bluuebunny/crossref_metadata_2025 huggingface dataset:
A review on thermal and electrical behaviours of liquid metal-based polymer composites
Authors: Jia Li-Chuan , Yue Yun-Fei , Zeng Jian-Feng , Wang Zhi-Xing , Nie Run-Pan , Xu Ling , Yan Ding-Xiang , Li Zhong-Ming
Published: September 2023

Liquid metals (LM) have attracted tremendous attention in the last decade, especially in the fabrication of LM-based polymer composites (LMPCs), due to the unique combination of their metallic and fluidic properties.
Levels of per- and polyfluoroalkyl substances (PFAS) in various wastewater-derived fertilizers – analytical investigations from different perspectives
Authors: Vogel Christian , Roesch Philipp , Wittwer Philipp , Piechotta Christian , Lisec Jan , Sommerfeld Thomas , Kluge Stephanie , Herzel Hannes , Huthwelker Thomas , Borca Camelia , Simon Franz-Georg
Published: September 2023

Sewage sludge and other fertilizers derived from wastewater contain various per- and polyfluoroalkyl substances (PFAS) and other fluorinated contaminants that can pose a problem for the recovery of phosphorus from wastewater.
ChainKeeper: A cross‐chain scheme for governing the chain by chain
Authors: Xu Yuwei , He Ran , Dai Shengjiang , Zhang Yujian
Published: September 2023

With the rapid application of consortium chains, supervising these systems has become a challenge for governments. The centralized model fails to deliver supervision services that are both open and transparent. Given the benefits of decentralization, non‐tampering, and traceability offered by blockchains, researchers propose the concept of ‘governing the chain by chain’, which involves supervising multiple consortium chains by constructing a blockchain. Under this idea, the cross‐chain scheme becomes the key to achieving excellent supervision. Existing studies have shortcomings and cannot meet the requirements of universality, security, and efficiency in cross‐chain supervision scenarios. Aiming at the challenges, we propose ChainKeeper, a cross‐chain scheme for governing the chain by chain. The innovation of our work lies in three points. First, a modular node proxy program is designed to adapt to various implementations of consortium chains. Second, a verifiable node random selection method is put forward to improve the throughput of cross‐chain data transmission. Finally, a verifiable identity threshold signature method is proposed to prevent the cheating behavior of malicious nodes. To verify the universality of ChainKeeper, we built a prototype system on three types of consortium chains. The experimental results show that ChainKeeper can achieve high throughput, outperforming two state‐of‐the‐art cross‐chain schemes.
Robust beamforming for dual‐function radar‐communication with imperfect channel state information
Authors: Zhu Jinkun , Song Yongping , Jin Tian , Liu Wei
Published: September 2023

Dual‐function radar and communication (DFRC) have recently received significant attention as an effective way to alleviate spectrum congestion and reduce system costs. Joint transmit beamforming plays a critical role in DFRC systems, as it can effectively reduce mutual interference and improve the performance of both the radar and communication systems. This paper investigates the problem of robust beamforming design with imperfect channel state information (CSI) to ensure communication performance while optimizing radar performance. Considering elliptically bounded CSI errors, the objective function is designed to minimize the radar loss function, which is related to the radar transmit beam pattern, subject to worst‐case signal‐to‐interference‐plus‐noise ratio constraints at each user, which ensure fairness between users. An efficient algorithm based on semidefinite relaxation and the S‐procedure is proposed to solve the non‐convex problem. Simulation results are presented to illustrate the effectiveness of the proposed robust beamforming scheme, which can reduce the impact of channel errors.
Bi‐level multi‐agent system (MAS) to protect DC microgrids (DCMGs) in free renewable sources and uncertainties penetration
Authors: Bamshad Ali , Ghaffarzadeh Navid
Published: September 2023

DC microgrids (DCMGs) have significant advantages, but their protection can be a challenge for DCMGs expansion expressly in distributed generation sources’ (DGS) tendance. This paper proposes a quick, and precise strategy to perceive and trip any fault in DCMGs in the free tendance of DGS. A bi‐level multi‐agent system (MAS) is proposed to protect the DCMG and DGs. The MAS first level perceives the fault in DCMG via a discrete wavelet transform (DWT). The multiply of two harvest levels’ summation of DWT is exerted to detect and distinguish DC lines faults. The MAS second level detects the fault in DGS and their switchers to the point of common connection (PCC) via a differential pole (DP) controller. A four bus DCMG containing solar PV and wind sources is implemented, and the results demonstrate that the proposed plan can recognize and trip the fault by 100% of reliability.
Microwave diagnostics of pulsed atmospheric discharge with electrolytic electrode and long‐lived luminous formation in its afterglow
Authors: Zhao Shixin , Lyu Xingbao , Astafiev Aleksandr , Yuan Chengxun , Miao Lin , Yao Jingfeng , Wang Ying , Kudryavtsev Anatoly , Chirtsov Aleksandr , Shabanov Gennadii , Zhou Zhongxiang
Published: September 2023

The Gatchina discharge phenomenon holds significant promise as a laboratory model for simulating ball lightning. However, crucial aspects concerning the plasma components of the resulting afterglow remain unresolved. Notably, the measurement of the electron density, a critical parameter, has not been fully achieved thus far. In this study, microwave diagnostics and video recording were employed during a pulsed Gatchina discharge, along with synchronous measurement of discharge current and voltage. Distinct antennas were positioned at different heights to enable separate diagnosis of the discharge and the ensuing long‐lived afterglow. The findings revealed that during the active phase of the Gatchina discharge, the plasma density was substantial enough to cause reflection of an electromagnetic wave with a frequency of 20 GHz from this highly conductive object. In the afterglow, the signal experienced only a moderate weakening of 10–20 percent, facilitating the determination of the time dependence of average electron density during the afterglow's passage between the two antennas. These measurements verified the unusually slow plasma decay in the afterglow of the Gatchina discharge, suggesting the potential significance of chemi‐ionisation processes involving long‐lived (metastable) particles.
Observation and verification of surface electrical explosion driven by radial‐distributed pulsed current in laboratory lightning strike test
Authors: Han Ruoyu , Cao Yuchen , Liu Yakun , Chen Xi , Li Ting , Li Chen , Li Pengfei
Published: September 2023

The laboratory lightning test is essential for assessing the effectiveness of lightning strike protection (LSP). Particularly, direct lightning strike damage can be performed with pulsed current injection into the specimen. This paper focuses on the dynamic process of arc plasma and shock wave behaviour in the vicinity of the ‘strike’ point. A rod‐plate discharge load is built for testing aluminium and coated plate under 40‐kA‐level pulsed current. The visualisation of the luminous discharge plasma and its flow field via high‐speed photography (from different angles) is meticulously designed and implemented, synchronised with electro‐physical diagnostics. The results indicate some new mechanisms for lightning strike damage, apart from the impulse heat loading from the thermal arc. The transient current injection through the arc root concentrates on a thin skin layer (skin‐depth effect), with the radial‐attenuated current density, driving asynchronously electrical explosions on the plate surface. The inhomogeneous Joule heating of the plate leads to outwardly propagating phase transition and shock wave along the conductive surface. In addition, the electro‐thermal instability is observed and regarded as the seed of irregular erosion region. Spectroscopic information reveals two different plasma states of main discharge arc channel and adjacent surface electrical explosion. The correspondence of the physical mechanism of electrical explosion and optical radiation is established. Microscopic images for different regions depict erosion characteristics and summarise influencing factors, further confirming the mechanism above. The research clarifies the role of skin‐depth effect in transaction arc erosion for electrode, complements the electrical explosion theory with unevenly distributed current and helps optimise strategies of LSP.
Fuzzy model predictive control for frequency regulation of temporary microgrids during load restoration
Authors: Wang Zhixian , Wang Ying , Wu Jiping , Zhang Kaifeng
Published: September 2023

Temporary microgrids containing a high proportion of distributed renewable generations can offer great benefits during the recovery stage after large‐scale power system blackout, by picking up critical load and speeding up the entire grid recovery process. To solve the frequency security problem of temporary microgrids faced in the load restoration process, this paper proposes an adaptive fuzzy model predictive control (adaptive fuzzy‐MPC) strategy to obtain effective frequency regulation to suit the special characteristics of this process. First, the load restoration plan within a short time frame is regarded as the feedforward information and assists in the establishment of the MPC model. Then, considering the uncertainty of renewable distributed generations, the regulation resources are cooperated by an adaptive fuzzy controller which provides the weights of different regulation resources adopted in MPC. Specifically, the base weights of the energy storage system and renewable distributed generations are obtained from fuzzy rules, and then the weight for each regulation resource is modified by the designed adjustment rules. Simulation results illustrate that the proposed strategy can efficiently improve frequency performance while making various frequency regulation resources with different regulation capacities cooperate properly, which can further accelerate the load restoration progress and enhance system resilience.
Research on single target cognitive electronic reconnaissance strategy for unmanned aerial vehicle
Authors: Zhang Yun , Chen Zili , Yan Yunbin , Jiang Fangqing , Gao Xijun
Published: September 2023

The integration of electronic reconnaissance platforms and payloads in the electromagnetic and spatial domains of cognition is necessary for the successful execution of cognitive electronic reconnaissance missions. However, in partially observable environments, platforms and payloads interact in separate operational domains, making it a challenge for the model. The authors create a theoretical model of cognitive electronic reconnaissance, present an analysis method of model elements and derives adequate requirements for optimal radiation source sorting or recognition. Then, a 3D cognitive reconnaissance simulator ‘Scouter’ to simulate the dynamic interaction process of space electronic reconnaissance missions is developed and a deep reinforcement learning framework to optimise the electronic reconnaissance strategies of Unmanned Aerial Vehicle (UAV) is designed. For the first time, a method for judging reconnaissance area coverage using a behavioural angle is proposed. This method enables a deep reinforcement learning‐based UAV with better reconnaissance behaviours and to realise the stable targeting of the target by the receiving antenna beam during reconnaissance. Moreover, the fast convergence of UAV agent training is ensured through the normalisation of partially observable status and reward shaping. Verified by adequate numerical simulations, a trained UAV can complete a 100 reconnaissance cycles mission with a completion rate of 91.9%. Even after the reconnaissance cycles are prolonged to 600, the mission completion rate can still be maintained at 78.5%. The most satisfying aspect is that the UAV comprehends the idea of reconnaissance and behaves in a way that is typical of it, such as by reciprocating or circling the edge of the radar's detecting power.
X-ray luminosity-star formation rate scaling relation: Constraints from the eROSITA Final Equatorial Depth Survey (eFEDS)
Authors: Riccio G. , Yang G. , Małek K. , Boquien M. , Junais  , Pistis F. , Hamed M. , Grespan M. , Paolillo M. , Torbaniuk O.
Published: September 2023

Aims.We present measurements of the relation between X-ray luminosity and star formation activity for a sample of normal galaxies spanning the redshift range between 0 and 0.25. We use data acquired by SRG/eROSITA for the performance and verification phase program called eROSITA Final Equatorial Depth Survey (eFEDS). The eFEDS galaxies are observed in the 0.2−2.3 keV band.

Methods.Making use of a wide range of ancillary data, spanning from the ultraviolet (UV) to mid-infrared wavelengths (MIR), we estimated the star formation rate (SFR) and stellar mass (Mstar) of 888 galaxies, using Code Investigating GALaxy Emission (CIGALE). In order to study sources whose X-ray emission is dominated by X-ray binaries (XRBs), we classified these galaxies into normal galaxies and active galactic nuclei by making use of the observed fluxes in the X-ray, optical, and MIR ranges, as well as the results from the SED fitting. To isolate the contribution of XRBs, which scale with the SFR andMstar, we subtracted the contribution of hot gas, coronally active binaries, and cataclysmic variables to the total X-ray emission. We divided our sample of normal galaxies in star-forming (SFGs) and quiescent galaxies according to their position on the main sequence.

Results.We confirm a linear correlation between the X-ray luminosity and the SFR for our sample of SFGs, shown previously in the literature. However, we find this relation to be strongly biased by the completeness limit of the eFEDS survey. Correcting for completeness, we find the fitted relation to be consistent with the literature. We also investigated the relation between X-ray emission from both LMXBs and HMXBs populations withMstarand SFR, respectively. Correcting for completeness, we find our fitted relation to considerably scatter from the literature relation at high specific SFR (SFR/Mstar). We conclude that without accounting for X-ray non-detections, it is not possible to employ eFEDS data to study the redshift evolution of the LMXBs and HMXBs contributions due to completeness issues. Furthermore, we find our sources to largely scatter from the expected Lx/SFR vs. specific SFR relation at high redshift. We discuss the dependence of the scatter on the stellar mass, metallicity, or the globular cluster content of the galaxy.
Interaction of H2S with H atoms on grain surfaces under molecular cloud conditions
Authors: Santos J. C. , Linnartz H. , Chuang K.-J.
Published: September 2023

Context. Hydrogen sulfide (H2S) is thought to be efficiently formed on grain surfaces through the successive hydrogenation of sulfur atoms. Its non-detection so far in astronomical observations of icy dust mantles thus indicates that effective destruction pathways must play a significant role in its interstellar abundance. While chemical desorption has been shown to remove H2S very efficiently from the solid phase, in line with H2S gas-phase detections, possible ice chemistry triggered by the related HS radical have been largely disregarded so far, despite it being an essential intermediate in the H2S + H reaction scheme.

Aims. We aim to thoroughly investigate the fate of H2S upon H-atom impact under molecular cloud conditions, providing a comprehensive analysis combined with detailed quantification of both the chemical desorption and ice chemistry that ensues.

Methods. We performed experiments in an ultrahigh vacuum chamber at temperatures between 10 and 16 K in order to investigate the reactions between H2S molecules and H atoms on interstellar ice analogs. The changes in the solid phase during H-atom bombardment were monitored in situ by means of reflection absorption infrared spectroscopy (RAIRS), and desorbed species were complementarily measured with a quadrupole mass spectrometer (QMS).

Results. We confirmed the formation of H2S2 via reactions involving H2S + H and quantified its formation cross section under the employed experimental conditions. Additionally, we directly assessed the chemical desorption of H2S by measuring the gas-phase desorption signals with the QMS, providing unambiguous desorption cross sections. Chemical desorption of H2S2 was not observed. The relative decrease of H2S ices by chemical desorption changed from ~85% to ~74% between temperatures of 10 and 16 K, while the decrease as the result of H2S2 formation was enhanced from ~15% to ~26%, suggesting an increasingly relevant sulfur chemistry induced by HS radicals at warmer environments. The astronomical implications are further discussed.
Possibilities of increasing biodiversity in the genus Elaeagnus L. during reproduction by soft cuttings
Authors: Sorokopudov V.N. , Zubik I.N. , Simahin M.V. , Sorokopudova O.A. , Sharafutdinov Kh.V. , Lvova A.D.
Published: September 2023

In this article, for the first time in Russia, the reproduction results of four species of the genus Elaeagnus L. by soft cuttings are presented comparatively. The promising genus of Elaeagnus L. have been identified in terms of fruiting and ornamentally. Their reproduction methods by soft cuttings with growth regulators, which make it possible to obtain high-quality seedlings for planting plantations, have been studied. Experiments on reproduction by soft cuttings were carried out in 2018 - 2020 on the territory of the Fruit Station of the RSAU-Moscow Agricultural Academy, named after K.A. Timiryazev. The cuttings were treated with three different growth regulators, stimulants of root formation (IMA-indolylbutyric acid, GHC-hydroxycinnamic acid (Zircon), and BCI + GGA (Universal rooting agent) and water was used as a control. The obtained results were processed by analysis of variance, as a result of which the morphological variability of rooted soft cuttings was revealed when treated with growth and development regulators. It was found that the genotype and stimulants significantly affect the average length and number of roots, the growth of shoots, their number, and the number of leaves on the shoot. The most effective was the growth and development regulator GKK + IMC. The results obtained make it possible to increase the biodiversity of valuable genotypes of the genus Elaeagnus L.
Development of technology for accelerated propagation of miscanthus (Miscanthus giganteus)
Authors: Shitikova A.V. , Vilkhovoy V.E.
Published: September 2023

Materials on the study of the low propagation coefficient of Miscanthus giganteus, the search for new ways of propagation and the development of technologies for accelerated propagation of this crop are presented. Artificial lighting and conditions of elevated temperature and humidity have shown a negative impact on the growth and development of Miscanthus gigantus plants in laboratory conditions. Artificial lighting stimulated the stretching of plants, which led to their lodging. Conditions of high temperature and humidity contributed to the development and rapid spread of brown rust disease.
Technological process scheme of the three-stage microwave convection hop drying
Authors: Goryacheva Natalia G. , Prosviryakova Mariana V. , Novikova Galina V. , Storchevoy Vladimir F. , Storchevoy Alexander V.
Published: September 2023

At a temperature of 110 ° C, the concentration of alpha-acid reaches 67.5%, beta-acid - 59%, which reduces the consumer properties of hops. The aim of the study is to develop a microwave convective hop dry-er, which provides a process flow rate of less than 0.5 to equalize the mois-ture content of hops in the structure during transportation through a toroi-dal resonator. We used the programs CST Microwave Studio 2018, Com-pass 3D V20. The hop dryer contains two truncated conical and toroidal resonators. In the central cylinder of the toroidal resonator there is no EMPSWH, here the moisture in the hop cones is equalized. In the capacitor part of the resonator, the electric field strength is sufficient to reduce the bacterial contamination of hops. A dielectric grid electric drive conveyor and a perforated ceramic trough are laid along all resonators. The techno-logical scheme of the process provides for determining the amount of evaporated moisture from each resonator, air flow, and the required power of heat guns. The electrical circuit provides control of three magnetrons and a conveyor. The expected specific heat consumption is 3.54 MJ/kg. The total air consumption is 300 m3/h, with a hop dryer capacity of 100 kg/h.
Management of compensatory shift of immunohematological parameters in poultry of industrial crosses in the presence of feed antibiotics in the diets
Authors: Poryvaeva A.P. , Isaeva A.G. , Krivonogova A.S. , Shkuratova I.A.
Published: September 2023

A comparative analysis of the immunological parameters in chickens of industrial crosses, which were fed diets with antibiotics (group 1) and antibiotics in combination with a phytobiotic (group 2), is presented. After 30 days of feeding antibiotic hemoglobin concentration in the blood of laying hens remained unchanged – 87.3-93.2 g/l. On the 30th day of the experiment, in group 1 was noted an increase in the number of leukocytes up to 30.13±2.84∙109/l and the proportion of eosinophils by 29.6%. In the same period, a decrease in the absolute number of immunocompetent cells – T-lymphocytes by 36.6% was observed and absorption capacity of phagocytes by an average of 27.9%. From the 30th to the 60th day of the experiment in the blood of the chickens of group 1, the dynamics of the increase in the CIC level was recorded (up to 143.8±12.1 c.u.). When antibiotic was introduced into the diet of laying hens in combination with a phytobiotic in group 2, only by the 60th day, the number of erythrocytes was increased by 17.4% compared to the “background values” (82.1±5.2∙1012/l). Hemoglobin fluctuation amplitude did not exceed 7%. On the 30th day of the experiment in laying hens of group 2, a decrease in the number of immunocompetent cells by 20.8% was registered compared to the background values. On the 45th day of the experiment after the abolition of antibiotic and phytobiotic, the content of T-lymphocytes did not significantly differ from the background values.
Application of remote monitoring and ground-based sensing in pastoralism
Authors: Oleinik S. , Skripkin V. , Lesnyak T. , Litvin D.
Published: September 2023

The development and implementation of an innovative system applying digital aerospace technologies in pastoralism constitute one of the current trends in agricultural development designed to solve numerous problems associated with soil fertility restoration in grazing pastures. Here, a promising line of research is to explore the feasibility of using satellite systems for an overall nutrient yield assessment per hectare of grazing land. The present article describes a comprehensive approach to the optimization of pastoralism that is based on remote methods for assessing pasture fertility using unmanned aerial vehicles (UAVs) and artificial Earth satellites. An analysis of existing methodological approaches reveals that the formalization of prediction processes is complicated by the lack of a theoretical basis for creating appropriate model-algorithmic support. The data on vegetation index dynamics and the nutritional values of forage plants obtained by interpreting imagery from a UAV camera and the multispectral cameras of a satellite service, as well as data from a portable handheld nitrogen sensor, were compared with the actual nutritional values of pasture plants. The study results provide a means to optimize the grouping of grazing animals, taking into account the actual possibility of achieving an increase in live weight. The provided findings indicate the possibility of achieving an additional 11.06% increase in daily live weight gain in young sheep (Jalgin Merino) when keeping them in pasture areas having a vegetation index of at least 0.5. Remote monitoring based on satellite service allows more efficient use of pastures. Study shows a positive relationship between remote sensing NDVI and feed nutritional value. Animal grazing optimization provides an additional 11.06% increase in live weight gain.
Diurnal and seasonal rhythm of the melon ladybird - Epilachna chreysomelina (Coleoptera, Coccinellidae) activity in the conditions of the Kashkadarya region of Uzbekistan
Authors: Tilavov T. , Bazarova N.Sh. , Uzakov Z.Z.
Published: September 2023

The paper describes that the first signs of beetle movement after night rest in the month of May occur at 8 am at an air temperature of about 200C. Increasing the temperature to 22-290C tends to increase their mobility. By 11 a.m., when the air temperature reached 340C, almost all the beetles went into the shade, into the lower part of the plants, where they remained immobile until almost 4 p.m. After 17 h. the air temperature dropped to 330С, by 20:00 to 200С. By this time, only a small part of the beetles remained active. In summer, the motor activity of beetles intensifies at 8-10 am, when the air temperature rises to 340C. From 11 a.m. to 6 p.m. at a temperature of 34-420C, humidity 34-40%, the beetles were placed in the shade and were inactive. In autumn, after night cooling, the air temperature increased later and the movement of beetles began at 11 am At noon hours (between 12-4 pm) at an air temperature of 20-250C. and humidity 55-60%, beetle activity was maximum. In summer, beetles actively feed in the morning (from 8-9 a.m.) and evening (from 19 to 22 p.m.) hours, when the air temperature was 26-330C. In the middle of the day (13-16 hours) and at night (3-5 hours), their feeding activity is somewhat reduced. The intensity of beetle feeding in the autumn months increases from 9 a.m. and reaches a maximum by 11-13 a.m., and after 5 p.m. it begins to decrease and almost stops at 9 p.m. in the evening.
Solving problems of agricultural production development by modeling using the cluster analysis method
Authors: Lubova Tatiana , Araslanbayev Irek , Salimova Guzel , Nigmatullina Gulnara , Islamgulov Damir
Published: September 2023

The article outlines the need to apply a systematic approach to the analysis and solution of agricultural production development problems. The system approach implementation is carried out using a multidimensional data analysis method – the cluster analysis method. A system of indicators characterizing the conditions and results of agricultural enterprises in the regions of the Central and Volga Federal Districts of the Russian Federation has been built, a multidimensional grouping of regions has been carried out to identify problems and directions for their solution. The multidimensional approach to the study allowed an objective analysis and formulation of well-founded specific conclusions and recommendations for the regions of each cluster. As a result, two clusters of regions were identified according to the level of agricultural production development. Subclusters are also allocated within clusters to detail and concretize proposals. Recommendations on agricultural production development are made to the regions of each cluster. The directions for the formation of the strategy for the development of agriculture of the corresponding groups of regions and territories are outlined.
Study on the Emission Characteristics in Renewable Energy Combustion under Different Working Conditions of Marine Two-Stroke Diesel Engine
Authors: Ding Yang , Fang Zixian , Wang Ruolan , Shao Guoyu , Yang Kunyong
Published: September 2023

In this paper, MAN 6S35ME-B9 two-stroke diesel engine is taken as the research object. By constructing a detailed combustion reaction mechanism including CH4, C4H10O, nitrides and other substances, CHEMKIN-PRO is used to simulate the same fuel mixing ratio and excess air coefficient. Under the condition of 1.5, the temperature, NO mole fraction and NH3 mole fraction in the reactor change and study the factors affecting the pollutant emission of marine diesel engine with the crank angle under different working conditions. The simulation shows that with the decrease of diesel engine speed, the maximum temperature of combustion reaction and the temperature at exhaust opening are obviously reduced. At the same time, mole fraction of NO and NH3 decreases with the decrease of rotational speed, and there is no nitride production in the combustion reaction at 25%.
Review on the Application and Preparation of Ozone Catalysts
Authors: Qu Jia , You Shaohong
Published: September 2023

This paper reviews the recent advances in the application of ozone catalysts and their preparation. The main categories of ozone catalysts are introduced, and the properties of the more widely used metal oxide catalysts, supported catalysts, carbonaceous material catalysts and novel catalysts are summarized. The supported catalysts and carbonaceous material catalysts have better catalytic effect compared with metal oxide catalysts. The four most commonly used catalyst preparation methods are reviewed, and the prospects for catalyst development based on the current research status are presented.
Sequential calibration of material constitutive model using mixed-effects calibration
Authors: Laboulfie Clément , Balesdent Mathieu , Brevault Loïc , Irisarri François-Xavier , Maire Jean-François , Da Veiga Sebastien , Le Riche Rodolphe
Published: September 2023

Identifying model parameters is nowadays intrinsically linked with quantifying the associated uncertainties. While classical methods allow to handle some types of uncertainties such as experimental noise, they are not designed to take into account the variability between the different test specimens, significant in particular for composites materials. The estimation of the impact of this intrinsic variability on the material properties can be achieved using population approaches where this variability is modeled by a probability distribution (e.g., a multivariate Gaussian distribution). The objective is to calibrate this distribution (or equivalently its parameters for a parametric distribution). Among the estimation methods can be found mixed-effects models where the parameters that characterize each replication are decomposed between the population averaged behavior (called fixed-effects) and the impact of material variability (called random-effects). Yet, when the number of model parameters or the computational time of a single run of the simulations increases (for multiaxial models for instance), the simultaneous, global identification of all the material parameters is difficult because of the number of unknown quantities to estimate and because of the required model evaluations. Furthermore, the parameters do not have the same influence on the material constitutive model depending for instance on the nature of the load (e.g., tension, compression). The method proposed in this paper enables to calibrate the model on multiple experiments. It decomposes the overall calibration problem into a sequence of calibrations, each subproblem allowing to calibrate the joint distribution of a subset of the model parameters. The calibration process is eased as the number as the number of unknown parameters is reduced compared to the full problem. The proposed calibration process is applied to an orthotropic elastic model with non linear longitudinal behavior, for a unidirectional composite ply made of carbon fibers and epoxy resin. The ability of the method to sequentially estimate the model parameters distribution is investigated. Its capability to ensure consistency throughout the calibration process is also discussed. Results show that the methodology allows to handle the calibration of complex material constitutive models in the mixed-effects framework.
Rural areas’ development and competitiveness through innovation ecosystems
Authors: Bankova Yovka , Tsvetanova Tsvetelina
Published: September 2023

The development of rural areas over the years has been raised as a problematic issue for many countries around the world. Different approaches are applied to solve that issue. One of them, currently, refers to the establishment of regional innovation ecosystems (RIEs). RIEs are complex systems involving multiple actors and resources to drive innovation and play crucial role in promoting sustainable economic development. Understanding the different types, traits, functions, and impact of RIEs can help policymakers and practitioners design targeted interventions and strategies for rural areas. The objective of the study is to explore the advantages of RIEs and their impact on the acceleration of development and improvement of competitiveness of rural regions. The study is conducted by the method of desk research. It aims to examine different types and functions of RIEs as a means to mobilise rural areas’ growth, potential and their role as a catalyst of competitiveness. As a result, a classification of Innovation ecosystems and of Regional Innovation ecosystems were developed. It was found that RIEs are capable of enhancing the competitiveness of rural regions by promoting economic diversification, driving innovation and productivity, facilitating access to markets and networks, attracting and retaining talent, providing business support and resources, contributing to branding and marketing efforts, and fostering collaboration and collective impact.
Usability of renewable energy in Bulgaria - challenges, opportunities and barriers
Authors: Markov Nedelin
Published: September 2023

Energy is a resource that both drives the world economy, but also sustains the existence of individuals. Energy is a strategic good that provides advantages for some and disadvantages for others. Traditional energy sources are not evenly distributed, and this is a challenge for politicians and economists to meet the ever-increasing energy demand. Renewable energy sources bridge the gap between traditional understandings of growth and modern demands for environmental protection. They are a compromise between the past and the future. The purpose of the report is to synthesize the possibilities and limitations of the use of renewable energy in Bulgaria. The research used empirical methods such as analysis and survey. The results, as expected, confirm that in our country there are unused opportunities for the development of energy production from renewable sources. The conclusions show that the poorly regulated electricity market, regulatory restrictions, and the low incomes of Bulgarians are a deterrent to the more intensive use of renewable energy.
A new approach for an old identity: Soufli, Greece as an open town-museum of silk
Authors: Gouridis Athanassios
Published: September 2023

Soufli, a small Greek border settlement, presents a widely recognized dipole of tourist destinations, a unique National Park and its silk tradition, including the circle of the relevant economy and its historical-architectural heritage. This prevailing local identity is gradually de-facto structured as a holistic model. Private entrepreneurship plays the first role, other stakeholders being local administration, education, associations and the citizens themselves as active participants. Thus, an open town-museum of silk is formulated, with five complementary museums and collections, two silk factories, an old emblematic factory, in restoration by the Municipality, numerous silk shops, decades of silkworm breeders enterprises, mulberry trees, two public, silk-oriented training foundations, an environmental center, events, International Conferences, workshops and exhibitions by world famous firms, Greek and foreign universities visiting and working on place, in a trans-border and transnational cooperation. In 2021 Soufli was chosen by the World Tourism Organization among the Best Tourism Villages, awarded with a valuable branding, which strengthens its position in the world map of silk.
Opportunities for development of the tourism sector in Bulgaria
Authors: Pavlov Pavlin
Published: September 2023

The main research goal is to present the opportunities for the development of the tourism sector in Bulgaria in the conditions of a dynamically changing environment. Emphasis is placed on innovations in the context of the circular economy, considering its essence and the possibilities of its application in the tourism sector as well. It should be borne in mind that the reorientation from a linear to a circular economic model in the tourism sector is a gradual process that requires time. Scientific methods such as the method of analysis and synthesis, content analysis, situational analysis, deduction, induction, comparative method and others are used. The results give an idea of the possibilities for progress of the tourism sector in Bulgaria in the context of the circular economy. There are good practices, the number of which is constantly increasing. In this way, the role and importance of circular tourism is growing. The conclusions present the achieved results in a synthesis and outline the prospects for the development of the tourism sector in Bulgaria, some recommendations are also made.
The impact of work motivation on job satisfaction with mediating effect of key work behaviour variables: A Bulgarian case of Generation Z employees
Authors: Dimitrov Kaloyan
Published: September 2023

Employers today are clearly aware that employee absenteeism, disengagement and turnover seriously disrupts the rhythm of work and leads to a loss of return on investment in human and social capital for them. With the phased entry of Generation Z, three different generational cohorts in the workforce (X, Y and Z) need to work together and be managed effectively within the organisation. Too little is known about the personalities, needs and issues associated with Generation Z. The research problem addressed in this article focuses on motivated and satisfied young employees in a professional work environment. The purpose is the purpose of this research was to examine the relationship of motivational issues with significant individual work attitudes pertaining to high motivated and satisfied young Bulgarian employees. Research methods include literature review, critical analysis, questionnaires and rating scales, statistical methods and techniques. The results show significant relationships between young employees’ work motivation, organizational commitment, work engagement and job satisfaction and the mediatiag effect of their committed and engaged.
Evolution of expectations models in economic thought
Authors: Hristova Vanya
Published: September 2023

Inflation expectations have been of prime interest for policymakers and researchers for decades. In 2023, when high inflation is one of the biggest challenges facing the world, economists must give them due weight. This article provides a systematic chronological treatment of the main approaches to expectations formation modelling in macroeconomics. While a number of surveys with focus on separate models are available, a full treatise (as per the author’s research) has been missing. This paper aims to fill the gaps. However, despite being exhaustive, it does not pretend to be coping with all contributions ever developed. The author has tried to present the topic in a way that is accessible and useful both to graduate students who encounter the subject for the first time and practitioners with previous knowledge who need a systematic treatment of the subject. The article starts with a general overview what are expectations and, in particular, inflation expectations, and why do they matter. This is followed by a chronological presentation of the main expectations models and a discussion of the prerequisites to appear, their implications and significance to economic thought, as well as, criticism. Finally, the author offers some perspectives and conclusions on the subject.
Establishing an effective partnership network in the sports paradigm
Authors: Kaloyanchev Valentin
Published: September 2023

The paper offers a theoretical overview based on strategic approaches to the establishment of an effective partnership network to help the adaptability of sports clubs to modern competitive and everchanging conditions. Methodologically, the article is conceptual, based on contemporary data and multi-perspective development directions. Initially, the article indicates the importance of establishing affiliate networks in business. Subsequently, presents strategies for creating long-term relationships with diverse organizations and guidelines for practical implementation. Sports organizations should analyse their resources and potential future partners and choose the most appropriate practices to connect with them. Thus, they would strengthen their effectiveness of strategic club cooperation.
Prediction of even and odd sunspot cycles
Authors: Asikainen Timo , Mantere Jani
Published: September 2023

Here we study the prediction of even and odd numbered sunspot cycles separately, thereby taking into account the Hale cyclicity of solar magnetism. We first show that the temporal evolution and shape of all sunspot cycles are extremely well-described by a simple parameterized mathematical expression. We find that the parameters describing even sunspot cycles can be predicted quite accurately using the sunspot number 41 months prior to sunspot minimum as a precursor. We find that the parameters of the odd cycles can be best predicted with maximum geomagnetic aa index close to the fall equinox within a 3-year window preceding the sunspot minimum. We use the found precursors to predict all previous sunspot cycles and evaluate the performance with a cross-validation methodology, which indicates that each past cycle is very accurately predicted. For the coming sunspot cycle 25 we predict an amplitude of 171 ± 23 and the end of the cycle in September 2029 ± 1.9 years. We are also able to make a rough prediction for cycle 26 based on the predicted cycle 25. While the uncertainty for the cycle amplitude is large we estimate that the cycle 26 will most likely be stronger than cycle 25. These results suggest an increasing trend in solar activity for the next decades.
Synthesis of Polycyclic Aromatic Hydrocarbons with Highly Twisted N-Doped Heptalene
Authors: Qiu Shuhai , Liu Junzhi
Published: September 2023

A series of N-doped heptalene-containing polycyclic aromatic hydrocarbons (PAHs) have been synthesized and characterized in comparison with the N-doped azulene analogs. The crystal structure revealed its highly twisted geometry with a dihedral angle of 105.7° in the cove region of the N-doped dibenzoheptalene backbone. In addition, the electronic structure was both theoretically and experimentally investigated compared with the PAH bearing N-doped azulene unit. Our study provides a new synthetic strategy towards N-doped heptalene-embedded PAHs, and gives insights into the electronic properties of novel π-systems with N-doped nonalternant topologies.
Systematic Review of WHO Grade 4 Astrocytoma in the Cerebellopontine Angle: The Impact of Anatomic Corridor on Treatment Options and Outcomes
Authors: Dang Danielle D. , Gong Andrew D. , Dang John V. , Mugge Luke A. , Mansinghani Seth , Ziu Mateo , Cohen Adam L. , Vyas Nilesh
Published: September 2023

Background Despite advances in multimodal oncologic therapies and molecular genetics, overall survival (OS) in patients with high-grade astrocytomas remains poor. We present an illustrative case and systematic review of rare, predominantly extra-axial World Health Organization (WHO) grade 4 astrocytomas located within the cerebellopontine angle (CPA) and explore the impact of anatomic location on diagnosis, management, and outcomes.

Methods A systematic review of adult patients with predominantly extra-axial WHO grade 4 CPA astrocytomas was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines through December 2022.

Results Eighteen articles were included comprising 21 astrocytomas: 13 exophytic tumors arising from the cerebellopontine parenchyma and 8 tumors originating from a cranial nerve root entry zone. The median OS was 15 months with one-third of cases demonstrating delayed diagnosis. Gross total resection, molecular genetic profiling, and use of ancillary treatment were low. We report the only patient with an integrated isocitrate dehydrogenase 1 (IDH-1) mutant diagnosis, who, after subtotal resection and chemoradiation, remains alive at 40 months without progression.

Conclusion The deep conical-shaped corridor and abundance of eloquent tissue of the CPA significantly limits both surgical resection and utility of device-based therapies in this region. Prompt diagnosis, molecular characterization, and systemic therapeutic advances serve as the predominant means to optimize survival for patients with rare skull base astrocytomas.
The Effect of SARS-CoV-2 İnfection on Perinatal Outcomes in Hypertensive Disorders of Pregnancy
Authors: Farisoğulları Nihat , Denizli Ramazan , Sakcak Bedri , Tanaçan Atakan , Kara Özgür , Şahin Dilek
Published: September 2023

Objective To evaluate the fetal and maternal effects of the severe acute respiratory syndrome virus 2 (SARS-CoV-2) infection in women with hypertensive disorders of pregnancy.

Methods Patients with hypertensive disorders of pregnancy and SARS-CoV-2 polymerase chain reaction (PCR) positivity (n = 55) were compared with cases with similar characteristics and PCR negativity (n = 53). The study group was further divided into two groups as severe (n = 11) and nonsevere (n = 44) coronavirus disease 2019 (COVID-19). The groups were compared in terms of clinical characteristics and perinatal outcomes.

Results The study and control groups were similar in terms of maternal age, parity, gestational age at diagnosis, type of hypertensive disorders, magnesium sulfate administration rate, gestational age at birth, birth weight, Apgar scores, and maternal complications. However, all cases of fetal loss (n = 6) were observed in the SARS-CoV-2 positive group (p = 0.027). From the 6 cases, there were 5 in the nonsevere group and 1 patient in the severe SARS-CoV-2 positive group. Moreover, higher rates of maternal complications, lower oxygen saturation values, and intensive care unit admissions were observed in the severe COVID-19 group.

Conclusion Physicians should be cautious about the management of hypertensive disorders of pregnancy cases with SARS-CoV-2 positivity. Fetal loss seems to be more common in cases with SARS-CoV-2 positivity and severe COVID-19 seems to be associated with higher rates of maternal complications. Close follow-up for fetal wellbeing and active management of severe cases in terms of maternal complications seem to be favorable.
Gelenkkontrakturen – Behandlungsbeispiel zum Verbessern der Knieflexion
Authors: Schomacher Jochen
Published: September 2023

Bewegungseinschränkungen in Flexion im Kniegelenk sind häufig. Oft fehlen die letzten Bewegungsgrade nicht nur nach Operationen und Verletzungen, sondern auch aufgrund von Nichtgebrauch beispielsweise wegen Schmerz (Arthrose), oder wenn wir nicht mehr täglich in die tiefe Hocke gehen (Bequemlichkeit). Selbstmobilisation und Lagerung bieten eine einfache Abhilfe.