bluuebunny/crossref_metadata_2025 huggingface dataset:
Distance-dependent resonance energy transfer in alkyl-terminated Si nanocrystal solids
Authors: Li Zhaohan , Robinson Zachary L. , Elvati Paolo , Violi Angela , Kortshagen Uwe R.
Published: March 2022

Understanding and controlling the energy transfer between silicon nanocrystals is of significant importance for the design of efficient optoelectronic devices. However, previous studies on silicon nanocrystal energy transfer were limited because of the strict requirements to precisely control the inter-dot distance and to perform all measurements in air-free environments to preclude the effect of ambient oxygen. Here, we systematically investigate the distance-dependent resonance energy transfer in alkyl-terminated silicon nanocrystals for the first time. Silicon nanocrystal solids with inter-dot distances varying from 3 to 5 nm are fabricated by varying the length and surface coverage of alkyl ligands in solution-phase and gas-phase functionalized silicon nanocrystals. The inter-dot energy transfer rates are extracted from steady-state and time-resolved photoluminescence measurements, enabling a direct comparison to theoretical predictions. Our results reveal that the distance-dependent energy transfer rates in Si NCs decay faster than predicted by the Förster mechanism, suggesting higher-order multipole interactions.
N-doped Fe nanoparticles confined in carbon matrix for high-performance oxygen evolution reaction
Authors: Yang Yong , Shi Ping , Hou Yinhui , Chen Mingyue , Zhou Wenda , Jiang Zhenzhen , Zhou Hang , Luo Xingfang , Yu Ting , Yuan Cailei
Published: March 2022

Fe-based nanoparticles are promising oxygen evolution reaction (OER) electrocatalysts. However, they often suffer from serious agglomeration during the electrocatalytic process, which leads to significant attenuation of catalytic performance. Herein, highly dispersed Fe nanoparticles with small sizes of ∼7 nm are confined in amorphous carbon matrix by pulsed laser deposition technology. Based on this, a simple N2 radio frequency plasma strategy is proposed to introduce N doping in the Fe nanoparticles. Electrochemical measurements suggest that N-doped Fe nanoparticles exhibit enhanced OER activity and stability, which offers a low overpotential of 246 mV at 10 mA cm−2 and the Tafel slope of 50 mV dec−1 in 1 M KOH solution. Based on experimental measurements combined with first-principles calculations, the outstanding OER performance of N-doped Fe nanoparticles can be attributed to the synergistic effect of the unique confined structure and N doping, which not only enhances the electrochemical surface area and improves electrical conductivity but also weakens the adsorption of intermediates and reduces the energy barrier of OER reaction. This work provides a facile method for the construction of metal nanoparticles with confined nanostructure and controlled N doping, which will greatly promote the development of OER electrocatalysts.
Symmetry evolution and modulation of multiferroic characteristics in Bi1−xLaxFeO3 ceramics
Authors: Liu Lu , Zhu Xiao Li , Gareeva Z. V. , Zvezdin A. K. , Eiras Jose Antonio , Chen Xiang Ming
Published: March 2022

The substitution of rare-earth ions has been recognized as an effective way to modify the multiferroic properties, especially to realize the electric field-controlled magnetism in BiFeO3 ceramics, in which the symmetry modulation of R3c/Pna21 and the unlocked ferromagnetism through breaking the cycloidal spin structure are the key issues. Here, the enhancement of ferroelectric polarization and weak ferromagnetism are investigated in Bi1−xLaxFeO3 ceramics together with the magnetoelectric coupling coefficient αME with the development of the Pna21 phase. The expected electric field-controlled magnetism is achieved at the phase boundary through the electric field-induced transition of Pna21/R3c, where the variation of magnetization reaches 34.18 emu/mol (58.95%) at x = 0.18 after poling.
Ab initio metadynamics determination of temperature-dependent free-energy landscape in ultrasmall silver clusters
Authors: Sucerquia Daniel , Parra Cristian , Cossio Pilar , Lopez-Acevedo Olga
Published: March 2022

Ab initio metadynamics enables the extraction of free-energy landscapes having the accuracy of first-principles electronic structure methods. We introduce an interface between the PLUMED code that computes free-energy landscapes and enhanced-sampling algorithms and the Atomic Simulation Environment (ASE) module, which includes several ab initio electronic structure codes. The interface is validated with a Lennard-Jones cluster free-energy landscape calculation by averaging multiple short metadynamics trajectories. We use this interface and analysis to estimate the free-energy landscape of Ag5 and Ag6 clusters at 10, 100, and 300 K with the radius of gyration and coordination number as collective variables, finding at most tens of meV in error. Relative free-energy differences between the planar and non-planar isomers of both clusters decrease with temperature in agreement with previously proposed stabilization of non-planar isomers. Interestingly, we find that Ag6 is the smallest silver cluster where entropic effects at room temperature boost the non-planar isomer probability to a competing state. The new ASE-PLUMED interface enables simulating nanosystem electronic properties under more realistic temperature-dependent conditions.
Infrared photodetector based on 2D monoclinic gold phosphide nanosheets yielded from one-step chemical vapor transport deposition
Authors: Zhang Yushuang , Chen Jie , Chen Cheng , Xu Tengfei , Gao Heng , Dong Zhuo , Zhang Yan , Li Chang , Yu Qiang , Yu Wenzhi , Miao Jinshui , Wang Peng , Ren Wei , Pan Anlian , Zhang Kai
Published: March 2022

Infrared detection by binary phosphides is of great interest due to their high carrier mobility, excellent stability, and high absorbance coefficient, as they have a wide range of applications in civil and military fields. As the only metastable phase in gold phosphide, Au2P3 has attracted great attention in fundamental research and optoelectronic applications. Here, we synthesized high-quality and environmentally stable Au2P3 nanosheets through a modified facile one-step mineralization-assisted chemical vapor transport method. Through systematic infrared photoluminescence characterizations, it is found that the as-synthesized Au2P3 nanosheets display an impressive mid-infrared luminescence band centered at about 6.64 μm (0.187 eV) at room temperature. Furthermore, Au2P3-based self-powered photodetectors display outstanding infrared detection performance with D* = 2.9 × 1010 Jones at 1550 nm and D* = 1.9 × 108 Jones at 2611 nm, respectively. Our results suggest that the synthesized Au2P3 nanosheets could be promising candidates for future chip-based infrared nanophotonic and optoelectronic circuitry.
High crystalline hydroxyapatite coating by eclipse type pulsed-laser deposition for low annealing temperature
Authors: Yashiro Hidehiko , Kakehata Masayuki
Published: March 2022

The eclipse type pulsed-laser deposition (PLD) scheme as a droplet-eliminated method with irradiation on a β-tricalcium phosphate (β-TCP) slab target was employed to achieve high density without holes, high purity, and high crystallinity hydroxyapatite (HAp) coating on a zirconia substrate with a low annealing temperature under an H2O vapor pressure. An obstacle ball was set between the target and the substrate so that ablated droplets would collide with the ball and be eliminated, while other ablated atoms went around the ball and were deposited on the substrate. A flat, transparent, and high-density coating layer was deposited on the substrate in an H2O vapor atmosphere at 0.1 Torr for different substrate surface temperatures from 20 °C to 650 °C. The phase of the coating layers was significantly changed from amorphous calcium phosphate to crystalline HAp when the temperature was set to over 360 °C, as determined from Raman microscopy measurements. Raman spectroscopy also showed that the HAp crystal size became larger as the temperature was increased to over 360 °C. It was concluded that the eclipse type PLD method with irradiation on a β-TCP target would improve the quality of HAp coatings and allow effective lowering of the annealing temperature.
Pseudoheterodyne near-field imaging at kHz repetition rates via quadrature-assisted discrete demodulation
Authors: Palato Samuel , Schwendke Philipp , Grosse Nicolai B. , Stähler Julia
Published: March 2022

Scattering-type scanning near-field optical microscopy enables the measurement of optical constants of a surface beyond the diffraction limit. Its compatibility with pulsed sources is hampered by the requirement of a high-repetition rate imposed by lock-in detection. We describe a sampling method, called quadrature-assisted discrete (quad) demodulation, which circumvents this constraint. Quad demodulation operates by measuring the optical signal and the modulation phases for each individual light pulse. This method retrieves the near-field signal in the pseudoheterodyne mode, as proven by retraction curves and near-field images. Measurement of the near-field using a pulsed femtosecond amplifier and quad demodulation is in agreement with results obtained using a CW laser and the standard lock-in detection method.
Unified one-electron Hamiltonian formalism of spin–orbit Jahn–Teller and pseudo-Jahn–Teller problems in tetrahedral and octahedral symmetries
Authors: Pradhan Ekadashi , Yao Guoying , Yang Zhenyu , Zeng Tao
Published: March 2022

Heavy element compounds with high symmetries often feature both spin–orbit coupling and vibronic coupling. This is especially true for systems with tetrahedral and octahedral symmetries, whose electronic states may be threefold degenerate and experience complicated Jahn–Teller and pseudo-Jahn–Teller interactions. To accurately describe these interactions, high quality spin–orbit vibronic Hamiltonian operators are needed. In this study, we present a unified one-electron Hamiltonian formalism for spin–orbit vibronic interactions for systems in all tetrahedral and octahedral symmetries. The formalism covers all spin–orbit Jahn–Teller and pseudo-Jahn–Teller problems in the symmetries with arbitrary types and arbitrary numbers of vibrational modes and generates Hamiltonian expansion formulas of arbitrarily high order.
Non-Hermitian cavity quantum electrodynamics–configuration interaction singles approach for polaritonic structure with ab initio molecular Hamiltonians
Authors: McTague Jonathan , Foley Jonathan J.
Published: March 2022

We combine ab initio molecular electronic Hamiltonians with a cavity quantum electrodynamics model for dissipative photonic modes and apply mean-field theories to the ground- and excited-states of resulting polaritonic systems. In particular, we develop a non-Hermitian configuration interaction singles theory for mean-field ground- and excited-states of the molecular system strongly interacting with a photonic mode and apply these methods to elucidating the phenomenology of paradigmatic polaritonic systems. We leverage the Psi4Numpy framework to yield open-source and accessible reference implementations of these methods.
Polygenic sex determination produces modular sex polymorphism in an African cichlid fish
Authors: Moore Emily C. , Ciccotto Patrick J. , Peterson Erin N. , Lamm Melissa S. , Albertson R. Craig , Roberts Reade B.
Published: March 2022

Significance

Sex differences in traits can occur when those traits are modified by genetic factors inherited on sex chromosomes. We investigated how sex differences emerge in a species with more than one set of sex chromosomes, measuring a variety of morphological, physiological, and behavioral traits. Rather than exhibiting sexual dimorphism associated with primary sex, the species has higher-order sexual polymorphism in secondary sexual characteristics or more than two phenotypic sexes. Variation in secondary sexual characteristics is modular, involving the interplay of sex-linked and sex-limited traits. Our findings provide implications for how sex determination systems and whole-organism fitness traits coevolve, including that significant creation or loss of variation in diverse traits can occur during transitions among sex chromosome systems.
The Multimodal Performance of Conversational Humor
Authors: Gironzetti Elisa
Published: March 2022

This volume is the first monograph exploring the functions of visual cues in humor, advocating for the development of a non-linguocentric theory of humor performance. It analyzes a corpus of dyadic, face-to-face interactions in Spanish and English to study the relationship between humor, smiling, and gaze, and shows how, by focusing on these elements, it is possible to shed light on the “unsaid” of conversations.
In the book, the humorous framing of an utterance is shown to be negotiated and co-constructed dialogically and multimodally, through changes and patterns of smiling synchronicity, smiling intensity, and eye movements. The study also analyzes the multimodal features of failed humor and proposes a new categorization from a dialogic perspective.
Because of its interdisciplinary approach, which includes facial expression analysis and eye tracking, this book is relevant to humor researchers as well as scholars in social and behavioral sciences interested in multimodality and embodied cognition.
The object position in Old Norwegian
Authors: Tiemann Juliane
Published: March 2022

OV/VO variation in Germanic languages is a widely discussed subject. However, Old Norwegian has so far received little attention and is syntactically generally treated as one with Old Icelandic. However, in contrast to the findings of Hróarsdóttir (2000, 2009) for Old Icelandic, stating that OV orders are triggered mainly by the prosodic weight of the object, the present study shows that OV/VO variation in Old Norwegian is still more dependent on an interplay of both information status and prosodic weight of a constituent in a clause. I argue that the results for the information status of the object reflect the syntactic development in the history of Norwegian as a change in the way information-structural categories are displayed in the grammar.
Informational aspects of the extraposition of relative clauses
Authors: Voigtmann Sophia
Published: March 2022

This paper investigates the correlation of information structure (givenness) and the extraposition of relative clauses from Early New High German (16th century) to early Modern German (19th century) via a corpus study of letters. It aims to determine whether relative clauses with a high proportion of new referents are more likely to be extraposed because new referents put more strain on the working memory and can therefore be better interpreted at a position where more memory capacities are available again (Gibson 1989) and help spread the information of the whole sentence more evenly (Levy & Jaeger 2007). Another goal of the paper is to show that there is a decreasing influence of information structure on extraposition over the centuries. It will be shown that there is evidence for both hypotheses put forward in the paper.
Cross-Cultural Violence Risk Assessment: Adapting the HCR-20V3 for Incarcerated Offenders in Mexico
Authors: Nijdam-Jones Alicia , García-López Eric , Merchan Rojas Libertad , Ruiz Guarneros Aura , Rosenfeld Barry
Published: March 2022

This prospective study investigated the predictive validity of a culturally adapted version of the Historical-Clinical-Risk Management-20 (HCR-20V3) with a sample of 114 incarcerated males in a medium-security prison in Mexico City. The goal was to integrate a culturally responsive approach to violence risk assessment by incorporating culturally relevant risk factors identified by forensic mental health professionals in Latin America who conduct violence risk assessments. These risk factors related to problematic family and peer relationships, machismo, normalization of violence, and economic disadvantage. Data collection for HCR-20V3 ratings involved clinical interviews and a review of institutional documents; data on aggressive incidents were collected through document review, self-report follow-up interviews, and guard reports. Participants who engaged in institutional violence during the 3-month follow-up period were given significantly higher scores on several culturally relevant risk factors than those who did not engage in institutional violence. Although the culturally adapted HCR-20V3 items did not provide incremental validity to the original HCR-20V3 items, the culturally adapted HCR-20V3 total score produced an area under the ROC curve of .73-.74. The findings provide evidence that the culturally adapted HCR-20V3 has strong predictive validity and the utility of adapting culturally relevant risk factors for the assessment of violence risk.
Structural properties and ring defect formation in discotic liquid crystal nanodroplets
Authors: Salgado-Blanco Daniel , Llanas-García Andrea H , Díaz-Herrera Enrique , Martínez-González José A , Mendoza Carlos I
Published: March 2022

In this work, we performed NpT Monte Carlo simulations of a Gay–Berne discotic liquid crystal confined in a spherical droplet under face-on anchoring and fixed pressure. We find that, in contrast to the unbounded system, a plot of the order parameter as function of temperature does not show a clear evidence of a first-order isotropic-nematic transition. We also find that the impossibility of simultaneously satisfy the uniform director field requirement of a nematic phase with the radial boundary conditions, results in the appearance of a ring disclination line as a stress release mechanism in the interior of the droplet. Under further cooling, a columnar phase appears at the center of the droplet.
Machine vision-based conveyor belt tear detection in a harsh environment
Authors: Wang Gongxian , Liu Zhiqi , Zhang Libin , Xiang Lei , Sun Hui
Published: March 2022

This work proposes a recognition method to improve the visual detection rate of longitudinal conveyor belt tears related to fog pollution and uneven illumination. It integrates the Haar feature with a modified dark channel defogging algorithm. Firstly, the dark channel algorithm was used to eliminate fog interference with belt images, and the processing time was reduced from 14.5 ms to 5 ms by calculating a single necessary image channel. The Haar feature was used to replace the traditional geometric features due to its high-efficiency feature expression and illumination robustness; this provided a strong feature basis for the learning and training of the classifiers. Next, the classifiers were trained and strengthened by the AdaBoost algorithm, and the strengthened classifiers were cascaded by the Cascade algorithm to improve the recognition ability. Finally, experiments were carried out under mixed fog pollution and uneven illumination. The results show that the average accuracy, recall, precision and false positive rate of the proposed method are approximately 98.4%, 96.9%, 99.9% and 0.1%, respectively, while the recognition period was only 52.3 ms. This shows strong adaptability and robustness to a harsh environment and demonstrates that the proposed method has important application value.
A review on intense pulsed light process as post-treatment for metal oxide thin films and nanostructures for device application
Authors: Noh Youngwook , Kim Gyu Young , Lee Horim , Shin Jaehak , An Kunsik , Kumar Manoj , Lee Dongjin
Published: March 2022

The intense pulsed light (IPL) post-treatment process has attracted great attention in the device fabrication due to its versatility and rapidity particularly for solution process functional structures in devices, flexible/printed electronics, and continuous manufacturing process. The metal oxide materials inherently have multi-functionality and have been widely used in form of thin films or nanostructures in device application such as thin film transistors, light emitting diodes, solar cells, supercapacitors, etc. The IPL treatment enhances the physical and/or chemical properties of the functional metal oxide through photothermal effects. However, most metal oxides are transparent to most range of visible light and require more energy for post-treatment. In this review, we have summarized the IPL post-treatment processes for metal oxide thin films and nanostructures in device applications. The sintering and annealing of metal oxides using IPL improved the device performances by employing additional light absorbing layer or back-reflector. The IPL process becomes an innovative versatile post-treatment process in conjunction with multi-functional metal oxides in near-future device applications.
Data-driven, energy-based method for estimation of scattered events in positron emission tomography
Authors: Efthimiou Nikos , Karp Joel S , Surti Suleman
Published: March 2022

Objective. Scattered events add bias in the reconstructed positron emission tomography (PET) images. Our objective is the accurate estimation of the scatter distribution, required for an effective scatter correction. Approach. In this paper, we propose a practical energy-based (EB) scatter estimation method that uses the marked difference between the energy distribution of the non-scattered and scattered events in the presence of randoms. In contrast to previous EB methods, we model the unscattered events using data obtained from measured point sources. Main results. We demonstrate feasibility using Monte Carlo simulated as well as experimental data acquired on the long axial field-of-view (FOV) PennPET EXPLORER scanner. Simulations show that the EB scatter estimated sinograms, for all phantoms, are in excellent agreement with the ground truth scatter distribution, known from the simulated data. Using the standard NEMA image quality (IQ) phantom we find that both the EB and single scatter simulation (SSS) provide good contrast recovery values. However, the EB correction gives better lung residuals. Significance. Application of the EB method on measured data showed, that the proposed method can be successfully translated to real-world PET scanners. When applied to a 20 cm diameter ×20 cm long cylindrical phantom the EB and SSS algorithms demonstrated very similar performance. However, on a larger 35 cm × 30 cm long cylinder the EB can better account for increased multiple scattering and out-of-FOV activity, providing more uniform images with 12%–36% reduced background variability. In typical PET ring sizes, the EB estimation can be performed in a matter of a few seconds compared to the several minutes needed for SSS, leading to efficiency advantages over the SSS implementation. as well.
Detections of Gamma-Rays from Globular Clusters ESO 452-SC11, NGC 6380, Palomar 6 and UKS 1 with Fermi-LAT
Authors: Yuan Min , Zheng Jiao , Zhang Pengfei , Zhang Li
Published: March 2022

The events from 157 globular clusters (GCs) are analyzed by using 12 yr long-term Pass 8 data from Fermi Large Area Telescope. Besides the 34 GCs reported in previous literatures, four additional GCs (ESO 452-SC11, NGC 6380, Palomar 6 and UKS 1) in the Milky Way are detected as gamma-ray GC candidates. Especially for UKS 1, these are known as the faintest GCs in long-wavelength bands. Further data analysis has been performed for the four GCs. While no pulsars are determined in radio and/or X-ray wavelengths so far, their gamma-ray pulsation emissions are not found, and no significant gamma-ray flux variability is detected. The numbers of MSPs within the four GCs are estimated based on the assumption that the MSPs within each GC emit similar amounts of gamma-rays. The gamma-ray results reported here could help us better understand the nature of gamma-ray emission origins for GCs.
Quantum random walk and tight-binding model subject to projective measurements at random times
Authors: Das Debraj , Gupta Shamik
Published: March 2022

What happens when a quantum system undergoing unitary evolution in time is subject to repeated projective measurements to the initial state at random times? A question of general interest is: how does the survival probability S

m
, namely, the probability that an initial state survives even after m number of measurements, behave as a function of m? We address these issues in the context of two paradigmatic quantum systems, one, the quantum random walk evolving in discrete time, and the other, the tight-binding model evolving in continuous time, with both defined on a one-dimensional periodic lattice with a finite number of sites N. For these two models, we present several numerical and analytical results that hint at the curious nature of quantum measurement dynamics. In particular, we unveil that when evolution after every projective measurement continues with the projected component of the instantaneous state, the average and the typical survival probability decay as an exponential in m for large m. By contrast, if the evolution continues with the leftover component, namely, what remains of the instantaneous state after a measurement has been performed, the survival probability exhibits two characteristic m values, namely,

m

1

⋆

(

N

)

∼
N

and

m

2

⋆

(

N

)

∼

N

δ

with δ > 1. These scales are such that (i) for m large and satisfying

m
<

m

1

⋆

(

N

)

, the decay of the survival probability is as m
−2, (ii) for m satisfying

m

1

⋆

(

N

)

≪
m
<

m

2

⋆

(

N

)

, the decay is as m
−3/2, while (iii) for

m
≫

m

2

⋆

(

N

)

, the decay is as an exponential. The results for the dynamics with the leftover component, already known for the case of measurements at regular intervals, are being extended here to the case of measurements at random intervals. We find that our results hold independently of the choice of the distribution of times between successive measurements, as have been corroborated by our results for a wide range of distributions including exponential and power-law distributions as well as for the case of measurements at regular intervals. This fact hints at robustness and ubiquity of our derived results.
Research on a small-scale drinking water quality detection system based on detection of laser-induced fluorescence
Authors: Chen H , Che X H , Bi Z J , Tian Z S
Published: March 2022

In this paper a small-scale drinking water quality detection system that can be used for real-time evaluation of Dissolved Organic Matter (DOM) and Total Dissolved Solids (TDS) is presented. The DOM detection is based on the principle that the intensity of the laser-induced fluorescence signal is proportional to the DOM concentration. In experiment, the DOM concentration of sodium humate solution and the TDS value of NaCl solution are tested, respectively. In addition, drinking water and tap water before and after purification are also detected by the system. The quality of purified water is significantly higher than that before purification. Detection results obtained in our laboratory indicate that the system described in this paper can detect the organic and inorganic contents of drinking water. Advantages of our system are small volume, high sensitivity and high precision.
An optical apparatus for inspecting adjacent surfaces defects of TEC components with equal-optical-path confocal imaging using optical wedge prisms
Authors: Shaobin Yan , Yafan Duan , Qilu Huang , Heng Zheng , Yantang Huang , Tingdi Liao
Published: March 2022

An optical apparatus with equal-optical-path confocal imaging has been proposed for simultaneously inspecting adjacent surfaces defects of thermoelectric cooler (TEC) components. The equal-optical-path confocal imaging of two adjacent surfaces with the desired separation can be obtained by using two optical wedges in the two optical imaging paths respectively. The optical apparatus has been designed and experimental investigations on defects inspection of two adjacent surfaces of TEC components have been conducted. The results showed that the proposed optical apparatus allows one to simultaneously inspect the defects of adjacent surfaces of TEC components. It was concluded that the optical apparatus can meet the technical requirements for inspecting adjacent surfaces defects of TEC components. The apparatus has advantages of freedom for imaging adjustment, increased inspection accuracy and improved system reliability etc. It has been found applications in the intelligent defects inspection system of TEC components.
Synthesis and research of a kind of perylene imide discoid molecule
Authors: Zhu Lei , Wang Ying , Wang Wenguang , Wu Xianyao , Wu Ti
Published: March 2022

Discotic liquid crystal molecules are excellent organic semiconductor materials due to their high carrier mobility. Dibenzocoronene derivatives obtained by nuclear expansion with perylene diimide as a matrix are one of the discotic molecules. The key factor for the application of this type of molecule is that it can form stable and long-range ordered organic nano-scale thin films. It can be used as an efficient carrier transport channel. This paper intends to use the “channel effect” to obtain the corresponding long-range orderly ideal film. The “channeling effect” referred to in this article is to bond functional discoid molecules on the substrate firstly, than generate the corresponding self-assembled monomolecular membranes (SAMs) to form an ordered channel on the surface which strongly induces and restricts the discoid molecules that arranged in parallel and orderly with each other along the “channels” created on the surface of the SAMs. Perylene diimide derivatives are a kind of good electron transport materials, which are characterized by high carrier mobility, low processing cost, and good thermal stability. However, it has the large rigid core and the melting point is relatively high. In this paper, a monobenzocoperylene diimide derivative is designed and synthesized, which will have a strong effect on the surface of the silicon substrate, and reduce the molecular melting point by reducing the size of the perylene imide discotic molecular core expansion.
Synthesis and Characterization of Novel Difuran-Coumarin Discoid Molecules
Authors: Wu Xianyao , Yv Zhen , Wang Wenguang , Zhu Lei , Li Zhongxiao
Published: March 2022

Two new types of novel difuran-coumarin discoid molecule substituted with long-chain alkyl groups were designed and synthesized, which furan-group was successfully coupled with coumarin as the starting material. In this paper, the synthesis method of the peripheral halogenation of novel difuran-coumarin discoid molecules was studied, and its solubility was improved through modification of its periphery, which makes them have high solution processability. And it can expectedly be used as one candidate of organic semiconductor materials.
A 3D Modulation Scheme for High-speed Baseband Digital Communication System
Authors: Feng Yeqing , Lai Zhengrong , Zhu Fusheng , Hu Zemin
Published: March 2022

To improve the transmission rate of wireless communications, the communication frequency band will gradually go higher, and the use of millimeter wave and terahertz will become mainstream in the future. However, the signal attenuation in high bands is considerable, which prevents the achievement of long-distance transmissions. In this paper, we propose a 3D modulation scheme that is especially suitable for high-speed baseband digital communication systems. The proposed scheme is simulated and tested in an experiment. With the same order of modulation, the 3D modulation shows a significant decrement in bit error rate and enables a longer transmission distance.
Research on DC voltage droop strategy based on optimal DC power flow
Authors: Dong J , Wang Z , Yan S , Wang Z , Jiang B , Zhu C , Wang C
Published: March 2022

A coordinated control based on the optimal DC power flow for MTDC is proposed to improve the transmission efficiency of multi-terminal HVDC, which adopts hierarchical structure including processing layer and implementation layer. The dcOPF model of optimal DC power flow is established in the solving layer. The minimum of the generation cost is set as the objective function, and the constraints include the line capacity, generator capacity, converter station capacity and power balance. The optimal solution is applied to the executing layer. When disturbs occur in some converter stations, new optimal solution will be re–calculated and updated to the executing layer and reduce the generation cost. The stability of the system will not be affected by communication fault. A four-terminal VSC-MTDC simulation model in the MATLAB/Simulink platform is built in the paper. The simulation results show that the proposed control strategy can minimize the generation cost and the control strategy has the advantages of simple structure and easy implementation.
Research on dynamic aerodynamic performance of wind turbine airfoil under large blade deformation
Authors: Zhao Tiantian , Sun Haitao
Published: March 2022

With the increase of wind power blades, the amount of blade design pre-bending and deformation in motion has increased significantly. Under the condition of large deformation of the wind turbine blade, the pitch axis deviates greatly from the centerline of the airfoil. At this point, the pitch movement of the wind turbine blade will lead to the dynamic change of the airfoil angle of attack and the horizontal movement of the airfoil at the same time. Concerning this problem, the dynamic stall characteristic of the S809 airfoil under the condition of large deformation was studied using CFD technology. The results show that the horizontal motion caused by the deviation of the pitch axis from the airfoil center can significantly change the stall characteristic of the airfoil. Based on this, the fatigue load changes caused by changes in dynamic stall characteristics under typical operating conditions are studied.
Modal Investigation in Space Truss Deployable Antenna
Authors: Fang Yonggang , Zheng Shinkun , Dong Longlei , Xue Yonggang , Zhou Jiaming
Published: March 2022

Due to the large size, low frequency, and poor transmission of the space truss deployable antenna (STDA), it is not easy to perform experimental modal analysis (EMA) using hammers or exciters. In this paper, the operational methods ensure that both the low-frequency and high-frequency modes of the STDA are excited. A parameter estimation method called PolyMAX is employed to identify modal shapes, modal frequencies and modal damping of the STDA only using dynamic responses. Further, a gravity unloading system is used to simulate the microgravity environment of the STDA in space, and the dynamic responses in this state are collected and processed. Finally, we discuss the difference of STDA modal parameters under the gravity and microgravity conditions through the previous test results. The technology used in this study can be further applied to the similar STDA structures.
The Seismic Response of a Lined Tunnel under Plane P-wave in a Slope Site
Authors: Luo Yan-ping , Feng Quan , Zhou Tao , Liu Tao , Xiao Zheng-yong , Wang Sheng
Published: March 2022

The indirect boundary element method (IBEM) is adopted to solve the 2D scattering problem of circular underground lining tunnels near canyons and slopes to the P-wave. The numerical results show that the canyon and slope topography near the underground lining tunnel has an evident influence on the surface displacement. The horizontal displacement amplification reaches nearly two times. The presence of slopes has a shielding effect on the nearby underground tunnels. The stress concentration exists at the top and bottom of the arch of the lining tunnel. The dynamic interaction between the slope and the tunnel should be considered when building a tunnel close to the slope.
Dynamic behavior of PMMA under planar shock conditions
Authors: Li Jin , Li Yun-liang , Zhang Xiang-rong , Zhu Yu-rong , Tan Shu-shun , Zhang Guan-jun
Published: March 2022

As a non-metallic low wave impedance material, PMMA has been widely used in experiments of blast and shock. But the dynamic performances of different kinds of PMMA vary greatly. In this paper, the plane shock-wave experiments were performed with a 57 mm bore single-stage light gas gun in order to determine the dynamic behavior of PMMA at stress levels between 0.4 and 3.8 GPa. The particle velocity and shock wave velocity were measured with electromagnetic particle velocity sensors embedded into the samples directly, and the velocity of the flyer was measured with a laser velocity measuring system. The typical wave forms of particle velocity and the Hugoniot data of the experiments were presented in this paper. The dynamic stress–strain relations of experiments at different pressure ranges were obtained by the Lagrangian analysis method based on one dimensional strain, and the loading and unloading characteristics of which were discussed.
Influence of angle-of-attack on drag force
Authors: Ma AIXIANG , Zhou SHIJIN , Wu QIAN , Zhu CHUANLEI
Published: March 2022

During the airdrop process, when the incoming flow flows through the parachute system at a certain angle of attack, it will affect the deceleration performance of the parachute system. This work studied the influence of angle-of-attack on the drag force of the parachute system. The elements of the “T- 11” parachute and “T- 11 reserve” parachute system were introduced. Numerical simulation was used to approach the real condition. The simulation results show that for a single canopy, the increase of angle-of-attack will cause the drag coefficient of the canopy to decrease; for the parachute system with load under the canopy, when the angle-of-attack is less than 20º, the increase of angle-of-attack will increase the drag coefficient of the canopy, and when the angle-of-attack continues to increase, the drag coefficient of the canopy will gradually decrease. In these simulations, the deformation of the parachute is not concerned.
Research on the collapse of Tacoma narrows bridge under the finite element application ANSYS of computational mechanics
Authors: Lin Yichang , Xie Xizhe , Yan Lingan , Zhou Yifan
Published: March 2022

Compared with the collapse of the Tacoma Bridge in 1940, other bridges constructed around the same period remain functional. This research objective is to compare Tacoma Bridge and George Washington Bridge to determine the critical factors of collapsing behavior. In order to accomplish the goal, two bridge models are constructed for analysis and comparison. The finite difference method is applied to modeling in this process. From the modal analysis in ANSYS, the data of total deformation of Tacoma bridge is much higher than that of George Washington Bridge. Therefore, four factors are combined to demonstrate the collapse of Tacoma. This 1940s event is regarded as having landmark meaning and provide relative experience in the modern bridge constructions.
Electrowetting Characteristics of an Insulating Droplet under Coplanar Electrode
Authors: He Yijia , Zhao Rui , Zhang Yue , Liang Zhongcheng , Kong Meimei , Chen Tao
Published: March 2022

Electrowetting on dielectric (EWOD) has become an effective droplet manipulation method in microfluidic technology. In this paper, a theoretical model based on energy conversation is established to depict the electrowetting behavior of an insulating droplet located on a coplanar electrode in conductive liquid. To validate the correctness of the theory, COMSOL is carried out to simulate wettability evolution of the silicone oil droplet surrounded by propylene glycol (PG) containing with 1 wt% tetrabutylammonium chloride (TBAC). Relative experiments are conducted to detect the contact angle (CA) and height (H) of the insulating droplet at different voltage. When the voltage is increased, the wettability of the conductive liquid changes and consequently the insulating droplet is squeezed inward. The silicon oil droplet in PG exerts continuous change in CA and H by operation of voltage adjustment. When the voltage is increased to 110V, the CA changes from 42.5° to 134°, and the relative H reaches up to 3.46 mm. The results show that theoretical model is basically consistent with the facts.
Seismic performance of buckling-restrained braced steel frames subjected to earthquake main shock-aftershock sequences
Authors: Gong Chao , Jia MingMing , Cheng XuanHao , Gritcuk Mishel
Published: March 2022

Recently, there are many papers report the development of some new buckling-restrained braced (BRB) frames and the evaluation of its characteristics. At the same time self-centering buckling-restrained braced (SCBRB) frames are considered as new solutions for the increasing of the structural resilience. In this thesis, the seismic performance of structures is analyzed subjected to earthquake main shock-aftershock sequences. There is comparison of two types of the additional BRB elements, and also there is comparison between them and original steel frame to show the effect of using BRB and SCBRB elements. To compare the seismic performance of BRBF and SCBRBF, the same main shock-aftershock sequences were used in this part. Because of the flag-shaped hysteretic curve of the SCBRB elements, big amount of the energy was dissipated during the motion. Compared to steel frame, smaller seismic responses and residual deformation occurred the structure. BRBF and SCBRBF can control the seismic responses effectively due to the energy dissipation of BRB, and SCBRB can also reduce the structural residual deformation. The earthquake aftershock after earthquake main shock can increase the structural damage and enlarge the structural seismic responses.
Fabrication and electron transport characteristics of suspended Graphene/hBN heterostructure Devices
Authors: Cui Ziru , Bai Zongqi , Luo Fang , Zhu Mengjian
Published: March 2022

Graphene has outstanding electrical properties such as high carrier mobility and large operation current density due to it’s unique two-dimensional carbon honeycomb lattice structure. However, the carrier mobility and on/off ratio in current of traditional silicon-integrated graphene devices are largely limited due to the substrate-induced scattering effect. Exploring new device structure to prepare graphene devices is an important way to improve their performance. In this work, we propose a new fabricate technique for suspended Graphene/hBN van der Waals heterostructure device with high vield. Combined with improved transfer technology, it greatly improves the probability of successful suspending graphene devices, and we found that the Dirac point of the suspended graphene device is located in nearly zero gate voltage, which reduced the doping in graphene effectively, and further proved the advantages of our device structure in fabricating suspended devices.
Research on sealing performance of special thread of tubing under complex load
Authors: Wang Chuanlei , Liu Xiangkang , Wang Hao , Li Yufei , Zhang Lin , Wang Han
Published: March 2022

In order to study the performance of a special threaded joint of a tubing under severe well conditions, a two-dimensional finite element model of this joint was established in the finite element software, and the mechanical properties and sealing performance of the special threaded joint under different working conditions were analyzed and studied. The results of the study indicate: under different make-up torques, the Mises stress value on the thread has a small difference, and there is a significant difference at the shoulder. When subjected to complex loads, the Mises stress on the load-bearing surface of the thread head and tail ends is high, the overall maximum Mises stress exceeds the yield limit of the material, but the stress level in most areas is low, there is no plastic penetration part and structural damage on the thread teeth. The sealing index of the threaded joint is greater than the critical sealing performance index. This shows that this threaded joint can meet the requirements of use.
Analytical investigation on the mechanical behavior of expansive soils: a simplified constitutive model
Authors: Xu Jianhua , Li Kai , Liu Mengmeng
Published: March 2022

Taking into account the high cost of damage to structures caused by uneven ground movements associated with expansive soils, the mechanical behavior of these materials is critically important to be studied theoretically and experimentally. A simplified constitutive model is proposed based on a 1-D mechanical design containing a parallel connection of the linear spring and the dashpot element, and its mathematical formation is presented in terms of the physical mechanism. The procedure of model parameters is introduced using cyclic suction-controlled tests by an expansive soil in France and a silt-bentonite mixture. The comparison between model simulations and tests is accomplished and this comparison explains that the simplified constitutive framework can describe basic features of expansive soils under wetting and drying cycles.
A beam dynamics study for efficient extraction from the VECC K500 superconducting cyclotron
Authors: Paul S. , Bhunia U. , Debnath J. , Dey M.K. , Bandyopadhyay A. , Som S.
Published: March 2022

Beam extraction from the K500 superconducting
cyclotron is very challenging due to its long extraction path of
about 330° with very high magnetic field gradient and low
acceptance. The initial attempts of beam extraction showed that the
pilot beams could successfully clear only a few magnetic
channels. To investigate the causes of the beam loss, magnetic field
measurements in different zones of the cyclotron were repeated. The
total field has been generated by superposition of the measured
field and the numerically computed field of the extraction
elements. Based on these data, extensive beam dynamics simulation
has been carried and beam distribution at the entry of the
extraction path obtained by accelerated orbit calculations. The
energy spread due to multi-turn deflector entry has been included in
the simulation. The beam envelope along the extraction path as well
as the beam transmission efficiency has been determined for
different positions of the extraction elements. The radial positions
of the extraction elements have been optimized parametrically to
compute the maximum transmission efficiency. The present studies
have enabled us to successfully extract the pilot beam (N4+)
from the cyclotron with beam current of around 20 enA.
Towards a transformational eco-metabolistic bio-based design framework in architecture
Authors: Thomsen Mette Ramsgaard , Tamke Martin
Published: March 2022

This paper discusses the foundations of a bio-based material paradigm for architecture. It argues that moving from a current reliance on the non-renewable materials of the geosphere, to the renewable and fundamentally cyclical materials of the biosphere can establish alternate foundations for thinking alternative sustainable building practices. By positioning architecture and the built environment as a particular case for bio-based materials, where the longer life spans of buildings support better carbon storage, this paper identifies the bottlenecks that limit their adaptation into the way architecture is thought, designed and built. If architectural ideation and design is traditionally understood through the durable and the permanent, our aim here is to challenge this foundation and bring forth the fundamental differences that bio-based materials engender. With focus on the embedded lifespans of living materials, the fundamental circularity and degradability of biomass and resulting transformative life cycles of the artefacts that they embody, this paper asks how a new representational framework for bio-based material paradigm can be conceptualised, instrumentalised and in turn materialised. The paper supports this positioning through a presentation of a series of methodological probes. The probes outline strategies for new methodologies by which we can capture, predict and steer the transformations of living materials and functionalise them as part of an architectural performance.