bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative insights into the differences of variability and intermittency between wind and solar resources on spatial and temporal scales in China
Authors: Ren Guorui , Wan Jie , Wang Wei , Liu Jizhen , Hong Feng , Yu Daren
Published: August 2021

Variability and intermittency are the intrinsic nature of wind and solar resources. Expanded wind and solar power development in China requires a deeper understanding of their differences in variability and intermittency, both spatially and temporally. To address this issue, this study provides a systematic quantitative comparison of the variability and intermittency between wind and solar resources across China. Compared with wind resources, solar resources show regular spatial patterns and highly similar temporal characteristics. Solar resources usually have larger daily variation amplitudes (1.0–3.5 times) and are more intermittent (1.0–10.0 times) than wind resources in most regions. Solar resources fluctuate 1.0–8.0 times faster than wind resources in western Xinjiang, most of central and southern China, and north and east of northeast China. However, the variation rate of solar resources is approximately 0.1–0.5 times the wind resources in the Qinghai–Tibet plateau and East China Sea. In general, wind and solar resources fluctuate faster and are more intermittent in spring and autumn. Onshore wind resources are more variable and intermittent in the periods of 6:00–12:00 and 16:00–22:00. However, the variability and intermittency of offshore wind resources are weak and have very small intra-day changes compared with onshore wind resources. Solar resources are usually more variable and intermittent during the periods of 2–4 h after sunrise and 2–4 h before sunset. Furthermore, the intra-day changes in the variability and intermittency of solar resources are significantly greater than the inter-month changes. Those quantitative insights contribute to better and more efficiently mitigate the variability and intermittency of wind and solar resources.
Multifunctional design of triangular lattice metamaterials with customizable thermal expansion and tunable bandgap properties
Authors: Xu Weikai , Lv Shuchen , Bai Liang , Qi Wuchao , Wang Wei
Published: August 2021

New approaches for realizing multifunctional research and tunable properties of materials are proposed by designing lattice metamaterials. In this study, the finite element method is used to study the bandgaps of the joint-bonded triangular cell lattice metamaterial. A new multifunctional design method is proposed for designing metamaterials with tunable bandgaps and specific thermal expansion properties. In this method, the geometric deformation characteristics of thermal expansion of materials are studied, and a design method for maximum bandgaps’ tunability under the condition of a specific coefficient of thermal expansion is proposed to realize the tuning of bandgaps’ characteristics based on external temperature change. Numerical results show that the proposed method and metamaterials can demonstrate significant tunability of bandgaps. This finding provides a common method for designing bandgaps’ tunable acoustic metamaterial systems, which have broad application potential under variable temperature loading and can be extended to other topological structures.
Vibrations of simplified rudder induced by propeller wake
Authors: Zhang Weipeng , Ning Xiaoshen , Li Fugeng , Guo Hang , Sun Shili
Published: August 2021

Severe wake-structure interaction induces intense vibrations and noises. In this study, the rudder is simplified into a plate fixed at two ends. The vibrations of the plate operating in the propeller wake are analyzed. Detached eddy simulation is employed to simulate the turbulence in the flow field and propeller wake. The structural deformation equation is solved via the finite volume method. The pressure fluctuations in the propeller wake and the vibrations on the plate are investigated. The results show that the excited vibrations coexist with natural vibrations on the plate. The natural vibration mode can be occupied by the excited vibration. The lock-in regime between the excited vibrations and natural vibrations leads to weaker vibration at excitation frequencies. The vibration mode induced by the hub vortex transfers to the first natural vibration mode when the shaft frequency approaches the first natural frequency. The vibrations on the plate are more dominant at the first natural frequency in the approach of the shaft frequency to the first natural frequency. This investigation of plate vibrations induced by the propeller wake contributes to the structural design of the ship.
Wide-field magneto-optical microscope to access quantitative magnetization dynamics with femtosecond temporal and sub-micrometer spatial resolution
Authors: Steinbach F. , Schick D. , von Korff Schmising C. , Yao K. , Borchert M. , Engel W. D. , Eisebitt S.
Published: August 2021

We introduce a wide-field magneto-optical microscope to probe magnetization dynamics with femtosecond temporal and sub-micrometer spatial resolution. We carefully calibrate the non-linear dependency between the magnetization of the sample and the detected light intensity by determining the absolute values of the magneto-optical polarization rotation. With that, an analytical transfer function is defined to directly map the recorded intensity to the corresponding magnetization, which results in significantly reduced acquisition times and relaxed computational requirements. The performance of the instrument is characterized by probing the magnetic all-optical switching dynamics of GdFe in a pump–probe experiment. The high spatial resolution of the microscope allows for accurately subdividing the laser-excited area into different fluence-regions in order to capture the strongly non-linear magnetization dynamics as a function of the optical pump intensity in a single measurement.
Enhanced directive terahertz radiation emission from a horn antenna-coupled W/Fe/Pt spintronic film stack
Authors: Shahriar B. Y. , Carnio B. N. , Hopmann E. , Elezzabi A. Y.
Published: August 2021

We demonstrate enhanced directive terahertz (THz) radiation emission from a horn-antenna coupled spintronic THz radiation emitter without the use of additional lenses. The waveguide-fed horn antenna is fabricated using 3D lithography and is coupled directly to the THz-emitting film serving to direct the highly divergent THz radiation emitted by the spintronic THz radiation emitter. The antenna-coupled emitter provides a 19.6 dB increase in the measured signal power at 1.5 THz compared to a bare emitter. Finite-difference time-domain simulations are conducted to gain insight into the behavior of the antenna at different frequencies, providing results that match those observed experimentally. Our device is well suited for platforms where footprint size is a constraint and can be modified to act as a directive bandpass filter.
Receptivity of a hypersonic flow over a blunt wedge to a slow acoustic wave
Authors: Chen Yifeng , Tu Guohua , Wan Bingbing , Su Caihong , Yuan Xianxu , Chen Jianqiang
Published: August 2021

The receptivity of the second mode for Mach 6 flow over a blunt wedge with a nose radius of 0.258 mm is investigated numerically. When a plane slow acoustic wave is imposed on the freestream, the receptivity process of the boundary layer goes through three stages, with the development of an entropy-layer mode, a fast mode, and nonmodal external disturbances, before exciting the second mode. The first two dominant modes can be obtained by linear stability theory in the entropy layer and the boundary layer, respectively, whereas the third is a complicated type of disturbance whose shape function peaks in the entropy layer. The results show that the nonmodal disturbances in the entropy layer play a leading role in the excitation of the second mode, which suggests that the growth of nonmodal disturbances could dominate nonmodal amplification, eventually leading to boundary-layer transition.
Toward a complete and comprehensive cross section database for electron scattering from NO using machine learning
Authors: Stokes P. W. , White R. D. , Campbell L. , Brunger M. J.
Published: August 2021

We review experimental and theoretical cross sections for electron scattering in nitric oxide (NO) and form a comprehensive set of plausible cross sections. To assess the accuracy and self-consistency of our set, we also review electron swarm transport coefficients in pure NO and admixtures of NO in Ar, for which we perform a multi-term Boltzmann equation analysis. We address observed discrepancies with these experimental measurements by training an artificial neural network to solve the inverse problem of unfolding the underlying electron-NO cross sections while using our initial cross section set as a base for this refinement. In this way, we refine a suitable quasielastic momentum transfer cross section, a dissociative electron attachment cross section, and a neutral dissociation cross section. We confirm that the resulting refined cross section set has an improved agreement with the experimental swarm data over that achieved with our initial set. We also use our refined database to calculate electron transport coefficients in NO, across a large range of density-reduced electric fields from 0.003 to 10 000 Td.
Effect of shock vector/polarization vector configuration on the generation of ultrahigh voltage by adiabatically compressed ferroelectric materials
Authors: Shkuratov Sergey I. , Baird Jason , Antipov Vladimir G.
Published: August 2021

Compact autonomous megawatt-power systems based on shock depolarization of ferroelectric materials are capable of producing kiloampere currents and ultrahigh-voltage pulses with amplitudes exceeding 100 kV. Herein, we report the results of experimental investigations of the generation of ultrahigh voltage by poled Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 and Pb0.99(Zr0.52Ti0.48)0.98Nb0.01O3 ferroelectrics subjected to shock loading at different shock vector/polarization vector configurations. Our experiments demonstrated that under loading perpendicular to the polarization vector (transverse stress mode) the ferroelectrics are capable of generating high voltages exceeding 400 kV, while the loading parallel to the polarization vector (longitudinal stress mode) causes a distortion of the depolarization process in ferroelectrics of large thicknesses, resulting in inefficient generation of ultrahigh voltage. It was shown that for transverse semi-planar shock waves, the presence of the longitudinal component of stress due to non-perfect planarity of the shock front can cause a complex electric field distribution in the shock front area, resulting in energy losses in ferroelectrics operating in the ultrahigh-voltage mode. The important finding is that a cylindrical, radially expanding shock wave results in no significant distortion of the depolarization process and energy losses during ultrahigh-voltage generation by transversely shock-compressed ferroelectrics. The experimental results indicate that the voltage amplitude generated by transversely shock-compressed ferroelectrics is directly proportional to the ferroelectric thickness in the range from 6 to 230 mm. We found that over the full range of investigated thicknesses the breakdown-field-on-thickness dependence of shocked ferroelectrics is described by a power law and the mechanism of initiation of electric breakdown does not significantly change with ferroelectric thickness.
Robust control of floral meristem determinacy by position-specific multifunctions of KNUCKLES
Authors: Shang Erlei , Wang Xin , Li Tinghan , Guo Fengfei , Ito Toshiro , Sun Bo
Published: August 2021

Significance

In floral meristem (FM), the transcription factor (TF) WUS and the secreted peptide CLV3 form a feedback loop to maintain robust stem cell activities. We found that the TF KNU is a temporally regulated repressor of
WUS
. However, how the spatial expression patterns of
CLV3
and
WUS
are fully extinguished during floral organogenesis is unknown. Here, we show that KNU has position-specific multifunctions that achieve termination of robust FM. Besides repressing
WUS
in the organizing center, in the central zone, KNU directly represses
CLV3
and inhibits WUS from sustaining
CLV3
. Furthermore, KNU represses
CLV1
and disrupts WUS–WUS and WUS–HAM1 interactions. Thus, KNU plays an essential role to promote FM determinacy for the proper formation of floral reproductive organs.
Microstructural stability of TMS-238™ Ni-base superalloy during long-term exposure at high temperature
Authors: Sowa Roman , Goehler Thomas , Dankl Lisa , Kirzinger Anna , Budziak Andrzej , Parlinska-Wojtan Magdalena
Published: August 2021

The microstructure evolution in Re–Ru containing high generation Ni-base single crystal superalloy has been investigated during long-term isothermal exposure at 1000°C. The chemical and physical characteristics are determined by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) measurements. In addition to the initial γ/γ’ phase structure, formation of HCP-structured Re–Ru–Ni-rich phase is confirmed. Based on high-resolution TEM imaging and phase structure analysis the theoretical atomistic model presenting the interfaces between the phases was constructed and evaluated with respect to precipitation kinetics. Growth of plate-like precipitates occurs mainly through the plate edge area due to stacking fault sequences between the surrounding matrix and the precipitates, while thickening is very limited due to good coherency with the surrounding phase in the longitudinal direction.
The cell biology of fertilization: Gamete attachment and fusion
Authors: Siu Karen K. , Serrão Vitor Hugo B. , Ziyyat Ahmed , Lee Jeffrey E.
Published: August 2021

Fertilization is defined as the union of two gametes. During fertilization, sperm and egg fuse to form a diploid zygote to initiate prenatal development. In mammals, fertilization involves multiple ordered steps, including the acrosome reaction, zona pellucida penetration, sperm–egg attachment, and membrane fusion. Given the success of in vitro fertilization, one would think that the mechanisms of fertilization are understood; however, the precise details for many of the steps in fertilization remain a mystery. Recent studies using genetic knockout mouse models and structural biology are providing valuable insight into the molecular basis of sperm–egg attachment and fusion. Here, we review the cell biology of fertilization, specifically summarizing data from recent structural and functional studies that provide insights into the interactions involved in human gamete attachment and fusion.
Vps13D functions in a Pink1-dependent and Parkin-independent mitophagy pathway
Authors: Shen James L. , Fortier Tina M. , Wang Ruoxi , Baehrecke Eric H.
Published: August 2021

Defects in autophagy cause problems in metabolism, development, and disease. The autophagic clearance of mitochondria, mitophagy, is impaired by the loss of Vps13D. Here, we discover that Vps13D regulates mitophagy in a pathway that depends on the core autophagy machinery by regulating Atg8a and ubiquitin localization. This process is Pink1 dependent, with loss of pink1 having similar autophagy and mitochondrial defects as loss of vps13d. The role of Pink1 has largely been studied in tandem with Park/Parkin, an E3 ubiquitin ligase that is widely considered to be crucial in Pink1-dependent mitophagy. Surprisingly, we find that loss of park does not exhibit the same autophagy and mitochondrial deficiencies as vps13d and pink1 mutant cells and contributes to mitochondrial clearance through a pathway that is parallel to vps13d. These findings provide a Park-independent pathway for Pink1-regulated mitophagy and help to explain how Vps13D regulates autophagy and mitochondrial morphology and contributes to neurodegenerative diseases.
Helios represses megakaryocyte priming in hematopoietic stem and progenitor cells
Authors: Cova Giovanni , Taroni Chiara , Deau Marie-Céline , Cai Qi , Mittelheisser Vincent , Philipps Muriel , Jung Matthieu , Cerciat Marie , Le Gras Stéphanie , Thibault-Carpentier Christelle , Jost Bernard , Carlsson Leif , Thornton Angela M. , Shevach Ethan M. , Kirstetter Peggy , Kastner Philippe , Chan Susan
Published: August 2021

Our understanding of cell fate decisions in hematopoietic stem cells is incomplete. Here, we show that the transcription factor Helios is highly expressed in murine hematopoietic stem and progenitor cells (HSPCs), where it is required to suppress the separation of the platelet/megakaryocyte lineage from the HSPC pool. Helios acts mainly in quiescent cells, where it directly represses the megakaryocyte gene expression program in cells as early as the stem cell stage. Helios binding promotes chromatin compaction, notably at the regulatory regions of platelet-specific genes recognized by the Gata2 and Runx1 transcriptional activators, implicated in megakaryocyte priming. Helios null HSPCs are biased toward the megakaryocyte lineage at the expense of the lymphoid and partially resemble cells of aging animals. We propose that Helios acts as a guardian of HSPC pluripotency by continuously repressing the megakaryocyte fate, which in turn allows downstream lymphoid priming to take place. These results highlight the importance of negative and positive priming events in lineage commitment.
Advanced Non-Metallic Coatings and Composite Materials for O & G Industry
Authors: Orlov M V , Badeghaish W O
Published: August 2021

Materials used in the oil and gas industry are required to possess resilient properties to sustain operational challenges. These include high pressures and temperatures of the working fluids created by both reservoir depths and compressors combined with the inherent aggressive and corrosive components. Multiple solutions have been introduced to the industry to minimize corrosion probability in recent years. Utilizing external and internal tubular non-metallic coating as well as switching to the products entirely made of the non-metallic composites are the most commonly used and best performing solutions. This paper presents a comprehensive overview of the advances of the most promising research and development activities in the area of protective coatings as well as non-metallic composite material products with real case studies in downhole applications. Special emphases are put on the most promising technological breakthroughs such as 3D printing with non-metallic composites containing nano-sized short fibers and continuous nanofibers, which could be potentially used in the fabrication of future downhole composite products. The breakthrough solutions in composite technologies such as self-healing systems, including capsule-based, fiber-based and vascular healing network, which are perfectly aligned with the 4th Industrial Revolution are also described.
Investigation of the structure and properties of the surface composite layer on VKS-5 steel
Authors: Ishmametov D A , Pomelnikova A S , Krasulya A A
Published: August 2021

Abstracts

In this work, were studied the structure and properties of the surface composite layer on heat-resistant steel VKS-5, obtained by combined chemical and thermal treatment, combining liquid electrolysis-free boriding with gas and ion-plasma nitriding. The properties of the surface composite layer are analyzed depending on various parameters of chemical and thermal treatment to determine the optimal mode. The study of the microstructure and properties of borated layers has shown that the most optimal properties can be obtained in the boron mode at a temperature of 1010 °C with an exposure time of 8 hours. The study of the microstructure of composite layers has shown that gas nitriding produces a layer of 80 microns in size, which penetrates deep into the borated layer, and in ion-plasma nitriding, the layer size is so small that it is not possible to determine it using optical microscopy. A study of the properties of composite layers obtained by combined chemical-thermal treatment has shown that combined chemical-thermal treatment, combining boriding and ion-plasma nitriding, allows you to get the best combination of high hardness and reduced microfragility.
Grain-boundary nitrogen diffusion model in multilayer materials
Authors: Polikevich K B , Plokhikh A I , Fomina L P , Putyrskii V E
Published: August 2021

The paper presents the dependencies for the formation of diffusion layers in materials having a laminar structure, when they are saturated with nitrogen. The influence of chemical composition on the thickness of the nitrided layer has been determined. Models for formation of diffusion layers depending on permeability of interlayer boundaries and chemical formula of the composition are proposed.
Properties and structure of composite solders for aluminum alloys
Authors: Shebeshev K , Pakhomova S A
Published: August 2021

The paper deals with the issues of improving the performance of solders for soldering aluminum alloys. The activity of fluxes under the conditions of interaction with aluminum alloys is investigated. The technological mode of flux production has been developed, which increases the tensile strength and corrosion resistance of brazed structures of radio-electronic equipment made of aluminum alloys.
Study on properties of conducting contacts made of aluminophosphate compositions for low-e glasses with electric heating
Authors: Savenko K O , Chuppina S V
Published: August 2021

Abstracts

This paper presents the results of a study of aluminophosphate compositions with different contents of PMS-N copper powder and SHS-carbon obtained from lignin for the formation of current-conducting contacts on the surface of low-emission glass with electric heating. The specific volumetric resistance of coatings made of aluminophosphate composition before and after their curing was determined. It is shown that the holding temperature of 100 °C and the holding time of 5 hours can be considered the optimal mode of curing aluminophosphate compositions on low-emission glass. It is shown that the wear resistance of aluminophosphate compositions containing PMS-N copper and SHS-carbon is primarily affected by the thickness of the formed layer. The pull-off strength was determined for the resulting coating of the aluminophosphate composition containing PMS-N copper and SHS-carbon, the value of which was 8.2 MPa.
Study of the tensile strength of a polymer composite material based on ABS-plastic and impregnated in epoxy resin with different types of hardener
Authors: Filippova A V , Lopatina Yu A , Sviridov A S
Published: August 2021

Annotation

This article examines the study of strength properties of polymer composite material, based on 3D-printed frame produced by FDM technology. The printing material is ABS plastic (acrylonitrile butadiene styrene). After the printing samples frames were soaked in pure epoxy resin with various hardeners. Subsequent curing went in two modes. After that, tensile tests were performed. The strength of impregnated, non-impregnated (clean frame) samples and samples made of pure resin was compared. Tests have shown that the strength of impregnated samples exceeds the strength of non-impregnated ones, but obtained strength value of impregnated samples were far from the expected theoretical values. It was found that low strength is associated with poor quality of the impregnation.
Creep Deformations of Curvilinear Anisotropic Media: Finite Element Modeling
Authors: Dimitrienko Yu I , Yurin Yu V , Gumirgaliev T R , Krasnov G A
Published: August 2021

This paper proposes a method for preliminary analysis of layer daynamics, it composition and assessment of deep-seated rock. Since physical knowledge is insufficient or the cannot be experimentally obtained, the phase of development and industrial launch of wells, mines, and open pits is nesessary. The method based on modeling the stress-strain state of rocks includes block-curvilinear anisotropy and creep. We develop methods that qualitatively describe the non-standard geometric shapes of deep rock layers. A block-curvilinear description of the rock model is given. We also offer the method for the effective numerical solution to the stress-strain state considering block-curvilinear anisotropy and creep. The software application is designed in the Scientific and Educational Center Supercomputer Engineering Modeling and Development of Software Systems at Bauman Moscow State Technical University (BMSTU). This software application helps to create, describe, solve and analyze both rocks and other mathematical models, as well as creep equation.
On the Asymptotics of Solutions of the Klein - Gordon - Fock Equation with Meromorphic Coefficients in the Neighborhood of Infinity
Authors: Korovina M V , Matevossian H A , Smirnov I N , Yu Smirnov V
Published: August 2021

In this paper we investigate the construction of uniform asymptotics of solutions for the Klein-Gordon-Fock boundary value problem with meromorphic coefficients as t → ∞. The difficulty in solving these problems is due to the fact that infinity, as known, is an irregular singular point of such equations. In the case of holomorphic coefficients, the order of degeneracy will be at most two, and in the case of meromorphic coefficients it can be arbitrary, and it will depend on the order of the poles of the meromorphic coefficients. The main method for constructing asymptotics in the neighbourhood of an irregular singular point is the method of resurgent analysis, which is based on the Laplace-Borel integral transform. Using this method, in this paper, a uniform asymptotics of the problem under consideration is constructed in a neighborhood of infinity for arbitrary meromorphic (or holomorphic) coefficients.
Method censored samples consideration in composite fatigue testing
Authors: Gadolina I V , Serebrjakova I L , Smelov S I
Published: August 2021

Taking into consideration the huge scatter of fatigue performance of composite, as well as the experimentally proved absence of unconditional fatigue limit, the method for statistical improvement was developed which allows to improve the statistical quality of fatigue curve. Some preliminary considerations about mechanical testing tool in quality control are shown. The source of data scatter in fatigue testing is discussed. For building of the method, the statistical approach from the group of intensive use of computer, namely, bootstrap was employed. The model example on the base of real testing was investigated. Applying the method will help to include the information of censored samples into the result of testing.
Influence of the ratio of organic solvent on the deposition of graphene oxide by spin-coating
Authors: Danilova E A , Denisenko E I , Peretiyagin V G , Komarov I A
Published: August 2021

In this work we investigate influence of the organic solvent addition on the deposition of graphene oxide solution by spin-coating. In order to overcome the poor wettability of polyethylene terephthalate substrate by water graphene oxide suspension we made series of multicomponent solution with different n-methylpyrrolidone to water ratio. We successfully showed possibility and good uniformity of graphene oxide films deposited from the multicomponent solution. According to AFM and Raman spectroscopy we achieved good local uniformity in all cases. The most uniform films were made with 2,35 mg/ml GO concentration. We also found that in case of 0,47 and 1,175 mg/ml concentrations we achieved few-layered graphene oxide with film thickness about 3 nm and less.
Organizational approaches to composite repair of products with deterioration
Authors: Brom Alla , Sidelnikov Ivan
Published: August 2021

In the article, the authors examined in detail how the return flow of products from consumers (operators) is formed. The authors emphasize which parameters need to be analyzed, in particular, pay attention to the analysis of the correlation between operating time and operating conditions. The article provides an algorithm for performing composite repairs.
Simulation of optimal control of return flow of products from composite materials
Authors: Sidelnikov Ivan , Brom Alla , Kotova Polina
Published: August 2021

This article discusses one of the possible approaches to modeling the process of controlling the return flows of composite materials products, taking into account the principle of low-waste production. During the simulation process, a model was developed that takes into account possible cost groups arising from the reverse logistics process. The developed model takes into account the requirements to minimize the cost of processes in the product recycling unit, as well as is aimed at determining the optimal volume of products from composite materials that are included in the return flow after the expiration of the assigned service life.
Stands with a reusable diaphragm for the production of composites materials used in engineering industrial companies
Authors: Stoyanova M V , Novikov A D
Published: August 2021

Abstracts

The article discusses the features of the stands with a reusable diaphragm use in technology development for engineering industrial companies (EIC). The main advantages of this solution are highlighted, as well as a comparison with the existing analogues. It is shown that the use of stands with a reusable diaphragm significantly increases the competence level, organizational and technological resources of the EIC, employed in the production of composite materials.
Polytetrahydrofuran from renewable natural raw materials and polymers based on it
Authors: Storozhuk I P , Pavlukovich N G , Polezhaev A V
Published: August 2021

A review of the works devoted to the synthesis and investigation of the properties of block copolymers containing fragments of polytetrahydrofuran obtained from renewable natural raw materials is presented. It is shown that the presence of chemically bonded blocks of elastic polytetrahydrofuran in rigid-chain polymer matrices increases their impact resistance and elongation at break, reduces the viscosity of the melt, and improves miscibility with other polymers. It is expected that a similar positive effect of polytetrahydrofuran elastic blocks will be observed in polymer composites filled with dispersed and continuous fibers.
Influence of γ→α transformation temperature range bias on structural stability of laminar steel materials
Authors: Plokhikh A I , Minakov A A , Vlasova D V
Published: August 2021

Abstracts

In this work laminar steel materials of W1-7 + AISI 304, W1-7 + AISI 430, 1008 + AISI 304 and 1008 + AISI 430 model compositions were studied. The γ→α transformation temperature range bias and influence of such bias dynamics on the laminar structure stability was studied by the differential scanning calorimetry method. The study results have shown that only in the laminar steel material of W1-7 + AISI 304 model composition the γ→α transformation temperature range bias to the low temperature region and the expansion of austenite field occurred, thus ensuring retention of the laminar structure in the process of material synthesis. Also, the nature of γ→α transformation was analyzed for all four compositions which showed that the observed γ→α transformation for each model composition of laminar steel materials was direct.
Thermoplastic polyether sulfones for composite materials reinforced with fabrics
Authors: Storoshuk I P , Alekseev V M , Pavlukovich N G , Borodulin A S , Kalinnikov A N , Poleshaev A V
Published: August 2021

The results of conducted controlled synthesis of thermoplastic high-performance polyether sulfones with different molecular weight are presented. It is shown that control of reaction time with other synthesis parameters being fixed makes it possible to synthesize polyether sulfones with desired molecular weight and hence viscosity of their melts. The latter is important for making high quality thermoplastic prepregs reinforced with carbon fiber.
New reprocessable branched polyurethane from biorenewable sources
Authors: Platonova E O , Pavlov A A , Polezhaev A V
Published: August 2021

Thermally-remendable and recyclable polyurethane was obtained via Diels-Alder reaction using branched glycol Voranol 3138 (glycerin-derived block-copolymer of polyethylene and polypropylene) as soft segment and toluene-2,4-diisocyanate (TDI) as hard segment subsequently functionalized by terminal difurfurylamine groups. By cross-linking via Diels-Alder reaction with N,N’-bismaleimido-4,4′-diphenylmethane (BMI) new self-healing branched polyurethane was obtained. Polymer structure was characterized by NMR and IR spectroscopy along with thermal analysis methods (DSC and TGA). Resulting material has good processability and opportunity for recycling.
Branched copolylactides: the effect of the synthesis method on their properties
Authors: Istratov V V , Polezhaev A V
Published: August 2021

In this work, L-lactide, acting as a cyclic AB monomer, was copolymerized with various AB2 comonomers. Depending on the nature of the AB2 comonomer, it was either a combination of L-lactide ring-opening polymerization with glycidol polymerization or a combination of L-lactide ring-opening polymerization with 2,2-bis (hydroxymethyl) propionic acid (BHP) polycondensation. Both synthetic methods resulted in branched copolyesters. A number of polymers with varying degrees of branching were obtained by systematically changing the proportion of comonomer AB2. The polymers were characterized using
1H NMR spectroscopy and SEC, and their thermal properties were studied using differential scanning calorimetry and thermogravimetric analysis. Also were investigated the viscosity of the solution and the wettability of the branched copolymers. Although structurally similar macromolecules were formed in both synthesis methods, polymers with BHP as AB2 comonomers have higher melting- and glass transition temperatures, higher thermal stability, solution viscosity and lower wettability than polymers with glycidol as AB2 comonomers.
Recent progress in self-healing polyurethanes based on Diels-Alder reaction
Authors: Borodulin A S , Ponomareva P F , Platonova E O , Pavlova V A
Published: August 2021

This review examines the latest advances in the synthesis and application of polyurethanes that have a self-healing effect due to the thermally reversible Diels-Alder reaction. A classification of strategies for improving the parameters of the final polymers is proposed, which includes the division into polyurethanes with a flexible organic linker, composites with nanoparticles, and systems with a dual self-healing mechanism both due to the Diels-Alder reaction and the reaction of the formation of a disulfide bonds from thiols. The possible applications of the obtained materials and the assumption about the further development of the field are considered.
Modeling of non-Newtonian fluid flows in porous textile structures under RTM technologies
Authors: Dimitrienko Yu I , Shuguang Li
Published: August 2021

In this paper, the investigation is devoted to the application of homogenization methods to the transport theory of non-Newtonian shear-thinning fluids in porous fabric structures. Mathematical model is proposed for describing the local transfer of non-Newtonian shear-thinning fluid over a periodic cell, and the symmetry of the microstructure and periodic boundary conditions are used to significantly reduce the complexity of the problem and the computational burden. Solving local problems allows us to find accurate local distributions of velocities, pressure and viscosity inside a separate pore, and also to evaluate the permeability of the porous medium and the effective viscosity of the fluid when only the geometry of the pore is known. Finally, the numerical results for the local transport of pseudoplastic fluid in porous media are given.
Asymptotic analysis of the two-layer plates bending with nonlinear interlayer friction
Authors: Dimitrienko Yu I , Gubareva E A , Makovskaya M O
Published: August 2021

Abstracts

The article is devoted to the study of the features of the occurrence of slip between layers of a thin two-layer plate with an initial ideal contact under the influence of critical pressure. A three-dimensional problem of the linear theory of elasticity for a thin two-layer plate with sliding conditions with friction at the interface is considered. To solve this problem, the method of asymptotic averaging is applied. An equation is established for calculating the critical pressure for a two-layer plate at which the layers begin to slip. A numerical example is considered for a two-layer fiberglass for different conditions of fixing at the ends. It is shown that the fixing conditions affect the critical pressure of the beginning of sliding.
Modeling nonlinear dielectric properties of laminated composites
Authors: Dimitrienko Yu I , Gubareva E A , Zubarev K M
Published: August 2021

Abstracts

The article is devoted to the development of a method for predicting the nonlinear dielectric properties of layered composites with complex dependences of the dielectric constant on the electric field strength, which consider the effects of a sharp increase and subsequent decrease in the dielectric constant with increasing field strength. The method is based on the use of the theory of asymptotic averaging proposed by N.S. Bakhvalov, E. Sanchez-Palencia, in relation to the nonlinear problem of electrostatics in a layered medium. As a result of applying this method, local nonlinear problems of electrostatics on a periodicity cell are formulated, and an algorithm for calculating effective nonlinear dielectric constants is proposed. It is shown that a layered composite is a transversely isotropic nonlinear dielectric material if its layers are isotropic materials. A numerical example of calculating the nonlinear properties of a 2-layer composite based on barium titanate and ferroelectric ceramic varicond VK4 is considered. Calculations have shown that the developed method for calculating the nonlinear-dielectric ratios of composites is quite effective and makes it possible to predict the dielectric properties of composites at various values of the electric field strength, including the regions where the dielectric permittivities of the layer materials are saturated. The developed technique can serve as a basis for designing new nonlinear dielectric composite materials with unusual properties.
3D Finite Element Modeling of Stresses in Filament Wound Structures
Authors: Dimitrienko Y I , Yurin Yu V , Maremshaova A A
Published: August 2021

Abstracts

A method for calculating stresses in the structure of a pressure cylinder made by winding a composite fibrous material has been developed. A special feature of the proposed method is that the problem is solved within the framework of the 3D formulation of the problem of the theory of elasticity, considering the curvilinear anisotropy of the structure, which changes from point to point. This technique allows one to consider the detailed microstructure of a composite material wound with overlapping tapes. To solve the problem, the 3D finite element method is used, as well as a special algorithm for constructing an additional mesh of elements, which makes it possible to relate the curvilinear anisotropy with the geometry of the thin-walled shell under study.
Numerical methods of Laplace transform inversion in the problem of determination of viscoelastic characteristics of composite materials
Authors: Valishin A A , Tinyaev M A
Published: August 2021

Abstracts

When designing products made of composite materials intended for operation in difficult conditions of inhomogeneous deformations and temperatures, it is important to consider the viscoelastic properties of the binder and fillers. The article analyzes the relationship between relaxation and creep characteristics. All known creep and relaxation nuclei in the literature are considered. The problem of transformation of creep characteristics into relaxation characteristics and Vice versa is discussed in detail. There is a simple relationship between the creep and relaxation functions in the Laplace image space. However, when returning to the space of the originals, in many cases there are great difficulties in reversing the Laplace transform. Two numerical methods for inverting the Laplace transform are considered: the use of the Fourier series in sine and the method of quadrature formulas. Algorithms and computer programs for realization of these methods are made. It is shown that the operating time of a computer program implementing the Fourier method by sine is almost 2 times less than the operating time of a computer program implementing the quadrature formula method. However, the first method is inferior to the latter method in accuracy of calculations: the relaxation functions and relaxation rates, it is advisable to find the first method, since the computational error is almost indiscernible, and the functions of creep and creep speed, the second way, because for most functions, the result obtained by the second method is much more accurate than the result obtained by the first method.
Application of the ultrajet diagnostic method to assess the damage of carbon fiber-reinforced plastic under cooling conditions
Authors: Papich A , Galinovsky A L , Izotov N A , Zhenyuan Chia
Published: August 2021

This paper considers the possibility of using the ultrajet diagnostic for studying the strength properties of carbon fiber-reinforced plastics after cryogenic temperature impact. The method is based on the interaction of a high-speed liquid jet and a fine-dispersed abrasive with the coating to be diagnosed. Analysis of the experimental data revealed a decrease in the material’s strength after cooling in liquid nitrogen. The deterioration of the composite strength properties is explained by the decrease in the adhesive strength in the “fiber-matrix” system.
Investigation of the properties of carbon fiber reinforced plastics after the seawater exposure
Authors: Vasiliev M D , Komarov I A
Published: August 2021

The results of experimental studies of the mechanical characteristics of carbon fibers (CFRPs) before and after their exposure at seawater are presented. The choice of seawater as an operation medium is due to the fact that this carbon fiber is intended for the manufacture of power elements of a manned underwater vehicle. Carbon fibers were made using vacuum infusion technology based on an epoxy binder, and biaxial carbon fabric was used as a reinforcing material. The prepared samples were kept in seawater for 384 h, which made it possible to estimate the amount of water absorption, as well as the change in mechanical characteristics after exposure to seawater. It has been established that the strength of CFRPs does not change during interlayer shear, decreases by 14% during bending, and the value of the elastic modulus, after exposure to seawater, decreases by 17%.
New ternary intermetallic compound SmRuSn2
Authors: Pavlova V A , Murashova E V , Borodulin A S
Published: August 2021

Ternary intermetallic compound SmRuSn2 was synthesized in the system Sm-Ru-Sn by arc-melting and annealing at 600 °C in field with high content of Sn. Its crystal structure was determined from single crystal X-ray diffraction data (at 240 K) and then confirmed by the powder X-ray diffraction data (at 295 K). The compound crystallizes in with space group Cmcm (No. 63), unit cell unit cell parameters: a=4.3954(19) Å, b=10.3783(13) Å, c=7.417(2) Å, Z=4. The intermetallic compound SmRuSn2 belongs to the structure type MgCuAl2.
Research on Multi-beam Handover Invitation Technology for GEO Mobile Satellite System
Authors: Jiang Yumeng
Published: August 2021

Different from the terrestrial cellular system, the GEO mobile satellite system has its own characteristics, such as the extremely large beams, the long propagation delay and the diversity of the MS (Mobile Station) velocity. Based on these characteristics, a cooperative beam-cluster is constructed, and a handover invitation technology based on the coordinated multi-beam is proposed in the paper. Using the sending mechanism of handover invitation by a variable sliding window, the technology can avoid the occurrence of the phenomenon of “ping pong” handover to realize seamless handover, and make the handover quick, efficient and reliable. Simulation results show that the algorithm significantly increases the handover success rate, prevents the unnecessary handoff and has a favourable adaptability to the high velocity MS.
Control Variables in Management Research
Authors: Atinc Guclu , Simmering Marcia J.
Published: August 2021

The use of control variables to improve inferences about statistical relationships in data is ubiquitous in management research. In both the micro- and macro-subfields of management, control variables are included to remove confounding variance and provide researchers with an enhanced ability to interpret findings. Scholars have explored the theoretical underpinnings and statistical effects of including control variables in a variety of statistical analyses. Further, a robust literature surrounding the best practices for their use and reporting exists. Specifically, researchers have been directed to report more detailed information in manuscripts regarding the theoretical rationale for the use of control variables, their measurement, and their inclusion in statistical analysis. Moreover, recent research indicates the value of removing control variables in many cases. Although there is evidence that articles recommending best practices for control variables use are increasingly being cited, there is also still a lag in researchers following recommendations. Finally, there are avenues for valuable future research on control variables.
Technology Standardization in Innovation Management
Authors: Narayanan Vadake , Baburaj Yamuna
Published: August 2021

The profound impact of technology standards—specifications for interfacing or compatibility between different components or products to interact and function synergistically—dictates an understanding of their evolution, processes by which they come to be, and their impact on businesses, industries, and countries. Technology standards span almost every conceivable aspect of the existing business landscape, especially in dynamic industry sectors. Standardization, the processes by which standards emerge and diffuse, is a complex phenomenon encompassing various actors at multiple levels (firm, industry, institutions) that engage in a sociopolitical process of negotiation and collaboration to facilitate the coalescing of multiple stakeholder interests on a chosen standard. Standardization is multifaceted and emerges through various mechanisms, mainly involving one or more of committee-based (de jure) standards, market-based competitive battles (de facto standards), and institutional (government-based) processes, most involving collective action. Market-based processes give prominence to dominant or pioneering firms that introduce technology leveraging the power of large installed base and network externalities, many times tipping the market in favor of the technology format that was first to market. Nonetheless, markets may not tip, and several technology formats may continue to dominate the market, as in the video game market. Standard-setting organizations (SSOs) spearhead convergence around standards by bringing various entities together to derive the specifications for technical compatibility through consensus. The role of governments in the emergence and diffusion of standards varies by the country, region, and nature of the standard. Standards have facilitated innovation at the firm and industry levels and broadly enhanced trade between nations. Intellectual property, specifically standard-essential patents (SEPs), has attracted significant attention due to the strategic and economic benefits that accrue to owners of such patents as well as the challenges they create within SSOs.