm, these leached amounts would exceed international reference values for drinking water.
Robust computation with rhythmic spike patterns
Authors: Frady E. Paxon , Sommer Friedrich T.
Published: August 2019

Significance

This work makes 2 contributions. First, we present a neural network model of associative memory that stores and retrieves sparse patterns of complex variables. This network can store analog information as fixed-point attractors in the complex domain; it is governed by an energy function and has increased memory capacity compared to early models. Second, we translate complex attractor networks into spiking networks, where the timing of the spike indicates the phase of a complex number. We show that complex fixed points correspond to stable periodic spike patterns. It is demonstrated that such networks can be constructed with resonate-and-fire or integrate-and-fire neurons with biologically plausible mechanisms and be used for robust computations, such as image retrieval.
Disintermediating your friends: How online dating in the United States displaces other ways of meeting
Authors: Rosenfeld Michael J. , Thomas Reuben J. , Hausen Sonia
Published: August 2019

We present data from a nationally representative 2017 survey of American adults. For heterosexual couples in the United States, meeting online has become the most popular way couples meet, eclipsing meeting through friends for the first time around 2013. Moreover, among the couples who meet online, the proportion who have met through the mediation of third persons has declined over time. We find that Internet meeting is displacing the roles that family and friends once played in bringing couples together.
Optimizing organic electrosynthesis through controlled voltage dosing and artificial intelligence
Authors: Blanco Daniela E. , Lee Bryan , Modestino Miguel A.
Published: August 2019

Significance

The electrification of chemical manufacturing can enable the integration of renewable electricity sources into a sustainable chemical industry. The combined experimental and artificial intelligence-enabled approach discussed in this work represents a paradigm shift in the electrosynthesis field and can help accelerate the industry’s transformation. The strategy that we present improves reaction selectivity (by 325%) and production rates (by 30%) for the largest organic electrochemical process in industry, the electrosynthesis of adiponitrile (ADN). These advances are achieved by carefully tuning the electrochemical environment around the electrocatalyst surface and implementing data-driven models to rapidly elucidate optimal reaction conditions unpredictable by existing physical models. Although this approach was demonstrated for ADN production, it can serve as a universal model for sustainable electrosynthesis development.
A kleptoplastidic dinoflagellate and the tipping point between transient and fully integrated plastid endosymbiosis
Authors: Hehenberger Elisabeth , Gast Rebecca J. , Keeling Patrick J.
Published: August 2019

Plastid endosymbiosis has been a major force in the evolution of eukaryotic cellular complexity, but how endosymbionts are integrated is still poorly understood at a mechanistic level. Dinoflagellates, an ecologically important protist lineage, represent a unique model to study this process because dinoflagellate plastids have repeatedly been reduced, lost, and replaced by new plastids, leading to a spectrum of ages and integration levels. Here we describe deep-transcriptomic analyses of the Antarctic Ross Sea dinoflagellate (RSD), which harbors long-term but temporary kleptoplasts stolen from haptophyte prey, and is closely related to dinoflagellates with fully integrated plastids derived from different haptophytes. In some members of this lineage, called the Kareniaceae, their tertiary haptophyte plastids have crossed a tipping point to stable integration, but RSD has not, and may therefore reveal the order of events leading up to endosymbiotic integration. We show that RSD has retained its ancestral secondary plastid and has partitioned functions between this plastid and the kleptoplast. It has also obtained genes for kleptoplast-targeted proteins via horizontal gene transfer (HGT) that are not derived from the kleptoplast lineage. Importantly, many of these HGTs are also found in the related species with fully integrated plastids, which provides direct evidence that genetic integration preceded organelle fixation. Finally, we find that expression of kleptoplast-targeted genes is unaffected by environmental parameters, unlike prey-encoded homologs, suggesting that kleptoplast-targeted HGTs have adapted to posttranscriptional regulation mechanisms of the host.
Verifying commuting quantum computations via fidelity estimation of weighted graph states
Authors: Hayashi Masahito , Takeuchi Yuki
Published: August 2019

The instantaneous quantum polynomial time (IQP) model is one of promising models to demonstrate a quantum computational advantage over classical computers. If the IQP model can be efficiently simulated by a classical computer, an unlikely consequence in computer science can be obtained (under some unproven conjectures). In order to experimentally demonstrate the advantage using medium or large-scale IQP circuits, it is inevitable to efficiently verify whether the constructed IQP circuits faithfully work. There exist two types of IQP models, each of which is the sampling on hypergraph states or weighted graph states. For the first-type IQP model, polynomial-time verification protocols have already been proposed. In this paper, we propose verification protocols for the second-type IQP model. To this end, we propose polynomial-time fidelity estimation protocols of weighted graph states for each of the following four situations where a verifier can (i) choose any measurement basis and perform adaptive measurements, (ii) only choose restricted measurement bases and perform adaptive measurements, (iii) choose any measurement basis and only perform non-adaptive measurements, and (iv) only choose restricted measurement bases and only perform non-adaptive measurements. In all of our verification protocols, the verifier’s quantum operations are only single-qubit measurements. Since we assume no independent and identically distributed property on quantum states, our protocols work in any situation.
Light pollution – an interesting context for teaching and learning optics
Authors: Haagen-Schützenhöfer Claudia , Kopper Manuela
Published: August 2019

Physics as a school subject is in general very unpopular. This fact is especially true for the situation in Austria. PISA results show that motivation, interest and self-efficacy of Austrian highschool students are significantly lower than the OECD average. In addition, a significant gender-gap in disadvantage for girls was shown. In general, one reason for low interest which was identified by previous research is that physics instruction is frequently decontextualized and students can hardly see any relevance of understanding physics for their lives. On the contrary, science and technology play a crucial and increasingly important role in our lives and in our globalized society. At the same time, edutainment focusing on science topics is booming. Interest studies like the ROSE-study may give reasons for this discrepancy: the choice of contexts does often not meet students’ interests. This contribution reports the development of a context-oriented learning environment on light pollution to stimulate learning processes and at the same time interest in introductory optics.
Using a smartphone to investigate classroom acoustics
Authors: Elejalde-García Maria Jesús , Macho-Stadler Erica
Published: August 2019

We present a proposal for active learning about environmental acoustics and room acoustics for high school and undergraduate students. Students work on the concepts of sound pressure level and reverberation time through a set of activities centred on speech communication in the school. For experimental work, they use smartphone applications for sound measurement. At the end of the work, students would be able to suggest some actions to improve the acoustic comfort in school. The students’ interest increases as they focus on their own experience. Moreover, they can apply and test the solutions that they propose.
From the dicey world to the physical laws: dice toy models for bridging microscopic and macroscopic understanding of physical phenomena
Authors: Onorato Pasquale , Gratton Luigi M , Oss Stefano , Malgieri Massimiliano
Published: August 2019

We discuss an educational approach to some different physical phenomena that can be explained by means of stochastic toy models, and explored by students with rolling dice. The discussion of the physical principles governing the phenomena, proceeds through a recurrent comparison between the outcomes obtained with the toy models and the results of real experiments.

The educational proposal allows students to compare experimental data they obtain to both analytical results and simulations.

The effectiveness of our approach was tested both with groups of undergraduate students and with a group of on service teachers.
Analyzing the measurement error from false positives in the Force Concept Inventory
Authors: Yasuda J , Mae N , Hull M M , Taniguchi M
Published: August 2019

We analyze the measurement error due to false positives of the Force Concept Inventory (FCI) focusing on four questions (Q.5, Q.6, Q.7, and Q.16). We determine whether or not a correct response to a given FCI question is a false positive using subquestions. Using the data of 1145 university students in Japan from 2015 to 2017, we find that the sum of the systematic error from the false positives of Q.5, Q.6, Q.7, and Q.16 is about 10% of the FCI score of a mid-level student. We consider what degree the error influences the measures of the effectiveness of a course, namely, the average normalized gain and Cohens’ d. Using a set of simulated data, we show that Cohens’ d is less sensitive to the systematic error due to false positives than the average normalized gain.
Analysis of the learning of electrostatic concepts in pre-service physics teachers
Authors: Garrido N , López V , Pintó R
Published: August 2019

The objective of this work is to analyze the explanations of pre-service physics teachers, when they experience with different electrostatic phenomena included in a teaching and learning sequence (TLS). This TLS was designed for students to use the model of distribution and interaction between electric charges at first, for then promote that they explain certain more complex phenomena with the electric field model. The results show a significant improvement of the students’ explanations throughout the TLS due to several factors, including the teacher’s role.
Discovery Cycle as Strategy of Science Teaching
Authors: Hernández Alejandro González y , Segarra Alberú María del Pilar
Published: August 2019

The discovery cycle is a strategy for reaching the scientific knowledge trough of discovery. We are applying this strategy with physics students of Mechanics Laboratory of the first year of university. The cycle is focused on research the dynamical behaviors of mechanical systems modeled with Newton’s Laws. It consists of seven stages: exploration, experimentation, empirical modeling, theoretical modeling, numerical modeling, model results versus experiment and prediction. Students carry out this strategy in a specific context of a mechanics system. In this paper, we analyze this strategy with a group of 24 students in the study of the motion of an object, sliding on a tilted plane, and present the results we got in the application of this strategy.
A mesoscopic mechanical model of the surface tension and some simulation results
Authors: Battaglia Onofrio Rosario , Fazio Claudio
Published: August 2019

Drops of mercury do not spread on a surface. A metal paper clip can float on water. These phenomena are macroscopic manifestations of molecular interactions and can be explained in terms of surface tension. In this study, we discuss a simple mesoscopic mechanical model of the surface tension and the results of numerical fluid dynamics simulations implemented on the basis of it. We study the droplet formation without and with gravity when it can drop from a narrow hole like a trickling tap and finally the behaviour of free surface liquid in a vessel. Teachers and students can be able to study the surface tension by using the computer simulation as a “tool” for analysing and discussing the droplet and the liquid behaviour in several different conditions.
Introducing an innovative approach of teaching the Standard Model of particle physics at high school
Authors: Lindenau Philipp , Kobel Michael
Published: August 2019

The role that is assigned to elementary particle physics in high school education differs all over the world. Even within a single country like Germany there are major differences in the depth of discussion. To help teachers to address the fundamental concepts of elementary particles and their interactions and to reduce the subject didactically with respect to the given general conditions, Netzwerk Teilchenwelt has developed teaching material with an innovative didactic spiral approach that points out connections to common contents of physics curricula and is focused on the fundamental interactions of the Standard Model of particle physics and the charges that generate them. This concept is being presented and discussed during in-service trainings for teachers all over Germany. Since 2017, roughly 290 teachers have been trained in at least two-day courses and enabled to teach this approach.
3D-vision lab @ Open Labs Graz, an out-of-school learning environment
Authors: Krumphals I , Haagen-Schützenhöfer C , Jungwirth H
Published: August 2019

Vision and three-dimensional perception have always been an integral part of our everyday life. The commercial availability of 3D-technology makes it easy for everybody to perceive 2D-objects like photos and films three-dimensional. Consequently, 3D-vision is part of most students’ everyday life. As known from the PISA-study, Austrian students have a low value in motivation for science. The topic of 3D-vision is related to human body and therefore, as known from the ROSE study, it should be equally interesting for male and female students. Based on these assumptions, a first version of an out-of-school learning environment at the Open Labs Graz covering the topic of 3D-vision was designed and evaluated with two 11 year classes (n = 32). We found mediocre to rather high values of intrinsic motivation as well as differences between male and female students.
Universal Arduino-based experimenting system to support teaching of natural sciences
Authors: Gingl Z , Mellár J , Szépe T , Makan G , Mingesz R , Vadai G , Kopasz K
Published: August 2019

The rapid evolution of intelligent electronic devices makes information technology, computer science and electronics strongly related to the teaching of natural sciences. Today almost everybody has a smart phone that can convert light, temperature, movement, sound to numbers, therefore all these can be processed, analysed, displayed, stored, shared by software applications. The fundamental question is how education can follow this knowledge and how can education take its advantages. Components and methods of modern technology are available for education also, teachers and students can play with parts and tools which were previously used only by engineers. A good example is the very popular Arduino board which is practically an industrial microcontroller whose pins are wired to easy-to-use connectors on a printed circuit board. In this paper we show a universal system which we have developed for the Arduino platform to support experimenting and understanding of the most fundamental principles of the operation of modern devices. We show our related educational concept and discuss the most important features of the system. Open source hardware and software are available and we provide a number of video tutorials as well.
Physics experiments using simultaneously more than one smartphone sensors
Authors: Monteiro M , Stari C , Cabeza C , Martí A C
Published: August 2019

In the last years, numerous Physics experiments using smartphone sensors have been reported in the literature. In this presentation we focus on a less-explored feature of the smartphones: the possibility of using (measure and register data) simultaneously with more than one sensor. To illustrate, in the field of mechanics simultaneous use of the accelerometer and gyroscope (angular velocity sensor) or in optics experiments synchronous use of the ambient light and orientation sensors have been proposed. Indeed, this is a characteristic that simplifies experimental setups allowing to see through the physics concepts and, last but not least, reducing the costs.
Physicists’ conceptions about the nature of theoretical physics
Authors: Heine Antje
Published: August 2019

Scientists’ conceptions of their discipline give interesting insights in authentic scientific practice. The existing studies about scientists’ view of nature of science are rare. Schwartz & Ledermann (2008) were not able to identify clear differences between the conceptions from scientists from several disciplines. Only the ones from theoretical physicists differ from the ones from other scientists. The aim of the current study is the reconstruction of conceptions from researchers in the field of physics about the nature of physics. Here the comparison between experimentally and theoretically working physicists is particularly interesting.
Simulation study on bubble motion in capillaries based on lattice boltzmann method
Authors: Wang Xinyu , Li Ruosong , Li Hanjun , Xu Yuanqing
Published: August 2019

The lattice Boltzmann method with mesoscopic properties can conveniently describe the interaction of multiphase molecules and has wide application prospects in the field of multiphase flow. In this paper, the improved Shan-Chen pseudo-potential multiphase model in lattice Boltzmann method was used to simulate the process of bubble passing through stenotic capillaries during the pathogenesis of decompression sickness, and the velocity variation of the fluid in the process of flow was studied. According to the research results, it can be concluded that: (1) in the direct channel, the velocity of the fluid slows down with the increase of the gas composition, and the clogging can cause a more obvious trend of deceleration; (2) in the narrow channel, the fluid velocity changes abruptly when the gas enters and leaves the narrow area, and with the increase of the gas composition, the velocity change tends to be stable when the gas can completely fill the narrow area. This research provides a theoretical basis for further understanding the pathogenesis of decompression sickness.
Combined Numerical and Experimental Investigation of the Cavitation and Erosion of Submerged Self-resonating Waterjet
Authors: Cui Lihua , Ma Fei , Cai Tengfei , Pan Yan , Liu Boshen , Qiu Linbin
Published: August 2019

In ocean exploitation of deep-sea mineral, cavitation always occurs. In this paper, a model based on the Rayleigh-Plesset equation for researching the cavitation of the self-resonating waterjet was build up. A three-dimensional Computational Fluid Dynamic (CFD) analysis method to demonstrate the possibly of using the pressure distribution phenomenon prediction the evolution of cavitation bubbles. Frequency bands of numerical simulations were in good agreement with experimental data. Based on this, we obtain the shedding frequency of the bubbles, researched the erosions effect. The results validate the proposed scheme, which could be used to adjust the erosions domains.
Exploration and study of fluid thrust vector nozzle
Authors: Xue Fei , Wang Huaqiang , Wang Yuchao
Published: August 2019

A fluid thrust vectoring nozzle model was established, and the numerical simulation was used to study the model and flow. When the control slot was closed at the same time, the control slot did not work and the main direction was in the central region. When the control slot opens at the same time, due to the influence of the mainstream low pressure, the outer air flow flows into the mainstream from the upper and lower air inlets respectively, and the mainstream flow increases slightly. The main flow will not deflect when the upper and lower air inlets are opened or closed at the same time, thus verifying the accuracy of the calculation model. When one side of the air inlet is opened and the other side of the air inlet is closed at the same time, the external gas flows into the mainstream from the open side of the air inlet and impacts the mainstream. As the mainstream is impacted asymmetrically, it deflects to the closed side of the entrance. Fluid thrust vectoring nozzle has the advantages of simple structure and high control efficiency.
Lattice Boltzmann study on drag reduction of a bluff body by slip boundary
Authors: Yang Liuming , Gao Yuan , Zhao Shuai , Yu Yang , Hou Guoxiang
Published: August 2019

Slip velocity at boundary will emerge when gas film or superhydrophobic coatings are applied to the surface. The no-slip boundary conditions are no longer efficient. In this work, an improved boundary treatment is proposed to obtain slip velocity. Numerical results of the Couette flow have verified the accuracy and reliability of the improved boundary condition. Taking into account the effect of boundary slip, the present research predicts the resistance of a bluff body under low Reynolds numbers using the lattice Boltzmann method. Results show that reasonable slip distribution may be favourable to the drag reduction effect.
Experiment and simulation on clam water taxiing of seaplane based on CFD
Authors: Zheng Xiaolong , Wu Bin , Wang Mingzhen , Tang Binbin
Published: August 2019

In order to verify the feasibility of STAR-CCM+ in handling the clam water taxiing problem of seaplane, capturing the kinetic characteristic of free surface by overlap mesh and Euler VOF method, and compare it with the experiment result. It shows that the simulation results are in good agreement with the experimental values, and the information of the flow field is well consistent with the actual phenomena. From qualitative and quantitative perspectives point of view, it is feasible to use STAR-CCM+ based on overlap mesh method to simulate the calm water taxiing of seaplane, a new method for predicting hydrodynamic performance of seaplane is provided.
Influence of velocity slippage on nonlinear shaft center trajectory of journal bearing
Authors: Chen Xiaochao , Jin Jian , Fu Yiyang
Published: August 2019

Reynolds equation considering boundary slippage was used to calculate the oil film pressure, and Euler method was used to establish the motion equation of the axis in the coordinate system to solve the acceleration, velocity and position coordinates of the axis. Due to the influence of velocity slippage, the oil film pressure increases with the increase of slippage length, thus increasing the oil film force, the vibration of the axis and aggravating the instability of the axis, but decreasing the rotational speed of vortex; the shaft center trajectory gradually moves down to reduce the maximum external bearing load. When the length-diameter ratio becomes large, the effect of slippage length on shaft center trajectory is gradually reduced.
Stability analysis of a class of non-newtonian fluids based on generalized vector variational-like inequalities on riemannian manifold
Authors: Deng Shuxian , Ge Xinxin
Published: August 2019

Fluid mechanics is a branch of mechanics. It is the science of studying fluid phenomena and related mechanical behaviors. So far, the mutual soaking and fusion between fluid mechanics and other disciplines have formed many branches, many physicists and Mathematicians are working on this aspect of research. The classical Newtonian fluid mechanics believe that in parallel flow, the shear force is proportional to the shear rate, and the proportional coefficient is called the viscosity coefficient. In recent years, with the increasing importance of non-Newtonian fluids, people have found that research on non-Newtonian flow is necessary. The variational inequalities based on Riemannian manifolds were first proposed by S.Z.Németh. S.Z.Németh studied the existence of solutions to variational inequalities on Hadamard manifolds. For the equivalence of non-differentiable vector optimization problems on Riemannian manifolds and generalized weak vector variational-like inequalities, we give some new conclusions.
Research and application of dust control technology based on long pressure and short pumping system in mechanized tunneling face of coal roadway
Authors: Chen Fang , Zhang Sheji , Ma Wei , Mo Jinming
Published: August 2019

In order to solve the problem of dust pollution in mechanized tunneling face, Master the best matching relationship between the long and forced ventilation and the dusting and short dust removal parameters in the working face, reducing the dust concentration of working flour to the maximum degree. This paper takes the high-yield dust comprehensive mining face of Wangjialing coal mine as the research background, by establishing CFD model, the effect of dust control on different axial and radial air out ratio of working face is compared, and the parameters range of effective dust control is obtained, and the actual application of the field is verified and analyzed in order to get the best matching parameters of the control dust removal process. The results show that, after increasing the dust control of the wall winder, a fresh air flow transparent wall along the wall of the tunnel is formed in the tail of the roadheader, the dust can be controlled in the area of the front of the work. When the ratio of the axial and radial air out is 1:3, the dust is controlled in the smaller area near working face, the dust control effect is the best. The total and respirable dust concentration of the driver’s position and the 5m position at the tail of the driving machine can be reduced to less than 26.1 mg/m3 and 12.7 mg/m3. The dust control efficiency is above 80%, the overall dust efficiency is up to 94%, the dust reduction effect is obvious, and reduces the occupational hazards of workers.
Solving fractional nonlinear partial differential equations by the modified Kudryashov method
Authors: Hao Menghan , Zhang Yanni , Pang Jing
Published: August 2019

There are more and more methods for transforming nonlinear partial differential equations into ordinary differential equations by using the traveling wave transform. In this paper, the modified Kudryashov method is used to use the new traveling wave transform, and the exact solution of the space-time fractional equal-width equation is obtained by means of symbolic computation. Search for solution of the equal-width equation becomes more direct and simple. It is also suitable for solving a large number of similar fractional-order nonlinear partial differential equations, the method provides a new idea for solving fractional-order nonlinear partial differential equations.