bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultra-sensitive broadband “AWESOME” electric field receiver for nanovolt low-frequency signals
Authors: Gurses B. Volkan , Whitmore Kevin T. , Cohen Morris B.
Published: February 2021

Longwave (defined here as 500 Hz–500 kHz) radio science drives many scientific and engineering applications, including lightning detection and geolocation, subsea and subsurface sensing and communications, navigation and timing, and ionospheric and magnetospheric remote sensing. The hardware performance (i.e., sensitivity and bandwidth) of the receivers that detect long waves determines the maximum amount of information that can be extracted from the acquired data. In this paper, we present and describe an ultra-sensitive electric field receiver that enables broadband radio reception from near-DC up to 470 kHz, augmenting the legacy of the “Atmospheric Weather Electromagnetic System for Observation Modeling and Education” (AWESOME), a state-of-the-art magnetic field receiver completed previously. The AWESOME electric field receiver uses capacitive coupling with a dipole antenna to detect the electric field components of long waves and attains a sensitivity of 0.677 nV/(mHz). This sensitivity allows the detection of natural radio atmospherics and man-made beacon emissions at a global range. The AWESOME electric field receiver can also be integrated with a magnetic field sensor for simultaneous electric and magnetic field reception. In this paper, we detail the design of the receiver, including the receiver architecture, its working principles, design methodology, and trade-offs. We showcase the receiver performance characterized through both numerical models and empirical measurements. We demonstrate a novel calibration method that is quick and straightforward, suitable for deployments in the field. Finally, we demonstrate some novel applications enabled by this receiver’s excellent sensitivity and simultaneous reception capability of electric and magnetic field components of long waves.
Exploiting the properties of TiO2 thin films as a sensing layer on (MEMS)-based sensors for radiation dosimetry applications
Authors: Shamma Khaled , Aldwayyan Abdullah , Albrithen Hamad , Alodhayb Abdullah
Published: February 2021

In this work, we investigate the potential of exploiting TiO2 thin films as sensing layers on silicon micro-electromechanical systems for the detection of gamma radiations. All samples are exposed to gamma rays produced by 60Co, with different doses ranging from 0 kGy to 40 kGy. Properties of silicon coated with a 200-nm-thick layer of TiO2 grown at 200 °C by atomic layer deposition are studied before and after its gamma irradiation using x-ray diffraction (XRD), scanning electron microscopy, and spectroscopic ellipsometry. Atomic force microscopy (AFM) is carried out on functionalized microcantilevers to measure the resonance frequency shift (Δf 0) resulting from irradiation of the TiO2 thin film. XRD results show a change in the films from a mixture of rutile and anatase phases to an anatase phase upon irradiation. Spectroscopic ellipsometry results show a change with a fixed pattern in the film thickness, roughness, void, and optical constants with different irradiation doses. This pattern appears as Δf 0 in AFM, where the response of sensors to doses between 0 kGy and 20 kGy was linear. The values of Δf 0 are convenient to control parameters for the proposed dosimeter, which is characterized by the reproducibility and sensitivity of measurements. The maximum detectable linear effect of the proposed dosimeter was found at a dose of 20 kGy. This makes a 200-nm thin layer of TiO2 coated on a microcantilever surface, a possible candidate for dosimetry for the range lower than 20 kGy applications, such as in personal dosimeters.
Low voltage drop tunnel junctions grown monolithically by MOCVD
Authors: Jamal-Eddine Zane , Hasan Syed M. N. , Gunning Brendan , Chandrasekar Hareesh , Crawford Mary , Armstrong Andrew , Arafin Shamsul , Rajan Siddharth
Published: February 2021

Tunnel junction devices grown monolithically by metal organic chemical vapor deposition were optimized for minimization of the tunnel junction voltage drop. Two device structures were studied: an all-GaN homojunction tunnel junction and a graded InGaN heterojunction-based tunnel junction. This work reports a record-low voltage drop in the graded-InGaN heterojunction based tunnel junction device structure achieving a de-embedded tunnel junction voltage drop of 0.17 V at 100 A/cm2. The experimental data were compared with a theoretical model developed through technology computer-aided design (TCAD) simulations that offer a physics-based approach to understanding the key components of the design space, which lead to a more efficient tunnel junction.
Atomically resolved structure of step-like uncharged and charged domain walls in polycrystalline BiFeO3
Authors: Condurache Oana , Dražić Goran , Sakamoto Naonori , Rojac Tadej , Benčan Andreja
Published: February 2021

The dynamics of domain walls (DWs) during polarization switching has a great influence on the electromechanical response of ferroelectrics. To understand the influence of DWs on the functional performance of the material, their local structure and properties must be revealed. There are many investigations of the DWs in ferroelectric thin films, while investigations of the DWs in polycrystalline ferroelectrics are fewer. Here, we report on a comparative study of uncharged and charged (“tail-to-tail”) DWs in BiFeO3 ceramics from the point of view of the atomically resolved strain and structure using scanning-transmission electron microscopy. Both types of DWs have a step-like morphology and have a non-Ising behavior. The strain, expressed as the unit-cell distortion, is higher and more concentrated in the case of uncharged walls, which we associate with a narrower transition region of the Fe-displacement vectors. Conversely, in the case of “tail-to-tail” charged DWs, the unit-cell distortion is smaller and more dispersed because of the wider transition region of the Fe-displacement vectors. All the types of step-like DWs reported here, regardless of their charge state, exhibit a comparable amount of Bi-vacancies segregation. Further details about the structural differences are discussed from the point of view of the Fe-displacement evolution through the wall for uncharged/“tail-to-tail” charged DWs. The results are useful as they provide an insight into the local structure and chemistry of charged and uncharged DWs in polycrystalline BiFeO3.
Dynamical transition orbitals: A particle–hole description in real-time TDDFT dynamics
Authors: Zhou Ruiyi , Kanai Yosuke
Published: February 2021

We expand the concept of natural transition orbitals in the context of real-time time-dependent density functional theory (RT-TDDFT) and show its application in practical calculations. Kohn–Sham single-particle wavefunctions are propagated in RT-TDDFT simulation, and physical properties remain invariant under their unitary transformation. In this work, we exploit this gauge freedom and expand the concept of natural transition orbitals, which is widely used in linear-response TDDFT, for obtaining a particle–hole description in RT-TDDFT simulation. While linear-response TDDFT is widely used to study electronic excitation, RT-TDDFT can be employed more generally to simulate non-equilibrium electron dynamics. Studying electron dynamics in terms of dynamic transitions of particle–hole pairs is, however, not straightforward in the RT-TDDFT simulation. By constructing natural transition orbitals through projecting time-dependent Kohn–Sham wave functions onto occupied/unoccupied eigenstate subspaces, we show that linear combinations of a pair of the resulting hole/particle orbitals form a new gauge, which we refer to as dynamical transition orbitals. We demonstrate the utility of this framework to analyze RT-TDDFT simulations of optical excitation and electronic stopping dynamics in the particle–hole description.
Ferroelectric field effect transistors: Progress and perspective
Authors: Kim Jae Young , Choi Min-Ju , Jang Ho Won
Published: February 2021

Ferroelectric field effect transistors (FeFETs) have attracted attention as next-generation devices as they can serve as a synaptic device for neuromorphic implementation and a one-transistor (1T) for achieving high integration. Since the discovery of hafnium–zirconium oxide (HZO) with high ferroelectricity (even at a thickness of several nanometers) that can be fabricated by a complementary metal–oxide–semiconductor-compatible process, FeFETs have emerged as devices with great potential. In this article, the basic principles of the FeFET and the design strategies for state-of-the-art FeFETs will be discussed. FeFETs using Pb(ZrxTi1−x)O3, polyvinylidene fluoride, HZO, and two-dimensional materials are emphasized. FeFETs, ferroelectric semiconductor field effect transistors, and metal–ferroelectric–insulator–semiconductor structures to which those materials can be applied are introduced, and their exotic performances are investigated. Finally, the limitations of these devices’ current performance and the potential of these materials are presented.
A thermodynamic condition for ignition and burn-propagation in cryogenic layer inertially confined fusion implosions
Authors: Hurricane O. A. , Maclaren S. A. , Rosen M. D. , Hammer J. H. , Springer P. T. , Betti R.
Published: February 2021

A Lawson-like criterion for ignition (where self-heating dominates over all energy losses) in a dynamic implosion is developed, which accounts for asymmetry and for differences in an implosion x-ray confinement quality. It is shown that the thermodynamic ignition condition is equivalent to yield amplification levels of 16–32. Since negative pdV work of expansion after stagnation increases energy losses above that of x-ray and electron-conduction losses, the Lawson-like ignition criterion is necessary but not sufficient for igniting the hot spot to propagate into the DT fuel with sufficient vigor to generate high gain. A higher dimensional generalization of the Lawson-like criterion, which includes the cooling of the implosion upon disassembly, does provide the needed criteria, and it shows that significantly higher temperature is needed for very high levels of yield amplification compared to what traditional ignition metrics imply.
Nodal deficiency of random spherical harmonics in presence of boundary
Authors: Cammarota Valentina , Marinucci Domenico , Wigman Igor
Published: February 2021

We consider a random Gaussian model of Laplace eigenfunctions on the hemisphere, satisfying the Dirichlet boundary conditions along the equator. For this model, we find a precise asymptotic law for the corresponding zero density functions, in both short range (around the boundary) and long range (far away from the boundary) regimes. As a corollary, we were able to find a logarithmic negative bias for the total nodal length of this ensemble relative to the rotation invariant model of random spherical harmonics. Jean Bourgain’s research, and his enthusiastic approach to the nodal geometry of Laplace eigenfunctions, has made a crucial impact in the field and the current trends within. His works on the spectral correlations {Theorem 2.2 in the work of Krishnapur et al. [Ann. Math. 177(2), 699–737 (2013)]} and Bombieri and Bourgain [Int. Math. Res. Not. (IMRN) 11, 3343–3407 (2015)] have opened a door for an active ongoing research on the nodal length of functions defined on surfaces of arithmetic flavor, such as the torus or the square. Furthermore, Bourgain’s work [J. Bourgain, Isr. J. Math. 201(2), 611–630 (2014)] on toral Laplace eigenfunctions, also appealing to spectral correlations, allowed for inferring deterministic results from their random Gaussian counterparts.
Scalable, cost-efficient synthesis and properties optimization of magnetoelectric cobalt ferrite/barium titanate composites
Authors: Safi Samghabadi Farnaz , Chang Long , Khodadadi Mohammad , Martirosyan Karen S , Litvinov Dmitri
Published: February 2021

Cobalt ferrite (CoFe2O4)/barium titanate (BaTiO3) particulate composites exhibiting high magnetoelectric coefficients were synthesized from low-cost commercial precursors using mechanical ball milling followed by high-temperature annealing. CoFe2O4 (20 nm–50 nm) and either cubic or tetragonal BaTiO3 nanoparticle powders were used for the synthesis. It was found that utilizing a 50 nm cubic BaTiO3 powder as a precursor results in a composite with a magnetoelectric coupling coefficient value as high as 4.3 mV/Oe cm, which is comparable to those of chemically synthesized core–shell CoFe2O4–BaTiO3 nanoparticles. The microstructure of these composites is dramatically different from the composite synthesized using 200 nm tetragonal BaTiO3 powder. CoFe2O4 grains in the composite prepared using cubic BaTiO3 powder are larger (by at least an order of magnitude) and significantly better electrically insulated from each other by the surrounding BaTiO3 matrix, which results in a high electrical resistivity material. It is hypothesized that mechanical coupling between larger CoFe2O4 grains well embedded in a BaTiO3 matrix in combination with high electrical resistivity of the material enhances the observed magnetoelectric effect.
Manually tunable ventilated metamaterial absorbers
Authors: Xiang Xiao , Tian Hongxing , Huang Yingzhou , Wu Xiaoxiao , Wen Weijia
Published: February 2021

For most acoustic metamaterials, once they have been fabricated, their operating frequencies and functions cannot be adjusted, which is an intrinsic barrier for the development of realistic applications. The study to overcome this limit has become a significant issue in acoustic metamaterial engineering. Although with the advance of metamaterials in the past two decades, a series of methods such as electric or magnetic control have been proposed, most of them can only work in the condition of no fluid passage. Some metamaterials with large transmission losses have been proposed, but the sounds are essentially reflected rather than absorbed. Here, to overcome this intrinsic difficulty, we propose a ventilated sound absorber that can be manually tuned in a large range after being manufactured. During the tuning that is achieved through an intricately designed slider, high-performance absorption and ventilation are both ensured. The tunable ventilated sound absorber is demonstrated experimentally and the effective model of coupled lossy oscillators can be employed to understand its mechanism. The manually tunable ventilated metamaterial has potential application values in various complicated pipe systems that require frequency adjustment and it also establishes the foundation for future development of active tunable ventilated acoustic metamaterials.
A novel method to identify and correct asymmetry of dumbbells in a multi-cell elliptical superconducting cavity
Authors: Mohania Praveen , Puntambekar Avinash , Mahawar Ashish , Singh Adarsh Pratap , Rajput Vikas , Namdeo Raj Kumar , Shrivastava Purushottam , Yadav Anand , Moulali Syed , Maurya Tilak , Bagre Manish , V. Vijayakumar , Srivastava V. K.
Published: February 2021

Raja Ramanna Centre for Advanced Technology (RRCAT) has an ongoing program to develop 650 MHz, 5-cell elliptical superconducting RF (SCRF) cavities under the Indian Institutes and Fermilab Collaboration. The elliptical multi-cell SCRF cavity fabrication process involves forming of half-cells and their precise machining and joining by electron beam welding to form end groups and dumbbells, which are then joined to make the final cavity. To ensure that the final welded cavity achieves physical lengths and resonant frequencies within design tolerance and has good field flatness, the measurement and correction of resonant frequency are carried out for dumbbells and end groups. A novel method to identify the frequency of individual half-cells in a dumbbell cavity and a dedicated tuning fixture to correct them had been developed. The paper details the RF characterization and correction procedure employed during fabrication of the first six 650 MHz cavities at RRCAT.
Probing thermal conductivity of subsurface, amorphous layers in irradiated diamond
Authors: Scott Ethan A. , Braun Jeffrey L. , Hattar Khalid , Sugar Joshua D. , Gaskins John T. , Goorsky Mark , King Sean W. , Hopkins Patrick E.
Published: February 2021

In this study, we report on the thermal conductivity of amorphous carbon generated in diamond via nitrogen ion implantation (N3+ at 16.5 MeV). Transmission electron microscopy techniques demonstrate amorphous band formation about the longitudinal projected range, localized approximately 7 μm beneath the sample surface. While high-frequency time-domain thermoreflectance measurements provide insight into the thermal properties of the near-surface preceding the longitudinal projected range depth, a complimentary technique, steady-state thermoreflectance, is used to probe the thermal conductivity at depths which could not otherwise be resolved. Through measurements with a series of focusing objective lenses for the laser spot size, we find the thermal conductivity of the amorphous region to be approximately 1.4 W m−1 K−1, which is comparable to that measured for amorphous carbon films fabricated through other techniques.
Enhancement of spin–orbit torque in WTe2/perpendicular magnetic anisotropy heterostructures
Authors: Lv Wenxing , Xue Hongwei , Cai Jialin , Chen Qian , Zhang Baoshun , Zhang Zongzhi , Zeng Zhongming
Published: February 2021

Spin–orbit torque (SOT), exerted to a ferromagnet from an adjacent non-magnetic layer, has been widely considered as a promising strategy to realize spintronic devices with high energy efficiency, endurance, and speed. Much effort has been devoted to the search for materials and structures that can generate strong SOTs. Recent investigations showed that two-dimensional (2D) transition metal dichalcogenides provide the potential to produce strong enough SOTs to manipulate the magnetic devices due to rich spin-dependent properties. Here, we present the study of SOT in WTe2/ferromagnet with perpendicular magnetic anisotropy devices, and an enhancement of SOT efficiency with the thickness of WTe2 is observed, which may be ascribed to the spin absorption at the WTe2/Ta interface and the spin Hall effect. This work demonstrates the possibility of manipulating magnetization by 2D materials and an avenue for engineering spintronic devices based on 2D materials.
Effect of defect interactions with interstitial Ag in the lattice of BixSb2−xTe3 alloys and their thermoelectric properties
Authors: Lee Jae Ki , Park Sungjin , Ryu Byungki , Lee Ho Seong , Park Jongho , Park SuDong
Published: February 2021

In this study, the effect of Ag defects on the lattice and thermoelectric properties of Ag-doped BixSb2−xTe3 (BST) alloys are systematically investigated. Using density-functional calculations, we reveal that Ag impurity defects occupying interstitial sites in the BST affect the formation of intrinsic defects in the host materials. Ag interstitial defects, which are responsible for increasing the lattice parameter of the c axis, lower the formation energies of BiTe and SbTe acceptor defects more effectively in the Bi-rich BST than in the Bi-poor BST. In addition, these Ag interstitials induce the formation of AgBi and AgSb in BixSb2−xTe3. Therefore, Ag-induced defect interactions can be used to finely optimize the defects and doping density by varying the Bi content. Furthermore, the phonon thermal conductivity is reduced with the formation of nanoscale twin structures with various stacking faults. Finally, a high figure of merit of 1.4 at 423 K is achieved for p-type BST alloys.
Core-shell Fe3O4@ZnO nanoparticles for magnetic hyperthermia and bio-imaging applications
Authors: Gupta Jagriti , Hassan P. A. , Barick K. C.
Published: February 2021

Combining two materials having different functional properties has become a current research area for biomedical applications. The progress of nanoplatforms brings new non-invasive imaging and therapeutic tools for cancer treatment. Here, multifunctional magnetic Fe3O4@ZnO core-shell nanoparticles (Fe3O4@ZnO CSNPs) have been developed by using a soft-chemical approach. Fe3O4@ZnO CSNPs is well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), physical properties measurement system (PPMS), and photoluminescence spectroscopy. XRD and XPS analyses confirm the presence of both Fe3O4 and ZnO phases. TEM micrograph reveals that Fe3O4@ZnO CSNPs are spherical in shape and an average size of 10 nm. Fe3O4@ZnO CSNPs conserve the intrinsic superparamagnetic behavior of its constituent Fe3O4 with a magnetization value of ∼ 31.2 emu/g. These CSNPs exhibit good heating efficacy under the applied AC magnetic field (ACMF). Further, they show a significant reduction in viability of human cervical cancer cells (HeLa) under ACMF and good fluoresecent based cellular imaging capability. Therefore, these results suggested that the multifunctional Fe3O4@ZnO CSNPs could be used as a promising material for image-guided magnetic hyperthermia.
Redox regulation of NADP-malate dehydrogenase is vital for land plants under fluctuating light environment
Authors: Yokochi Yuichi , Yoshida Keisuke , Hahn Florian , Miyagi Atsuko , Wakabayashi Ken-ichi , Kawai-Yamada Maki , Weber Andreas P. M. , Hisabori Toru
Published: February 2021

Significance

Plant chloroplasts have acquired an evolutionary “redox switch” that regulates the activities of photosynthesis-related enzymes in response to a dynamically changing environment. Because the metabolic state in chloroplasts drastically fluctuates in response to changes in the surrounding environment, it has been considered essential to adjust the activities of chloroplast enzymes. Many efforts have been made to elucidate this regulation in detail. Its physiological role is thought to be due to the fact that fine-tuning of the activity is essential for efficient photosynthesis, but it is still unclear how this is really the case. We have shown that the redox switch of NADP-malate dehydrogenase plays a crucial role in the optimal growth of plants under fluctuating light conditions and prolonged darkness.
Absence of retbindin blocks glycolytic flux, disrupts metabolic homeostasis, and leads to photoreceptor degeneration
Authors: Sinha Tirthankar , Du Jianhai , Makia Mustafa S. , Hurley James B. , Naash Muna I. , Al-Ubaidi Muayyad R.
Published: February 2021

Significance

The retina has one of the highest energy requirements, and it harbors the highest flavins’ content, essential factors for energy metabolism. It is unclear how the retina manages to preserve the high level of flavins, a topic for investigation. We recently reported a retinal riboflavin-binding protein, called retbindin. Here we report that absence of retbindin results in a significant reduction in retinal flavins, causing toxic metabolite buildup and triggering the retina to lend support to the impaired free-radical scavenging system by repurposing glucose. These have a domino effect, leading to reduced ATP synthesis and metabolic breakdown and results in retinal degeneration. This research emphasizes the role of metabolic changes as a primary cause behind retinal degeneration.
In vivo NIR-II structured-illumination light-sheet microscopy
Authors: Wang Feifei , Ma Zhuoran , Zhong Yeteng , Salazar Felix , Xu Chun , Ren Fuqiang , Qu Liangqiong , Wu Anna M. , Dai Hongjie
Published: February 2021

Significance

Three-dimensional microscopy in the NIR-II window (1,000 to 1,700 nm) allows noninvasive deep-tissue optical sectioning of live mammals with high spatiotemporal resolution due to suppressed light scattering and reduced tissue autofluorescence. Herein, we present a NIR-II structured-illumination light-sheet microscopy (NIR-II SIM) with both excitation and emission wavelengths in the NIR-IIb window (1,500 to 1,700 nm). Integrating structured illumination into NIR-II light-sheet microscopy further diminished out-of-focus background and improved spatial resolution, facilitating in vivo imaging of cell behavior in the intact tissues without any invasive surgery during a long period. NIR-II SIM enabled longitudinally multiplexed molecular imaging of immune cells in response to immunotherapy in the tumor microenvironment.
Ionization rate and Stark shift of a one-dimensional model of the hydrogen molecular ion
Authors: Henriques J C G , Pedersen Thomas G , Peres N M R
Published: February 2021

In this paper we study the ionization rate and the Stark shift of a one-dimensional model of the

H

2

+

ion. The finding of these two quantities is reduced to the solution of a complex eigenvalue problem. We solve this problem both numerically and analytically. In the latter case we consider the regime of small external electrostatic fields and small internuclear distances. We find an excellent agreement between the ionization rate computed with the two approaches, even when the approximate result is pushed beyond its expected validity. The ionization rate is very sensitive to small changes of the external electrostatic field, spanning many orders of magnitude for small changes of the intensity of the external field. The dependence of the ionization on the internuclear distance is also studied, as this has a direct connection with experimental methods in molecular physics. It is shown that for large distances the ionization rate saturates, which is a direct consequence of the behavior of the energy eigenvalue with the internuclear distance. The Stark shift is computed and from it we extract the static polarizability of

H

2

+

and compare our results with those found by other authors using more sophisticated methods. This work provides an extension of what is usually covered in a course of quantum mechanics where the double delta-potential is studied, while also establishing the connection to a concrete physics problem.
Volume fraction determination of microgel composed of interpenetrating polymer networks of PNIPAM and polyacrylic acid
Authors: Franco S , Buratti E , Ruzicka B , Nigro V , Zoratto N , Matricardi P , Zaccarelli E , Angelini R
Published: February 2021

Interpenetrated polymer network microgels, composed of crosslinked networks of poly(N-isopropylacrylamide) and polyacrylic acid (PAAc), have been investigated through rheological measurements at four different amounts of PAAc. Both PAAc content and crosslinking degree modify particle dimensions, mass and softness, thereby strongly affecting the volume fraction and the system viscosity. Here the volume fraction is derived from the flow curves at low concentrations by fitting the zero-shear viscosity with the Einstein–Batchelor equation which provides a parameter k to shift weight concentration to volume fraction. We find that particles with higher PAAc content and crosslinker are characterized by a greater value of k and therefore by larger volume fractions when compared to softer particles. The packing fractions obtained from rheological measurements are compared with those from static light scattering for two PAAc contents revealing a good agreement. Moreover, the behaviour of the viscosity as a function of packing fraction, at room temperature, has highlighted an Arrhenius dependence for microgels synthesized with low PAAc content and a Vogel–Fulcher–Tammann dependence for the highest investigated PAAc concentration. A comparison with the hard spheres behaviour indicates a steepest increase of the viscosity with decreasing particles softness. Finally, the volume fraction dependence of the viscosity at a fixed PAAc and at two different temperatures, below and above the volume phase transition, shows a quantitative agreement with the structural relaxation time measured through dynamic light scattering indicating that interpenetrated polymer network microgels softness can be tuned with PAAc and temperature and that, depending on particle softness, two different routes are followed.
Resolution-dependent subsonic non-thermal line dispersion revealed by ALMA
Authors: Yue Nan-Nan , Li Di , Zhang Qi-Zhou , Zhu Lei , Henshaw Jonathan , Mardones Diego , Ren Zhi-Yuan
Published: February 2021

We report here Atacama Large Millimeter/submillimeter Array (ALMA) N2H+ (1–0) images of the Orion Molecular Cloud 2 and 3 (OMC-2/3) with high angular resolution (3″ or 1200 au) and high spatial dynamic range. Combining a dataset from the ALMA main array, Atacama Compact Array (ACA), Nobeyama 45-m Telescope and Very Large Array (VLA) (providing temperature measurement on matching scales), we find that most of the dense gas in OMC-2/3 is subsonic (σ
NT / C
s = 0.62) with a mean line width (Δυ) of 0.39 km s−1 full width at half maximum (FWHM). This is markedly different from the majority of previous observations of massive star-forming regions. In contrast, line widths from the Nobeyama Telescope are transonic at 0.69 km s−1 (σ
NT / C
s = 1.08). We demonstrated that the larger line widths obtained by the single-dish telescope arose from unresolved sub-structures within their respective beams. The dispersions from larger scales σls
(as traced by the Nobeyama Telescope) can be decomposed into three components such that

σ

ls

2

=

σ

ss

2

+

σ

bm

2

+

σ

rd

2

, where small-scale σ
ss is the line dispersion of each ALMA beam, bulk motion σ
bm is dispersion between peak velocity of each ALMA beam and σ
rd is the residual dispersion. Such decomposition, though purely empirical, appears to be robust throughout our data cubes. Apparent supersonic line widths, commonly found in massive molecular clouds, are thus likely due to the effect of poor spatial resolution. The observed non-thermal line dispersion (sometimes referred to as ‘turbulence’) transits from supersonic to subsonic at ∼ 0.05 pc scales in the OMC-2/3 region. Such transition could be commonly found with sufficient spatial (not just angular) resolution, even in regions with massive young clusters, such as the Orion molecular clouds studied here.
A testability allocation method suitable for engineering application
Authors: Gong Jie , Yang Min-jing
Published: February 2021

Firstly introduces the commonly used distribution methods of testability in engineering, and points out that the existing distribution methods have poor operability and inconvenience.A new method of assigning testability index according to failure rate is proposed. This method uses the undetectable rate and the unisolated rate to distribute the primary testability index. Then according to the data obtained in the designer’s design, the secondary distribution is carried out in combination with the reliability index and data. This method not only improves the implementability of testability allocation, but also harmonizes the relationship between testability allocation and reliability allocation. Finally, an airborne wireless communication unit is taken as an example to verify the feasibility and effectiveness of this method.
Stability analysis and control for composite tape winding process
Authors: He Xiao-dong , Li Hua-lian , Yang shi-xin , Li Hai-qing
Published: February 2021

In the composite winding process of thermal protection materials, the thickness errors of prepreg tape will result in an unstable winding process. In order to alleviate this problem, a control system is required. Therefore, a winding control system had been designed to control the stability by eliminate the winding error based on the analysis of stability winding process. The control system consists a speed controlled rotational roller. The thickness errors of the tape can be detected, and the rotational roller can be controlled to eliminate the errors and maintain the stability of winding process. Experimental results illustrate that the winding speed is converged in 30 second with a 30% initial thickness error, and winding control system could maintain the stability of winding process.
Failure Analysis of Asphalt Foaming Device Based on FEMA and FTA
Authors: Luo Zhun , Cheng Hai-Ying
Published: February 2021

The FMEA method is a bottom-up method, and the FTA method is a top-down method. This paper proposes to combine the two methods, using the complementarity of the FMEA method and the FTA method, and targeting the innovative product- The six subsystems of the bubble device perform fault analysis, grasp the key parts of the fault, and propose corresponding solutions based on a comprehensive analysis of the fault. The analysis results show that the failures of the asphalt foaming device mainly occur before and during the asphalt foaming. The FMEA table reflects that the RPN value of the two failure factors of the blockage of the asphalt pipeline and the blockage of the water nozzle is the largest. The three failure factors with the highest severity level (SER) are heater damage, motor damage and PLC control device failure.
Research on Performance Optimization Technology of Complex Equipment Software Database
Authors: Liu Bo-Jiang , Wu Li-Jin , He Wei , Han Xin-Yu , Tang Long-Li
Published: February 2021

Complex equipment software usually uses a database to store data. In order to enable it to run stably and efficiently during use, it is necessary to ensure the performance of database access. How to design and manage the database reasonably and optimize the database query has attracted much attention. This article studies the database access performance problems of MySQL equipment used by complex equipment software, studies database optimization techniques, and provides a database optimization solution for the database access delay problems that occur during project operation. Reduced waste of resources, thereby improving the efficiency of system database access, and solving the problem of system access to the database delay.
Research on the Requirement Analysis and Management Method of Aircraft PHM System
Authors: Chen C , Ma X L
Published: February 2021

Recent years, the forward design based on requirements has become the mainstream mode of aircraft and its component systems development. Requirements analysis and management not only runs through the whole process of system development and validation activities, but also plays an important role in these activities. However, there are some practical problems in the requirement analysis and management of prognostics and health management (PHM) system of aircraft, such as lack of method and process guidance, incomplete stakeholder analysis, and nonstandard requirement description. Therefore, based on the theory of system engineering, this paper puts forward the basic methods and suggestions of PHM system stakeholder analysis, formulates the technical process and key points of PHM system requirement analysis in demonstration and scheme stage, and clarifies the basic principles of PHM system requirement specification. And the related research of this paper aims to improve the quality and efficiency of requirement analysis and management of aircraft PHM system, and to lay the foundation for the development of system architecture and function as well.
Product life cycle-based digital plant modelling method for process industry
Authors: Gong Zhong-Xia , Zhang Wen-Xin , Li Tie-Ke , Wang Bai-Lin
Published: February 2021

Digital factory is a core technology of intelligent manufacturing, which provides a powerful guarantee for production quality, reliability and stability. For building a digital factory of complex process industry, this paper presents a product life cycle-based data modelling method that is oriented towards the product life cycle and core business in process industry. Firstly, it identifies key manufacturing nodes and management nodes, extracts core characteristics and parameters of production, products, and equipment, and then digitizes physical entities in the plant. A data model including conceptual models and logical models is then built, thereby formalizing the entities in the plant and the relationships among them to achieve unified data integration management. This digital plant model defines equipment data, product data, quality data, product specifications, process specifications, management rules and so on to meet the requirements of both production management and production control. It builds a highly structured data model that horizontally covers multiple production lines and vertically supports multiple levels of production control and management systems, providing core technology for digital plant in complex process industry.
Dynamic Safety Assessment of Aircraft Mechanism using Extremum Framework with Fault Tree Analysis
Authors: Chen J Y , Feng Y W , Guo Y N , Lu C
Published: February 2021

In this paper, a hybrid two-level inventory allocation method based on multi-echelon technique for recoverable item control (METRIC) was applied to the spare parts allocation of amphibious aircraft. Firstly, the principle of the spare parts inventory configuration model of amphibious aircraft based on hybrid two-level repair was expounded. The mathematical model was established with maintenance cost as objective function and availability and volume of spare parts as constraints. Secondly, marginal analysis was used to help allocate spare parts, the process of solving the mathematical model was discussed, and the calculation formulas of the quantities involved were briefly stated. Finally, with the line replaceable units of landing gear as the research object, the spare parts inventory allocation of a amphibious aircraft was solved according to the method proposed in this paper. This paper provides an approach to allocate spare parts of amphibious aircraft.
Feasibility Study of Pinhole Inspection via Magnetic Flux Leakage and Hydrostatic Testing in Oil & Gas Pipelines
Authors: Zhang Hailiang , Sha Shengyi , Willis Chris , Qingshan Feng , Chen Pengchao
Published: February 2021

Oil & Gas pipeline pinhole leaks are more likely to lead to serious consequences than larger leaks because they are difficult to discover through conventional monitoring and patrolling. An undetected pinhole leak can lead to significant soil and groundwater pollution over time. The effectiveness and applicability of magnetic flux leakage (MFL) in characterizing and sizing pinhole defects is studied by pull test in a 10-inch pipe string with manufactured defects. MFL technologies from five vendors were tested in blind scenarios. In addition, the feasibility of using hydrostatic testing to detect pinhole defects is investigated. The results show that the MFL signal may be affected by pinhole diameter, depth, position, and so on. An optimal practice was developed by comparing the gap between MFL tracks, sampling frequency, intensity of magnetic field, etc. And there was no significant reduction in pressure capacity within the test pipe segment with pinhole. So it is speculated that hydrostatic testing can only identify pinholes that have fully penetrated the pipe wall.
Bearing fault diagnosis method based on CNN-LightGBM
Authors: Jia Xin , Xiao Boping , Zhao Zhanjuan , Ma Lin , Wang Naichao
Published: February 2021

In recent years, deep neural networks have been widely used in bearing fault diagnosis. Aiming at the problem that the traditional convolutional neural network (CNN) has insufficient generalization ability and low accuracy in rolling bearing fault diagnosis, this paper presents a new fault diagnosis model based on CNN and light gradient boosting machine (LightGBM). By using the original vibration signal directly, the new model firstly uses the deep convolutional neural network with small kernel to extract features and introduces the batch normalization and the Adam algorithm to improve the rolling bearing fault diagnosis model convergence speed and generalization ability. Then, combined with the efficient and accurate characters of LightGBM in classification prediction, the extracted features are imported into LightGBM for training to complete bearing fault diagnosis of different fault types. This new model can realize the fault diagnosis of rolling bearing directly from end to end without extracting the fault feature of rolling bearing vibration signal by hand. The results of the comparative experiments on the Case Western Reserve University (CWRU) public bearing dataset show that the new model improves the accuracy compared to just using CNN. The experimental results also confirm that the proposed method has feature learning ability and has good ability for fault diagnosis.
Friction energy map for sliding wear of Al2O3-TiO2 and Cr2O3-TiO2 coatings
Authors: Mehar Sanket , Sapate S G , Vashishtha Nitesh , Bagde Pranay , Rathod Avishkar
Published: February 2021

The present study deals with the development of friction energy map for plasma sprayed Al2O3-TiO2 and Cr2O3-TiO2 coatings. Al2O3-TiO2 and Cr2O3-TiO2 coatings were deposited by atmospheric plasma spray technique. The structural and mechanical properties of coatings were studied using Scanning Electron Microscopy (SEM), x-ray Diffraction (XRD) and Vickers macro and micro hardness test. Sliding wear tests were performed on coated specimens over a range of sliding speed and load using pin on disc test apparatus. The analysis of worn surface and wear debris was carried by SEM, XRD and Raman Spectroscopy. Cr2O3-TiO2 coating showed higher hardness and elastic modulus and relatively lower fracture toughness than Al2O3-TiO2 coating. Al2O3-TiO2 coatings exhibited 1.8 times better wear resistance and 11%–30% lower friction coefficient, as compared to Cr2O3-TiO2 coating, depending upon the wear test conditions. The reduction in friction coefficient and wear rate at higher sliding speed was due to the formation of tribofilms on worn surface. A good correlation was observed between friction energy and contact severity; which incorporates mechanical properties of coatings. Friction energy map was used to rationalize wear rates of Al2O3-TiO2 and Cr2O3-TiO2 coatings, for the identification of various wear regimes and failure modes of the coating.
Alternative pulmonary artery reconstruction technique in the arterial switch operation
Authors: Hongu Hisayuki , Yamagishi Masaaki , Maeda Yoshinobu , Itatani Keiichi , Shimada Masatoshi , Nakatsuji Hiroki , Hohri Yu , Nabeshima Jyunya , Yaku Hitoshi
Published: February 2021

OBJECTIVES

Late complications of arterial switch operations (ASO) for transposition of the great arteries, such as neo-pulmonary artery (PA) stenosis and/or neoaortic regurgitation, have been reported. We developed an alternative reconstruction method called the longitudinal extension (LE) method to prevent PA bifurcation stenosis (PABS).

METHODS

We identified 48 patients diagnosed with transposition of the great arteries and performed ASO using the Lecompte manoeuvre for neo-PA reconstruction. In 9 consecutive patients (from 2014), the LE method was performed (LE). Before 2014, conventional techniques were performed in 39 patients (C). The median body weight and age in the LE and C groups were 3.0 and 3.1 kg and 12 and 26 days, respectively. In the LE group, 1 patient underwent bilateral PA banding before ASO. In C, PA banding and arch repair were performed in 1 patient each. Patients who received concomitant procedures were included.

RESULTS

The median follow-up in LE and C groups was 1.9 and 10.1 years, respectively. Early mortality/late death was not found in group LE and in 1 patient in group C. Only 1 case required ascending aorta sliding plasty in LE, and 8 patients needed PA augmentation for PABS in C. The median velocity of right/left PA was measured as 1.6/1.9 m/s in LE and 2.1/2.3 m/s in C, so it showed a lower value in LE.

CONCLUSIONS

Excellent mid-term results were obtained with the LE method. It was considered a useful procedure in preventing PABS, which is a primary late complication of ASO. Further follow-up and investigations are needed.
Diffraction of elastic waves by a fluid-filled crack in a fluid-saturated poroelastic half-space
Authors: Liu Zhongxian , Liu Jiaqiao , Meng Sibo , Sun Xiaojian
Published: February 2021

An indirect boundary element method (IBEM) is developed to model the 2-D diffraction of seismic waves by a fluid-filled crack in a fluid-saturated poroelastic half-space, using Green's functions computed considering the distributed loads, flow and fluid characteristics. The influence of the fluid-filled crack on the diffraction characteristics is investigated by analysing key parameters, such as the excitation frequency, incident angle, crack width and depth, and medium porosity. The results for the fluid-filled crack model are compared to those for the fluid-free crack model under the same conditions. The numerical results demonstrate that the fluid-filled crack has a significant amplification effect on the surface displacements, and that the effect of the depth of the fluid-filled crack is more complex compared to the influence of other parameters. The resonance diffraction generates an amplification effect in the case of normally incident P waves. Furthermore, the horizontal and vertical displacement amplitudes reach 4.2 and 14.1, respectively. In the corresponding case of the fluid-free crack, the vertical displacement amplitude is only equal to 4.1, indicating the amplification effect of the fluid in the crack. Conversely, for normally incident SV waves at certain resonance frequencies, the displacement amplitudes above a fluid-filled crack may be lower than the displacement amplitudes observed in the corresponding case of a fluid-free crack.
On Radon Measures Invariant Under Horospherical Flows on Geometrically Infinite Quotients
Authors: Landesberg Or , Lindenstrauss Elon
Published: February 2021

We consider a locally finite (Radon) measure on $ {\operatorname{SO}}^+(d,1)/ \Gamma $ invariant under a horospherical subgroup of $ {\operatorname{SO}}^+(d,1) $ where $ \Gamma $ is a discrete, but not necessarily geometrically finite, subgroup. We show that whenever the measure does not observe any additional invariance properties then it must be supported on a set of points with geometrically degenerate trajectories under the corresponding contracting $ 1 $-parameter diagonalizable flow (geodesic flow).
Introduction
Authors: Veljanovski Cento
Published: February 2021

This introductory chapter provides an overview of cartel damages. The Damages Directive 2014/104/EU Article 2(14) defines a cartel as ‘an agreement or concerted practice between two or more competitors aimed at coordinating their competitive behaviour on the market or influencing the relevant parameters of competition’. Not only do cartels harm their customers and suppliers, they restrict and distort competition as well as markets, and retard economic growth, productivity, and product innovation. As such, a cartel is illegal under Article 101 TFEU and in the UK is a Chapter I Prohibition under the Competition Act 1998. Indeed, competition authorities around the world are cracking down on cartels. In the last two decades, the European Commission has focused on cartels, imposing heavy fines and encouraging those who have been harmed to sue for damages. The UK, Ireland, Australia, and other countries have followed the US by making price-fixing a criminal offence and have jailed and disqualified directors. This chapter then considers the implications of Brexit for competition law and private damages actions.
Statistical Evidence
Authors: Veljanovski Cento
Published: February 2021

This chapter discusses the econometric approach, and its forensic use and misuse. Econometrics is a set of statistical techniques which estimate the overall and individual effects of variables that affects a variable of interest whether it be prices, output, and so on. The major attraction of multiple regression analysis is its ability to simultaneously account for, estimate, and quantify the myriad factors which influence prices or output. Specifically, in the context of cartel damage, it holds out the possibility of estimating the ‘but for’ price adjusted for the non-cartel factors which affect prices in a systematic and credible way. There are three general multiple regression approaches to estimating overcharges: dummy variable (DVA), predictive, and difference-in-differences. Other statistical techniques can be useful in damages cases such as time series analysis and event studies.