bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of dynamics of the population inversion in attosecond pulse amplification in the active medium of a plasma-based X-ray laser dressed by an optical laser field
Authors: Antonov V. A. , Khairulin I. R. , Ryabikin M. Yu. 
Published: December 2020

Abstract
We study the role of dynamics of the population inversion of an active medium of an X-ray laser dressed by a strong infrared (IR) laser field in the amplification of an attosecond pulse train produced via high-harmonic (HH) generation by the same IR field. We derive an analytical solution for the case of a recombination hydrogen-like X-ray laser, which shows that the time dependence of the population inversion strongly affects the level of the HH amplification and the envelope of the amplified attosecond pulse train. The possibilities for experimental implementation are discussed for the case of C5+ X-ray laser with the transition wavelength ∼ 3.4 nm in the “water window” range.
Superluminal phase velocity approach for suppression of Numerical Cherenkov Instability in Maxwell solver
Authors: Samsonov A , Pukhov A , Kostyukov I 
Published: December 2020

Abstract
A modification of a standard finite-difference time-domain (FDTD) Maxwell solver is proposed based on the inclusion of the terms of the higher order in the finite differences approximation. By selecting the coefficients of this hybrid scheme the numeric dispersion of the electromagnetic waves can be fine-tuned. It is shown that a particular choice of the coefficients leads to the phase velocity of all the waves being slightly larger than speed of light. Results of the 3D Particles-In-Cells (PIC) simulations demonstrate that the proposed scheme of the Maxwell solver is efficient to mitigate the Numerical Cherenkov Instability (NCI) when simulating ultrarelativistic charged beams.
Clock transition excitation efficiency determination using an additional short clock π-pulse
Authors: Provorchenko D , Mishin D , Fedorova E , Tregubov D , Golovizin A , Sorokin V , Khabarova K , Kolachevsky N 
Published: December 2020

Abstract
We demonstrate a simple and efficient readout procedure of the 1.14^m clock transition excitation efficiency in neutral thulium atoms. Our method utilizes additional but short clock n-pulse to measure number of atoms excited by spectroscopic clock pulse, that allows to determine excitation probability insensitive to fluctuation of number of atoms in the trap. It is important that this method can be used for both hyperfine components of the clock transition and does not require any additional lasers in the setup.
Resonant signal transmission in optical structures with periodical profile of permittivity
Authors: Bogatskaya A V , Nikiforova P M , Popov A M 
Published: December 2020

Abstract
We consider a general physical approach to enhance the efficiency of terahertz bolometric detectors. The approach is based on the concept of resonant tunneling of an electromagnetic wave which is similar to quantum particle tunneling in quantum mechanics. Placing resonator under nontransparent conductive layer (plasma, metal or superconductor) helps to increase under certain conditions the field intensity both beyond the nontransparent layer and within it, thus enhancing the detection efficiency. If the frequency of the incident radiation matches with one of the eigenfrequencies of a resonator the effect of resonant tunneling through the conducting layer can be observed. Replacing single resonator with a resonator sequence separated with conductive layers result in formation of an absorption band instead of one resonant frequency. The calculations have shown that absorption of up to 60% of the energy of the THz pulses can be easily achieved in the considered structures even at the detection of broadband radiation.
Numerical simulations of the polarization-sensitive response in nanospikes array
Authors: Busleev N. I. , Kudryashov S. I. , Saraeva I. N. , Danilov P. A. , Rudenko A. A. , Zayarny D. A. , Ionin A. A. , Minh P. H. 
Published: December 2020

Abstract
In experimental backscattering spectra of a gold film were found resonances which may reveal features of the film inner structure. The explanation of these features based on the analysis of the structure’s unit cell and its response to laser radiation was proposed.
Ultrafast electron dynamics and energy deposition during IR-visible femtosecond laser ablation of fluorite
Authors: Danilov P A , Galkin M L , Kovalev M S , Rupasov A E , Smayev M P , Zolot’ko A S , Ionin A A , Kudryashov S I , Zakoldaev R A 
Published: December 2020

Abstract
The action of ultrashort laser pulses on dielectrics leads to the processes of redistribution of the laser pulse energy in the interaction region. The mechanisms of ultrafast energy deposition and the electron dynamics under the action of ultrashort laser pulses determine the type of final structures or elements in the transparent dielectrics. One type of these elements is a birefringent nanogratings formed with an orientation perpendicular to the laser radiation. In this work, laser-induced birefringent structures in calcium fluoride (CaF2) bulk were obtained under the action of tightly-focused laser pulses with durations 0.3-3.8 ps and wavelengths of 515 and 1030 nm. Birefringence in modified region was analyzed using polarization contrast optical microscope with Abrio imaging system.
Comparative study of low-order harmonic generation in gas and cluster media at Ti:Sa femtosecond laser intensity up to 2000 TW/cm2
Authors: Zhvaniya I A , Dzhidzhoev M S , Semenov T A , Savel’ev A B , Stremoukhov S Y , Usmanov T , Gordienko V M 
Published: December 2020

Abstract
In comparative experiments, it was found that the maximum efficiency of third harmonic generation (THG) in cluster nanoplasma was ∼9x10−5 and was approximately 4 times less effective than the case of THG in gas under similar experimental conditions. This result is consistent with theoretical calculations and show that THG amplitude in a gas is about an order of magnitude higher than in a cluster medium. The discrepancy between the THG efficiency in gas and clusters obtained theoretically and experimentally in discussed.
Numerical modeling of pulse-pumped ultrafast regenerative amplifier with unstable pump laser
Authors: Kostryukov P V , Cheshev E A 
Published: December 2020

Abstract
A numerical model of a regenerative amplifier based on the Frantz-Nodvik equation with spatially dependent stored energy density in the active medium has been developed. The model was used to investigate the stability of the output energy of the amplifier associated with fluctuations of the pump energy and pump beam position. It was found that, same as in the known case with the fluctuations of the pump energy, the influence of the fluctuations of the pump beam position is much weaker at oversaturated operation of the regenerative amplifier. Opposite to fluctuations of the pump energy, fluctuations of the pump beam position result in highly-asymmetric histogram of the output energy, which is highly skewed to the lower energies.
Painlevé type reductions for the non-Abelian Volterra lattices
*
Authors: Adler V E 
Published: December 2020

Abstract
The Volterra lattice admits two non-Abelian analogs that preserve the integrability property. For each of them, the stationary equation for non-autonomous symmetries defines a constraint that is consistent with the lattice and leads to Painlevé-type equations. In the case of symmetries of low order, including the scaling and master-symmetry, this constraint can be reduced to second order equations. This gives rise to two non-Abelian generalizations for the discrete Painlevé equations and and for the continuous Painlevé equations P3, and P5.
Characteristics of visiting urban open spaces in Sana’a city in Yemen
Authors: Alwah A A Q , Li W , Al-Attar A N M 
Published: December 2020

Abstract
Knowledge of the characteristics of visiting and using urban open spaces is the key to the effective design, development, and management of these spaces. Although research has conducted many studies related to the use and importance of urban environments in Europe, America, Australia, China, and some East Asian countries, there is a lack in such studies in the Middle East, especially in Yemen. This study covers a part of the knowledge gap by verifying the characteristics of visiting and using three selected open spaces in Sana’a city in Yemen through self-reporting of the users of these spaces. The study shows that Yemenis go to open spaces for recreation, family seating, playing with children, and walking. Furthermore, users prefer spaces that provide appropriate and adequate seating areas, various and modern entertainment facilities, a high level of hygiene and maintenance, and safe spaces that are free from intruders. This knowledge benefits the urban designers and developers in Yemen to rehabilitate degraded open areas and design new public spaces.
Simulation study on performance of plate heat exchanger for heat pump
Authors: Yuqing Zhao , Jianfeng Shao , Yun Dai , xin Yang , jiayu Deng 
Published: December 2020

Abstract
For the plate heat exchanger of heat pump system, the convection heat transfer correlation of condenser and evaporator was used to simulate the heat transfer of heat exchanger, and the experimental test of heat exchanger was carried out in the heat pump system. The numerical simulation results were compared with the experimental results. The results show that the average error between the numerical simulation results of condenser and evaporator and the experimental results are 5.75% and 1.13% respectively, which proves that the simplified hypothesis, the heat transfer model and the solution method used in the numerical simulation are reasonable for the evaporation and condensation process of plate heat exchanger for heat pump.
Research on Planning and Design of Resident-Friendly Community Parks: Taking the Huapu Park of Jinan City as an Example
Authors: Deyi Kong , Cheng Li 
Published: December 2020

Abstract
The outbreak of the novel coronavirus pandemic in early 2020 has raised people’s concern about living and ecological problems in densely populated cities. Community parks turn into the most accessible ecological green spaces shared by the public. Through questionnaires, this paper surveys the functional zones, cultivation of vegetation and public utilities of the Huapu Park which is situated in Jingshi Road, Jinan City. The purpose is to explore the improvement of landscape planning when community parks play a role in emergency and disaster prevention, and interactive participation, so as to provide constructive suggestions for the building of resident-friendly community parks.
Research on the Optimal Spacing of Urban Environmental Sanitation Facilities: Smoke-extinguishing Pillar as an Example
Authors: Li Yong , Zhou Cheng , Lu Haixiang , Xu Han , Li Gang 
Published: December 2020

Abstract
Since the spacing of urban environmental sanitation facilities is not reasonable enough, customers and service desks in the queuing theory were used to simulate the environmental sanitation facilities and pedestrians in daily life, and the established queuing system was then optimized based on the purpose of minimum costs. This optimization model was used to determine the optimal spacing of the sanitation facilities for street-like linear sites, and quantify the positive and negative utility of whether garbage is thrown into the sanitation facilities. Moreover, the optimal spacing of the sanitation facilities on street-like linear places was calculated according to the coefficient “k” and the maximum tolerable distance “s” of pedestrians holding a piece of garbage. Moreover, an algorithm for park-like flat sites was provided by establishing a set covering model. Then the maximum tolerable distance of pedestrians holding a piece of garbage was obtained through field research, which was then used in practical calculation. Finally, conclusions and suggestions were given correspondingly.
Analysis of the Causes and Solutions of Apartheid Based on Schelling Model with Welfare Policy
Authors: Pan Jiateng , Yoshikawa Atsushi , Yamamura Masayuki 
Published: December 2020

Abstract
In recent years, with the widespread dissemination of the concept of anti-racial discrimination, various countries have introduced a series of welfare policies for ethnic minorities, trying to control population apartheid to alleviate the generation of racial conflicts, and many achievements have been made. However, apartheid seems to have rebounded recently. This paper proposes the Schelling model with welfare policies to analyze the reasons for the rebound phenomenon and propose possible solutions.
Analysis of The MICE Tourism Research in China in the Last Twenty Years
Authors: Xu Jin , Ruhanen Lisa , Solnet David J. 
Published: December 2020

Abstract
The Meetings, Incentives, Conferences and Exhibitions (MICE) tourism has developed rapidly in China and has become an important tourism product. By use of CiteSpace software, authors performed the scientific measurement and visual analysis of MICE tourism research papers collected in China National Knowledge Infrastructure (CNKI), including the research institutions, important journals, core authors and other external characteristics, and the knowledge graphs of co-occurrence, clustering, burst and time-line of keywords. The results showed that MICE tourism research in China has achieved great progress in the last 20 years. However, these researches generally lack of long-term investigation and cooperation, and the technology and forward-looking are not strong enough. The future research needs to be improved in depth, precision and technology, and sustainable MICE tourism should be regarded as an important concept and goal. The paper provides a new perspective for the scientific observation and analysis of MICE tourism research and development in China.
Evaluation of the EDPs’ Cultural Assimilation Based on Epidemic Model
Authors: Chen Shubai , Sun Shuo 
Published: December 2020

Abstract
In recent UN resolutions, EDPs are defined as refugees. Based on the systematic effects caused by EDPs, we propose an optimization model to predict the number of EDPs and protect the traditional culture of EDPs. Based on the basis of our proposed model, we can demonstrate the importance of the policy proposed based on our model.
Firstly, we use climate phenomena such as sea-level rise and soil desertification to determine the countries at risk. Kiribati and Mongolia are studied in our model. We propose to use the power-law distribution to calculate the number of EDPs in the countries at risk. Through the qualitative analysis, it shows that “national collective migration to countries with similar cultural backgrounds” can effectively reduce the risk of cultural loss.
Secondly, in terms of cultural protection, we use SIS and SEIR infectious disease models to simulate the process of cultural assimilation and budget the time needed for cultural assimilation of EDPs. We also revised the policy according to the index of refugee and the speed of cultural assimilation. (1) international organizations should give appropriate economic assistance to the recipient countries. (2) the recipient country should take strong cultural protection measures when EDPs start to migrate. (3) the recipient country should try its best to provide jobs to EDP without harming the interests of its own people.
Finally, we proposed an optimization model to verify that when the policy is implemented, the cultural protection has been greatly improved. By comparing with the natural state of the policy not adopted, the importance of the optimization model of human rights and cultural protection based on EDPs proposed by us is illustrated.
Study on landscape rheology of architectural cultural heritage in Shandong section of Beijing Hangzhou Grand Canal
Authors: Sui Yanhui , Zhang Jian 
Published: December 2020

Abstract
Architectural heritage is an important part of the cultural heritage of Beijing Hangzhou Grand Canal and an important carrier of historical culture. On the basis of expounding the temporal dynamic pattern of architectural cultural heritage of Beijing Hangzhou Grand Canal, this paper reveals its leading process and main factors. The results show that the time dynamic pattern mainly depends on political, cultural, institutional and economic factors. At the same time, this paper puts forward some innovative strategies for its protection and sustainable development.
CBR-based dynamic decision-making method for emergencies
Authors: Wang Cui , Song Yinghua , Fang Danhui 
Published: December 2020

Abstract
The randomness of emergencies is very important to emergency management, and case-based reasoning has attracted the attention of emergency decision-makers. In order to improve the one-sidedness of the existing emergency decision-making method based on static case-based reasoning, this paper fully considers the development and evolution stage of the event, and proposes a CBR-based dynamic emergency decision-making method. First, the emergency event is decomposed into multiple time stages; then the comprehensive attributes of each stage are determined according to the event description and treatment measures to calculate the attribute similarity; then the case similarity is calculated through the attribute similarity, and the decision-making plan of current event stage is formed by combining the treatment measures of the case with the highest similarity; at the same time, the current decision-making measures are involved in the case reasoning of the next stage. Finally, a high-rise building fire case in the city shows the feasibility of this method.
Applying beacon sensor alarm system for construction worker safety in workplace
Authors: Huang Ying , Fansheng Kong , Yifei He 
Published: December 2020

Abstract
The construction site is one of the most dangerous workplaces among all the industries, workers are exposed to various hazards sources. Ubiquitous accidents occur even with detailed regulations and laws. Situation awareness theory revealed that there are three processes when people are dealing with the changing environment: perception of environmental situation, comprehension of what people are dealing with and decision-making. The likelihood of risky behaviours increases a lot when any of these processes go wrong. In this paper, the author proposed an alarm system to help workers get a better perception of construction site and improve the efficiency and quality of safety management. In this system, a beacon sensor will be deployed on the hazard source and it will keep send Bluetooth package to receiver equipment. Workers will carry the receiver, a BLE sensor, to calculate the distance between people and the hazard point. If the distance is less than the setting number, the sensor will trigger the alarm to broadcast siren and send the unsafety behaviour event to manager backend to archive the entire process.
Assessing temporal and spatial patterns of surface-water quality with a multivariate approach: a case study in Uruguay
Authors: Gorgoglione A , Alonso J , Chreties C , Fossati M 
Published: December 2020

Abstract
The ecological state of inland waters of the Santa Lucía watershed, the primary drinking water source of Uruguay, has raised interest since it presents the seasonal phenomenon of eutrophication. For this reason, an in-depth understanding of the behaviour in time and space of the water-quality variables that characterize this stream is essential. Therefore, this study aims to evaluate the occurrence of spatial and temporal patterns of water-quality variables (Q, turbidity, T, TN, NO3
-, NO2
-, NH4
+, TP, DO, BOD5) in the Santa Lucía Chico watershed with the aid of multivariate statistical tools. The principal component analysis, coupled with k-means cluster analysis, helped to identify a seasonal variation (fall-winter and spring-summer). The hierarchical cluster analysis allowed us to classify the water-quality monitoring stations in three groups in the fall-winter season. The loadings values of the cluster analysis highlighted the most significant pollutants at each monitoring station. The outcomes of this work are expected to contribute valuable knowledge for determining effective management strategies to reduce stream pollution and protect the aquatic ecosystem health of the study area.
Effect of particle size on the physicochemical property of the peel powder from Aloe barbadensis
Authors: Ma L K , Chen K , Tian X F , Gao Y H , Zhang S A , Zhu L X 
Published: December 2020

Abstract

Aloe barbadensis (Aloe vera) has long been used in food, cosmetic and pharmaceutical industries. In order to maximally extract soluble sugars, different drying methods, such as heat-drying (HD), air-drying (AD), vacuum freeze drying (VFD), and microwave drying (MD), on the sugar content were investigated in the present work. Besides, the relationship between the particle size and the physicochemical property of the peel powder obtained by ultramicro-pulverization was also explored. The results showed that different drying method did have significant effect on the soluble sugar content. HD, AD, and VFD possessed similar sugar content (approximately 8.27, 8.46, and 8.46 g/100g, respectively). The highest sugar content was found in MD (9.36 ± 0.30 g/100g), indicating that MD was the most effective way to extract sugars from Aloe vera peel among these four methods. The particle size of the peel power after dried by MD was affected by the crusher time and power. The higher the power, and the longer crusher time, the smaller particle size of the powder. Along with the decreasing of particle size, the color parameter (B value) of the peel powder significantly decreased from 24.47 to 16.90 (P < 0.05). The water holding capacity also decreased when the D (0.5) reduced due to the lower binding capacity of small size particle towards water. As the reduction of D (0.5) value, the water holding capacity decreased (from 6.21% to 3.52%). The present work could provide valuable information for the comprehensive utilization of the by-products of Aloe vera.
Influence of trophic status on zooplankton structure in Chelyabinsk region lakes (Russia)
Authors: Mashkova Irina , Kostryukova Anastasiya , Shchelkanova Elena , Trofimenko Viktor 
Published: December 2020

Abstract
Eutrophication of water-bodies, as well as lakes, is currently one of the crucial problems of both theoretical and applied ecology. Zooplankton is sensitive to changes in the ecological state of different types of reservoirs. The article analyses differences and similarities of zooplankton communities in 10 lakes of Kisegach - Miassovo hydrological system of Chelyabinsk region (Russia). The current research aims at identifying taxonomic structure of zooplankton communities of the lakes in Chelyabinsk region (Russia) and stating the influence of some abiotic factors on its formation. Integrated samples were gathered in summer 2015 - 2019. The given paper studied the correlation of the main taxonomic groups of zooplankton, marked a regular decrease in the number of zooplankton species under adverse environment. When the trophic level of water in natural fresh lakes changes in the direction of oligotrophic-mesotrophic-eutrophic, the total number of zooplankton decreases from 400.90 individuals per L−1 to 106.06 individuals per L−1. In the same direction, the number of Cladocera representatives decreases (from 362.03 individuals per L−1 to 66.34 individuals per L−1) and the number of Copepoda representatives decreases (from 34.01 individuals per L 12.67 individuals per L−1), and the number of Rotifera representatives increases (from 6.97 individuals per L−1 to 26.60 individuals per L−1).