bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow dynamics of a fluidic oscillator with internal geometry variations
Authors: Wen Xin , Li Ziyan , Zhou Luanliang , Yu Chengji , Muhammad Zubair , Liu Yudan , Wang Shiqi , Liu Yingzheng
Published: July 2020

An experimental study is conducted to examine the impact of internal geometry of a fluidic oscillator on its working mechanisms, i.e., the widths of the inlet wedge W1, mixing chamber W2, and exit throat W3, normalized by the width of the inlet throat W0. Using time-resolved particle image velocimetry, the flow dynamics both inside and outside the oscillator are measured simultaneously. The phase-averaged flow fields are obtained using proper orthogonal decomposition analysis based on which the pressure fields are computed. It is found that the external jet spreading angle and the oscillation frequency are proportional to the width of the inlet wedge up to W1/W0 = 2. This is because the inlet wedge controls the feedback flow and accordingly the recirculation bubble in the mixing chamber. At a critical lower value of W1/W0 = 0.8, there is no feedback flow with a stable external sweeping jet. The mixing chamber width W2/W0 controls the size of the recirculation bubble, which has a notable proportional control on the spreading angle. With a small mixing chamber of W2/W0 = 2.9, it is also found that the strong feedback flow can still produce a stable sweeping jet motion but with a small spreading angle. The exit throat width W3/W0 has non-monotonous control on the external jet spreading angle and the oscillation frequency. It is noteworthy that the jet can still produce a stable sweeping motion even with a large value of W3/W0 = 4.2, which can significantly reduce the blocking effect of the exit.
Room temperature quantum cascade laser with ∼31% wall-plug efficiency
Authors: Wang F. , Slivken S. , Wu D. H. , Razeghi M.
Published: July 2020

In this article, we report the demonstration of a quantum cascade laser emitting at λ ≈ 4.9 μm with a wall-plug efficiency of ∼31% and an output power of ∼23 W in pulsed operation at room temperature with 50 cascade stages (Ns). With proper fabrication and packaging, this buried ridge quantum cascade laser with a cavity length of 5 mm delivers more than ∼15 W output power, and its wall-plug efficiency exceeds ∼20% at 100 °C. The experimental results of the lasers are well in agreement with the numerical predictions.
Speed enhancement of magnetic logic-memory device by insulator-to-metal transition
Authors: Pu Yuchen , Mou Hongming , Lu Ziyao , Nawaz Seeraz , Wang Guilin , Zhang Zhigang , Yang Yuanjun , Zhang Xixiang , Zhang Xiaozhong
Published: July 2020

Complementary metal-oxide-semiconductor logic circuits used in conventional computers require frequent communication with external nonvolatile memory, causing the memory wall problem. Recently reported magnetic logic with reconfigurable logic operation and built-in nonvolatile memory can potentially bridge this gap. However, its high-frequency performance is not well studied. Here, we first perform experimental and theoretical investigation on the switching time of magnetic logic-memory devices combining magnetic units and negative differential resistance (NDR) of semiconductors. It is found that the switching time of S-type NDR (transistor circuits) in logic operations is ∼300 ns and determined by the transistor's internal turn-on properties. We then propose a magnetic logic-memory device by coupling the anomalous Hall effect in magnetic materials and the insulator-to-metal transition in VO2. Our device realizes reliable output (output ratio > 1000%), a low work magnetic field (<20 mT), and excellent high-frequency performance (switching time = 1–10 ns).
Terahertz master-oscillator power-amplifier quantum Cascade laser with controllable polarization
Authors: Zhu Haiqing , Zhu Huan , Wang Kai , Yu Chenren , Chang Gaolei , Wang Fangfang , Chen Jianxin , Li Lianhe , Davies A. Giles , Linfield Edmund H. , Xu Gangyi , He Li
Published: July 2020

We report the realization of controllable linear-to-circular polarization states in single-mode terahertz master-oscillator power-amplifier quantum cascade lasers (THz-MOPA-QCLs). The MOPA device contains a first-order distributed feedback (DFB) laser as the master-oscillator, a preamplifier, and a 2D periodical antenna array as the power extractor. The polarization state is determined by the orientation and the phase relationship between the antennas. The antenna array is carefully designed to efficiently extract the THz radiation and not to induce field oscillation in the array or influence the mode oscillation in the DFB section. Each demonstrated device exhibits single-mode emission with a side mode suppression ratio of ∼26 dB and a single-lobed beam with a low divergence of ∼23°×30°. Realized in different devices, the degree of linear or circular polarization reaches as high as 97.5% or 99.3%. Both the operation frequency and the polarization state of the radiation are lithographically tunable.
Propagation of spin waves through a Néel domain wall
Authors: Wojewoda O. , Hula T. , Flajšman L. , Vaňatka M. , Gloss J. , Holobrádek J. , Staňo M. , Stienen S. , Körber L. , Schultheiss K. , Schmid M. , Schultheiss H. , Urbánek M.
Published: July 2020

Spin waves have the potential to be used as a next-generation platform for data transfer and processing as they can reach wavelengths in the nanometer range and frequencies in the terahertz range. To realize a spin-wave device, it is essential to be able to manipulate the amplitude as well as the phase of spin waves. Several theoretical and recent experimental works have also shown that the spin-wave phase can be manipulated by the transmission through a domain wall (DW). Here, we study propagation of spin waves through a DW by means of micro-focused Brillouin light scattering microscopy (μBLS). The 2D spin-wave intensity maps reveal that spin-wave transmission through a Néel DW is influenced by a topologically enforced circular Bloch line in the DW center and that the propagation regime depends on the spin-wave frequency. In the first regime, two spin-wave beams propagating around the circular Bloch line are formed, whereas in the second regime, spin waves propagate in a single central beam through the circular Bloch line. Phase-resolved μBLS measurements reveal a phase shift upon transmission through the domain wall for both regimes. Micromagnetic modeling of the transmitted spin waves unveils a distortion of their phase fronts, which needs to be taken into account when interpreting the measurements and designing potential devices. Moreover, we show that, by means of micromagnetic simulations, an external magnetic field can be used to move the circular Bloch line within the DW and to manipulate spin-wave propagation.
Ultracompact metaimage display and encryption with a silver nanopolarizer based metasurface
Authors: Zhang Yilun , Cheng Yu , Chen Ming , Xu Ronghui , Yuan Libo
Published: July 2020

Governed by the Malus law, nanopolarizer-based metasurfaces can continuously modulate the intensity of incident linearly polarized (LP) light pixel-by-pixel, which has been applied to display metaimages with ultracompactness and high resolution. One unique characteristic of the Malus-assisted image display technique is that no matter the polarization direction of incident LP light, the image with different contrast always appears, which would affect the security of a metaimage. Here, inspired by the orientation degeneracy of the Malus law, we show that metaimage displays can be controlled in two fixed polarization directions, merely by reconfiguring the orientations of nanopolarizers. Specifically, for each metaimage pixel, there are two options for the orientation angle of the nanopolarizer corresponding to an equal grayscale value. By randomly selecting the orientation angle among two choices, the metaimage will be blurred or even hidden, except for the polarization direction of 0° for the original image and 90° for its contrast reversed partners. We experimentally demonstrate this concept by encoding a Lena image with pixels of 1000 × 1000 into a silver nanopolarizer-based metasurface and decoding/encrypting it in a polarization-controlled optical setup. The proposed metaimage display with the encryption functionality has advantages such as continuous grayscale modulation, ultrathinness, and high density, which can be applied in ultracompact image displays, high-end anti-counterfeiting, high-density optical information storage, information encryption, etc.
Multiple metastable network states in urban traffic
Authors: Zeng Guanwen , Gao Jianxi , Shekhtman Louis , Guo Shengmin , Lv Weifeng , Wu Jianjun , Liu Hao , Levy Orr , Li Daqing , Gao Ziyou , Stanley H. Eugene , Havlin Shlomo
Published: July 2020

Significance

Different traffic states experienced by commuters may be due to localized random jams or overall network states, which is decided by system response to perturbations. While for natural systems, the existence of multiple states is common, the evidence for multiple states in transportation has so far been unclear, which hinders our ability to predict and prevent the spread of traffic jams. Based on percolation theory and high-resolution GPS datasets, we find strong evidence for the existence of multiple metastable network states corresponding to distinct system performance regimes. Our results may provide deep insight for a city traffic manager seeking to design early warning signals to prevent the system from shifting to a state of severe congestion.
Sea-level rise and the emergence of a keystone grazer alter the geomorphic evolution and ecology of southeast US salt marshes
Authors: Crotty Sinéad M. , Ortals Collin , Pettengill Thomas M. , Shi Luming , Olabarrieta Maitane , Joyce Matthew A. , Altieri Andrew H. , Morrison Elise , Bianchi Thomas S. , Craft Christopher , Bertness Mark D. , Angelini Christine
Published: July 2020

Significance

Human disturbances, climate change, and their combined effects on species distributions and environmental conditions are increasingly modifying the organization of our world’s oceans, forests, grasslands, wetlands, tundras, and reefs. Here, we reveal that these contemporary conditions can trigger the emergence of novel keystone species. Across the southeastern US coastal plain, sea-level rise is outpacing salt marsh vertical accretion, causing these grasslands to be tidally inundated for longer and softening marsh substrates to levels optimal for crab burrowing. Using field experiments, measurements, surveys, and models, we show that these conditions amplify the burrowing and grazing effects of a previously inconspicuous crab, enabling it to redefine predator–prey interactions, eco-geomorphic feedbacks, and the mechanisms by which salt marshes are responding to climate change.
Ancestors of domestic cats in Neolithic Central Europe: Isotopic evidence of a synanthropic diet
Authors: Krajcarz Magdalena , Krajcarz Maciej T. , Baca Mateusz , Baumann Chris , Van Neer Wim , Popović Danijela , Sudoł-Procyk Magdalena , Wach Bartosz , Wilczyński Jarosław , Wojenka Michał , Bocherens Hervé
Published: July 2020

Significance

Most of today’s domesticates began as farm animals, but cat domestication took a different path. Cats became commensal of humans somewhere in the Fertile Crescent, attracted to early farmers’ settlements by rodent pests. Cat remains from Poland dated to 4,200 to 2,300 y BCE are currently the earliest evidence for the migration of the Near Eastern wildcat to Central Europe. Tracking the possible synanthropic origin of that migration, we used stable isotopes to investigate the paleodiet. We found that the ecological balance was already changed due to the expansion of Neolithic farmlands. We conclude that among the Late Neolithic Near Eastern wildcats from Poland were free-living individuals, who preyed on rodent pests and shared ecological niches with native European wildcats.
Fast spiking interneuron activity in primate striatum tracks learning of attention cues
Authors: Banaie Boroujeni Kianoush , Oemisch Mariann , Hassani Seyed Alireza , Womelsdorf Thilo
Published: July 2020

Significance

Cognitive flexibility entails the ability to disengage attention from stimuli when they fail to predict positive outcomes, and to engage attention to newly rewarding stimuli. This reconfiguration of attention is likely supported by neural circuits that assign values to visual features. We report that activity of two separable groups of fast spiking striatal interneurons are likely part of that neural circuit. We electrophysiologically identified distinct cell populations in the primate striatum and found that fast spiking interneurons changed their firing specifically at the onset of an attention cue during learning. These findings provide evidence for a role of fast spiking striatal neurons to mediate the flexible reconfiguration of attentional priorities during learning.
The pseudo-caspase FLIP(L) regulates cell fate following p53 activation
Authors: Lees Andrea , McIntyre Alexander J. , Crawford Nyree T. , Falcone Fiammetta , McCann Christopher , Holohan Caitriona , Quinn Gerard P. , Roberts Jamie Z. , Sessler Tamas , Gallagher Peter F. , Gregg Gemma M. A. , McAllister Katherine , McLaughlin Kirsty M. , Allen Wendy L. , Egan Laurence J. , Ryan Aideen E. , Labonte-Wilson Melissa J. , Dunne Philip D. , Wappett Mark , Coyle Vicky M. , Johnston Patrick G. , Kerr Emma M. , Longley Daniel B. , McDade Simon S.
Published: July 2020

Significance

p53 is the most frequently mutated, well-studied tumor-suppressor gene, yet the switch from p53-induced cell-cycle arrest to apoptosis remains poorly understood. We unexpectedly identify a critical role for the only human pseudo-caspase FLIP(L) in regulating this switch. Genetically or pharmacologically inhibiting expression of FLIP(L), which we identify as a new p53 transcriptional target, promoted apoptosis over cell-cycle arrest in response to p53 activation. Mechanistically, FLIP(L) inhibited p53-induced apoptosis by blocking ligand-independent activation of caspase-8 by the TRAIL-R2/DR5 death receptor. Notably, FLIP(L) also modulated transcription of canonical p53 target genes: increasing expression of cell-cycle regulator p21 and suppressing upregulation of apoptosis-inducing PUMA. Thus, we report unexpected, therapeutically exploitable roles for FLIP(L) in regulating the switch from p53-induced cell-cycle arrest to apoptosis.
Exploiting evolutionary trade-offs for posttreatment management of drug-resistant populations
Authors: Melnikov Sergey V. , Stevens David L. , Fu Xian , Kwok Hui Si , Zhang Jin-Tao , Shen Yue , Sabina Jeffery , Lee Kevin , Lee Harry , Söll Dieter
Published: July 2020

Significance

The therapeutic use of drugs against microbial pathogens and cancer is currently undergoing a paradigm shift from traditional therapies toward adaptive therapies, which attempt to minimize the risk of the evolution of drug resistance. Adaptive therapies treat pathogens with short bouts of drug application followed by periods without treatment to allow resistant cells to be naturally outcompeted by susceptible cells. However, the fitness cost of drug resistance is frequently too small for resistant cells to be rapidly outcompeted by susceptible cells, compromising the effectiveness and the future of adaptive therapies. In this study, we show that this problem can be potentially solved by amplifying the fitness cost of drug resistance to encourage the natural competition between resistant and susceptible cells.
Peatland warming strongly increases fine-root growth
Authors: Malhotra Avni , Brice Deanne J. , Childs Joanne , Graham Jake D. , Hobbie Erik A. , Vander Stel Holly , Feron Sarah C. , Hanson Paul J. , Iversen Colleen M.
Published: July 2020

Significance

Peatlands store up to two-thirds of the world’s soil carbon, but this carbon may be released under warmer conditions, creating an important climate feedback. The belowground warming response of peatlands is particularly uncertain even though factors such as plant root growth regulate ecosystem water, carbon, and nutrient cycles. We studied how peatland fine roots respond to warming in a whole-ecosystem experiment. Fine-root growth increased dramatically, +130% for a degree of warming, primarily driven by soil drying. This warming response is 20 times stronger than in other ecosystem experiments, highlighting peatland vulnerability to warming. Our study elucidates large and rapid belowground changes that will affect peatlands of a warmer world and their ability to store carbon into the future.
Hyperpolarized Xe NMR signal advancement by metal-organic framework entrapment in aqueous solution
Authors: Zeng Qingbin , Bie Binglin , Guo Qianni , Yuan Yaping , Han Qi , Han Xiaocang , Chen Mingwei , Zhang Xu , Yang Yunhuang , Liu Maili , Liu Pan , Deng Hexiang , Zhou Xin
Published: July 2020

Significance

Hyperpolarized
129
Xe NMR/MRI is a useful method for diagnosis of diseases of the respiratory system. However, the sensitive detection of specific compounds in blood remains a challenge because of the weak
129
Xe signal in aqueous solution. We developed a way, Hyper-SAME, to promote the
129
Xe signal in aqueous solution. The
129
Xe signal intensity is four times beyond that of free
129
Xe in water and 200 times better than the benchmark molecular cage, cryptophane-A, in its saturated aqueous solution. Additionally, the hyperpolarized
129
Xe signal can be amplified further by combining Hyper-SAME with hyperpolarized
129
Xe chemical exchange saturation transfer.
Peptidylglycine α-amidating monooxygenase is required for atrial secretory granule formation
Authors: Bäck Nils , Luxmi Raj , Powers Kathryn G. , Mains Richard E. , Eipper Betty A.
Published: July 2020

Significance

Transmission electron microscopy of atrial cardiomyocytes revealed dense granules resembling those in endocrine cells and neurons, leading to the discovery of the natriuretic peptides stored in these granules. Subsequent studies revealed features unique to atrial granules, including high-level expression of peptidylglycine α-amidating monooxygenase (PAM), an enzyme required for the synthesis of many neuropeptides, but not for the synthesis of natriuretic peptides. The discovery that atrial myocytes lacking PAM are unable to produce granules and that PAM lacking its monooxygenase activity can rescue granule formation provides new information about the proANP secretory pathway. A better understanding of the unique features of atrial cell biology should provide insight into atrial fibrillation, the most common cardiac arrhythmia, atrial amyloidosis, and heart failure.
In vivo anticancer activity of a rhodium metalloinsertor in the HCT116 xenograft tumor model
Authors: Threatt Stephanie D. , Synold Timothy W. , Wu Jun , Barton Jacqueline K.
Published: July 2020

Significance

This study describes our first evaluation in mice of the rhodium complex Rh-PPO, which selectively targets DNA base-pair mismatches and shows cytotoxicity within mismatch repair-deficient cancer cells. Rh-PPO displays notable in vivo anticancer activity and increases mouse survival when administered intraperitoneally. This work marks the development of a promising metal chemotherapeutic and a new strategy for mismatch-repair-deficient cancers.
The unusual
dRemp
retrotransposon is abundant, highly mutagenic, and mobilized only in the second pollen mitosis of some maize lines
Authors: Wang Qinghua , Huang Jun , Li Yubin , Dooner Hugo K.
Published: July 2020

Significance

The frequent spontaneous mutations recovered recently in the pollen of some maize inbred lines arise mainly from the meiotic movement of retrotransposons present in few copies in the genome. This article reports that mutations in inbred line M14, identified earlier by breeders as being highly unstable, arise exclusively from the movement at the second pollen mitosis of a short retrotransposon that is present in hundreds of copies. Thus, this finding is unique because of the multicopy nature of the mutagenic retrotransposon and the specific developmental window in which it moves. It may also shed light on the possible basis for inbred genetic instability in maize.
The control and censorship of linguistic resources in an online Community of Practice
Authors: Donlan Lisa
Published: July 2020

This research utilises a corpus of one million posts retrieved from Popheads, an online Reddit-based Community of Practice (CoP), to analyse the power dynamics associated with language censorship in online CoPs. In 2018, the moderators of the community banned the community-salient word wig (‘surprised’ or ‘impressed’). Ostensibly, this was a top-down performance of linguistic control where the officially-appointed moderators put a stop to the diffusion of a seemingly beloved part of the community’s shared linguistic repertoire. However, through a mixed-methods analysis of the events surrounding the banning of wig, this research shows that moderators have not unilaterally enforced linguistic censorship. Instead, moderators have seemingly responded to a call, led primarily by members with markers of unofficial power, to restrict usage.
Talking about women
Authors: Dayter Daria , Rüdiger Sofia
Published: July 2020

In this chapter, we examine how pick-up artists (PUAs; a male community preoccupied with interacting with women) talk about women in their online discourse. To this end, we take and test three approaches: (1) introspection and elicitation, (2) manual tagging of a small specialized corpus, and (3) automatic semantic tagging and reverse collocation of a large corpus of PUA computer-mediated communication. Instead of misogynistic derogatory references to women, which are only used infrequently, we find that PUAs rely on common references (often condescending or objectifying) and on PUA-specific vocabulary. In terms of method, manual tagging turned out most comprehensive, but automatic semantic tagging allowed for the processing of a far bigger dataset with minimal loss of total types retrieved.
Patterns of intra-individual variation in a Swiss WhatsApp corpus
Authors: Felder Samuel
Published: July 2020

Analysing written data from a large WhatsApp corpus, which was collected in Switzerland in 2014, this study examines how individuals may change their linguistic behaviour over time and how such changes are connected to the language use of the interlocutor. Therefore, this is one of the very first studies analysing intra-individual real-time change and long-term accommodation processes in written digital data. Focussing on WhatsApp chats that are primarily written in Swiss German, evidence for the possibility of rapid changes within the language use of individuals on several linguistic levels is presented: dialectal variation, phoneme-grapheme correspondence, punctuation, lexis, and use of emojis/emoticons. Furthermore, based on multiple examples from the corpus, several different types of long-term accommodation processes in two-person chats are distinguished.
Influence of deformation process on microstructure and properties of 2014 aluminium alloy
Authors: Li Fushan , Chen Songyi , Chen Kanghua , Huang Lanping , He Longlong , Chen Geng
Published: July 2020

The comparisons of forging-extrusion multistage hot deformation, forging and extrusion hot deformation processes on microstructure, mechanical property and impact toughness of 2014 Al alloy have been investigated. Results showed that the strength and impact toughness of the samples under forging-low extrusion multistage deformation process were significantly improved compared with that under forging deformation process due to the formation of smaller insoluble particles, finer grains and higher density of matrix precipitates. However, the strength and impact toughness of the samples under forging-extrusion multistage hot deformation process are lower than that under extrusion hot deformation process. The strengthening and fracture mechanisms with different deformation process have been discussed in detailed.
Kinetic analysis of inhibition of α-glucosidase by leaf powder from Morus australis and its component iminosugars
Authors: Qiao Ying , Nakayama Juri , Ikeuchi Takeaki , Ito Masaaki , Kimura Toshiyuki , Kojima Kenji , Takita Teisuke , Yasukawa Kiyoshi
Published: July 2020

Mulberry leaves contain iminosugars, such as 1-deoxynojirimycin (1-DNJ), fagomine, and 2-O-α-D-galactopyranosyl deoxynojirimycin (GAL-DNJ) that inhibit α-glucosidase. In this study, we quantified iminosugars in Morus australis leaves and made the kinetic analysis in the hydrolysis of maltose by α-glucosidase. By LC-MS/MS, the concentrations of 1-DNJ, fagomine, and GAL-DNJ in the powdered leaves were 4.0, 0.46, and 2.5 mg/g, respectively, and those in the roasted ones were 1.0, 0.24, and 0.73 mg/g, respectively, suggesting that the roasting process degraded iminosugars. Steady-state kinetic analysis revealed that the powdered and roasted leaves exhibited competitive inhibition. At pH 6.0 at 37ºC, the IC50 values of the extracts from the boiled powdered or roasted leaves were 0.36 and 1.1 mg/mL, respectively. At the same condition, the IC50 values of 1-DNJ, fagomine, and GAL-DNJ were 0.70 μg/mL, 0.18 mg/mL, and 2.9 mg/mL, respectively. These results suggested that in M. australis, 1-DNJ is a major inhibitor of α-glucosidase.

Abbreviations

1-DNJ: 1-deoxynojirimycin; GAL-DNJ: 2-O-α-D-galactopyranosyl-DNJ
Different levels of physical activity and depression symptoms among older adults from 18 countries: A population‐based study from the Survey of Health, Ageing and Retirement in Europe (SHARE)
Authors: Marques Adilson , Gaspar de Matos Margarida , Bordado Joana , Gouveia Élvio R. , Peralta Miguel , Gomez‐Baya Diego
Published: July 2020

Objective: Analyse the relationship between different levels of physical activity (PA) and depression symptoms in a representative sample of European older adults. Methods: Data on PA, depression symptoms and sociodemographic variables from 64688 (28015 men) older adults participating in SHARE wave 6 was collected through a face‐to‐face interview. The EURO‐D 12‐item scale was administered for depression symptoms. Participants reported the frequency they engaged in moderate‐intensity PA (MPA) and vigorous‐intensity PA (VPA). Results: Men and women engaging in MPA and VPA once or more than once a week had less depression symptoms than those who engage less than once a week. MPA and VPA once or more than once a week were inversely associated with the depression symptoms score. Furthermore, engaging in MPA and VPA decreased the odds of depression (cut‐off point of ≥4 depression symptoms) compared to engaging in PA less than once a week. Conclusions: Policies for promoting mental health should include PA for the prevention or treatment of depression symptoms. PA presents physical and psychological benefits and can be used as an overall health‐promoting strategy, facing numerous problems at a time.
Through the Fractured Looking Glass
Authors: Mitchell Sandra D.
Published: July 2020

I argue that diversity and pluralism are valuable not just for science but for philosophy of science. Given the partiality and perspectivism of representation, pluralism preserving integration can increase accuracy. Perspectivism is often supported by appeal to visual representation. I draw further insights from multimodel sensory integration for understanding experiment-based predictions of protein structure. The epistemic lessons learned from the scientific case also apply to philosophy of science itself. Finally, I suggest that a critical, nuanced philosophical view of legitimate sources of pluralism in science has an important role to play in public discourse.
A New Approach for Residual Stress Analysis of GH3535 Alloy by Using Two-Dimensional Synchrotron X-Ray Diffraction
Authors: Jiang Sheng , Zhang Ji-Chao , Yan Shuai , Li Xiao-Li
Published: July 2020

We propose a new method to evaluate residual stress based on the analysis of a portion of a Debye ring with two-dimensional synchrotron x-ray diffraction. The residual stress of a nickel-based alloy GH3535 evaluated by the proposed method is determined to be – 1149±34 MPa based on the quantitative analysis of the deformation of the (200) reflection, and the residual stress obtained by analyzing THE (111) plane is –933± 68 MPa. The results demonstrate that the GH3535 alloy surface is highly compressive, as expected for a polishing surface treatment. The proposed method provides insight into the field of residual stress measurement and quantitative understanding of the residual stress states in GH3535.
Direct Spatially Resolved Snapshot Interferometric Phase and Stokes Vector Extraction by Using an Imaging PolarCam
Authors: Ibrahim Dahi , Kim Daesuk
Published: July 2020

We extract the 3D phase Δ and the Stokes parameter S
3 of a transmissive anisotropic object spatially using an interferometric PolarCam. Four parallel interferograms with a phase shift of π/2 between the images are captured in a single snapshot and then reconstructed by the four-bucket algorithm to extract the 3D phase of the object. The S
3 is then calculated directly from the obtained 3D phase Δ. The extracted results of Δ and S
3 were compared with those extracted from the non-interferometric PolarCam and the Thorlabs polarimeter, and the results match quite well. The merit of using the interferometric PolarCam is that no mechanical movement mechanisms are included, and hence the Δ and S
3 of the object can be extracted, with high accuracy and within a part of a second (three times faster than non-interferometric PolarCam and Thorlabs polarimeter methods). Moreover, this method can be applied in the field of the dynamic spectro–interferometric PolarCam and can be implemented using swept-wavelength approaches.
Head-on Collision of Solitary Waves Described by the Toda Lattice Model in Granular Chain
Authors: Wu Qianqian , Liu Xingyi , Jiao Tengfei , Sen Surajit , Huang Decai
Published: July 2020

We study the head-on collision of two solitary waves in a precompressed granular chain using the discrete element method. Our study takes the Toda chain solution as the initial condition for the simulations. The simulation covers the dynamical evolution of the collision process from the start of the incident wave to the end of the collision. The interaction has a central collision region of about five-grain width in which two solitary waves merge completely and share only one peak. Four stages, i.e., the pre-in-phase traveling stage, lag-phase collision state, lead-phase collision state, and post-in-phase traveling stage, are identified to describe the complex collision processes. Our results may be helpful for explaining the existence of long-lived solitary waves seen in the simulations by Takato and Sen [Europhys. Lett. 100 (2012) 24003].
Evolution of Energy in Submerged Granular Column Collapse
Authors: Zhang Wen-Tao , An Yi , Liu Qing-Quan , Wang Xiao-Liang , Sun Yun-Hui
Published: July 2020

The evolution of energy in subaerial and subaqueous granular column collapses is studied. Employing the refractive index matching method and planar laser-induced fluorescence technique, we obtain granular and liquid images simultaneously in a single experiment of subaqueous flow. Particle image velocimetry and particle tracking velocimetry are used to process the data for the fluid and granular phase. We find stepwise decreases in the total kinetic energy of the granular material. The stage of rapidly falling energy corresponds to large transverse changes in the direction of the massive granular particles. Moreover, in this stage, a major fraction of the granular kinetic energy transferred from the granular potential energy is lost or transferred. Interestingly, compared with dry granular flow, the existence of an ambient liquid seems to reduce the total dissipated energy, which may be the reason why previous studies observed similar granular runout distances in subaqueous and dry granular collapses.
Interface Width Effect on the Weakly Nonlinear Rayleigh–Taylor Instability in Spherical Geometry
Authors: Yang Yun-Peng , Zhang Jing , Li Zhi-Yuan , Wang Li-Feng , Wu Jun-Feng , Ye Wun-Hua , He Xian-Tu
Published: July 2020

Interface width effect on the spherical Rayleigh–Taylor instability in the weakly nonlinear regime is studied by numerical simulations. For Legendre perturbation mode Pn
with wave number kn
and interface half-width L, the commonly adopted empirical linear growth rate formula

γ
n

em

(
L
)
=

γ
n

/

1
+

k
n

L

is found to be sufficient in spherical geometry. At the weakly nonlinear stage, the interface width affects the mode coupling processes. The development of the mode P
2n
is substantially influenced by the interface width. Moreover, the nonlinear saturation amplitude increases with the interface width.
Comparison of Cavities Formed in Single Crystalline and Polycrystalline α-SiC after H Implantation
Authors: Liao Qing , Kang Long , Zhang Tong-Min , Liu Hui-Ping , Wang Tao , Li Xiao-Gang , Li Jin-Yu , Yang Zhen , Li Bing-Sheng
Published: July 2020

Cavities and extended defects formed in single crystalline and polycrystalline α-SiC implanted with H+ ions are compared. The samples are investigated by cross-sectional transmission electron microscopy. H2 bubbles are formed during H implantation and H2 molecules escape the sample to form cavities during thermal annealing at 1100°C. Microcracks and the extended defects prefer to nucleate in single crystalline α-SiC, but not polycrystalline α-SiC. Grain boundaries can account for the experimental results. The formation of cavities on grain boundaries is investigated.
Theoretical Simulation of the Temporal Behavior of Bragg Diffraction Derived from Lattice Deformation
Authors: Guo Cong , Sun Shuai-Shuai , Wei Lin-Lin , Tian Huan-Fang , Yang Huai-Xin , Gao Shu , Tan Yuan , Li Jian-Qi
Published: July 2020

A theoretical study on the structural dynamics of the temporal behavior of Bragg diffraction is presented and compared with experimental results obtained via ultrafast electron crystallography. In order to describe the time-dependent lattices and calculate the Bragg diffraction intensity, we introduce the basic vector offset matrix, which can be used to quantify the shortening, lengthening and rotation of the three lattice vectors (i.e., lattice deformation). Extensive simulations are performed to evaluate the four-dimensional electron crystallography model. The results elucidate the connection between structural deformations and changes in diffraction peaks, and sheds light on the quantitative analysis and comprehensive understanding of the structural dynamics.
Ultrathin Al Oxide Seed Layer for Atomic Layer Deposition of High-κ Al2O3 Dielectrics on Graphene
Authors: Yang Hang , Chen Wei , Li Ming-Yang , Xiong Feng , Wang Guang , Zhang Sen , Deng Chu-Yun , Peng Gang , Qin Shi-Qiao
Published: July 2020

Due to the lack of surface dangling bonds in graphene, the direct growth of high-κ films via atomic layer deposition (ALD) technique often produces the dielectrics with a poor quality, which hinders its integration in modern semiconductor industry. Previous pretreatment approaches, such as chemical functionalization with ozone and plasma treatments, would inevitably degrade the quality of the underlying graphene. Here, we tackled this problem by utilizing an effective and convenient physical method. In detail, the graphene surface was pretreated with the deposition of thermally evaporated ultrathin Al metal layer prior to the Al2O3 growth by ALD. Then the device was placed in a drying oven for 30 min to be naturally oxidized as a seed layer. With the assistance of an Al oxide seed layer, pinhole-free Al2O3 dielectrics growth on graphene was achieved. No detective defects or disorders were introduced into graphene by Raman characterization. Moreover, our fabricated graphene top-gated field effect transistor exhibited high mobility (∼6200 cm2V−1s−1) and high transconductance (∼117 μS). Thin dielectrics demonstrated a relative permittivity of 6.5 over a large area and a leakage current less than 1.6 pA/μm2. These results indicate that Al oxide functionalization is a promising pathway to achieve scaled gate dielectrics on graphene with high performance.
Giant-Capacitance-Induced Wide Quantum Hall Plateaus in Graphene on LaAlO3/SrTiO3 Heterostructures
Authors: Tao Ran , Li Lin , Zhu Li-Jun , Yan Yue-Dong , Guo Lin-Hai , Fan Xiao-Dong , Zeng Chang-Gan
Published: July 2020

Hybrid structures of two distinct materials provide an excellent opportunity to optimize functionalities. We report the realization of wide quantum Hall plateaus in graphene field-effect devices on the LaAlO3/SrTiO3 heterostructures. Well-defined quantized Hall resistance plateaus at filling factors v = ± 2 can be obtained over wide ranges of the magnetic field and gate voltage, e.g., extending from 2 T to a maximum available magnetic field of 9 T. By using a simple band diagram model, it is revealed that these wide plateaus arise from the ultra-large capacitance of the ultra-thin LAO layer acting as the dielectric layer. This is distinctly different from the case of epitaxial graphene on SiC substrates, where the realization of giant Hall plateaus relies on the charge transfer between the graphene layer and interface states in SiC. Our results offer an alternative route towards optimizing the quantum Hall performance of graphene, which may find its applications in the further development of quantum resistance metrology.
Superconductivity at the Normal Metal/Dirac Semimetal Cd3As2 Interface
Authors: Zhang Shuai , Wang Yiyan , Ma Chaoyang , Zhu Wenliang , Ren Zhian , Shan Lei , Chen Genfu
Published: July 2020

We investigate the interface between a three-dimensional Dirac semimetal Cd3As2 and a normal metal via soft-point contact spectroscopy measurement. The superconducting gap features were detected below 3.8 K and 7.1 K in the case of Cd3As2 single crystals sputter-coated with the Pt and Au films, respectively, in the differential conductance dI/dV–V plots of the point contacts. As the applied magnetic field increased, the drop in the zero-bias contact resistance shifted toward lower temperatures. The topologically non-trivial band structure of Cd3As2 is considered to play a crucial role in inducing the superconductivity. Apart from realizing superconductivity in topological materials, our creative approach can be used to investigate possible topological superconductivity and exhibits a high application potential in electronic devices.
Multiplexed Metasurfaces for High-Capacity Printing Imaging
Authors: Fang Zhenyu , Xu Haofei , Zheng Yaqin , Chen Yuelin , Zhou Zhang-Kai
Published: July 2020

We successfully overcome the problem of cross-talk in multiplexed metasurface design and realize the multiplexed metasurface with five printing images in both theoretical and experimental aspects, by employing the coherent pixel design considering coherent superposition of all the sub-elements. Compared with most previous studies where the integrated printing images were usually no more than three, our study shows obvious improvement. More importantly, in our approach all the sub-elements, which were crystalline silicon nanobricks with the size of 320 × 80 × 230 nm3, were arranged in a square space of 1.45 × 1.45 μm2 following the closest packing way, enabling our multiplexed metasurface to have a potential of effective physical information capacity of printing image reaching the optical diffraction limit. Our study not only enlarges the information capacity of metasurfaces by expanding the integrated number of printing image in one metasurface, but also can promote metasurface applications in various fields such as information storage and encoding.
Geometry of the phase retrieval problem
Authors: Barnett Alexander H , Epstein Charles L , Greengard Leslie F , Magland Jeremy F
Published: July 2020

One of the most powerful approaches to imaging at the nanometer length scale is coherent diffraction imaging using x-ray sources. For amorphous (non-crystalline) samples, raw data collected in the far-field can be interpreted as the modulus of the two-dimensional continuous Fourier transform of the unknown object. The goal is then to recover the phase through computational means by exploiting prior information about the sample (such as its support), after which the unknown object can be visualized at high resolution. While many algorithms have been proposed for this phase retrieval problem, careful analysis of its well-posedness has received relatively little attention. In this paper, we show that the problem is, in general, not well-posed and describe some of the underlying issues that are responsible for the ill-posedness. We then show how this analysis can be used to develop experimental protocols that lead to better conditioned inverse problems.
A projective averaged Kaczmarz iteration for nonlinear ill-posed problems
Authors: Tong Shanshan , Han Bo , Tang Jinping
Published: July 2020

The averaged Kaczmarz iteration is a hybrid of the Landweber method and Kaczmarz method with easy implementation and increased stability for solving problems with multi nonlinear equations. In this paper, we propose an accelerated averaged Kaczmarz type iterative method by introducing the search direction of homotopy perturbation Kaczmarz and a projective strategy. The new iterate is updated by using an average over the intermediate variables. These variables are obtained by the metric projection of previous iterates onto the stripes which are related to the property of forward operator and noise level. We present the convergence analysis of the proposed method under the similar assumptions of Landweber Kaczmarz method. The numerical experiments on parameter identification problem validate that the proposed method has evident acceleration effect and reconstruction stability.
Pose measurement approach based on two-stage binocular vision for docking large components
Authors: Chen Yuanze , Zhou Fuqiang , Zhou Mingxuan , Zhang Wanning , Li Xiaosong
Published: July 2020

Large components docking is an important step in industrial manufacturing. During the docking process, the relative pose of joining components needs real-time and accurate acquisition. Existing methods rely on expensive and complex optical instruments. Photogrammetry has the advantages of low cost and fast measurement speed, but its measurement accuracy decreases sharply along with the increase of the measurement range. This paper proposes a two-stage binocular vision which consists of two sets of binocular vision systems with different accuracy levels in the same coordinate system. Binocular system with corresponding structural parameters is designed for pose measurement at corresponding stages to solve the contradiction between the range and accuracy in measurement. A triangulation and spatial plane fitting method is proposed to calculate relative poses without introducing coordinate transformation errors. We adopt a novel 3D optimization method to further improve the accuracy. Experiment results show that this method can meet the measurement range and accuracy requirements for large components docking. Compared with traditional combined vision measurement station based on multi-vision sensor, the proposed method reduces coordinate transformation errors and overcomes the contradiction between the measurement range and accuracy, which can improve the accuracy and meet the requirements of engineering application.
Conversion Principle and Control Method of Synchro Signal
Authors: Lv Wenfa
Published: July 2020

The synchro is a kind of micromotor used for angle measurement. It can output analog signals containing angle information, which is widely used in the fire control system. In order to facilitate the processing, it is necessary to digitize these analog signals. In this paper,8255A is used as the main control chip, and high-speed, high-precision digital to analog and analog to digital converters are used for real-time analog acquisition or mathematical conversion of selsyn signals to realize real-time data communication between fire control equipment and external equipment, and selsyn signals are used for real-time data communication, The technology has the characteristics of flexible control, simple circuit, strong real-time, high reliability, and it has been widely used in the fire control system of naval gun, and achieved good results
A New Handwritten Number Recognition Method Using HMM Based on MNIST
Authors: Lu Ruhua , Li Yalan
Published: July 2020

Taking MNIST data-set as research object, the HMM is introduced into the Handwritten Number Recognition for the first time. After the implementation of the classical HMM training algorithm, some optimization methods are proposed for the problems existing in the training. The general random initialization parameters lead to long training time and unstable data. The training of initialization parameters based on observations can speed up the training and avoid data overflow. The number of iterations in the training process is not positively related to the output probability. In order to obtain an optimal model, after the algorithm converges when the cross entropy loss function of the output probability of two adjacent iterations is the minimum, the training ends. Finally, a comparative experiment between the classical method and the optimization method is carried out in the two stages of training and recognition. In the training stage, compared with the classical method, the optimization method has the advantages of short average training time, high average output probability, fast iteration speed and high accuracy. In the test stage, the accuracy of the optimization method is higher than that of the classical method. The experimental results show that the HMM can be effectively applied in the field of Handwritten Number Recognition. And through the optimization method, to a certain extent, the recognition accuracy is improved. In a word, the method in this paper is an effective and feasible method.
Analysis and Elimination of Common Interference in Satellite Communications
Authors: Liu Qianqian , Tang Baoyan , Wang Yuanyuan
Published: July 2020

Because the satellite communication system is an open system, the satellite’s frequency resources and transponder power are limited. Although there are international organizations and satellite companies in various countries for orbit, frequency, and power allocation and coordination, satellite communications cannot be completely prevented from being interfered. The well-known Falun Gong interference with Xinnuo satellite is an obvious example. Articles on satellite communication interference are scattered in various professional newspapers. This article will discuss the causes, judgment methods and solutions of common interference in satellite communication, focusing on the practical methods of solving interference.
Research on Knowledge Graph Model for Cybersecurity Logs Based on Ontology and Classified Protection
Authors: Tao Yuan , Li Moyan , Hu Wei
Published: July 2020

In order to audit and analyse cybersecurity events from massive logs, the knowledge graph model for cybersecurity logs is proposed. The data layer and the pattern layer of the knowledge graph model for cybersecurity logs is obtained based on ontology and classified protection. Entity classification of cybersecurity logs is extracted by using classified protection standards in the data layer of the knowledge graph. The relationship and attribute of ontology from cybersecurity logs is defined. The pattern layer of the knowledge graph model for cybersecurity logs is defined, classified protection data is integrated in entity alignment, and classified protection information gain is used in ontology construction. The structure of the knowledge graph for cybersecurity logs is given. So that the efficient association and deep mining analysis of cybersecurity logs are realized, and it can be directly analysed and processed on the data without the need for precise modelling of the problem. The efficiency of logs analysis is improved. The model has heuristic characteristics and generalization abstract ability, and the model is suitable for big data analysis of large-scale cybersecurity logs.