bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparative Retrospective Analysis of Tension Band Wiring and 3.5 mm Precontoured Plate Used for Fixation of Chevron Osteotomy in Type C Distal Humerus Fractures
Authors: Nayak Mayur , Yadav Rahul , Batra Sahil , Sharma Vijay , Farooque Kamran , Maredupaka Siddhartha
Published: December 2020

Introduction Complex distal humerus fractures are rare and difficult to treat and traditionally requires an open reduction and internal fixation via a transolecranon approach. However, controversy remains regarding the better method of fixation of the chevron osteotomy. The purpose of the present study was to compare the clinical efficacy of tension band wiring (TBW) and 3.5 mm precontoured plate in treating the chevron osteotomy.

Materials and Methods A consecutive series of 49 patients who required olecranon osteotomy for type C distal humerus fractures were identified and grouped according to the construct used. Clinic–radiological evaluation was done at 3 months, 6 months, 1 year, and 2 years. A total of 34 males and 15 females with a mean age of 36.9 ± 12.64 years (18–62 years) were included in the study. Surgical duration, range of motion, Mayo elbow performance score (MEPS), and complications were noted at the follow-up.

Results The mean range of motion was initially lower in the plate group (105 degrees ± 9.9 in plate, 107 degrees ± 9.15 in TBW) that subsequently increased at 6 months. The forearm rotation was similar in both the groups. The mean MEPS was found to be higher in the plate group at 2 years (81.83 ± 5.85 in plate, 77.76 ± 8.02 in TBW). A significantly higher rate of complications, that is, nonunion (p = 0.03), loss of reduction (p = 0.03), and revision (p = 0.04) was observed in the TBW group. However, other complications such as symptomatic hardware, wound complication, and removal of hardware were found to be higher in the plate group.

Conclusion Both TBW and 3.5 mm precontoured plate provide comparable functional outcomes; however, the complication rate in terms of nonunion, loss of reduction, and revision is seen in the TBW, whereas wound complication and symptomatic hardware are more commonly seen in the plate.
Microfluidics enhance viral detection methods
Authors: Larter Raima
Published: December 2020

Infectious diseases, such as COVID-19, involve gene biomarkers that can be detected using an array of microfluidics technologies.
Multiscale measures of phase-space trajectories
Authors: Alberti Tommaso , Consolini Giuseppe , Ditlevsen Peter D. , Donner Reik V. , Quattrociocchi Virgilio
Published: December 2020

Characterizing the multiscale nature of fluctuations from nonlinear and nonstationary time series is one of the most intensively studied contemporary problems in nonlinear sciences. In this work, we address this problem by combining two established concepts—empirical mode decomposition (EMD) and generalized fractal dimensions—into a unified analysis framework. Specifically, we demonstrate that the intrinsic mode functions derived by EMD can be used as a source of local (in terms of scales) information about the properties of the phase-space trajectory of the system under study, allowing us to derive multiscale measures when looking at the behavior of the generalized fractal dimensions at different scales. This formalism is applied to three well-known low-dimensional deterministic dynamical systems (the Hénon map, the Lorenz ’63 system, and the standard map), three realizations of fractional Brownian motion with different Hurst exponents, and two somewhat higher-dimensional deterministic dynamical systems (the Lorenz ’96 model and the on–off intermittency model). These examples allow us to assess the performance of our formalism with respect to practically relevant aspects like additive noise, different initial conditions, the length of the time series under study, low- vs high-dimensional dynamics, and bursting effects. Finally, by taking advantage of two real-world systems whose multiscale features have been widely investigated (a marine stack record providing a proxy of the global ice volume variability of the past 5×106 years and the SYM-H geomagnetic index), we also illustrate the applicability of this formalism to real-world time series.
A charge control method for space-mission inertial sensor using differential UV LED emission
Authors: Yang Fangchao , Bai Yanzheng , Hong Wei , Sumner Timothy J. , Zhou Zebing
Published: December 2020

Various space missions and applications require the charge on isolated test masses to be strictly controlled because any unwanted disturbances will introduce acceleration through the Coulomb interaction between the test masses and their surrounding conducting surfaces. In many space missions, charge control has been realized using ultraviolet (UV) photoemission to generate photoelectrons from metal surfaces. The efficiency of photoelectron emission strongly depends on multiple physical parameters of gold-coated surfaces, such as the work function, reflectivity, and quantum yield. Therefore, to achieve satisfactory charge control performance, these parameters need to be measured accurately. This paper describes a charge control method that achieves self-adaptive charge neutralization while removing the need to measure the above-mentioned physical parameters. First, to explain the principle, a differential illumination model is constructed based on the typical structure of an inertial sensor. A charge management system based on a torsion pendulum system is then introduced along with an UV light emitting diode coupling system. Finally, experimental results are obtained in a vacuum chamber system with a pressure of 10−7 mbar, showing that precise calibration allows the test mass potential to be automatically controlled below 10 mV without considering the physical parameters or measuring the potential of the test mass before or after the control process.
Edge-cloud computing application, architecture, and challenges in ubiquitous power Internet of Things demand response
Authors: Pan Xiaowu , Jiang Aihua , Wang Haojie
Published: December 2020

Demand response (DR) is an effective way to control demand-side resources for power grids through advanced information and communication technologies. In the context of ubiquitous power Internet of Things (UPIoT), single cloud computing can hardly meet the requirements of large-scale real-time data processing in DR. Edge computing is a computing paradigm that deploys computing resources on the edge of the network, and its combination with cloud computing will help improve the ability of the power system to process large-scale sensor data. However, there is currently no comprehensive investigation on the application of edge computing technology in UPIoT DR. In this paper, the concept of DR and recent advances in the context of UPIoT are introduced first. Besides, the concept of edge-cloud computing (ECC) is introduced. Then, a comprehensive review of the existing work on DR based on ECC is presented. Furthermore, according to the existing work of Internet of Things (IoT) architecture based on ECC, a DR edge-cloud collaborative control architecture is proposed to meet the demand of UPIoT for ubiquitous perception and intelligent control. On this basis, the challenges in the practical application of edge computing in the UPIoT DR are introduced.
Determining the deformation and resulting coupling efficiency degradation of ultrastable fiber-coupled optical benches under load
Authors: Marburger Jean Pierre , Korn Christian , Mihm Moritz , Hellmig Ortwin , Wenzlawski André , Windpassinger Patrick
Published: December 2020

Fiber-coupled optical benches are an integral part of many laser systems. The base of such an optical bench is usually a slab of solid material, onto which optical components are fixed. In many environments, the ability to retain high fiber coupling efficiency under mechanical loads is essential. In this article, we study the fiber-to-fiber coupling efficiency under the application of static mechanical loads experimentally and theoretically: We constructed a simple three-point bending setup to interferometrically measure the deformation of an optical bench under load. Using the same setup, we further recorded the resulting coupling efficiency variations. The examined optical benches are based on Zerodur optical benches used in sounding rockets and International Space Station missions. We also developed an analytical model that incorporates an Euler–Bernoulli beam deformation model and a simple model for calculating the coupling efficiency, to which the experimentally obtained data are compared. Furthermore, we use a finite element method simulation to compare to the recorded deformation data. Recorded data, the analytical model, and simulations show good agreement. We also show how the presented analytical model can easily be expanded to contain more complex beam paths and, thus, be used to estimate coupling losses for experimentally relevant optical benches under load.
Magnetically tuning the loss tangent in La(Al1−xFex)O3 using low field electron paramagnetic resonance transitions
Authors: Gonzales Justin , Gajare Siddhesh , Nguyen Sophie , Wu Alicia , Newman Nathan
Published: December 2020

In 2012, we demonstrated that microwave loss in practical microwave dielectrics is dominated by electron paramagnetic resonance transitions at cryogenic temperatures. We later used this understanding to develop “smart” materials that switch Fe-doped Al2O3 (εr = 9.8) dielectric ceramics between a low-loss “on state” and a high-loss “off state” at frequencies of ∼12 and ∼19 GHz with a small magnetic field (<100 G). In this report, we extend our work on smart materials to the large dielectric constant (εr = 24) host La(Al1−xFex)O3 so that it can be used in compact resonator and filter designs operating at ∼4 GHz to ∼7 GHz. The Fe3+ ions' zero-field splitting energies are determined by the crystal-field parameters D = 1.55 GHz and E = 0 GHz, along with significant contributions from the higher-order terms, B40(−6.467 MHz) and B43 (160 MHz). These switchable dielectrics may have applications in future communication and Doppler technology.
Carrier dynamics near a crack in GaN microwires with AlGaN multiple quantum wells
Authors: Finot Sylvain , Grenier Vincent , Zubialevich Vitaly , Bougerol Catherine , Pampili Pietro , Eymery Joël , Parbrook Peter J. , Durand Christophe , Jacopin Gwénolé
Published: December 2020

Relaxation of tensile strain in AlGaN heterostructures grown on a GaN template can lead to the formation of cracks. These extended defects locally degrade the crystal quality, resulting in a local increase in non-radiative recombinations. The effect of such cracks on the optical and structural properties of core–shell AlGaN/AlGaN multiple quantum wells grown on GaN microwires is comprehensively characterized by means of spectrally and time-correlated cathodoluminescence (CL). We observe that the CL blueshifts near a crack. By performing 6 × 6 k.p simulations in combination with transmission electron microscopy analysis, we ascribe this shift to the strain relaxation by the free surface near cracks. By simultaneously recording the variations of both the CL lifetime and the CL intensity across the crack, we directly assess the carrier dynamics around the defect at T = 5 K. We observe that the CL lifetime is reduced typically from 500 ps to less than 300 ps and the CL intensity increases by about 40% near the crack. The effect of the crack on the optical properties is, therefore, of two natures. First, the presence of this defect locally increases non-radiative recombinations, while at the same time, it locally improves the extraction efficiency. These findings emphasize the need for time-resolved experiments to avoid experimental artifacts related to local changes of light collection.
Machine learning approach to constructing tight binding models for solids with application to BiTeCl
Authors: Nakhaee M. , Ketabi S. A. , Peeters F. M.
Published: December 2020

Finding a tight-binding (TB) model for a desired solid is always a challenge that is of great interest when, e.g., studying transport properties. A method is proposed to construct TB models for solids using machine learning (ML) techniques. The approach is based on the LCAO method in combination with Slater–Koster (SK) integrals, which are used to obtain optimal SK parameters. The lattice constant is used to generate training examples to construct a linear ML model. We successfully used this method to find a TB model for BiTeCl, where spin–orbit coupling plays an essential role in its topological behavior.
Pulsatile twin parallel jets through a flexible orifice with application to edge-to-edge mitral valve repair
Authors: Sargordi Maziar , Chtchetinina Anna , Di Labbio Giuseppe , Ng Hoi Dick , Kadem Lyes
Published: December 2020

Edge-to-edge repair is a procedure introduced to overcome mitral valve regurgitation. However, it leads to an unusual flow in the left ventricle characterized by twin parallel pulsed jets. This type of flow has not been extensively investigated in the literature. We set up a basic experiment to better characterize this type of flow from a fundamental point of view. Planar time-resolved particle image velocimetry measurements were performed downstream of three configurations of mitral valves corresponding to healthy and repaired valves. The flow field is characterized using velocity profiles, viscous energy dissipation, and time-frequency spectra, and their potential clinical impact is highlighted.
Room temperature exciton-polaritons in high-quality 2D Ruddlesden–Popper perovskites (BA)2(MA)n-1PbnI3n+1 (n = 3, 4)
Authors: Ouyang Chenxing , Li Yao , Fu Xianwei , Zeng Zhouxiaosong , Huang Lanyu , Liu Siman , Wang Xiao , Gao Tingge , Pan Anlian
Published: December 2020

Due to large binding energy and oscillator strength, 2D Ruddlesden–Popper perovskites are promising materials for the realization of room temperature coupled exciton-polaritons. Here, we demonstrate room temperature exciton-polaritons in high-quality exfoliated 2D RPP (BA)2(MA)n−1PbnI3n+1 (n = 3, 4) flakes without the use of external Distributed Bragg Reflectors. By angle-resolved PL spectroscopy, we obtain multi-mode low polariton branches and the Rabi splitting in the range of about 160 meV–180 meV for n = 3 and n = 4 flakes. The realization of room temperature exciton-polaritons in 2D RPPs with a large n value provides a potential platform for polaritonic device applications.
Combining the best of two worlds: Stimulated Raman excited fluorescence
Authors: Xiong Hanqing , Min Wei
Published: December 2020

The pursuit of a hybrid spectroscopy that combines the superb sensitivity of fluorescence and the high chemical specificity of Raman scattering has lasted for 40 years, with multiple experimental and theoretical attempts in the literature. It was only recently that the stimulated Raman excited fluorescence (SREF) process was successfully observed in a broad range of fluorophores. SREF allows single-molecule vibrational spectroscopy and imaging in the optical far field without relying on plasmonic enhancement. In this perspective, we will first review the historical efforts that lead to the successful excitation and detection of SREF, followed by the underlying physical principles, then the remaining technical challenges will be discussed, and, at last, the future opportunities in this old but yet newly emerged spectroscopy are outlined.
Mean-field density matrix decompositions
Authors: Eriksen Janus J.
Published: December 2020

We introduce new and robust decompositions of mean-field Hartree–Fock and Kohn–Sham density functional theory relying on the use of localized molecular orbitals and physically sound charge population protocols. The new lossless property decompositions, which allow for partitioning one-electron reduced density matrices into either bond-wise or atomic contributions, are compared to alternatives from the literature with regard to both molecular energies and dipole moments. Besides commenting on possible applications as an interpretative tool in the rationalization of certain electronic phenomena, we demonstrate how decomposed mean-field theory makes it possible to expose and amplify compositional features in the context of machine-learned quantum chemistry. This is made possible by improving upon the granularity of the underlying data. On the basis of our preliminary proof-of-concept results, we conjecture that many of the structure–property inferences in existence today may be further refined by efficiently leveraging an increase in dataset complexity and richness.
On the unsteady throttling dynamics and scaling analysis in a typical hypersonic inlet–isolator flow
Authors: Sekar K. Raja , Karthick S. K. , Jegadheeswaran S. , Kannan R.
Published: December 2020

The flow field in a two-dimensional three-ramp hypersonic mixed-compression inlet in a freestream Mach number of M∞ = 5 is numerically solved to understand the unsteady throttling dynamics. Throttling conditions are simulated by varying the exit area of the isolator in the form of plug insets. Different throttling ratios between 0 ≤ ζ ≤ 0.7 in steps of 0.1 are considered. No unsteadiness is observed for ζ ≤ 0.2, and severe unsteadiness is found for 0.3 ≤ ζ ≤ 0.7. The frequency of unsteadiness (f) increases rapidly with ζ. As ζ increases, the amount of reversed mass inside the isolator scales with the frequency and the exit mass flow rate. A general framework is attempted to scale the unsteady events based on the gathered knowledge from the numerical study. The inlet–isolator flow is modeled as an oscillating flow through a duct with known upstream design conditions such as the freestream Mach number (M∞) and the isolator inlet Mach number (Mi). Factors such as the mass occupied by the duct volume, the characteristic unsteady frequency, the throttling ratio, and the exit mass flow rate through the duct are used to form a non-dimensional parameter β, which scales with the upstream design parameter ξ = Mi/M∞. The scaling parameters are further exploited to formulate a semi-empirical relation using the existing experimental results at different throttling ratios from the open literature. The unsteady frequencies from the present two-dimensional numerical exercise are also shown to agree with the proposed scaling and the resulting semi-empirical relation.
Large pressure-induced magnetoresistance in a hybrid ferromagnet-semiconductor system: Effect of matrix modification on the spin-dependent scattering
Authors: Arslanov T. R. , Zalibekov U. Z. , Kilanski L. , Fedorchenko I. V. , Chatterji T. , Ahuja R.
Published: December 2020

Magnetic nanocomposites based on MnAs clusters embedded in a chalcopyrite host usually do not exhibit large magnetoresistance (MR) at room temperature, while pronounced effects are localized at very low temperatures. In the present work, we observed an appearance of large pressure-induced negative and positive MR at room temperature in the Zn0.1Cd0.9GeAs2 hybrid system containing 10% MnAs inclusions. With the applied pressure, a substantial modification of the electron transport from semimetallic to semiconducting type occurs, followed by a subsequent structural transition at P ≈ 3.5 GPa into almost metallic high-pressure phase. This picture is simultaneously supported by temperature-dependent and room temperature high-pressure transport measurements. Using a semiempirical expression, taking into account a spin-dependent scattering of charge carriers due to MnAs nanoclusters, as well as a two-band conductivity model, we have been able to partially describe the observed MR effects. The predominantly weak positive contribution at P = 1 GPa, which is well described in the framework of the proposed approach indicates the presence of spin-polarized charge carriers. Based on the two-band model calculations, a negative spin polarization was found at P ≥ 3 GPa that ascribed to a structural change of the matrix. As our results indicate, an emerging MR in the structural transition region is characterized by a complex behavior. In particular, the negative part of MR demonstrates a magnetic field dependence different than Δρ/ρ0 ∼ H2, suggesting the presence of unusual scattering mechanisms in magnetotransport.
Preventing rangeland degradation: a shared problem for Australia and China
Authors: Hodgkinson Kenneth C. , Wang Deli
Published: December 2020

Rangeland degradation continues in Australia, China and elsewhere. The stocking rate/animal production relationship has been a successful concept for pastoralists wanting to avoid degradation and/or raise incomes. However, there are no means available of alerting pastoralists to the approach of critical thresholds that would ‘flip’ rangelands into alternative states when grazing-stressed. Critical threshold forecasting for avoiding degradation (and seizing restoration opportunities) could be made available online. Research has yet to find, assemble and test the set of indicators needed to forecast the approach of critical thresholds envisaged in State-and-Transition thinking. Forecasting at paddock, property and regional scales would have to involve high-performance computing because the thresholds will be space and time dependent. The case for Australia and China to contribute cooperatively to this research effort rests on the large number of contrasting rangeland ecosystems across the two countries that represent rangelands globally. A proven history of past collaboration is extant with existing research programs on plant population dynamics, landscape patchiness/leakiness and soil biota status, and their responses to the separate and combined effects of climate and grazing animals. The road to adoption would involve partnerships with pastoralists throughout the process, remote sensing to identify approaching thresholds in real time, application of high-performance computing and possibly artificial intelligence, and packaging of forecasts for different socio-economic rangeland systems.
Nonequilibrium models of optimal enhancer function
Authors: Grah Rok , Zoller Benjamin , Tkačik Gašper
Published: December 2020

Significance

Simple biophysical models successfully describe bacterial regulatory code, by predicting gene expression from DNA sequences that bind specialized regulatory proteins. Analogous simple models fail in multicellular organisms, where regulatory proteins bind DNA very transiently, yet, nevertheless, effect precise control over gene expression. To date, the more general, “nonequilibrium” models have proven difficult to analyze and connect to data. Here, we reduce this complexity theoretically, by constructing simple nonequilibrium models which perform optimal gene regulation within known experimental constraints.
Unit-lapse versions of the Kerr spacetime
Authors: Baines Joshua , Berry Thomas , Simpson Alex , Visser Matt
Published: December 2020

The Kerr spacetime is perhaps the most astrophysically important of the currently known exact solutions to the Einstein field equations. Whenever spacetimes can be put in unit-lapse form it becomes possible to identify some very straightforward timelike geodesics, (the ‘rain’ geodesics), making the physical interpretation of these spacetimes particularly clean and elegant. The most well-known of these unit-lapse formulations is the Painlevé–Gullstrand form of the Schwarzschild spacetime, though there is also a Painlevé–Gullstrand form of the Lense–Thirring (slow rotation) spacetime. More radically there are also two known unit-lapse forms of the Kerr spacetime—the Doran and Natário metrics—though these are not precisely in Painlevé–Gullstrand form. Herein we shall seek to explicate the most general unit-lapse form of the Kerr spacetime. While at one level this is ‘merely’ a choice of coordinates, it is a strategically and tactically useful choice of coordinates, thereby making the technically challenging but astrophysically crucial Kerr spacetime somewhat easier to deal with. While in the current article we focus on the ‘rain’ geodesics, it should be noted that the explicit unit-lapse metrics we present are also useful for looking at other more complicated geodesics in the Kerr spacetime.
Micro-machined stent flow sensor for detecting breathing and heartbeat from airflow in airway of rat
Authors: Noma Hayato , Hasegawa Yoshihiro , Matsushima Miyoko , Kawabe Tsutomu , Shikida Mitsuhiro
Published: December 2020

We developed a stent flow sensor using micro-electromechanical systems (MEMS) technology in order to measure airflow in the airways of laboratory animals. An airflow waveform contains a respiration signal produced by lung motion and heartbeats as these functions are physically connected. This enables both respiration and heart functions to be evaluated under unrestrained and unanesthetized conditions during drug development. Using MEMS technology, we fabricated a tube flow sensor based on a thermal principle, and the stent structure was produced by photolithography and wet etching. The fabricated flow sensor and stent were integrated via a connection area on both elements. In the proof-of-concept trial, we verified that the flow sensor was placed in the center of the tube by expanding the stent. We evaluated the flow detection characteristics, sensor output vs flow rate and sensor response and used the developed stent flow sensor to measure the airflow in the airway of a rat. The respiration and heartbeat signals were successfully identified from the airflow waveform by applying Fourier transform analysis.
Influence of transition group elements on the stability of the γ″-phase in nickelbase alloys
Authors: Bäker Martin , Rösler Joachim
Published: December 2020

Alloy 718-type wrought nickel-based superalloys are the materials of choice for many high temperature applications. They are strengthened by the γ″-phase that forms small precipitates with a large lattice distortion. However, at temperatures above 650 °C, this phase may transform to the thermodynamically stable δ-phase. It is therefore important to understand the influence of alloying elements on the stability of these phases. In this paper, density functional theory calculations at 0 K are performed to determine the effect of aluminium and of the transition group elements on the stability and the lattice parameters of the γ″-phase. It is shown that the substitution energy is mainly determined by two parameters, the charge transfer and the change in the lattice constant. Solution energies are compared to those in the δ-phase and some conclusions for the design of 718-type alloys are drawn.
Optical quantum yield in plasmonic nanowaveguide
Authors: Singh Mahi R , Brassem Grant , Yastrebov Sergey
Published: December 2020

We have developed a theory of the quantum yield for plasmonic nanowaveguide where the cladding layer is made of an ensemble of quantum dots and the core layer consists of an ensemble of metallic nanoparticles. The bound states of the confined probe photons in the plasmonic nanowaveguide are calculated using the transfer matrix method based on the Maxwell equations. It is shown that the number of bound states in the nanowaveguide depends on the dielectric properties of the core and cladding layers. The surface plasmon polaritons (SPPs) produced by the metallic nanoparticles interacts with the excitons of the quantum dots. The radiative and nonradiative linewidths of excitons in the quantum yield are calculated using the quantum mechanical perturbation theory. We have found that the quantum yield decreases as the dipole–dipole interaction between metallic nanoparticles increases. We have also calculated the photoluminescence and found that the enhancement in photoluminescence is due to the SPPs coupling. On the other hand, the quenching in the photoluminescence is due to the quantum yield. We compared our theory with experiments of a nanowaveguide where the core is fabricated from Ag- nanoparticles and the cladding is fabricated from the perovskite quantum dots. A good agreement between theory and experiments is found. Our analytical expressions of the quantum yield and photoluminescence can be used by experimentalists to proforma new types of experiments and for inventing new types of nanosensors and nanoswitches.
Electron–optical-phonon scattering rates in cubic group III-nitride crystals: path-integral corrections to Fermi golden rule matrix elements
Authors: Singh Ramji , Dutta Mitra , Stroscio Michael A
Published: December 2020

III-nitride semiconductors with a cubic crystal structure have shown promise in enhancing efficiency in photonic and optoelectronic applications. The recent interest in cubic III-nitrides has arisen due to the inability to realize enhanced efficiency in optoelectronic applications of the wurtzite phase due to spontaneous polarization effects, crystal defects due to growth on lattice mismatched substrates, and also due to the requirement to fabricate normally-off transistors for high-mobility transistors. Cubic III-nitride materials are characterized by the strong coupling of carriers to optical phonons in which the standard perturbative approach—based on first order perturbation theory—breaks down. In this paper we determine the necessary corrections to the Fermi golden rule electron–optical-phonon matrix elements for selected cubic III-nitrides via the nonperturbative Thornber–Feynman path-integral techniques. Specifically, we report electron transport parameters such as the threshold electric field, threshold velocity, mobility and runaway length for BN, AlN, GaN and InN. 72.10.Di, 72.15.Lh, 72.80.Ey.
Number-resolved preparation of mesoscopic atomic ensembles
Authors: Hüper A , Pür C , Hetzel M , Geng J , Peise J , Kruse I , Kristensen M , Ertmer W , Arlt J , Klempt C
Published: December 2020

The analysis of entangled atomic ensembles and their application for interferometry beyond the standard quantum limit requires an accurate determination of the number of atoms. We present an accurate fluorescence detection technique for atoms that is fully integrated into an experimental apparatus for the production of many-particle entangled quantum states. Number-resolved fluorescence measurements with single-atom accuracy for 1 up to 30 atoms are presented. According to our noise analysis, we extrapolate that the single-atom accuracy extends to a limiting atom number of 390(20) atoms. We utilize the accurate atom number detection for a number stabilization of the laser-cooled atomic ensemble. For a target ensemble size of 7 atoms prepared on demand, we achieve a 92(2)% preparation fidelity and reach number fluctuations 18(1) dB below the shot noise level using real-time feedback on the magneto-optical trap.
Linear instability of charged massless scalar perturbation in regularized 4D charged Einstein-Gauss-Bonnet anti de-Sitter black holes *
Authors: Liu Peng , Niu Chao , Zhang Cheng-Yong
Published: December 2020

We study the linear instability of the charged massless scalar perturbation in regularized 4D charged Einstein-Gauss-Bonnet-AdS black holes by exploring their quasinormal modes. We find that the linear instability is triggered by superradiance. The charged massless scalar perturbation becomes more unstable with increasing Gauss-Bonnet coupling constant or black hole charge. Decreasing the AdS radius, on the other hand, will make the charged massless scalar perturbation more stable. The stable region in parameter space (α, Q, Λ) is given. Moreover, we find that the charged massless scalar perturbation is more unstable for larger scalar charge. The modes of multipoles are more stable than that of the monopole.
Measurement of the 27Al+ and 87Sr absolute optical frequencies
Authors: Leopardi Holly , Beloy Kyle , Bothwell Tobias , Brewer Samuel M , Bromley Sarah L , Chen Jwo-Sy , Diddams Scott A , Fasano Robert J , Hassan Youssef S , Hume David B , Kedar Dhruv , Kennedy Colin J , Leibrandt David R , Ludlow Andrew D , McGrew William F , Milner William R , Nicolodi Daniele , Oelker Eric , Parker Thomas E , Robinson John M , Romisch Stefania , Sherman Jeff A , Sonderhouse Lindsay , Yao Jian , Ye Jun , Zhang Xiaogang , Fortier Tara M
Published: December 2020

We perform absolute measurement of the 27Al+ single-ion and 87Sr neutral lattice clock frequencies at the National Institute of Standards and Technology and JILA at the University of Colorado against a global ensemble of primary frequency standards. Over an eight month period multiple measurements yielded the mean optical atomic transition frequencies

ν

Al

+

=
1

121

015

393

207

859.50

(

0.36

)

Hz and ν
Sr = 429 228 004 229  873.19(0.15) Hz, where the stated uncertainties are dominated by statistical noise and gaps in the observation interval (‘dead-time’ uncertainty).
Search for exotic states in photoproduction at GlueX
Authors: Hamdi Abdennacer
Published: December 2020

Understanding the hadron spectrum is one of the primary goals of non-perturbative QCD. Many predictions have been experimentally confirmed, but others remain under experimental investigation. Of particular interest is how gluonic excitations give rise to states with constituent glue. One class of such states are hybrid mesons that are predicted by theoretical models and Lattice QCD calculations. Searching for and understanding the nature of these states is a primary physics goal of the GlueX experiment at the CEBAF accelerator at Jefferson Lab in the US. We will give an overview of the experiment, and present the status of the search for a hybrid meson candidate, Y(2175).
Model checking games and a genome sequence search
Authors: Staroletov S M
Published: December 2020

The paper is considered a concept of model checking games to solve algorithmic puzzles. We describe current approaches in this field and move to a game between a user and a software model checker with the goal to provide a solution to a problem, encoded in a transition system and an LTL formula with a requirement. We show how to encode and solve some problems using this approach. Then we move to the problem of searching a pattern in a genome sequence. We implement the Z-function search method in Promela, construct the model, provide the input of real viral data, and then play a model checking game with SPIN verifier. We created a fuzzy substring search method using the non-deterministic choice operator. Based on experiments we made, we discuss that the problem to find a pattern with some deviations is only solvable using the swarm verification and hash compact methods.
Design of PD-type second-order ILC law for PMSM servo position control
Authors: Riaz Saleem , Lin Hui , Bilal Anwar Muhammad , Ali Haider
Published: December 2020

An iterative learning control method is better to control the high-order nonlinear strong coupling and external disturbances in the permanent magnet synchronous motor position servo system. This paper proposes a second-order P.D. type iterative learning control strategy, which can effectively achieve the optimal tracking control algorithm. By using the generalization of the Young inequality of convolution, the Lebesgue-p norm is obtained under the adequate condition that the tracking error converges monotonously. Furthermore, the convergence rate of second-order iterative learning control is compared, and it is proved by the mathematical knowledge that second-order iterative learning control is much better than a first-order iterative learning control under satisfactory conditions. Simulation results show that the effectiveness of the proposed algorithm is better than that of the traditional method, and the error of the iterative learning control strategy is smaller but with higher accuracy.
Change of quantum correlation for two simultaneously accelerated observers
Authors: Li Yue , Pan Yongjie , Zhang Baocheng
Published: December 2020

The influence of Unruh effect on the quantum and classical correlation of a quantum entangled state is investigated, when one or two of the observers are accelerated. It is found that the quantum and classical correlation would approach to a finite value with the increase of the acceleration when only one observer is accelerated, but they would decrease to zero quickly when two observers are accelerated. The latter result implies that the gravitational field would break the correlation obviously when the acceleration is caused by the gravitational field. Thus, when the two observers stay in the gravitational field, the quantum or classical correlation would not easy to be preserved for a long time.
Qualitative research on the relationship between spindle vibration characteristics and bearing thermal load
Authors: Zhang Leilei , Xuan Jianping
Published: December 2020

The dynamic performance of machine tool is one of the most important factors affecting the machining accuracy. As the core part of machine tool, the dynamic performance of spindle directly determines the performance of machine tool. In this paper, the spindle of machine tool is taken as the research object, and the change of fit clearance between bearing inner and outer rings, rotating shaft and bearing seat caused by spindle bearing heat, and its influence on the stiffness of spindle system are analyzed. Based on Timoshenko beam theory and finite element method, this paper qualitatively analyzes the variation characteristics of spindle stiffness caused by bearing overheating and grease lubrication failure during high-speed machining.
Design and test of porosity testing apparatus for granular materials
Authors: Mai Zhiwei , Wang Biying
Published: December 2020

In order to improve the accuracy and reliability of porosity measurement of granular materials, on the basis of equation of state of ideal gas and gas displacement method, a rapid measurement apparatus for porosity of granular materials with constant volume was studied and an automatic detection control system was developed. Within measurement range of 0.1∼ 0.4 MPa, the standard stainless-steel spheres, plastic quadrangular prisms, cobblestones and fine gravels with different shapes accurately measurable were adopted, and it was found that the higher the inflation pressure of the system, the smaller the measurement error and the better the repeatability. Using standard stainless-steel sphere and cylinder with porosity of 16.02%, 25.14%, 35.57%, 49.05%, 58.42%, 67.79%, 76.57%, 85.36% and 94.14% respectively, the formula of compensation coefficient was given. The measurement error was 0.3%, which proved the reliability of the measurement results.
Research on influencing factors of injection capacity in cycle steam stimulation process with horizontal well in Bohai oilfield
Authors: Liu Quangang , Wang Hongshen , Ren Lei , Zhong Liguo , Liu Yigang
Published: December 2020

Since the beginning of the 21st century, the proportion of heavy oil production has been increasing. Cycle steam stimulation (CSS in short) is the prevailing technology for the development of heavy oil reservoirs and has made a great contribution to the development of heavy oil. However, the current research on the factors affecting the steam injection capacity of CSS heavy oil reservoirs and the degree of influence of each factor is insufficient. Oil recovery and heat utilization efficiency are poor, especially in the oil fields with poor reservoir conditions and severe heterogeneity. In this paper, the reservoir geological model of the Bohai oilfield was established, and the CSS development was predicted. The problems in the development process of CSS in Bohai oilfield were pointed out. Then, laboratory experiments were carried out to study the steam absorption law of CSS heavy oil reservoirs in consideration of reservoir permeability, steam injection rate, steam injection temperature and crude oil viscosity. The result showed that higher formation permeability and steam injection temperature could improve oil displacement efficiency; higher steam injection rate would reduce oil displacement efficiency. Finally, the influence rules of different injection-production parameters were clarified to shed some lights on the efficient exploitation of heavy oil reservoirs.
Experimental investigation on the injection profile variation in the weak gel injection process
Authors: Zhao Peng , Han Yugui , Meng Xianghai , Yuan Yujing , Zhang Xiaoran , Zhong Liguo , Yu Zewen
Published: December 2020

In this paper, the gel-forming performance and rheological properties of weak gel systems were studied through laboratory gel-forming experiments. The plugging behavior and mechanism of the weak gel system for sand-packed tubes with different permeability were evaluated. The results showed that intramolecular cross-linking was dominated when the polymer concentration was low and the viscosity increased litter after gelation. Intermolecular cross-linking plays a major role when the polymer concentration is high. The injection speed has a great influence on the resistant factor (RF in short) of the weak gel. During low-speed injection, the weak gel has a large amount of retention on the surface of the rock particles, resulting the high viscosity of the weak gel. The RF during low-speed injection is much higher than that in high-speed injection and it keeps increasing as the injection volume increase. The impact of the injection rate on RF of hydrolyzed polyacrylamide (HPAM) is significantly lower than weak gels, because the retention of HPAM in the sand-packed tube reaches a stable level, the RF remains basically unchanged.
Suggestion on using the hexapod robot as a coordinate measuring machine in digitizing data and measuring space surfaces
Authors: Trang Thanh-Trung , Le Thi-Thu-Thuy , Pham Thanh-Long
Published: December 2020

Testing or digitizing the machined surface in inverse manufacturing always requires the use of modern, interconnected measuring devices, and these devices share tool control programs with probe trajectory to check 3D surfaces through CAM software. Coordinate measuring machines with a large workspace need very rigid mechanical structures and parallel structures used instead are one of the solutions to this problem. Despite the extremely high stiffness, the characteristics of the parallel structure are of compound design and kinematics. One of the typical difficulties is that the forward and inverse kinematic problems have many solutions. When used as a measuring machine, solving the kinematic problem is often required. If there are not enough bases to unique identify the endpoint coordinates, the application of robots such as hexapods to make CMM machines will fail. This paper introduces a technical solution to achieve a unique solution when solving a forward kinematic problem using a hexapod device. The sensors are mounted on the device to recognize the generalized coordinates and the auxiliary parameters at the same time, then the unique solution of the problem will be determined. The illustrative application on the parallel structure of the SRS and SPS hexapod configuration shows the correctness of the research idea.
Learning hydrodynamic signatures through proprioceptive sensing by bioinspired swimmers
Authors: Pollard Beau , Tallapragada Phanindra
Published: December 2020

Objects moving in water or stationary objects in streams create a vortex wake. Such vortex wakes encode information about the objects and the flow conditions. Underwater robots that often function with constrained sensing capabilities can benefit from extracting this information from vortex wakes. Many species of fish do exactly this, by sensing flow features using their lateral lines as part of their multimodal sensing. To replicate such capabilities in robots, significant research has been devoted to developing artificial lateral line sensors that can be placed on the surface of a robot to detect pressure and velocity gradients. We advance an alternative view of embodied sensing in this paper; the kinematics of a swimmer’s body in response to the hydrodynamic forcing by the vortex wake can encode information about the vortex wake. Here we show that using artificial neural networks that take the angular velocity of the body as input, fish-like swimmers can be trained to label vortex wakes which are hydrodynamic signatures of other moving bodies and thus acquire a capability to ‘blindly’ identify them.
Forest effects on runoff under climate change in the Upper Dongjiang River Basin: insights from annual to intra-annual scales
Authors: Li Zehua , Zhou Ping , Shi Xiaogang , Li Yongkun
Published: December 2020

Climate change and large-scale afforestation characterize the conditions in the Upper Dongjiang River Basin (UDRB), which is one of the most important headwater basins in southern China. It is important to understand whether, and to what extent, the observed runoff change can be attributed to forest and/or climate change. Using process- and relation-based methods, we found precipitation in spring (March–May) decreased notably, while precipitation in summer (June–August) showed an increase from the reference period (1961–1990) to the afforestation period (1991–2010). In comparison, annual averaged potential evapotranspiration did not change much. Both of the methods indicated forest had a positive effect while climate change exerted a negative impact on annual averaged runoff in the UDRB. As a result, the observed annual averaged runoff only showed a little decrease from the reference period to the afforestation period. The climate change impact on monthly averaged runoff basically followed the pattern of precipitation change. Except in July and August, climate change exerted negative or little impact on runoff in most of other months. In comparison, the forest effects on monthly averaged runoff change showed a totally different pattern. Except in May and June, forest exerted positive impact on runoff in other months. As a result, the observed monthly averaged runoff in May and June experienced notable reduction, while those in other months experienced increase or no change. The UDRB provides evidence that additional forest cover would not injure but even increase runoff, especially dry season runoff. The study has important implications for sustainable water management and afforestation in this subtropical region and for similar river basins.
Biochar from Biomass Slow Pyrolysis
Authors: Cai Nan , Zhang Huili , Nie Jiapei , Deng Yimin , Baeyens Jan
Published: December 2020

Pyrolysis is widely used in the chemical industry to produce e.g. carbon black from heavy fuel oil (HFO) and coke from coal, to convert post-consumer plastic waste into chemicals, to transform heavier hydrocarbons into lighter ones, and to thermo-chemically treat biomass. Whereas a lot of work has been presented on the fast pyrolytic production of bio-oil from biomass, the objectives of biochar and added-value chemicals are now a major focus when using biomass in a slow pyrolysis reactor. Fast pyrolysis targets mostly bio-oil (up to 60 or 70 wt%). Slow pyrolysis targets mostly biochar (up to ∼60 wt%), together with 25-30 wt% of bio-oil and the balance as gas. The paper presents results from biomass pyrolysis in the slow operating mode and assesses the products formed and their application perspectives.
Kinetic Analysis of Durian Rind Pyrolysis Using Model-Free Method
Authors: Bampenrat A , Boonkitkoson A , Seangwattana T , Suttiarporn P , Sukkathanyawat H
Published: December 2020

In this study, the thermal degradation behavior and kinetic parameters of durian rind were investigated by using the thermogravimetric analysis technique. The experiments were performed in the temperature range of 313 – 1,073 K with the heating rate of 5, 10, 20 and 40 Kmin−1. Three model-free methods namely Friedman (FR) method, Kissinger-Akahira-Sunose (KAS) method, and Flynn-Wall-Ozawa (FWO) method were used to attain the kinetic parameters. The results show that the thermal degradation of durian rind exhibits 3 stages including dehydration stage (up to 380 K), active pyrolysis stage (380 – 680 K) and passive pyrolysis stage (above 680 K). A maximum rate loss shifts to a higher temperature with an increases in the heating rate. The values of kinetic parameters obtained from FR, KAS and FWO methods are in a good agreement with the experimental results. The average activation energies calculated by FR, KAS and FWO methods are reported at 243.02, 220.38 and 218.33 kJmol−1, respectively. Combining with heating value and chemical structure of durian rind, it can be stated that durian rind can become a useful source of alternative fuels and/or chemical feedstocks.