bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and test of high-voltage, high-repetition rotary trigger double spark gap switch
Authors: Cho Chuhyun , Han Seong-Tae , Jin Yun-Sik
Published: January 2021

Spark gap switches are used in various high-power pulse systems because they can quickly transfer the energy stored in the capacitor to the load. A rotary trigger double spark gap (RTDSG) switch is proposed in this paper as a type of switch capable of high repetition at high power. It was found that a pulse switching of 20 kV and 1 kHz was possible by applying the multiple RTDSG switches to increase the repetition rate of the switch. In addition to the basic operating principle of the RTDSG, the effects of switching-related parameters on the operating frequency of the switch were analyzed. As an example of promising applications of the high repetition RTDSG, the generation of shock waves by underwater discharge and the effective dispersion of carbon nanotubes using the shock waves are reported.
Wide range tunable bandgap and composition
β
-phase (AlGa)2O3 thin film by thermal annealing
Authors: Liao Che-Hao , Li Kuang-Hui , Torres-Castanedo Carlos G. , Zhang Guozheng , Li Xiaohang
Published: January 2021

We have demonstrated wide bandgap and composition range β-(AlxGa1−x)2O3 thin films by employing thermal annealing of β-Ga2O3/sapphire templates. With proper annealing conditions at 1000–1500 °C, the β-Ga2O3 thin films transformed to the β-(AlxGa1−x)2O3 thin films with different bandgaps and compositions due to the Al diffusion from sapphire. Meanwhile, the Ga atoms diffused into sapphire. The interdiffusion process caused an increased film thickness, which was enhanced in proportion to the annealing temperature. It was confirmed by secondary ion mass spectrometry (SIMS) and transmission electron microscopy. Thus, higher temperatures resulted in high Al contents in the β-(AlxGa1−x)2O3 films. Also, the SIMS measurements show highly homogeneous Al contents throughout the β-(AlxGa1−x)2O3 films annealed at 1200 °C and above. Evaluated by x-ray diffraction (XRD), the Al content range of the samples is 0–0.81 for the β-Ga2O3 templates without annealing and with annealing up to 1500 °C. Evaluated by UV-Vis spectroscopy, the optical bandgap range of the samples is 4.88–6.38 eV for the β-Ga2O3 templates without annealing and with annealing up to 1400 °C, translating to the Al content range of 0–0.72. Moreover, the crystal quality of β-(AlxGa1−x)2O3 improved as the Al composition became larger due to higher annealing temperatures. The proposed technique is promising for the preparation of β-(AlxGa1−x)2O3 thin films without employing “direct-growth” techniques.
Reconstituting the dynamics of endothelial cells and fibroblasts in wound closure
Authors: Tefft Juliann B. , Chen Christopher S. , Eyckmans Jeroen
Published: January 2021

The formation of healthy vascularized granulation tissue is essential for rapid wound closure and the prevention of chronic wounds in humans, yet how endothelial cells and fibroblasts coordinate during this process has been difficult to study. Here, we have developed an in vitro system that reveals how human endothelial and stromal cells in a 3D matrix respond during wound healing and granulation tissue formation. By creating incisions in engineered cultures composed of human umbilical vein endothelial cells and human lung fibroblasts embedded within a 3D matrix, we observed that these tissues are able to close the wound within approximately 4 days. Live tracking of cells during wound closure revealed that the process is mediated primarily by fibroblasts. The fibroblasts migrate circumferentially around the wound edge during early phases of healing, while contracting the wound. The fibroblast-derived matrix is, then, deposited into the void, facilitating fibroblast migration toward the wound center and filling of the void. Interestingly, the endothelial cells remain at the periphery of the wound rather than actively sprouting into the healing region to restore the vascular network. This study captures the dynamics of endothelial and fibroblast-mediated closure of three-dimensional wounds, which results in the repopulation of the wound with the cell-derived extracellular matrix representative of early granulation tissue, thus presenting a model for future studies to investigate factors regulating vascularized granulation tissue formation.
Are charged tips driving TERS-resolution? A full quantum chemical approach
Authors: Fiederling K. , Kupfer S. , Gräfe S.
Published: January 2021

Experimental evidence suggests an extremely high, possibly even sub-molecular, spatial resolution of tip-enhanced Raman spectroscopy (TERS). While the underlying mechanism is currently still under discussion, two main contributions are considered: The involved plasmonic particles are able to highly confine light to small spatial regions in the near-field, i.e., the electromagnetic effect and the chemical effect due to altered molecular properties of the sample in close proximity to the plasmonic tip. Significant theoretical effort is put into the modeling of the electromagnetic contribution by various groups. In contrast, we previously introduced a computational protocol that allows for the investigation of the local chemical effect—including non-resonant, resonant, and charge transfer contributions—on a plasmonic hybrid system by mapping the sample molecule with a metallic tip model at the (time-dependent) density functional level of theory. In the present contribution, we evaluate the impact of static charges localized on the tip’s frontmost atom, possibly induced by the tip geometry in the vicinity of the apex, on the TERS signal and the lateral resolution. To this aim, an immobilized molecule, i.e., tin(II) phthalocyanine (SnPc), is mapped by the plasmonic tip modeled by a single positively vs negatively charged silver atom. The performed quantum chemical simulations reveal a pronounced enhancement of the Raman intensity under non-resonant and resonant conditions with respect to the uncharged reference system, while the contribution of charge transfer phenomena and of locally excited states of SnPc is highly dependent on the tip’s charge.
Magnetic and electronic structures of antiferromagnetic topological material candidate EuMg2Bi2
Authors: Marshall Madalynn , Pletikosić Ivo , Yahyavi Mohammad , Tien Hung-Ju , Chang Tay-Rong , Cao Huibo , Xie Weiwei
Published: January 2021

EuMg2Bi2 has been investigated to understand the electronic and magnetic behaviors as an antiferromagnetic (AFM) topological semimetal candidate. High-quality single crystals of EuMg2Bi2 were grown via a Bi flux and, subsequently, characterized to be consistent with the previously reported bulk magnetic and resistivity properties. A ferromagnetic interaction is indicated by the positive Curie–Weiss temperature obtained through fitting the bulk magnetic susceptibility data. The bulk resistivity measurements reveal an interesting electronic behavior that is potentially influenced by a competing antiferromagnetic and ferromagnetic interaction in and out of the ab plane. From the resulting refinement of the neutron diffraction data, EuMg2Bi2 was found to exhibit an A-type magnetic structure with Eu2+ moments ferromagnetically aligned in the plane and antiferromagnetically stacked between neighbor ferromagnetic Eu layers. The power law fitting magnetic ordering parameter below TN ∼ 8 K agrees with the 2D Heisenberg model, indicating a weak interlayer antiferromagnetic interaction. Considering the magnetic structure determined by neutron diffraction, the surface state calculation suggests that EuMg2Bi2 is an AFM topological insulator candidate. Linearly dispersed Dirac surface states were also observed in our angle-resolved photoemission spectroscopy measurements, consistent with the calculation.
Fano resonances in nanohole oligomers in a gold film
Authors: Hajebifard Akram , Hahn Choloong , Walia Jaspreet , Suleman Hamid , Variola Fabio , Weck Arnaud , Berini Pierre
Published: January 2021

The optical properties of nanohole oligomers in a gold film have been investigated theoretically and experimentally. Helium focused ion beam milling was used to create arrays of close-packed heptamer-arranged nanoholes (HNH) in a gold film on a fused silica substrate. The holes are slightly elliptical about a nominal diameter of 100 nm and are separated by 15 nm Au regions (“bridges”) to form close-packed heptamer arrangements. Optical responses are reported as transmittance spectra, showing various Fano resonances due to different excitations on the structure: surface plasmon polaritons localized to the HNH, symmetric and asymmetric surface plasmon polaritons propagating along with the film, and surface waves associated with Wood’s anomaly. All resonances observed involve the coupling (bonding and anti-bonding) of magnetic dipoles within the holes of HNH and in some cases of magnetic hexapoles within the central hole. The sensing performance was investigated by measuring the bulk sensitivity of the resonances, anticipating application to biosensing, yielding 380 nm RIU−1 in the best case. Surface-enhanced Raman scattering measurements were also performed on HNH, where adventitious carbon was detected directly through the identification of D and G bands (spectra taken from nearby un-milled Au areas were essentially featureless).
A study of the effect of mechanical preloads on hysteresis loop of magnetorheological elastomers
Authors: Kiarie Winnie M. , Jiles Member IEEE, and David C. , IEEE Life Fellow,
Published: January 2021

In this work, an investigation of the effect of mechanical preloads on the hysteresis loop of composite soft magnetorheological elastomer (MRE) was carried out. MRE is a “smart” composite material that consists of magnetically permeable particles in a non-magnetic polymeric elastomer. When subjected to an external magnetic field, a large deformational change occurs in the mechanical properties of these materials. Due to their coupled magnetomechanical response, these materials have been found suitable for various engineering applications. Inspired by experimental work, we present a model of the effect of mechanical preloads on the magnetization response of MRE based on a general continuum formulation. Using the Jiles - Atherton (JA) model parameters derived from the fitting of experimental measurement, the hysteresis loop of isotropic MRE was numerically resolved, which was then coupled to mechanical fields based on an energetically constitutive model valid for finitely strained MREs. Simulation analysis is performed for uniaxial stresses parallel to the direction of the applied magnetic field. For the applied tensile and compressive stresses, only a small change is observed in the hysteresis loop of these materials. Additionally, microscale modeling of the magnetization behavior of the isotropic MRE based on experimental results was performed. Considering the interaction between the magnetic particles, the magnetic and mechanical fields are resolved explicitly inside the composite material. A computational homogenization scheme was utilized to relate the microscopic behavior to the effective macroscopic properties of the MRE. In principle, the predicted effective magnetization behavior is observed to agree with the measured hysteresis loop of MRE materials.
Observations on the behaviour of the northern hairy-nosed wombat (Lasiorhinus krefftii) in a translocated population
Authors: Jørgensen Kristina Sand , Melzer Alistair , Harper Dave , Nevin Owen T.
Published: January 2021

The natural distribution of the critically endangered northern hairy-nosed wombat (Lasiorhinus krefftii) is confined to Epping Forest National Park, Queensland; however, a small number of animals have been translocated to establish an insurance population at Richard Underwood Nature Refuge (RUNR), Queensland. Northern hairy-nosed wombat behaviour is poorly understood, mostly due to its cryptic behaviour. Thirty-two wildlife cameras set up at burrow mouths at RUNR were used to capture social and solitary behaviour. Over a six month period between December 2016 and May 2017, 0.3% (21 videos of 6607) of recordings captured social behaviour, suggesting that the northern hairy-nosed wombat actively avoids social interactions at the burrow mouth. Vocalisation was only observed during social interaction. The results were similar to data from Epping Forest National Park and studies on other wombat species. In this respect the translocated population appeared to behave in a manner typical of the wild population.
IMITATION SWITCH is required for normal chromatin structure and gene repression in PRC2 target domains
Authors: Kamei Masayuki , Ameri Abigail J. , Ferraro Aileen R. , Bar-Peled Yael , Zhao Fangzhou , Ethridge Christina L. , Lail Kathleen , Amirebrahimi Mojgan , Lipzen Anna , Ng Vivian , Grigoriev Igor V. , Schmitz Robert J. , Liu Yi , Lewis Zachary A.
Published: January 2021

Significance

Polycomb Repressive Complex 2 (PRC2) methylates histones to regulate multicellular development, maintenance of stem cell identity, X-chromosome inactivation, and other important processes. Given these essential roles, there is significant interest in identifying components that function with PRC2 to establish and maintain transcriptionally repressive heterochromatin. Here we document an unexpected new role for a well-studied and conserved chromatin remodeling factor, ISWI. We found that the
Neurospora
ISWI homolog is required for normal facultative heterochromatin structure and gene repression at PRC2 target regions, and we defined requirements for ATP-dependent catalytic activity and accessory regulatory proteins. These findings provide mechanistic insights into the formation and function of facultative heterochromatin in a model eukaryote.
The joint dynamics of investor beliefs and trading during the COVID-19 crash
Authors: Giglio Stefano , Maggiori Matteo , Stroebel Johannes , Utkus Stephen
Published: January 2021

Significance

We analyze how investor expectations about economic growth and stock returns changed during the February−March 2020 stock market crash induced by the COVID-19 pandemic, as well as during the subsequent partial stock market recovery. Our results provide guidance for the design of macro and finance models and related economic policies.
Self-inhibition effect of metal incorporation in nanoscaled semiconductors
Authors: Zhu Bin , Yi Ding , Wang Yuxi , Sun Hongyu , Sha Gang , Zheng Gong , Garnett Erik C. , Tian Bozhi , Ding Feng , Zhu Jia
Published: January 2021

Significance

Understanding and controlling the incorporation of metal into nanoscaled semiconductor is foundational for semiconductor processing. Through theoretical calculation and experimental results, we reveal that the interstitial atoms in the Si lattice such as Mn can quickly diffuse out of Si nanowires conveniently, thus can achieve high purity of Si nanowires. This finding of self-inhibition effect not only provides understanding of impurity incorporation at nanoscale, but also provides an extra knob for rational catalyst designs of nanoscale building blocks, and fine-tuning their electrical, optical, and thermal properties for various applications.
Moiréless correlations in ABCA graphene
Authors: Kerelsky Alexander , Rubio-Verdú Carmen , Xian Lede , Kennes Dante M. , Halbertal Dorri , Finney Nathan , Song Larry , Turkel Simon , Wang Lei , Watanabe Kenji , Taniguchi Takashi , Hone James , Dean Cory , Basov Dmitri N. , Rubio Angel , Pasupathy Abhay N.
Published: January 2021

Significance

Micrometer-sized uniform four-layer (ABCA) rhombohedral graphene is realized by introducing a small twist angle between two bilayers of Bernal graphene. By means of scanning tunneling spectroscopy we observe an extremely sharp van Hove singularity of 3–5-meV half-width and a correlated many-body gap of 9.5 meV at neutrality, thus making small twisted double-bilayer graphene a unique platform to realize electronic correlations in the absence of a moiré potential. Furthermore, ABCA graphene domain walls display tunable topological edge states, of great interest in Floquet engineering.
Longitudinal shear stress response in human endothelial cells to atheroprone and atheroprotective conditions
Authors: Maurya Mano R. , Gupta Shakti , Li Julie Yi-Shuan , Ajami Nassim E. , Chen Zhen B. , Shyy John Y.-J. , Chien Shu , Subramaniam Shankar
Published: January 2021

Significance

Endothelial cell types such as HUVECs and HAECs have been used as model systems to study vascular health. This study provides a comprehensive, time-dependent comparison of the transcriptomic responses of HAECs and HUVECs to shear stress by making measurements at 1, 4, and 24 h to capture the responses at early, mid, and late time points after shearing. The results indicate that the responses of HAECs and HUVECs are qualitatively similar for endothelial function-relevant genes and several pathways such as inflammation, oxidative stress, and angiogenesis. The findings also show that HAECs exhibit faster kinetics as compared to HUVECs. This study offers insights into the mechanisms of common and differential stress responses across cell types.
Symmetrical arrangement of proteins under release-ready vesicles in presynaptic terminals
Authors: Radhakrishnan Abhijith , Li Xia , Grushin Kirill , Krishnakumar Shyam S. , Liu Jun , Rothman James E.
Published: January 2021

Significance

Neuronal cells maintain a small number of synaptic vesicles (SVs) that are “primed,” i.e., ready to release upon receiving the triggering signal to allow for tightly regulated and rapid release of neurotransmitters. The proteins involved in this process are known, but how they assemble and operate together is poorly understood. Here we report the visualization of protein organization under primed SVs in cultured neurons under native conditions. Using cryoelectron tomography analysis, we find that there is a symmetric arrangement of exactly six protein densities at the docking interface, suggesting the fusion machinery is well ordered and prearranged for fast and precise release of neurotransmitters.
Effect of 6 weeks of very low‐volume high‐intensity interval training on oral glucose‐stimulated incretin hormone response
Authors: Hindsø Morten , Kuhlman Anja Birk , Dohlmann Tine Lovsø , Lund Michael Taulo , Hartmann Bolette , Holst Jens Juul , Larsen Steen , Helge Jørn Wulff
Published: January 2021

Introduction: Decreased fasting and oral glucose‐stimulated incretin hormone concentrations following moderate‐intensity continuous endurance training interventions have been reported in glucose‐tolerant people, however results are conflicting. The effect of more time‐efficient, very low‐volume, high‐intensity interval training (HIT) on circulating incretin hormone levels has never been studied.

Materials and methods: Ten sedentary and overweight‐to‐obese participants (4 women and 6 men; age 43 ± 6 years (mean ± SD); BMI 30.2 ± 3.2 kg∙m−2; HbA1c 35 ± 5.1 mmol∙mol−1 (5.3 ± 0.3%); VO2max 30 ± 5 ml∙min−1∙kg−1) from the Copenhagen cohort of the METAPREDICT trial underwent 6 weeks of supervised low‐volume HIT (3 sessions per week: 7 × 1 min at ∼100% VO2max separated by 1 min of active recovery). We measured glucose, insulin, C‐peptide, glucagon, GLP‐1 and GIP concentrations during a frequently sampled 75 g oral glucose tolerance test as well as VO2max and body composition before and after the intervention.

Results: Training compliance was 100%. Relative VO2max improved after the intervention (median 2.69 ml∙min−1∙kg−1, IQR [0.43; 3.14], p = 0.037) while there were no significant effects on body weight and composition. No significant effects on oral glucose‐stimulated glucose and hormone responses or estimates of insulin sensitivity and β‐cell function were observed.

Conclusion: Low‐volume HIT improved aerobic fitness, but neither affected glucose tolerance nor oral glucose‐stimulated incretin hormone responses in sedentary and overweight‐to‐obese people.

Highlights

Ten sedentary, overweight‐to‐obese, glucose‐tolerant participants underwent 6 weeks of supervised, very low‐volume HIT.

Aerobic fitness improved.

Fasting and oral glucose‐stimulated incretin hormone concentrations were not affected.
Microtubule pivoting enables mitotic spindle assembly in S. cerevisiae
Authors: Fong Kimberly K. , Davis Trisha N. , Asbury Charles L.
Published: January 2021

To assemble a bipolar spindle, microtubules emanating from two poles must bundle into an antiparallel midzone, where plus end–directed motors generate outward pushing forces to drive pole separation. Midzone cross-linkers and motors display only modest preferences for antiparallel filaments, and duplicated poles are initially tethered together, an arrangement that instead favors parallel interactions. Pivoting of microtubules around spindle poles might help overcome this geometric bias, but the intrinsic pivoting flexibility of the microtubule–pole interface has not been directly measured, nor has its importance during early spindle assembly been tested. By measuring the pivoting of microtubules around isolated yeast spindle poles, we show that pivoting flexibility can be modified by mutating a microtubule-anchoring pole component, Spc110. By engineering mutants with different flexibilities, we establish the importance of pivoting in vivo for timely pole separation. Our results suggest that passive thermal pivoting can bring microtubules from side-by-side poles into initial contact, but active minus end–directed force generation will be needed to achieve antiparallel alignment.
JEM career launchpad
Authors: Bigas Anna , Zanoni Ivan , Hepworth Matthew R. , Eisenbarth Stephanie C. , Masters Seth Lucian , Kipnis Jonathan , Vinuesa Carola G. , Good-Jacobson Kim L. , Tangye Stuart G. , Yamazaki Sayuri , Hivroz Claire , Tait Wojno Elia , Shulman Ziv , Colonna Marco
Published: January 2021

JEM has been a launching pad for scientific careers since its inception. Here is a collection of testimonials attesting to the diversity of the scientific community it serves.
Plenty of soliton solutions to the DNA Peyrard-Bishop equation via two distinctive strategies
Authors: Ouahid Loubna
Published: January 2021

Here, the Deoxyribo-Nucleic Acid (DNA) dynamic equation that arises from the oscillator chain named the Peyrard-Bishop model for plenty of solitary wave solutions is presented. The efficacy of newly designed algorithms are investigated, namely, the extended Auxiliary equation method and Kudryashov expansion method for constructing the new solitary wave solutions of the DNAdynamic Peyrard-Bishop model with beta-derivative. Here, the proposed methods contribute to a range of accurate solutions for soliton, including light, dark, and other solutions are obtained. In addition, some results are also clarified by computer simulations demonstrating the uniqueness of our work relative to the existing literature on the classic Peyrard-Bishop model. These solutions lead to the issue of the possibility to expand the method to deal with other non-linear equations of fractional space-time derivatives in non-linear science. It is noted that the newly proposed approach is accurate and is used to create new general closed-form solutions for all other fractional NPDEs.
The new physics of dust in plasmas
Authors: Mamun A A
Published: January 2021

The new physics of dust, which arises due to dust-plasma interaction in space environments and laboratory devices, is presented. The new research horizons (different new fields of physics involving many challenging research problems and open issues) introduced by this new physics of dust in plasmas are explained. The basic features of dust-plasma interaction, particularly, basic characteristics of dust in plasmas, and typical dusty plasma parameters for different space and laboratory conditions are presented. The complexity and the diversity of the field of the new physics of dust in plasmas are briefly discussed. The theoretical and experimental discoveries of dust associated linear waves, nonlinear structures, and some other important phenomena are mentioned. The basic features of dust associated nonlinear structures (viz. solitary waves, shock structures, and Mach cones) obtained from our recent published works are briefly discussed.
Doping and disorder dependent isotope exponent in hole doped cuprates
Authors: Islam R S , Naqib S H
Published: January 2021

The nature of the variation of oxygen isotope exponent (IE) with the number of doped holes, p, in the CuO2 planes has been a source of considerable debate. The large IE over certain range of hole concentrations always casts a shadow over any proposal where non-phononic mechanism is invoked to describe pairing in cuprates. On the other hand, existing theoretical schemes, based on electron-phonon interactions, cannot describe the anomalous features shown by the IE as a function of hole concentration/disorder, either quantitatively or qualitatively. Based on an experiment relating the possibility of Fermi-surface reconstruction to the thermoelectric transport measurements (Laliberté et al. Nature Commun. 2, 432 (2011)), we propose here a simple scenario where isotope substitutions affect the charge/spin stripe state via the coupling to the underlying lattice and thereby change the superconducting Tc
. In this picture, significant part of the IE, over an extended p-range, actually originates from the isotope induced stripe modulation and is not directly related to the characteristic energy scale of the phonons mediating the Cooper pairing. This proposal qualitatively explains all the disorder- and p-dependent features of the IE seen in hole doped high-Tc
cuprates. We also provide with an outline of some experiments that can verify the degree of validity of the proposed scheme.
Non-monotonic potential description of the cross-section, vector and tensor analyzing powers of the 6Li+12C elastic scattering at 30 and 50 MeV†
Authors: Nilima Athoy , Hossain S , Azad M M B , Billah M M , Tariq A S B , Uddin M A , Bhattacharjee S , Azizur Rahman M , Basak A K
Published: January 2021

This work illustrates, for the first time, the analysis of tensor analyzing powers (T
20, T
21, T
22) along with the differential cross-section (CS) and the vector analyzing power iT
11 for the 6Li+12C elastic scattering at 30 and 50 MeVwithin the framework of an optical model (OM) using microscopic shallow non-monotonic (NM) potentials. The NM potential is generated from the energy density functional formalism (EDF) [Brueckner et al., Phys. Rev., 168 (1968) 1184] using a realistic two-nucleon interaction incorporating Pauli Exclusion principle. The shallow NM potential can describe the experimental angular distributions of CS and analyzing powers of the elastic scattering data. The OM analysis of the data at this energy does not indicate their sensitivity on the nuclear matter incompressibility K.
Using X-ray Fluorescence Technique Propagation of Chromium (Cr) from Poultry Feeds to Different Parts of Chicken including her Eggs†
Authors: Rajib Arifuzzaman , Tariqur Rahman Md. , Md. Ismail Abu Bakar
Published: January 2021

This paper presents the detection and propagation of heavy metals, particularly Chromium (Cr), in poultry in the Rajshahi area using the X-ray fluorescence (XRF) technique. The investigation was done to assess the possible transfer of heavy metals from poultry feeds to chicken meat. The study was carried out in the Rajshahi including collection feeds to chicken. It was found that a considerable amount of Cr was confirmed in all four locally produced poultry feeds and also assured that the Cr contained in chicken propagates to the chicken meat and egg. Among the four most widely used feeds in the Rajshahi region, “Adorsho Feed (Pabna)” shows a maximum Cr concentration of 17.3 ppm. Six different parts of the chicken for different ages which were grown by “Adorsho Feed” were considered for further study. About 4.3 ppm of Cr was found in Yolk whereas a little small about 2.7 ppm was found in the albumin. The average value of Cr in six parts of chicken remains almost the same, which is 3.74 ppm, irrespective of age. It is found that about 21.6% of Cr was propagated from the poultry feed to chicken flesh and also about 90% of Cr was propagated from the chicken to egg. The experimental results indicate that the investigation of the transmission of heavy metals like Cr from feed to egg and poultry is efficiently evaluated by using X-ray Fluorescence Technique.
A Multi-Layers Perceptron for predicting weekly learner commitment in MOOCs
Authors: Mourdi Youssef , Sadgal Mohammed , El Kabtane Hamada , El Abdallaoui Hasna El Alaoui
Published: January 2021

Since they were first set up in 2008, MOOCs have continued to integrate very deeply into the distance learning field. They have been adopted by a very large number of universities in order to complement face-to-face learning and thus remedy the massive number of students that the infrastructures can no longer support. In spite of the investments made for their development, MOOCs suffer from a huge drop-out rate of around 90%. This problem creates a number of difficulties for the instructors, including monitoring learners and group formation. In order to help the instructors to identify learners at risk of dropping out, this paper presents a model based on Multi-Layer Perceptron (MLP) that provides weekly predictions of each learner's engagement based on their behaviour. Our model has been tested on a data set of 3585 learners and has shown a high ability to identify this type of learner with an average accuracy of 90.3%.
Numerical estimation of log-GARCH model with relaxed moment assumptions
Authors: Settar Abdeljalil , Fatmi Nadia Idrissi , Badaoui Mohammed
Published: January 2021

This paper provides algorithms for the numerical estimation of the log-GARCH model parameters with no assumptions on the existence of the log-moment orders greater than one. Our approach is based on the quasi-maximum likelihood estimation combined with the information filter. The proposed estimation is employed for two aims. The first is to treat the zero returns considered as missing values through an EM imputation algorithm. The second is to compute the kurtosis of the log-GARCH process by the so-called, right and left measures. A Monte Carlo simulation is performed to investigate the potential of the proposed algorithms to improve the accuracy of the quasi-maximum likelihood for the parameter estimation and the treatment of zero returns as well as to check the robustness of the used kurtosis measures.
A coupled Meshless-FEM method based on strong form of Radial Point Interpolation Method (RPIM)
Authors: El Kadmiri R. , Belaasilia Y. , Timesli A. , Kadiri M. S.
Published: January 2021

In this present work, we are implementing a novel hybrid method based on the coupling of RPIM in strong form and Finite Element Method (FEM). The basic idea is to ensure the coupling between the two methods through the collocation technique based on RPIM interpolation. This technique is used to evaluate the local equations of the problem at the interface between FEM and RPIM regions. We can avoid numerical integrations of a big part of nodes using the strong form of RPIM. Numerical studies show that this method gives reasonably accurate results consistent with the theory.
Application and Typical Case of Unmanned Aerial Vehicles Combined with Building 3D Modeling
Authors: Li Minhui , Yin Hang , Cheng Dongji , Xu Xinli , He Ya
Published: January 2021

With the development of unmanned aerial vehicle (UAV) technology, the application of UAV is becoming more and more extensive, including the application of UAV in building 3D modeling. This paper introduces the composition of commonly used related equipment and some key UAV technologies combined with building 3D modeling: 3D laser scanning technology, Photogrammetry, Multi-view 3D reconstruction technology and Seismic disaster prevention technology. This paper also studies practical applications and related cases. On the one hand, UAV can be used in the protection of ancient building heritage. Combined with photography, measurement, modeling technology, UAVs can rapid and efficient access to relevant building three-dimensional information, including building damage and overall configuration, then provide important information and reference for building heritage protection. On the other hand, UAVs can also carry out multi-faceted evaluation and survey of modern buildings, collect topography, guide seismic planning and post-disaster reconstruction, and save project costs.
Technology Application Base on ASP.NET Model View Controller
Authors: Liu Yuanchun , Zhu Heyi
Published: January 2021

The Music Mall System is developed by ASP.NET model view controller technology. It realizes the functions of registration and login, song search, playing songs, collecting and commenting, shopping mall and so on. This paper firstly introduces the function design, the database design of the music mall system, secondly describes the architecture and finally elaborates the implementation codes of the specific modules. Using this system, users can quickly search and listen to relevant music, buy related music peripheral products. Through reasonable page layout and detailed user experience, users can feel happy and satisfied.
RobotDrlSim: A Real Time Robot Simulation Platform for Reinforcement Learning and Human Interactive Demonstration Learning
Authors: Sun Te , Gong Liang , Li Xvdong , Xie Shenghan , Chen Zhaorun , Hu Qizi , Filliat David
Published: January 2021

Deep reinforcement learning (DRL) techniques give robotics research an AI boost in many applications. In order to simultaneously accommodate the complex robotic behaviour simulation and DRL algorithm verification, a new simulation platform, namely the RobotDrlSim, is proposed.

First, we design a standardized API interfacing mechanism for coordinating diverse environments on RobotDrlSim platform, where PyBullet simulator is equipped with an API to form a physical engine for robotics simulation. Second, benchmark DRL models are included in the baseline library for evaluation. Third, real-time human-robot interactions can be captured and imported to drive the RobotDrlSim tasks, which provide big data-stream for reinforcement learning. Experimentations show that cutting-edge DRL algorithms developed in python can be seamlessly deployed to the robots, and human interactions can be availed in training the robots. RobotDrlSim is valid for efficiently developing DRL algorithms for artificial intelligence models of robots, and it is especially suitable for the robot educational purposes.
Optimal Model and Algorithm of Cross-layer Dynamic Resource Allocation based on Multi-Period and Utility
Authors: Shao Qing , Su Yang
Published: January 2021

An optimal model and algorithm for dynamic resource allocation in satellite communication systems is proposed to further promote the system throughput and fairness based on user satisfaction. It takes the parameters of application layer, data link layer and physical layer into consideration and constructs a new kind of utility function by using the cross-layer design strategy and converts the resource allocation problem into a utility maximization model. The optimal solution of the model is solved by the combination of the Lagrange multiplier method and the Greedy algorithm, which maximizes the utility and ensures the optimal resources allocation of the satellite communication system in the multiple periods. The simulation results show that the proposed optimal model and algorithm effectively promote the throughput and fairness based on user satisfaction on the premise of ensuring service quality, therefore it can meet the requirements of the variety and the dynamic change of the service in the satellite communication system.
Adaptive Conflict Detection Algorithm Based on Rochester Software Transactional Memory
Authors: Liu Ying , Liu Junting , Gao Fuxiang
Published: January 2021

When the transactional memory system detects conflicts, the more read-write addresses are, the higher the false positive rate of this algorithm is. This paper studies the problem and proposes a new signature based optimization algorithm, adaptive increase signature algorithm (AISA). The algorithm can calculate the saturation value of the number of read-write addresses, and dynamically adjust the size of bit string through the calculated saturation value, thus greatly reducing the false positive rate. The experimental results show that AISA can control the false positive rate at a low level on the basis of considering the space cost, and its effect is almost the same as that of 6 times of space, which will improve the performance of transactional memory system greatly.
Structured Data Extraction Method of Hazard Description Text Based on Strong Part-of-speech Matching
Authors: Zhou Yi , Chen Cheng , Zhang Peng , Wu Aizhi , Ai Xinbo
Published: January 2021

In the field of work safety, the hazard description text is an important basis for accident investigation. However, because the text is unstructured, it causes a lot of inconvenience for subsequent analysis and processing, so it’s necessary to extract structured information from hazard description text. At present, there are few corpus and annotated data of hazard description text, cause it’s difficult to extract structured information based on machine learning models. To solve this problem, we proposed a new method based on strong part-of-speech pattern matching This method is based on the short length and relative simplicity of the hazard description text, matching predefined patterns through the part-of-speech sequences of the text, and then extract structured information of hazard entity and entity description. The method achieved 86.2% accuracy with text processing speed 5514 iters/s when only a small amount of annotated data required.
Extended LDA Based Topic Analysis for Big Sentiment Data
Authors: Xie Shengzhen , Sui Ling , Li Jiaxin , Kou Kaiqi , Wang Zhiqiong
Published: January 2021

Owing to the massive emergence of multi-modal data related to big sentiment events, the topic analysis of the text cannot accurately reflect the topic distribution of the whole data set. There are some problems such as semantic deficiency and difficulty in integration. Therefore, the extended LDA(eLDA) based topic analysis for big sentiment data is posed. Firstly, the semantic analysis of text and image data is carried out by probability generation method respectively. The semantic correlation between multi-modal data is used for visual topic learning, a visual topic model is established, and the mapping between visual data and text topics is realized. Furthermore, the fusion of text, audio, video and image data is realized, and multimodal theme analysis is carried out accordingly. The experimental results show that the multimodal topic analysis method can effectively obtain the subject words related to the semantics of big sentiment data. The effect of the subject words tracked by the multi-modal data analysis method is better than that of the single text subject words extraction, which can provide basis for emotional analysis of big sentiment events.
Study on Denoising Algorithm for Power Quality Disturbances Based on Variational Mode Decomposition
Authors: Li Yan , Li Kaicheng , Liu Chang , Xiao Xiangui , Chen Xiya , Wang Menghao
Published: January 2021

The power quality signals are always mixed with noise, which will influence the accurate measurement and characteristic extraction. Therefore, it’s important to denoise for the signal processing. This paper puts forward a novel denoising algorithm for power quality disturbances (PQDs) based on variational mode decomposition (VMD) and the truth that the energy density times the average period of each intrinsic mode function (IMF) is a constant. Firstly, the VMD algorithm is used to decompose the white noise into several IMF components. Then, the average period energy product of each IMF component is calculated, and some of the IMF components are selected for reconstruction according to the judgment criterion to obtain the denoised signal. The simulation results show that the proposed algorithm can greatly improve the signal-to-noise ratio (SNR), and the denoising effect is better than that of wavelet threshold and ensemble empirical mode decomposition (EEMD) algorithm.
Part of the Unipotency of Free Group Generated by Two Elements Whose Maximum Jordan Matrix Does Not Exceed 8 Times
Authors: Zhen Chaoran , Yang Xinsong
Published: January 2021

Intelligent calculations can already assist in the completion of mathematical proofs. We have completed a partial verification of an important theory with data calculation as the main method. When the dimension is ten, free group generated by two elements with linear representation is unipotent when the primitive elements are unipotent and the maximum Jordan block does not exceed the eighth order, at the same time there is a primitive element with the maximum Jordan block not exceeding the second order.
Optimization Study on Emergency Communication in the Great East Japan Earthquake
Authors: Guo Jia , Xu Zhen , Zhao Yu
Published: January 2021

Emergency communication is a special communication mechanism used for disaster rescue. The article took the Great East Japan Earthquake as the research object. It was found that mobile communication was the main way in general communication and social media played an important role in emergency communication. The causes of traffic congestion were studied to provide strategies for PSTN and mobile communication. Unitary management system in Japan for the restoration of services was studied, too. At last, the development of satellite communication in Japan and its needs for emergency communication were researched to provide references for emergency communication in China.
Bullet Engraving Automated Comparison Optimization Method Based on Second Moment Invariant
Authors: He Chenggang , Ding Chris H. Q. , Chen Sibao , Wang Jiaxin , Tan Shicheng
Published: January 2021

In the research of bullet engraving comparison method at home and abroad, the traditional method is through visual observation by microscope, comparing line-type engraving of two bullets to distinct whether the line match, which is inefficient and having big error. In this paper we proposed method based on moment invariant to identify the bullet engraving, which eliminate the actual measurement error (translation error and rotation error). Finally we get the high performance result of bullet engraving identifying based on second moment invariant.
Quantile S-N Curve and its Application based on Tukey’s g-and-h Distribution and Whale Optimization Algorithm
Authors: Zhang Jinbao , Zhang Aiju , Wang Min , Wei Yuhu , Gui Peng
Published: January 2021

Tukey’s g-and-h distribution is a generalized implicit distribution based on the transformation of normal distribution, which has a stronger fault-tolerant capability for the fitting of life data distribution. In this paper, the P-S-N curve is modelled through its corresponding location-scale model with quantile expression, so as to improve the life prediction accuracy of mechanical parts in reliability design. Two groups of life experiment data concerning G20CrNi2Mo bearing steel and 104 rolling bearing are used to verify the proposed model. The mean square error (MSE) of experimental data and simulation data is taken as the objective function, and the parameter estimation of the model is realized with the whale optimization algorithm (WOA). The results show that the proposed approach could accurately express the trend of life varying with different loads, and the quantile expression of life data can be realized conveniently.
Optimization Analysis of Max-Link Secure Relay Selection in Buffer-Aided Cooperative Networks
Authors: Zhang Yajun , Wu Jun , Wang Bing
Published: January 2021

Cooperative communication technology has been proved to be an useful approach to accomplish physical layer security. In recent years, more and more attention has been paid to the collaboration network with buffer relay. This paper studies the safety performance of the maximum link level options. Compared with the existing buffer-assisted cooperative security schemes, max-Link secure relay selection (Max-Link-SRS) does not require the eavesdropper’s channel state information (CSI) and has a lower complexity. Based on markov chain theory, a new closed form expression of secure interrupt probability (SOP) is derived. Numerical simulation results confirm our analysis and demonstrate that the functioning of max-Link-SRS is superior to the previously reported buffer-less aided cooperative security scheme. It provides a significant coding obtain at a smaller buffer size, while ensuring diversity gain is close to the upper limit of the double number of relays at a bigger buffer zone.
Optimizing Allocation of Sea Area Utilization Based on Genetic Algorithm
Authors: Wang Xiaowen , Kang Minjie
Published: January 2021

Optimal allocation of sea area utilization solves the problem of quantity allocation and spatial distribution of sea area used by various departments. It is a necessary method to coordinate the conflicts between different departments and realize the dual goals of development and ecological protection. This paper presents an optimal allocation method of sea area utilization based on genetic algorithm. The basic principle and solving process of optimal allocation of sea area utilization based on genetic algorithm are described. The fitness evaluation model, genetic operator and constraint conditions are designed.
Optimization Technology of Optical Fiber Communication Network Based on Service Classification
Authors: Zhang Ning , Chen Bingjun , Yang Yansong , Sun Huijuan , Chen Ming , Chen Tingting , Chen Xiaodan , Xiao Mingming , Luo Yang
Published: January 2021

Optical fiber has huge bandwidth, as a physical medium, it has good anti electromagnetic interference characteristics and excellent security performance, which is very suitable for the establishment of backbone transmission network. Wavelength division multiplexing(WDM) network based on optical fiber has been widely used. Using optical fiber for information transmission can give full play to the nearly unlimited transmission capacity of optical fiber. With the advent of the information age, data service has become the mainstream business, replacing the original telephone voice service. The great development of data transmission service further promotes the continuous development of WDM network technology. Among all kinds of services in optical network, IP service accounts for the largest proportion. In optical networks, switching is an important technology. Network performance is directly related to switching technology. With the development of optical communication technology, a variety of optical switching devices are introduced into WDM optical network, such as optical packet switching, optical burst switching and so on. This makes WDM layer have the ability of dynamic path establishment and removal similar to IP layer. In order to improve the performance of the optical network and reduce the blocking rate of the network, in WDM optical network, the services are designed in different levels. For some very important services, the highest priority is given, and the optical path channel with better survivability and higher fault tolerance is selected. For general services, it can be designed as a lower level service, and choose the appropriate optical path channel for transmission. The experimental results show that this hierarchical service design method can make more effective use of network resources, reduce the network blocking rate, and improve the overall performance of the network.