bluuebunny/crossref_metadata_2025 huggingface dataset:
Unstructured road parameter cognition for ICVs using multi‐frame 3D point clouds
Authors: Xie Guotao , Yan Kangjian , Wang Dongsheng , Sun Ning , Gao Hongbo
Published: April 2021

Road parameter cognition is essential for intelligent and connected vehicles (ICVs) operating on unstructured roads because it can influence their path planning and motion control. A method is presented for the extraction of longitudinal slopes and lateral slopes and the roughness of unstructured roads using multi‐frame three‐dimensional point clouds. First, a segmentation method based on the multiple features is proposed to extract and divide the regions of interest into blocks with different slopes, which is valuable for further study on ground segmentation. Second, a parameter cognition method is proposed to estimate the slope and roughness of unstructured roads. Last but not least, a multi‐frame fusion method is proposed to improve cognition accuracy. Experimental tests on unstructured roads demonstrate that the proposed algorithm has satisfactory performance in terms of the accuracy of recognizing road slopes and roughness.
Compact empty substrate integrated waveguide with high performance and its application in microwave
Authors: Qiang Jingxia , Xu Feng , Yang Ling , Zhan Junlin
Published: April 2021

A compact slow‐wave empty substrate integrated waveguide (SW‐ESIW) structure is proposed in this article. This structure is composed of an empty substrate with a bottom layer including several rows of internal metallised via holes. In order to decrease both the lateral and longitudinal dimensions, the slow wave effect, caused by physical separation of electric and magnetic fields, is introduced while retaining the advantages of ESIW, such as high quality factor, small insertion loss, and the advantages of SIW, such as low cost and easy processing. Compared to the classical ESIW, the proposed SW‐ESIW structure achieves a size reduction of 37% and retains the triple‐layer structure. At the same time, in contrast with general SW‐SIW structure, which needs double layer with dielectric material, the novel waveguide obtains a significant performance improvement in insertion loss and quality factor. In the article, a fourth‐order filter is designed to verify the idea that the SW‐ESIW technology provides the low loss, high quality factor and compact structure. By combining the advantages of SW‐SIW and ESIW technology, the proposed SW‐ESIW structure can be widely applied to the microwave integrated circuits with miniaturisation and high quality factor.
Resistance switching and conduction mechanism on ferroelectric copolymer thin film device
Authors: Qin Xue , Xiao Xia , Qin Shu‐Chao , Dong Rui‐Xin , Yan Xun‐Ling
Published: April 2021

The memristor of sandwich structure is prepared by employing the ferroelectric copolymer poly (vinylidene fluoride/trifluoroethylene) (P(VDF‐TrFE)). The device exhibits great bipolar resistance switching characteristics. The low on–off voltage (3/−2.7 V) and high Ion/Ioff ratio (≈103) as well as fast switching speed are obtained in this device. Based on the intrinsic spontaneous polarization characteristics of ferroelectric materials, the conduction mechanism model of ferroelectric film conductive channel is established and the linear relationship between conductivity and average polarization intensity is given. The calculated results of conductance–voltage (G–V) curve show an obvious hysteresis phenomenon and the distinguishable high/low conductivity states. This physical model is consistent with the experimental results, indicating a reasonable conduction mechanism of the device.
Complementary frequency modulated radar waveforms and optimised receive processing
Authors: Jones Christian C. , Mohr Charles A. , McCormick Patrick M. , Blunt Shannon D.
Published: April 2021

Design methodologies are developed for complementary frequency modulated (FM) waveforms and for optimised complementary mismatched filtering (MMF) of arbitrary non‐repeating waveforms. The former is a sub‐class of random FM waveforms denoted as complementary FM (Comp‐FM) while the latter extends a practical instantiation of least‐squares mismatched filtering yielding the mismatched complementary‐on‐receive filtering (MiCRFt) scheme. Both of these approaches have an emphasis on the non‐ideal physical effects of the radar transmitter and receiver, thereby permitting high‐fidelity simulation analysis and subsequent experimental demonstration of their efficacy using open‐air measurements.
Modelling radio luminosity functions of radio-loud AGN by the cosmological evolution of supermassive black holes
Authors: Tucci Marco , Toffolatti Luigi
Published: April 2021

Aims. We develop a formalism to model the luminosity functions (LFs) of radio-loud active galactic nuclei (AGN) at GHz frequencies by the cosmological evolution of the supermassive black hole (SMBH) hosted in their nuclei. The mass function and Eddington ratio distributions of SMBHs computed in a previous work published by one of the authors have been taken as the starting point for this analysis.

Methods. Our approach is based on physical and phenomenological relations that allow us to statistically calculate the radio luminosity of AGN cores, corrected for beaming effects, by linking it with the SMBH at their centre, through the fundamental plane of black hole activity. Moreover, radio luminosity from extended jets and lobes is also computed through a power-law relationship that reflects the expected correlation between the inner radio core and the extended jets and lobes. By following a classification scheme well established in the field, radio-loud AGN are further divided into two classes, characterized by different accretion modes onto the central BH. If the Eddington ratio, λ, is ≤0.01 they are called low-kinetic (LK) mode AGN; if λ ≥ 0.01, they are called high-kinetic (HK) mode AGN, this critical value roughly corresponding to the transition between radiatively inefficient and efficient accretion flows. The few free parameters used in the present model are determined by fitting two different types of observational data sets: local (or low-redshift) LFs of radio-loud AGN at 1.4 GHz and differential number counts of extragalactic radio sources at 1.4 and 5 GHz.

Results. Our present model fits well almost all published data on LFs of LK mode AGN and of the total AGN population up to redshifts z ≤ 1.5 and also in the full range of luminosities currently probed by data. On the other hand, it tends to underestimate some recent measures of the LF of HK mode AGN at low redshifts, but only at low radio luminosities. All in all, the good performance of our model in this redshift range is remarkable, considering that all the free parameters used but the fraction of HK mode AGN are redshift independent. The present model is also able to provide a very good fit to almost all data on number counts of radio-loud sources at 1.4 and 5 GHz.
Theoretical and practical aspects of the production of powdered semi-finished product from cultivated mushrooms pleurotus ostreatus
Authors: Myachikova Nina , Remnev Alexey , Boltenko Yuri , Korotkyh Irina , Binkovskaya Olga , Zinoveva Irina
Published: April 2021

The substantiation of the technology of powdered semi-finished product from cultured mushrooms Pleurotus ostreatus is presented. The composition of volatile substances of fresh mushrooms Pleurotus ostreatus was studied. It was ascertained that these substances can bind by starch polysaccharides. The results of the conducted study showed that the best flavor-forming substances are preserved in the sample containing 8% of potato starch to the mass of mushrooms boiled in their own juice. Starch is recommended to insert in dry form at the temperature of mushrooms 45°С.
Modification of Zeolites Y and ZSM-5 adsorption of nanoparticles of transition metals from back-micellar solutions for separation of gas mixtures
Authors: Dudoladov Aleksandr , Alekhina Marina , Revina Aleksandra , Souvorova Olga
Published: April 2021

On the basis of granular synthetic zeolites NaY, HY, and ZSM-5, adsorbents containing nanoparticles of silver, cobalt, molybdenum, and tungsten were obtained. The samples have a lower surface polarity in comparison with the initial zeolites, which is reflected in the selectivity of a number of samples with respect to argon. This is due to the fact that the argon molecule interacts with zeolites only through nonspecific forces. Modification was performed by interacting with reverse-micellar solutions of nanoparticles. The actual sizes of metal particles and their distribution over the surface of the modified samples of zeolites have been determined by the method of transmission electron microscopy. The samples’ equilibrium adsorption capacities for oxygen and argon (25°С and atmospheric pressure) and the separation coefficient of the argon–oxygen mixture as the ratio of Henry’s coefficients have been determined. It has been demonstrated that samples of the NaY zeolite modified with silver nanoparticles have the separation coefficient value of the argon–oxygen gas mixture equal to 1.6.
Results of a pharmacoeconomic analysis of the rationality of the use of acute myeloid leukemia chemotherapy regimens with the use of various doses of cytarabine
Authors: Panfilova Hanna , Goncharova Anastasiya , Korzh Iuliia , Zhirova Irina , Tsurikova Oksana , Bezuglaia Natalia
Published: April 2021

A pharmacoeconomic study of the rationality of the use of various chemotherapy regimens (“7 + 3” scheme) in the treatment of patients with acute forms of myeloid leukemia has been carried out. The use of the chemotherapy regimen “7 + 3” with 200 mg / m2 / per day dosage of cytarabine on 1-7 days allows to achieve a unit of treatment efficacy at a lower cost (CEA = 19.22 US $ / per unit of efficacy), compared with another dosage of cytarabine that was two times less, i.e., 100 mg / m² / day at the same period (CEA = US $ 20.18 / unit of effectiveness). The presented research results can be used in the formation of programs for the rational use of limited resources in the purchase of anticancer drugs for hematological cancer patients, as well as in the development of schemes for providing them with effective medical care in a hospital setting.
Genus Metagentiana T. N. Ho & S. W. Liu (Gentianaceae Juss.) – a new record for flora of Vietnam
Authors: Khuat Van Quyet , Ha Minh Tam , Nguyen Thi Thuy Hang , Nguyen Thanh Hai
Published: April 2021

Ho et al. proposed to exclude Stenogyne section from the genus Gentiana and classifying it as a distinct genus (Metagentiana). Fourteen species of this genus have been recorded and distributed in China, Myanmar and Thailand. This is the first time there has been a confirmed genus Metagentiana distributed in Vietnam. This genus has two species: Metagentiana rhodantha and Metagentiana primuliflora, which are proposed in Vietnam. Particularly, Metagentiana rhodantha, which had only been known from China, was reported in Vietnam. A detailed description along with their distribution, habitat, ecology, illustrations, and photos has been provided to aid species identification. The key to identify all taxa of the genus has been constructed
Introduction of hyssopus officinalis l . into in vitro culture to optimize the conditions for obtaining callus tissues and microclonal propagation as a promising metod of innovative agrobiotechnologies
Authors: Maslova Elena , Gulya Natalya , Perelugina Tatyana , Semykina Valeria , Kalashnikova Elena
Published: April 2021

The sterilization process of plant explants of H. officinalis was optimized when introduced into an in vitro culture, the most effective sterilization modes, optimal sterilizing agents, their exposure time and concentration were selected. Callus tissues and mini-plants of H. officinalis were obtained in vitro and the most optimal nutrient media were determined both for microclonal propagation and for the induction of callus tissue H. officinalis, which can be further used for mass cultivation of cell and culture and obtaining safe bio-additives with active substances for livestock and crop production as a part of the development of modern agrobiotechnologies.
Vulnerability and mutual insurance
Authors: Eisen Roland
Published: April 2021

Vulnerability comes, according to Orio Giarini, with two risks: human-made risks, also called entrepreneurial risks, and natural or pure risks such as accidents and earthquakes. Both types of risk are growing in dimension and are increasingly interrelated. To control the vulnerability, sophisticated insurance products are called for. Here, mutual insurance is relevant, in particular when risks are large, probabilities uncertain or unknown, and events interrelated or correlated. In this paper the following three examples are discussed and the advantages of mutual insurance are shown: unknown probabilities connected with unforeseeable events, correlated risks and macroeconomic or demographic risks.
Changes in mobility and socioeconomic conditions during the COVID-19 outbreak
Authors: Dueñas Marco , Campi Mercedes , Olmos Luis E.
Published: April 2021

Since the outbreak of the 2019 novel coronavirus (COVID-19) pandemic, governments have been implementing containment measures aimed at mitigating the spread of the virus, including restrictions to human mobility. The ability to adapt to the pandemic and respond to containment measures can be bound by socioeconomic conditions, which are heterogeneous in large urban areas of low-income and middle-income countries. In this paper, we analyse mobility changes following the implementation of containment measures in Bogotá, Colombia. We characterise the mobility network before and during the pandemic and analyse its evolution and changes between January and July 2020. We observe a general reduction in mobility trends, but the overall connectivity between different areas of the city remains after the lockdown, reflecting the resilience of the mobility network. Then, we estimate a gravity model to assess the effect of socioeconomic conditions on mobility flows. We find that the responses to lockdown policies depend on the socioeconomic conditions of the population. Before the pandemic, the population with better socioeconomic conditions shows higher mobility flows. Since the lockdown, mobility presents a general decrease, but the population with worse socioeconomic conditions shows lower reductions in mobility flows. We conclude by deriving policy implications.
Experimental investigation on the single event gate rupture and hardening of the 600 V trench IGBT
Authors: Wei Zhichao , Zhang Hongwei , Sun Yi , Wu Wangran , Luo Lei , Yu Qingkui , Tang Min
Published: April 2021

In this paper, a single particle irradiation experiment is performed on the 600 V trench insulated gate bipolar transistor for the first time. The experimental results show that, at the collector voltages of 100 V and 300 V, single event gate rupture occurs in the device under the linear energy transfer of 81.35 MeV cm2/g. The damage occurs in the gate oxide layer near the bottom of the trench gate. The simulation results show that the holes accumulated at the bottom of the trench gate increase the electric field under irradiation, which causes the failure of the gate oxide. Furthermore, the hardening device structure is proposed by increasing the thickness of the bottom gate oxide.
Coupled optical and thermal simulation of the thermal performance of a 50 MWe external cylindrical solar receiver
Authors: Zhou Hao , Zuo Yuhang , Zhou Mingxi , Li Yawei
Published: April 2021

The performance of the central receiver is directly related to the efficiency and power generation capacity of the solar tower power plant. In this paper, by combining the analytical approximation method and the finite volume method, the coupled optical and thermal performance of a 50 MWe external cylindrical receiver was numerically evaluated. The thermal performance of the receiver under design parameters was first simulated, and the model was verified by the comparison with the method in Zhou et al. [Renewable Energy 164, 331–345 (2021)]. The effects of key parameter and uniformity of incident flux distribution on the thermal performance were then extensively investigated. Finally, the thermal performance changes in one day were explored. The results showed that direct normal radiation (DNI), salt inlet mass flow, salt inlet temperature, and coating absorption rate strongly affected the receiver's thermal performance. Compared with the non-uniform incident flux distribution, the accurate salt outlet temperature could also be obtained under the uniform incident flux distribution, but the thermal efficiency was underestimated by 0.5%, and the wall temperature on the front side of the tube was generally underestimated, reaching 5.6% at the location of the maximum wall temperature. Evolution trend of the salt outlet temperature and maximum wall temperature on vernal equinox was similar to that of the DNI distribution. From 14:00 to 18:00, they decreased by 18.3% and 12.3%, respectively. The maximum wall temperature from 13:00 to 16:00 exceeded the design value of 700 °C, which was detrimental to the safe operation of the receiver and might cause decomposition of molten salt in the tube.
Dual artificial intelligence methods-based analysis of the impact of domain oscillations on functions of ficin protein
Authors: Nishiyama Katsuhiko
Published: April 2021

Thermal oscillations observed in proteins are acknowledged as essential to managing the biological capabilities of this complex molecule. However, their behavior and characteristics are yet to be clarified. In this research, affinities of tetrapeptides in active areas of ficin, where domain oscillations were observed, were analyzed using dual artificial intelligence methods and computer simulations. The results show that the oscillations were able to handle temporal alteration of their affinities in its active areas. Moreover, it was inferred that the improvement in the flexibility of the β strand between the domains would enhance the oscillations and reduce the optimal temperature. Finally, the decision tree presented important attributes that would play key roles in molecular design.
Phases competition in half-doped La0.5-xDyxCa0.5-ySryMnO3 films
Authors: Tang Y. F. , Zhang A. M. , Wu X. S. , Zhai Z. Y.
Published: April 2021

This paper reports the effects of substrate-induced strain on the high-quality La0.5-xDyxCa0.5-ySryMnO3 (0≤x≤0.2) (LDCSMO) films grown on (00l) SrTiO3 (STO) substrate. LDCSMO films were epitaxially grown on the STO substrate along [001] direction. The lattice parameter c of the film increases relatively with the thickness increasing, and the in-plane tensile strain was controlled by varying the film thickness. The Raman results at room temperature show that the in-plane Mn-O bond stretching and MnO6 distortion were suppressed by the in-plane tensile strain with the thickness of film decreasing. The magnetic results show that the CO-AFM insulating phase and the weak FM phase coexist at low temperature, and spin-glass effect was found in all films. The ferromagnetic order and insulating state were enhanced by tensile strain in thinner film. This abnormal enhancement of insulating state may be ascribed to the disordering state due to the stronger FM and AFM competition and the dominated “dead layer” in thinner film. The improved FM ordering is resulted from the increased double-exchange interaction for the MnO6 distortion suppressed by the in-plane tensile strain in thinner film. These results indicate spin-phonon coupling could be manipulated by controlling strain in manganese oxide films.
Deletion mutation within the goat
Authors: Bai Yangyang , Li Jie , Zhu Haijing , Liu Jinwang , Dong Shuwei , Li Longping , Qu Lei , Chen Hong , Song Xiaoyue , Lan Xianyong
Published: April 2021

The protein phosphatase 3 catalytic subunit α (PPP3CA) gene is a high reproduction traits candidate gene for goats as revealed by a genome-wide association study. The aim of this work was to explore the genetic variations of the goat PPP3CA as well as to evaluate the genetic effects on litter size. Three novel insertions/deletions (indels) within the goat PPP3CA were found and their minor allelic frequencies (MAF) were 0.105, 0.066, and 0.042, respectively. The results showed that only the 20 bp indel polymorphism was significantly associated with litter size in Shaanbei white cashmere goats (P < 0.05) and individuals with deletion/deletion (DD) genotypes demonstrated the junior phenotypes when compared with those with other genotypes. These findings suggested that the 20 bp indel is a potential DNA marker for selecting superior individuals in marker-assisted selection for breeding concerning fecundity in goats.
Scalable deep learning to identify brick kilns and aid regulatory capacity
Authors: Lee Jihyeon , Brooks Nina R. , Tajwar Fahim , Burke Marshall , Ermon Stefano , Lobell David B. , Biswas Debashish , Luby Stephen P.
Published: April 2021

Significance

Monitoring compliance with environmental regulations is a global challenge. It is particularly difficult for governments in low-income countries, where informal industry is responsible for a large amount of pollution, because the governments lack the ability to locate and monitor large numbers of dispersed polluters. This study demonstrates an accurate, scalable machine-learning approach for identifying brick kilns, a highly polluting informal industry in Bangladesh, in satellite imagery. Our data reveal widespread violations of the national regulations governing brick manufacturing, which has implications for the health and well-being of the country. Our approach offers a low-cost, replicable method for regulatory agencies to generate information on key pollution sources.
Communication-efficient federated learning
Authors: Chen Mingzhe , Shlezinger Nir , Poor H. Vincent , Eldar Yonina C. , Cui Shuguang
Published: April 2021

Significance

Federated learning (FL) is an emerging paradigm that enables multiple devices to collaborate in training machine learning (ML) models without having to share their possibly private data. FL requires a multitude of devices to frequently exchange their learned model updates, thus introducing significant communication overhead, which imposes a major challenge in FL over realistic networks that are limited in computational and communication resources. In this article, we propose a communication-efficient FL framework that enables edge devices to efficiently train and transmit model parameters, thus significantly improving FL performance and convergence speed. Our proposed FL framework paves the way to collaborative ML in large-scale networking systems such as Internet of Things networks.
Impact of land use and land cover changes on carbon storage in rubber dominated tropical Xishuangbanna, South West China
Authors: Sarathchandra Chaya , Alemu Abebe Yirga , Worthy Fiona Ruth , Lakmali Wijerathne Iresha , Ma Huaixia , Yingfeng Bi , Jiayu Guo , Chen Huafang , Yan Qiaoshun , Geng Yanfei , Weragoda Dayani S. , Li Li-Li , Fengchun Yang , Wickramasinghe Sriyani , Xu Jianchu
Published: April 2021

Land use and land cover (LULC) play a significant role in carbon regulation. South-China accounts for ~65% of China’s carbon sink. In Xishuangbanna (South-China), rubber is expanding rapidly creating an urgent need to understand and monitor LULC change and how spatial variation affects carbon storage (CS). This is vital for the formation and implementation of better land use management practices. We studied LULC changes of 22-year period; addressing how these changes have affected the CS. We quantified LULC changes between1988 and 2010 using remote sensing methods and calculated CS changes using InvEST. Results showed that between 1988 and 2010, the rate of deforestation accelerated to 203.2 km
2
 y
−1
 and ~23% of forest were lost. Conversion of natural forest to rubber was responsible for 78% of this deforestation. Rubber expansion rate was 153.4 km
2
 y
−1
. Changes to LULC drove a temporal CS reduction 0.223 Tg C/km
2
. Local stakeholders have strong economic interest in converting land to more profitable plantations. Government efforts is required to control land conversion through new policies and incentives to retain natural forest. Assessment of specific potential land use change will be required to avoid promoting the conversion of high carbon storage land uses to low carbon storage land uses.
Distance sensor with a tunable aperture actuated by thermal expansion of silicon chevron beams
Authors: Hong Chong Ho , Kim Hyeon Cheol , Jatmiko Wisnu , Kurnianingsih  , Chun Kukjin , Park Byung-Gook
Published: April 2021

To measure the distance of an object, we propose a distance sensor that combines a tunable aperture operated by the thermal expansion of silicon chevron beams with a commercial camera similar to the automotive black box. The distance sensor is composed of a tunable aperture, a lens with an 8 mm focal length, and a 1/4-inch full high definition image sensor, where a tunable aperture is attached to the camera lens. To estimate the distance to the object, the blur difference is expressed in the form of a depth map using the depth from defocus algorithm. The mean error of distance estimation was 0.29 m. The area of the tunable aperture in the distance sensor is 1.18 mm2 at OFF state and 2.79 mm2 when the voltage is applied. The distance sensor can display an image and a distance simultaneously and can be applied to autonomous vehicles, drones, and robots.
Operando SAXS study of a Pt/C fuel cell catalyst with an X-ray laboratory source
Authors: Schröder Johanna , Quinson Jonathan , Kirkensgaard Jacob J K , Arenz Matthias
Published: April 2021

Small-angle X-ray scattering (SAXS) is a powerful technique to investigate the degradation of catalyst materials. Ideally such investigations are performed operando, i.e. during a catalytic reaction. An example of operando measurements is to observe the degradation of fuel cell catalysts during an accelerated stress test (AST). Fuel cell catalysts consist of Pt or Pt alloy nanoparticles (NPs) supported on a high surface area carbon. A key challenge of operando SAXS measurements is a proper background subtraction of the carbon support to extract the information of the size distribution of the Pt NPs as a function of the AST treatment. Typically, such operando studies require the use of synchrotron facilities. The background measurement can then be performed by anomalous SAXS or in a grazing incidence configuration. In this work we present a proof-of-concept study demonstrating the use of a laboratory X-ray diffractometer for operando SAXS. Data acquisition of operando SAXS with a laboratory X-ray diffractometer is desirable due to the general challenging and limited accessibility of synchrotron facilities. They become even more crucial under the ongoing and foreseen restrictions related to the COVID-19 pandemic. Although, it is not the aim to completely replace synchrotron-based studies, it is shown that the background subtraction can be achieved by a simple experimental consideration in the setup that can ultimately facilitate operando SAXS measurements at a synchrotron facility.
Obtaining impact ionization-induced hole current by electrical measurements in gallium nitride metal–insulator–semiconductor high electron mobility transistors
Authors: Yeh Yu-Hsuan , Chang Ting-Chang , Huang Wei-Chen , Zheng Hao-Xuan , Tsao Yu-Ching , Ciou Fong-Min , Lin Yu-Shan , Tan Yung-Fang , Sun Li-Chuan , Zhou Kuan-Ju , Chen Kuan-Hsu , Huang Jen-Wei
Published: April 2021

In this paper, an extraction method for measuring impact ionization-induced hole current in gallium nitride (GaN) metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) is proposed. The results show that the non-monotonic impact ionization current characteristic can be easily acquired by the extraction method. Further, different hot-carrier stress (HCS) conditions can be obtained based on the I
G–V
G curve, and the reliability tests can act as verification of the impact-ionization curve. In addition, electrical reliability tests indicate that the threshold voltage (V
TH) shift and on-state current (I
on) degradation in the MIS-HEMTs have a positive correlation to impact ionization-generated hole current. During HCS operation, the V
TH will shift positively and I
on decreases due to hot electrons trapping into the GaN layer. This model is validated by TCAD simulation.
Morphology-dependent catalytic activity of tungsten trioxide (WO3) nanostructures for hydrogenation of furfural to furfuryl alcohol
Authors: Ali Wesam A , Bharath G , Morajkar Pranay P , Salkar Akshay V , Haija Mohammad Abu , Banat Fawzi
Published: April 2021

The development of effective and low-cost catalysts for the hydrogenation and stabilization of bio-oils is still a challenge that needs to be overcome. Several nanostructured WO3 catalysts were synthesized in this study to investigate the effect of their morphology on their catalytic activity and selectivity for the hydrogenation of biomass-derived compounds such as furfural (FF). The morphology of the catalysts was tuned via a surfactant-assisted hydrothermal process. Nanorod and nanoprism WO3 catalysts were produced using dodecyl dimethylammonium bromide (DAB) and poly (ethylene-alt-maleic anhydride), respectively, while WO3 nanocubes were produced without the use of surfactants. Various analytical techniques were used to characterize the morphology of the synthesized WO3 catalyst. Furthermore, the hydrogenation of FF was used as a probe reaction to evaluate the catalytic performance of the WO3 nanostructures. Notably, DAB-assisted WO3 nanorods (D-WO3) exhibited a relatively high furfuryl alcohol (FFA) selectivity of 85% with an FF conversion of 52% at 100 °C, under 10 bar of H2 pressure over a reaction time of 120 min. A plausible route for the hydrogenation of FF into FFA and other products over D-WO3 nanocatalyst was illustrated. The D-OW3 nanocatalyst’s promising results indicate that it could be a viable, low-cost, and efficient alternative catalyst for hydrogenating FF into FFA.
Recent development in friction of 2D materials: from mechanisms to applications
Authors: Guo Yanbao , Zhou Xuanli , Lee Kyungjun , Yoon Hyun Chul , Xu Quan , Wang Deguo
Published: April 2021

Two-dimensional (2D) materials with a layered structure are excellent candidates in the field of lubrication due to their unique physical and chemical properties, including weak interlayer interaction and large specific surface area. For the last few decades, graphene has received lots of attention due to its excellent properties. Besides graphene, various new 2D materials (including MoS2, WS2, WSe2, NbSe2, NbTe2, ReS2, TaS2 and h-BN etc.) are found to exhibit a low coefficient of friction at the macro- and even micro-scales, which may lead to widespread application in the field of lubrication and anti-wear. This article focuses on the latest development trend in 2D materials in the field of tribology. The review begins with a summary of widely accepted nano-scale friction mechanisms contain surface friction mechanism and interlayer friction mechanism. The following sections report the applications of 2D materials in lubrication and anti-wear as lubricant additives, solid lubricants, and composite lubricating materials. Finally, the research prospects of 2D materials in tribology are presented.
Nitrogen-doped graphene supported Ni as an efficient and stable catalyst for levulinic acid hydrogenation
Authors: Ding Qianqian , Wang Yuan , Ma Liang
Published: April 2021

Transforming levulinic acid (LA) to γ-valerolactone (GVL) is a significant route for converting biomass into valuable chemicals. The development of an efficient and robust heterogeneous catalyst for this reaction has aroused great interest. In this work, nitrogen-doped graphene (NG) supported nickel (Ni) based heterogeneous catalyst with excellent activities was successfully synthesized. The Ni/NG catalyst shows outstanding performance for hydrogenation of LA to GVL at a relatively low temperature of 140 °C, which is superior to most of reported heterogeneous catalysts. Further investigations indicate Ni nanoparticles are the active sites and the NG also plays an indispensable role. The catalytic performance is highly depended on the crystallinity, particles sizes and electronic structure of Ni in Ni/NG catalyst, which can be optimized by nitrogen doping. This work affords a new route for designing robust and excellent heterogeneous catalysts by doping method to optimize the support.
A note on the overall efficiency of back-to-back Carnot cycles
Authors: Reed B Cameron
Published: April 2021

The overall efficiency of a reversible thermodynamic cycle comprising steps around the periphery of back-to-back Carnot cycles is equal to the efficiency-weighted average heat-energy inputs taken over all of the cycles. A proof of this assertion is straightforward and brief enough to be suitable for classroom presentation.
Multi-level aggregation of conjugated small molecules and polymers: from morphology control to physical insights
Authors: Li Qi-Yi , Yao Ze-Fan , Wang Jie-Yu , Pei Jian
Published: April 2021

Aggregation of molecules is a multi-molecular phenomenon occurring when two or more molecules behave differently from discrete molecules due to their intermolecular interactions. Moving beyond single molecules, aggregation usually demonstrates evolutive or wholly emerging new functionalities relative to the molecular components. Conjugated small molecules and polymers interact with each other, resulting in complex solution-state aggregates and solid-state microstructures. Optoelectronic properties of conjugated small molecules and polymers are sensitively determined by their aggregation states across a broad range of spatial scales. This review focused on the aggregation ranging from molecular structure, intermolecular interactions, solution-state assemblies, and solid-state microstructures of conjugated small molecules and polymers. We addressed the importance of such aggregation in filling the gaps from the molecular level to device functions and highlighted the multi-scale structures and properties at different scales. From the view of multi-level aggregation behaviors, we divided the whole process from the molecule to devices into several parts: molecular design, solvation, solution-state aggregation, crystal engineering, and solid-state microstructures. We summarized the progress and challenges of relationships between optoelectronic properties and multi-level aggregation. We believe aggregation science will become an interdisciplinary research field and serves as a general platform to develop future materials with the desired functions.
Data-driven sliding mode control of shape memory alloy actuators with prescribed performance
Authors: Liu Mingfang , Zhao Zhirui , Hao Lina
Published: April 2021

This paper proposes a data-driven sliding mode control (SMC) method with tracking error constraint for a shape memory alloy (SMA) actuated system. More specifically, a new SMC method with prescribed performance is investigated by adopting the equivalent dynamic linearization technique and a novel transformed error algorithm to guarantee that the tracking error can converge into a preassigned region. Meanwhile, the proposed control method can effectively ensure the convergence rate and the steady-state error within a prescribed bound, merely depending on the input/output data without implicit or explicit information of the systems, which is more valuable for the practical application. The presented control method has been implemented on an SMA actuated system successfully and experimental results have shown that the proposed control is easily applicable and highly precise. In addition, the tracking error of the SMA actuated system can be constrained in a preassigned domain by the proposed control method.
Analytical modeling of one-dimensional resonant asymmetric and reciprocal acoustic structures as Willis materials
Authors: Groby Jean-Philippe , Malléjac Matthieu , Merkel Aurélien , Romero-García Vicente , Tournat Vincent , Torrent Daniel , Li Jensen
Published: April 2021

As building blocks of acoustic metamaterials, resonant scatterers have demonstrated their ability to modulate the effective fluid parameters, which subsequently possess extreme properties such as negative bulk modulus or negative mass density. Promising applications have been shown such as extraordinary absorption, focusing, and abnormal refraction for instance. However, acoustic waves can be further controlled in Willis materials by harnessing the coupling parameters. In this work, we derive the closed forms of the effective parameters from the transfer matrix in three asymmetric and reciprocal one-dimensional resonant configurations and exhibit the differences in terms of coupling coefficients. The way in which Willis coupling occurs in spatially asymmetric unit cells is highlighted. In addition, the analysis shows the absence of odd Willis coupling for reciprocal configurations. These effective parameters are validated against experimental and numerical results in the three configurations. This article paves the way of a novel physical understanding and engineering use of Willis acoustic materials.
Quantum manipulation through finite fluctuations for a generalized parametric oscillator using a lie algebra representation
Authors: Beus T , Van Huele J F , Berrondo M
Published: April 2021

In this paper, we focus on the effects of temporally compact fluctuations on the parameters m(t) (mass),

ω
(
t
)

(frequency), and

γ
(
t
)

(spatial dilation coefficient), for the generalized Caldirola-Kanai Hamiltonian. We propose an algorithm such that given control over the timing of repeated compact fluctuations, one can produce any time-evolution associated with complete parameter control of the generalized Caldirola-Kanai Hamiltonian. Computational simplicity is achieved in this endeavor using a faithful representation of the Hamiltonian’s associated Lie algebra. Further simplification occurs as a result of using unitarity conditions for the time-evolution operator. We apply our analysis to the effects of Dirac delta fluctuations in mass and frequency, both separately and simultaneously. We also numerically demonstrate control of the generalized Caldirola-Kanai system for the case of timed Gaussian fluctuations in the mass term. Furthermore, we use the faithful Lie algebra representation to show that any unitary evolution of this generalized Caldirola-Kanai system is given by the squeeze operator multiplied with a phase factor. We also show that the classical evolution of a probabilistic Gaussian phase space distribution and the evolution of the Wigner function of a coherent state in the quantum Caldirola-Kanai system are identical.
Study of engine-oil based CNT nanofluid flow on a rotating cylinder with viscous dissipation
Authors: Khan Masood , Sarfraz Mahnoor , Ahmed Awais , Malik M Y , Alqahtani Ali S
Published: April 2021

An axisymmetric viscous carbon nanotube (CNT) nanofluid flow exterior to a rotating circular cylinder of radius a
0 along with viscous dissipation and magnetohydrodynamic (MHD) is considered here. The two-phased Buongiorno’s model is employed to observe the thermal energy transport in nanofluid with engine-oil as a background fluid and two distinct nanoparticles, i.e., single-walled (SWCNTs) and multi-walled (MWCNTs). The flow is driven because of the torsional motion and stretching of the cylinder along the z-direction, which constitutes the axial pressure gradient. It is seen that in the presence of a magnetic field, the axially dependent swirling motion of the cylinder creates a light transverse flow in the meridional plane, which is the principal cause for the wall jet phenomenon on the axial axis. The function computing the numerical solution is bvp5c, which is available in Matlab®. It is noted that for both SWCNTs/MWCNTs cases, thermal and mass transport coefficients are decreasing function of Prandtl and Schmidt numbers, respectively. However, they are augmented due to the presence of strong Lorentz force. The values for wall stress parameters (WSPs) are determined as a function of a magnetic parameter for 0.01 ≤ Re ≤ 102 (where Re is Reynolds number). It is also perceived that the axial WSP decreases due to an increase in values of Re, but an increase in numerical values of azimuthal WSP and Nusselt number is noticed.
Computational analysis of fuzzy fractional order non-dimensional Fisher equation
Authors: Ahmad Shabir , Ullah Aman , Ullah Abd , Akgül Ali , Abdeljawad Thabet
Published: April 2021

In recent decades, fuzzy differential equations of integer and arbitrary order are extensively used for analyzing the dynamics of a mathematical model of the physical process because crisp operators of integer and arbitrary order are not able to study the model being studied when there is uncertainty in values used in modeling. In this article, we have considered the time-fractional Fisher equation in a fuzzy environment. The basic aim of this article is to deduce a semi-analytical solution to the fuzzy fractional-order non-dimensional model of the Fisher equation. Since the Laplace-Adomian method has a good convergence rate. We use the Laplace- Adomian decomposition method (LADM) to determine a solution under a fuzzy concept in parametric form. We discuss the convergence and error analysis of the proposed method. For the validity of the proposed scheme, we provide few examples with detailed solutions. We provide comparisons between exact and approximate solutions through graphs. In the end, the conclusion of the paper is provided.
Perturbations in a scalar field model with virtues of ΛCDM
Authors: Sinha Srijita , Banerjee Narayan
Published: April 2021

In the era of precision cosmology, the cosmological constant Λ gives quite an accurate description of the evolution of the Universe, but it is still plagued with the fine-tuning problem and the cosmic coincidence problem. In this work, we investigate the perturbations in a scalar field model that drives the recent acceleration in a similar fashion that the cosmological constant does and has the dark energy (DE) density comparable to the dark matter (DM) energy density at the recent epoch starting from arbitrary initial conditions. The perturbations show that this model, though it keeps the virtues of a ΛCDM model, has a distinctive qualitative feature, particularly it reduces the amplitude of the matter power spectrum on a scale of 8 h-1 Mpc, σ8 at the present epoch.
Neutrino-assisted early dark energy: theory and cosmology
Authors: Carrillo González Mariana , Liang Qiuyue , Sakstein Jeremy , Trodden Mark
Published: April 2021

The tension between measurements of the Hubble constant obtained at different redshifts may provide a hint of new physics active in the relatively early universe, around the epoch of matter-radiation equality. A leading paradigm to resolve the tension is a period of early dark energy, in which a scalar field contributes a subdominant part of the energy budget of the universe at this time. This scenario faces significant fine-tuning problems which can be ameliorated by a non-trivial coupling of the scalar to the standard model neutrinos. These become non-relativistic close to the time of matter-radiation equality, resulting in an energy injection into the scalar that kick-starts the early dark energy phase, explaining its coincidence with this seemingly unrelated epoch. We present a minimal version of this neutrino-assisted early dark energy model, and perform a detailed analysis of its predictions and theoretical constraints. We consider both particle physics constraints — that the model constitute a well-behaved effective field theory for which the quantum corrections are under control, so that the relevant predictions are within its regime of validity — and the constraints provided by requiring a consistent cosmological evolution from early through to late times. Our work paves the way for testing this scenario using cosmological data sets.
Steady-state teleportation fidelity and Bell nonlocality in dissipative environments
Authors: Xie Yu-Xia
Published: April 2021

We investigate quantum teleportation and Bell nonlocality for two channel qubits coupled via the Heisenberg interaction and subject to two independent dissipative environments. Compared with the case of two uncoupled qubits, it is shown that the interaction Hamiltonian is beneficial for enhancing the teleportation fidelity and Bell nonlocality, and remarkably, it can also be used to create nonclassical teleportation fidelity and Bell nonlocality even from the initial product states. Moreover, the interaction Hamiltonian guarantees the generation of steady-state nonclassical teleportation fidelity, which is independent of the initial state and therefore one can take any state as the initial channel state.
A secure image protection algorithm by steganography and encryption using the 2D-TSCC*
Authors: Li Qi , Wang Xingyuan , Wang He , Ye Xiaolin , Zhou Shuang , Gao Suo , Shi Yunqing
Published: April 2021

Based on the two-dimensional (2D) tan-sin-cos-coupling (2D-TSCC), a new image protection method is designed, this method includes steganography and encryption. First, a 2D-TSCC system is designed. The 2D-TSCC has a large parameter space in a hyperchaotic state. The chaotic trajectory fills the entire window. The chaotic sequence generated by the 2D-TSCC has a good pseudorandomness, so it can be used in steganography and encryption. Then, the amount of information contained in each bit of the cover image is analyzed, and the three bits which carry the least amount of information are selected. The secret image is hidden in these three bits base on the 2D-TSCC. Finally, the carrier image is scrambled and diffused by the 2D-TSCC. The ciphertext is generated in this way. Send the ciphertext to the recipient through channel transmission, and the recipient obtains the secret image by decrypting twice.
Magnetic impurity in hybrid and type-II nodal line semimetals*
Authors: Yang Xiao-Rong , Huang Zhen-Zhen , Wang Wan-Sheng , Sun Jin-Hua
Published: April 2021

We study the Kondo screening of a spin-1/2 magnetic impurity in the hybrid nodal line semimetals (NLSMs) and the type-II NLSMs by using the variational method. We mainly study the binding energy and the spin–spin correlation between magnetic impurity and conduction electrons. We find that in both the hybrid and type-II cases, the density of states (DOS) is always finite, so the impurity and the conduction electrons always form bound states, and the bound state is more easily formed when the DOS is large. Meanwhile, due to the unique dispersion relation and the spin–orbit couplings in the NLSMs, the spatial spin–spin correlation components show very interesting features. Most saliently, various components of the spatial spin–spin correlation function decay with 1/r
2 in the hybrid NLSMs, while they follow 1/r
3 decay in the type-II NLSMs. This property is mainly caused by the special band structures in the NLSMs, and it can work as a fingerprint to distinguish the two types of NLSMs.