bluuebunny/crossref_metadata_2025_split huggingface dataset:
Actuator grid method for turbulence generation applied to yawed wind turbines
Authors: Houtin–Mongrolle F. , Benard P. , Moureau V. , Lartigue G. , Bricteux L. , Reveillon J. 
Published: September 2020

Abstract
The aerodynamics of yawed wind turbine wakes remains a major investigation topic, especially for the use of yaw angle in control strategies. Large-Eddy Simulations are employed here to study the influence of yaw and inflow conditions on the prediction of the wind turbine wake structure. A single wind turbine setup with different yaw angles and three different inflow conditions is investigated and discussed with respect to experimental data. The wind turbine blades are modeled using the actuator line method (ALM) while tower and nacelle are represented with a body-fitted unstructured mesh. The high levels of upstream turbulence, experimentally generated by turbulence grids, are emulated here with oscillating ALM. Such approach demonstrates to be highly predictive on the turbulent flow characteristics compared to the emptied wind tunnel experimental data. Results with turbine show good agreement to the experiment data with only a slight overestimation on the magnitude of the wake deflection due to yaw. When compared to a deflection model, the confinement of the wind tunnel is highlighted. The radial and azimuthal time-averaged angle of attack exhibits a high probability of dynamic stall near the hub for a yawed turbine. These results show large discrepancies on the blade loading, highlighting the need for improved and specific models.
A Novel Wind Turbine Wake Steering Model Employing the Ainslie Velocity Deficit
Authors: Bernard V , Santos Pereira R B , Bénard P 
Published: September 2020

Abstract
Wind turbine wakes are an important source of production losses in wind parks, and strategies to mitigate these effects are being explored. One such strategy is yaw steering, where a wind turbine is purposefully misaligned with the wind to deflect its wake away from a downstream turbine, increasing overall farm power production. In order to optimize yaw steering control, fast and accurate models for wake deflection are necessary. Several models have been proposed in literature, often based on approximations of the wake shape. In the present work, a new model is proposed that computes wake deflection based on the result of the Ainslie wake deficit model used in the Dynamic Wake Meandering (DWM) approach that has recently entered the IEC61400 standard for wind turbines. The proposed formulation makes few additional assumptions and introduces no additional fitting parameters beyond those of the DWM wake deficit model. Results obtained using the new methodology are compared to two models from literature and to LES-ALM simulations in a limited number of cases, showing satisfactory results. More extensive comparisons in a variety of cases should be performed in order to better evaluate the proposed methodology. Possible future improvements to the presented formulation are put forward.
Features of electromagnetic wave propagation in a longitudinally magnetized gyrotropic elliptic waveguide
Authors: Itigilov G B , Sh Shirapov D , Kravchenko V A 
Published: September 2020

Abstract
In scientific literature the electromagnetic waves propagation in gyrotropic elliptic waveguides has not been studied enough due to: 1) difficulties of deriving Helmholtz equations for gyrotropic elliptic waveguides in arbitrary magnetization directions, 2) difficulties of solving Helmholtz equations and deriving the dispersion equations, 3) difficulties of solving the dispersion equations themselves. In this work, for the first time, dispersion equations for longitudinally magnetized gyrotropic elliptic waveguides were solved. Basing on the solutions results, the dependencies of the constant propagation: 1) on the strength and direction of the magnetizing field, 2) on the waveguide ellipticity at a constant ferrite magnetization were investigated. Studies have revealed previously unknown features inherent only to the electromagnetic waves in such waveguides propagation and showed that: 1) with the ferrite magnetization increase -3,1 times the polarization plane rotation angle increases by «5,4 times; 2) the gyrotropic elliptic waveguide polarization plane rotation angle is greater than that of a similar round waveguide. The results show the main advantage of gyrotropic elliptic guide systems over circular ones consists in the possibilities of varying both external and geometric parameters of gyrotropic elliptic guide systems and obtaining significant phase raids, which in turn allows developing more efficient phase shifters.
Determining the repetition period of transionospheric radio channel sounding to retrain a facility of correction for dispersion distortions
Authors: Ivanov D V , Ivanov V A , Ryabova N V , Kislitsin A A 
Published: September 2020

Abstract
Correction for dispersion distortions in the transionospheric radio channel poses a topical problem of determining the appropriate repetition period of sounding. Research focused on studying the variations of the sounding repetition period to increase the efficiency of correction for dispersion distortions in the channel. There is proposed a method for experimental studying the diurnal variations of the coherence time (“lifetime”) of the transionospheric channel. The method is supported by the derived equations that establish relations between the channel lifetime and the time derivative of the total electron content of the ionosphere. Research findings allowed to determine the appropriate repetition period of channel sounding to retrain the facility of correction for dispersion distortions in the transionospheric radio channels.
Improvement of methods for studying internal gravity waves in the Earth’s atmosphere using radiosonde measurements
Authors: Gubenko V N , Kirillovich I A , Andreev V E 
Published: September 2020

Abstract
Internal gravity waves (IGWs) determine atmospheric dynamics at all heights providing an effective mechanism for the transfer of wave energy and momentum upward from the lower levels. The dynamical (shear) and convective instabilities contribute most to the energy dissipation and saturation of internal waves in the Earth’s atmosphere. The wave saturation assumption is a key point at the radio occultation (RO) investigations of IGWs, therefore, verification of its implementation in the Earth’s atmosphere using radiosonde studies is an important task of atmospheric physics. We propose an upgraded hodograph method based on combined analysis of the velocity and temperature measurements. To achieve the minimal errors in obtained results of reconstructing the internal wave characteristics, the polarization relation between the wave wind speed and temperature variations in the Earth’s atmosphere has been used. It has been shown that the improved method of wind speed hodograph analysis is especially relevant for cases when the intrinsic frequencies of analyzed IGWs noticeably exceed the Coriolis parameter values.
Revisiting the conducting of measurements from the board of International Space Station by decimeter synthetic aperture radar system
Authors: Kalinkevich A A , Kutuza B G , Yu Manakov V , Masyuk V M , Plyushchev V A 
Published: September 2020

Abstract
Nowadays the importance of using synthetic aperture radar (SAR) in the P and VHF bands for object recognition, as well as for surface and subsurface sensing of the Earth’s surface has been proven. However, the space experiment using P-band SAR has not yet been implemented. One of the most important reasons for this is destructive influence of the ionosphere on the quality of synthesized images. It is expected that the polarimetric radar survey of the Earth’s surface in the years to come will be provided by two spacecraft – ”BIOMASS” and ”ISS-SAR(P) (International space station-SAR(P)”, operating at frequencies ∼435 MHz. Variety of phenomena related to radio wave propagation through the ionosphere, as well as the temporal and spatial inhomogeneities of its properties, has been the subject of research for many decades. In the case of the use of SAR of P and VHF bands for remote sensing of the Earth (ERS), the situation is aggravated by the fact that various processes in the ionosphere begin to concentrate, that reduces the unique properties of the performance of these devices to a minimum. As a result, a number of provisions concerning the application of the SAR of P and VHF bands for remote sensing require clarification and additional studies of the ionospheric influence on electromagnetic radiation passing the ”Satellite – Earth – reflection from the Earth’s surface – Satellite” route. Such studies can be carried out directly in the course of the space experiment (SE) by creating specialized ground test sites, equipment of which works according to the program coordinated with the operation of SAR. The ISS-SAR(P) experiment in the area of a ground-based test site should primarily be considered as the development of methods for additional ionosphere research, and also as an improvement in methods for compensating the influence of the ionosphere on radar images.
Design of a push-broom multi-beam radiometer mapping system based on toroidal SAT TV antenna
Authors: Gerasimov O A , Drozdov D V , Rybakov Yu V 
Published: September 2020

Abstract
A functional diagram of a surface radiation mapping microwave radiometer system is presented. The system is proposed for use in agriculture, to map fields soil moisture, effectiveness of draining systems, etc. It has also many other useful applications, such as early detection of subsurface fires in peats and many more. Previous single-beam systems used a number of passes and long lasting flight times to obtain a map of the underlying surface. Some multi-beam systems used bulky electromechanical scanning antennae unsuitable for light aerial vehicles. Thus those systems were unaffordable to use for small agricultural businesses due to high production and operational costs. Authors propose low-cost microwave push-broom system that is based on a toroidal antenna and other budget components mass-produced for satellite television. Due to its low weight the complex can be mounted on an unmanned aerial vehicle. The microwave complex is designed to use six to fourteen radiometer channels of different bands on a single toroidal antenna. This allows to form the underlying surface map containing radiation data with limited number of aircraft passes significantly reducing survey time. The possibility of simultaneous operation in the Ku and C bands has been successfully investigated.
Simulating a microstrip vibrator emitter
Authors: Ovchinnikova E V , Dinh To Nguyen , Kondratyeva S G , Shmachilin P A , Gadzhitv E V , Gigolo A I 
Published: September 2020

Abstract
There has been a shift from omnidirectional antennas in the azimuth plane to active phased antenna arrays with wide-angle scanning in ground communication systems. The report presents models of such antenna arrays and demonstrates the possibility of increasing the energy potential by using spatial schemes for constructing such antennas. To practically implement spatial antenna arrays, omnidirectional emitters in the azimuthal plane are used: balanced and unbalanced unipoles. It is advisable to manufacture vibrators using printed technology. The report presents the design of a micro-strip vibrator emitter for a cylindrical or concentric cylindrical antenna array. The results of numerical electrodynamic modeling are presented. The parameters and main characteristics of the emitter in the antenna array are determined.
Use of the Sun’s radiothermal radiation as an external source for research of multi-frequency microwave radiometric system antenna parameters with background noise compensation
Authors: Rostokin I N , Fedoseeva E V , Rostokina E A , Shchukin G G 
Published: September 2020

Abstract
The work belongs to the field of solving problems related to the metrological support of microwave radiometric research of radiothermal radiation of the atmosphere. The article contains a comparative analysis of the most widely used reference sources of noise radiation used both for internal and external calibration of microwave radiometric equipment for atmosphere control. In the given work the research of a method of external calibration of the antenna system of multifrequency microwave radiometric system with compensation of background noise on radiothermal radiation of the Sun is executed, questions of its practical realization are solved and results of an estimation of directional properties of the antenna system of microwave radiometric system on radiothermal radiation of the Sun are received. The results of practical research of the directional properties of the antenna system of a stationary variant of the multi-frequency microwave radiometric system, consisting in measuring the experimental antenna radiation pattern of the multi-frequency two-mode antenna system on the main measuring channel on two linear polarization (vertical and horizontal) and additional measuring channel with a predominant reception of background radiation coming from the side lobes are presented.
Heterologous Expression and Enzymatic Properties of Exocellulase CelA
Authors: Sui Ming , Rong Jiachao , Zhang Yang , Qu Peng , Zhu Yusong 
Published: September 2020

Abstract
The gene of glycosyl hydrolase CeIA is derived from Bacillus licheniformis and the GenBank accession number is AAU40776.1. The sequence analysis of this gene was carried out by online software, and the celA gene was cloned from the genome of the strain by homologous amplification. The gene was ligated into the pMAL-c2x vector, transformed into E. coli Transetta for heterologous expression, and the catalytic properties of the recombinant enzyme CeIA were studied.
Study on the preparation technology of Sanqi hemostatic spongia for percutaneous absorption
Authors: Liu Shijun , Li Lin , Tang Zhishu , Zhang Yu , Sun Jing , Song Zhongxing , Xu Hongbo , Cui Chunli , Liu Hongbo 
Published: September 2020

Abstract
Objective: To optimize the preparation technology and matrix ratio of Sanqi hemostatic spongia. Methods: The effects of Twain 80, formaldehyde and twelve sodium alkyl sulfate on the matrix formability of the spongia were investigated by the L9 (33) orthogonal test, and the optimum ratio of the matrix was optimized through the water absorption, the thickness uniformity, the softness and the color degree. The orthogonal test results showed that the matrix ratio was Twain 80 1.4g, formaldehyde 1.6 mL, sodium dodecyl sulfate 1.0 g, and Sanqi hemostatic spongia was superior when the proportion of other substrates was fixed. Conclusion: Sanqi hemostatic spongia was produced by orthogonal test and matrix ratio is stable, uniform in thickness and good in quality.
The Optimal Environment Selection Strategy of Risk Model With Perturbed Diffusion
Authors: Guo Shumei , Zhang Lili , Guo Jie , Li Xinna , Yang Jiandong 
Published: September 2020

Abstract
In this paper, the authors consider the optimal investment of the risk model with perturbed diffusion. Insurance companies invest the surplus in risky asset and risk-free asset. This paper discusses the problem of minimizing the ruin probability of insurance company. By solving the corresponding Hamilton-Jacobi-Bellman equations, the optimal investment portfolio and the upper bound of Lundberg of the minimal ruin probability are obtained. Especially,when the claim distribution is exponential distribution, asymptotic optimality and asymptotic uniqueness of strategy A* and R are obtained.
Performance comparison of initial and optimized designs of dual stator HEFSM for aerospace applications
Authors: Ali Hassan , Sulaiman Erwan , Jenal Mahyuzie , Ali Irfan 
Published: September 2020

Abstract
For aerospace propulsion system, electrical machines are capable to deliver high torque density and are dominant for the viability of direct-drive electrical propulsion for aircraft applications. Besides light “weight and high torque ability, the machines “should also be inherently fault tolerant for it to be used in aircraft applications. For these reasons, a new type of machine has been introduced in last decade know as flux switching machine (FSM). FSM contains all its flux excitation sources on stator side with robust piece of rotor which is free from permanent magnets (PMs) and coils. Since, these machines have shown high torque-to-weight ratios and high efficiency during research in the last decade. Regardless of this, the task of designing a machine appropriate for aerospace application goes beyond the electromagnetic design and into the area of mechanical design much deeper than traditional designs. Therefore, in this paper, a new structure of dual stator (DS) HEFSM with segmental rotor is proposed and analysed. Moreover, the initial structure of proposed design” is optimized using deterministic optimization method. Furthermore, the performance of initial and optimized designs are compared and investigated using 2D-FEA method.
Analytical Design Structure of New Segmental Stator Permanent Magnet Flux Switching Motor
Authors: Othman S.M.N.S. , Sulaiman Erwan , Jenal Mahyuzie 
Published: September 2020

Abstract
Permanent Magnet Flux Switching Machines (PMFSM)s are among the most widely investigated types of electric motor because of high flux density compared to switch reluctance motor (SRM). The aim of the present work is to design a three phase 12Slot-14Pole segmental stator (SegSta) PMFSM and to investigate the flux linkage of U, V, W phase. In this study, 12S- 14P SegSta PMFSM is investigated by using 2-D finite element analysis (FEA) software develop by JMAG designer ver 15.0. The geometry structure of the 12S-14P PMFSM design is 264 mm diameter and the permanent magnet total weight is approximately 2 kg. The results of the 2-D FEA simulation indicate that the open angle between each SegSta is 30 degree for uniformly flux distribution in each SegSta core. It is found that the amplitude difference for each U, V, W phase is approximately zero since at 30 degree the flux density is evenly distributed at stator core with concentrated winding. Overall, this paper contributes to the methodology for designing a segmental stator 12Slot-14Pole PMFSM..
Study of permanent magnet configuration in alternate circumferential and radial flux permanent magnet flux switching machines (AlCiRaF-PMFSM)
Authors: Jenal Mahyuzie , Othman S. M. N. S. , Sulaiman Erwan 
Published: September 2020

Abstract
Alternate circumferential and radial flux (AlCiRaF) is new design in PMSFM. AlCiRaF PMFSM offers high torque and power density. However, AlCiRaF PMFSM is a novel design that a good opportunity to be potential improved further. In this research, the nine design of permanent magnet configuration in AlCiRaF PMFSM is proposed to compare each performance possibilities. The configurations of permanent magnet are introduced to study the performance effect by changing the permanent magnet position which is PM-Bottom, PM-Middle and PM-Top for both circumferential and radial direction. Besides, the permanent magnet structure design will improve field winding area structure to provide space for future improvement. Weight of all the permanent magnets are estimated to be 0.5 kg altogether. Initially, design procedures of the all motor including parts drawing, material and condition setting, the properties setting are all explained. Then, coil arrangement test is conducted to perform 3 phase armature coil arrangement. Then, no load analysis is conducted to analyze cogging torque, flux linkage, flux distribution and back-EMF of motor followed by load analysis which analyze the torque speed characteristics and output power of the motor with different permanent magnet configuration. No load analysis and load analysis are conducted using finite element analysis of JMAG Designer 16.0. Finally, it is found that there is no significant difference that resulted and the best permanent magnet configuration compared to the Existing AlCiRaF PMFSM permanent magnet design is TRBC PM and MRBC PM due to the capability to produce high output torque and power based on the analysis conducted.
Visible light responsive BiPO4/g-C3N4 for enhanced photocatalysis of 2-4 dichlorophenol under solar irradiation
Authors: Jang Ng Jit , Hon Leong Kah , Ching Sim Lan , Heng Chin Yik , Pichiah Saravanan 
Published: September 2020

Abstract
In this study, bismuth phosphate (BiPO4) incorporated with graphitic carbon nitride (g-C3N4) was successfully constructed by a facile thermal deposition. The morphology, optical property and crystal structure were systematically studied by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectra (UV-DRS). The morphology confirmed that the BiPO4 is successfully deposited on the surface of g-C3N4. With the deposition of g-C3N4 had enhanced the light absorbance, especially in the visible light region with 2.5% dopant dosage giving the highest absorbance. This significantly improved the photocatalysis of 2,4 dichlorophenol (2-4DCP) under solar irradiation attributed by 2.5% BiPO4/g-C3N4 with achieved a complete removal in 90 min. This study could inspire new ideas and alternative solution for photodegradation of other organic pollutants under solar irradiation.
Enhanced Biomass Properties In Sludge Bulking: Impact of Static Magnetic Field
Authors: Syamimi Zaidi Nur , Sohaili Johan , Hussein Norelyza , Burhanuddin Bahrodin Muhammad 
Published: September 2020

Abstract
Occurrence of sludge bulking with regard to prolong sludge age declines the removal performances attributable to the failure of aggregation by the floc-formers and insufficient adhesion among cells’ surfaces. Approach of sufficiently minimizing the sludge age had been taken most of the times. This approach, however, eliminated the floc-formers although it was found to inhibit the bulking. The aim of the present study, therefore, is to investigate the potential of magnetic field application as an alternative approach to control the sludge bulking. Two sequencing batch reactors, Reactor A (SBRA) and Reactor B (SBRB), were operated in long sludge age to induce the bulking. SBRA was subjected to 88.0 mT magnetic field intensity while SBRB served as a control system. The findings showed that the magnetic field was able to enhance the biomass properties including the aggregation ability, relative hydrophobicity and maintain significant negative surface charge under an adverse effect of long sludge age thus led to more stable flocs been formed. This had resulted with consistent high removal of SBRA compared to SBRB. Consequently, this approach minimizes the occurrence of sludge bulking.