bluuebunny/crossref_metadata_2025_split huggingface dataset:
Overview of coordinated spherical tokamak research in Japan
Authors: Takase Y. , Ejiri A. , Fujita T. , Hanada K. , Idei H. , Nagata M. , Onchi T. , Ono Y. , Tanaka H. , Tsujii N. , Uchida M. , Yasuda K. , Kasahara H. , Murakami S. , Takeiri Y. , Todo Y. , Tsuji-Iio S. , Kamada Y. 
Published: September 2021

Abstract
Spherical tokamak (ST) research in Japan has produced many innovative results: (i) plasma start-up to I
p > 70 kA was achieved by electron cyclotron wave (ECW) with N
∥ = 0.75, while electron heating to T
e > 500 eV was achieved with N
∥ = 0.26 on QUEST. (ii) The radiofrequency (RF)-induced transport model was combined with the x-ray emission model, and extended magnetohydrodynamics equilibrium with kinetic electrons was developed to interpret fast-electron-dominated lower hybrid wave sustained plasmas on TST-2. (iii) Density as high as 30 times the cutoff density was achieved by electron Berstein wave current drive combined with electron beam injection on LATE. (iv) Multiple plasmoids formed by tearing instability in the elongated current sheet were observed, and flux closure and ion heating by plasmoid-mediated fast magnetic reconnection were observed on HIST. (v) Optimization of ECW-assisted inductive start-up with a vertical field with positive decay index was performed on TST-2. (vi) Stabilization of the vertical displacement event by a set of upper and lower helical field coils was demonstrated on TOKASTAR-2. (vii) A 6 h discharge was achieved by cool-down of the center stack cover on QUEST, where the plasma duration limit was consistent with the wall saturation time estimated by modeling. (viii) Extension of ion heating by plasma merging was achieved on TS-3U, TS-4U, UTST, MAST, and ST40.
Classification of the reducible Verma modules over the Jacobi algebra

G2
Authors: Aizawa N , Dobrev V K , Doi S 
Published: September 2021

Abstract
In the present paper we study the representations of the Jacobi algebra. More concretely, we define, analogously to the case of semi-simple Lie algebras, the Verma modules over the Jacobi algebra

G

2

. We study their reducibility and give explicit construction of the reducible Verma modules exhibiting the corresponding singular vectors. Using this information we give a complete classification of the reducible Verma modules. More than this we exhibit their interrelation of embeddings between these modules. These embeddings are illustrated by diagrams of the embedding patterns so that each reducible Verma module appears in one such diagram.
Design of android based Unmanned Surface Vehicles (USV) for oil spill monitoring
Authors: Ardiansyah  , Oktaviano I Z , Sutrisno I , Adhitya R Y , Arfianto A Z , Suharso D D , Suwondo I , Ardhana V Y P , Soeroso H , Mulyodiputro M D 
Published: September 2021

Abstract
In this research, a USV will be developed that can detect oil spills on the waters, so in the future it can overcome the problem of water pollution. To be able to determine the thickness of the oil on the water surface, TEMT6000 and LED sensors are used. The light intensity will be converted into ADC value by the TEMT6000 sensor. Furthermore, on this system USV will be controlled by Android and can monitor water surface conditions. Android applications will be connected to Wemos via wifi. Then Wemos is connected serially with a RF915 and another RF915 will be connected to the microcontroller of the USV. From the results of the USV test, the USV can be controlled via Android by moving forward, backward, turning left and right. The maximum range of RF915 is 493.3 meters. Then the oil spill detection average error is 5.45% and the the average of the success rate is 94.55%.
Analysis of equipment for biaxial material testing
Authors: Hassasroudsari P , Kubec V , Prantl A 
Published: September 2021

Abstract
This paper aims to analyze the operation of the equipment for biaxial testing. The equipment’s stiffness is one of the main factors influencing the magnitude of reaction forces in the device’s guidance, consequently affecting the measurement accuracy. Based on intensive research on the topic of biaxial testing devices, the present paper deals with the analysis and optimization of the equipment’s current design.
Determination of mechanical properties of steam turbine rotor materials
Authors: Rund M , Džugan J , Konopík P , Nesládek M , Kuželka J , Růžička M , Méšt’ánek P 
Published: September 2021

Abstract
Increasing share of renewable energy sources in the electricity production results in a pressure on the thermal power plants to cover the power fluctuation very frequently. The increasing number of the start-ups and shutdowns as well as requirements for prompt ramping and for higher operation temperature has cardinal influence on the lifetime of the steam turbine. This all brings new challenges in to the designing process of the new steam turbines and lifetime analysis of currently operated ones. This paper aims to present experimental work, basic material parameters such as tensile test properties and FATT are determined here. Additionally, advanced material properties are probed by fracture toughness tests, fatigue crack growth tests and stress intensity factor threshold tests under various temperature ranges and cycle asymmetries R. The study is carried out for several steels used for the turbine shafts design.
The use of induction heating in reaction apparatus small tonnage production
Authors: Savina A S , Men’shikov V V , Boldyrev V S , Razvodova A A , Bogatov N A , Zotkin A P 
Published: September 2021

Abstract
Currently, in the planning and further implementation of technological processes that require heating of products to operating temperatures of about 1300 C, the issue of selecting energy-efficient environmentally friendly reactors using various heating methods is an acute issue. This scientific article discusses the effective use of electric and non-electric heating methods. Recommendations on the practical application of these methods are given, based on the final product and the specific features of the technological cycle of a particular enterprise. The question of the compliance of both methods with modern international requirements for the small-tonnage chemistry devices under consideration is considered. On the example of the Scientific Production Association «Lakokraspokrytiye» the main advantages in the application of induction heating in reactors used in technological lines for the production of paints and varnishes and coatings are shown. Examples are given of devices that are currently being developed and implemented in the Scientific Production Association «Lakokraspokrytiye», their basic characteristics are described. The described small-tonnage chemistry devices are widely used in the Russian Federation, CIS countries and Eastern Europe.
Problems with Surface Protection of Welded Joints by Vitreous Enamel Coating
Authors: Sternadelová K , Mohyla P , Kozák J , Krupová H , Krejčí L 
Published: September 2021

Abstract
This work deals with the application of a vitreous enamel coating on welded joints, whereas vitreous enamel being intentionally applied in high thicknesses. As a base material, we used low-carbon steel Kosmalt E 300 T. Two different processes were chosen for pre-treatment-chemical and mechanical. The resulting enamel coating consisted of two successively applied layers of base and cover enamel coating. The thickness and microhardness of the coating were measured. The metallographic analysis was also performed on selected samples. The results show that the high thickness of the enamel coating significantly impairs the useful properties of the product.
Material characterization of Au/Ni nanocatalyst for low-temperature carbon dioxide methanation
Authors: Tomiczek Blażej , Szindler Marek , Pawlyta Miroslawa , Borylo Paulina 
Published: September 2021

Abstract
The nanocatalyst for the carbon oxide methanation process is used, among others, in environmental protection, chemical industry, and renewable energy sources. The use of a suitable catalyst allows a chemical reaction to be carried out between unreacted gaseous substrates. The most frequently studied monometallic catalysts are: Ni, Ru, Rh, Pt, Au, Cu, Fe. Bimetallic nanocatalysts are equally popular. Their catalytic properties differ from those of pure component metals. Numerous studies indicate a positive effect in catalysts containing particles: Au-Ag, Au-Pt, Au-Pd, Pd-Ni, Pd-Cu. A review of the literature indicates that examples of the use of metal nanoparticles of spherical shape deposited on a nickel substrate in the methanation process are known, but so far no attempt has been shown in publications to produce a catalyst based on gold nanoparticles with developed surface in the form of spiky (nanourchins, nanostars) on a nickel base as presented in the article. Gold nanourchins are deposited on a nickel substrate in the form of a nickel molecular mesh. The prepared nanocatalyst has been subjected to structural analysis using a transmission electron microscope (TEM). Scanning Electron Microscopic (SEM) images were taken with a Zeiss Supra 35. Qualitative studies of chemical composition were also performed using the Energy Dispersive Spectrometer (EDS). Based on the TEM results, the appearance of the X-ray diffraction pattern was computer modelled. A nanocatalyst was obtained with a high coverage of the nickel molecular mesh surface with gold nanoparticles not exceeding 50 nm in diameter.
Chemical-mechanical polishing of TRIP steel surface
Authors: Ambrož O , Černík D , Rychlý D , Jozefovič P , Mikmeková Š 
Published: September 2021

Abstract
TRIP steels are mostly used due to their high mechanical properties in the automotive industry. The excellent mechanical properties of these steels are inseparably related to the retained austenite phase (γ) phase. Therefore, accurate knowledge of γ phase volume fraction, size, and distribution within a matrix is crucial for a correct understanding of the structure-properties relationship. This study aims to clarify the effect of the sample preparation technique on the results of phase analysis obtained by an electron back-scattered diffraction (EBSD) method. For EBSD analysis, the TRIP steel specimens were prepared by various techniques, such as mechanical polishing, chemical-mechanical polishing (CMP), and electropolishing. The CMP technique shows the most promising results. Therefore, this work focuses mainly on a methodology for optimizing this technique.
Modelling of inhomogeneous chamber states in rotary positive displacement vacuum pumps
Authors: Pleskun Heiko , Jünemann Timo , Bode Tobias , Brümmer A. 
Published: September 2021

Abstract
Chamber model simulation is a common approach to simulate rotary positive displacement vacuum pumps. Therefore the pump is abstracted into working chambers and connecting clearances, whereby the clearance leakages can be identified as the major loss mechanism in such machines. The clearance mass flow rates are calculated with respect to the thermodynamic states in the adjacent chambers, which are normally considered to be homogeneous. In this work it is shown, that the chamber state is inhomogeneous for rarefied gases due to the movement of the pistons which causes a pressure gradient within the chamber. This effect increases with higher Knudsen numbers, because of the increasingly dominant friction. An efficient way to model these inhomogeneous states with a one-dimensional approach for geometrically abstracted chambers is shown. The approach is applied to chamber model simulations of a screw spindle vacuum pump (SSVP) and the results are compared to simulations with homogeneous chamber states and to measurements.
Optimization of the tip profile of orbiting scroll in an asymmetry suction chamber scroll compressor
Authors: Shuaihui Sun , Zhe Wang , Pengcheng GUO , bo ZHANG , Zhenkai MAO 
Published: September 2021

Abstract
The scroll compressors with asymmetrical suction chamber have large discharge loss, as the pressure in outside chamber is far larger than the discharge pressure when the discharge process begins. It is necessary to optimize the scroll profile around the discharge port to reduce the discharge loss. The theoretical method is to redesign the tip profile to obtain the same volume ratio of outside working chamber with the inner working chamber. However, as it is difficult to predict the discharge loss through the flank gap in discharge chamber, the optimum design cannot be obtained. In this paper, we establish an optimization platform based on the CFD method. The profile of orbiting scroll tip is parametrized with CAD software, then the CFD calculation will be done and the performance parameters will be extracted. The MOST optimization algorithm is used to search the best performance parameters and control the parameterized value of scroll profile. After iterations, the best profile with the modification angle of 66.3° was obtained. Compared to the original model, the volumetric efficiency of the compressor increased by 4.11%; and the isentropic efficiency increased by 4.91%. Afterwards, the flow field are analysed to study the characteristics of the optimized scroll compressor. The results show that the backflow, the secondary vortex in discharge chamber and the discharge mass flow pulsation were reduced, which led to the decrease of the discharge loss and the improvement of the isentropic efficiency.
Flow computation inside a scroll compressor based on open-source code
Authors: Fadiga E , Casari N , Angel B , Picavet A 
Published: September 2021

Abstract
Computational fluid dynamics (CFD) is an essential tool for improving the performance of positive displacement machines, which are commonly adopted in vapour compression applications. The numerical analysis of such machines is characterized by several modelling challenges. Firstly, the relative motion of the wraps and the presence of particularly small gap sizes need to be considered during the implementation of a reliable meshing strategy. In addition to that, the operating conditions are close to the saturated-vapour line, requiring a real gas equation of state for the determination of fluid thermophysical properties.
In this work, a commercial scroll compressor has been simulated at three different operating conditions. The geometrical modelling, meshing strategy and compression process have been obtained thanks to a set of libraries built in OpenFOAM-v2006. The results have been compared with experimental data of the pressure evolution in the compression chambers. Furthermore, a complete fluid flow analysis is presented to assess the capabilities of the developed tool when applied to a compressor operating with R410a.
Mechanical and deformation characteristics of rotary compressor discharge valve
Authors: Hu YS , Xu J , Yang O X , Gao J , Zhang X Y , Hu Y P 
Published: September 2021

Abstract
The discharge valve plays an important role in the rotary compressor. For better understanding the mechanical characteristics of discharge valve in the process of movement, a mechanical model considering the coupling effect with limiter is established. Some major parameters, i.e., displacement, stress, stiffness and elastic force, are obtained to characterize the mechanical properties of the discharge valve. Two cases of valve component are calculated by the mechanical model, and the results indicated that the profile of limiter has an important influence on the movement of discharge valve. In order to verify the accuracy of the model, finite element method and high-speed photography are used. The comparison results show the calculation error of valve stiffness obtained by the model is within 3.9% compared with the finite element method results, and the valve motion is consistent with the high-speed photography results. Based on the above analysis, the profile of limiter in one valve component is optimized. The initial winding displacement of the valve is advanced from 2.115 mm to 1.453 mm after the optimization of limiter profile, which exhibits better limiting effect.
Development of the Universal Modelling Method mathematical model and the practice of its application
Authors: Galerkin Y.B. , Solovyeva O.A. , Drozdov A.A. , Semenovskiy V.B. 
Published: September 2021

Abstract
We present the latest improvements to the Universal Modelling Method for optimal gas-dynamic design of centrifugal compressors. The calculation of the gas velocity at the inlet to the impeller blade cascade was corrected. The flow restructuring scheme at the inlet to the impeller blade cascade has been refined. In accordance with this, the mathematical model of the non-incidence gas inlet to an impeller has been improved. A new approach to modelling the velocity diagram on the blade surfaces is proposed, based on the flow parameters corresponding to the non-incidence flow inlet. A mathematical model with quasi-three-dimensional approach to calculating losses in 3D impellers has been developed. The method of gas-dynamic functions is applied to the calculation of flow parameters in control sections. The new mathematical model was identified based on the test results of model stages and compressors. The mathematical model showed a 0.525% error in modelling efficiency of stages with 2D impellers for the design flow rate. For stages with 3D impellers, the modelling error is 0.889%. To verify the new model, the characteristics of 11 low-flow-rate model stages were calculated. The efficiency modelling error for the design flow rate is 1.08%. A series of model stages with a range of design flow rates coefficient 0.15–0.015 and design loading factor of 0.5 was designed. Four of these model stages were tested on the Gas dynamics of turbomachines laboratory ECC-55 test rig. The measured gas-dynamic characteristics confirmed those declared in the design.
Dynamic modelling and experimental validation of Coupled Vane Compressor
Authors: Shakya P , Ooi K T 
Published: September 2021

Abstract
The newly developed Coupled Vane Compressor (CVC) consists of a unique feature that is a couple of vanes cut through the rotor diametrically. Theoretically, this allows the rotor of any diameter which can accommodate the coupled vanes, to be able to operate CVC. Thus, unlike other rotary compressors, CVC design is mostly free of geometrical constraints imposed on the size of its rotor, making it one of the most compact compressors. Nevertheless, CVC suffers from frictional losses similar to other rotary compressors and therefore, studies of dynamic forces acting in CVC is of great interest. In this paper, dynamic forces acting on its components and frictional losses occurring due to rubbing of various components were studied and analysed. Unlike in other vane compressors, in which frictional losses are mostly due to the rubbing of vane tips against cylinder wall and vane sides against vane slot in the rotor, in CVC, the loss also occurs due to rubbing between the coupled vanes. A CVC prototype of 44 cm3 was developed and the compressor power consumption was experimentally studied in an open-type test circuit using air as an operating fluid. The predicted and measured power consumed by CVC were compared and the predicted results were found to have maximum discrepancy of ±15% with the measured results.
Effects of Lubricating oil on the performance of a Four-Intersecting-Vane Rotary Expander
Authors: Murthy A A , Norris S , Subiantoro A 
Published: September 2021

Abstract
Lubrication plays an important aspect in machinery. It seals internal leakage gaps, reduces friction and cools components. The present investigation is intended to test the effects of lubrication to an expander’s performance. Polyester lubricating oil grades (Grade 48 and Grade 68) were tested at various operating conditions. The expander prototype is of the rotary mechanism with four vanes comprising two intersecting bars. An experimental test rig was designed and built. The pressure diagram as function of rotational angle was recorded by six pressure transducers arranged in the working chamber, based on which the features of the expansion process of the four-intersecting-vane rotary expander were analysed. To start with, the working fluid was compressed air, but the eventual intended application is in a vapour compression refrigeration system. The experimental study revealed that the rotary vane expander worked steadily at different operating conditions. The experimental results showed that the expander flow rate was generally lower with a thinner oil (POE grade 46), whereas the volumetric efficiency increased from 23.2% to 27.2%. The adiabatic efficiency decreased from 22.5% to 18.1% with a higher viscosity lubricating oil (POE grade 68).
Application of LDV and PIV techniques for flow measurements in the suction port of a screw compressor
Authors: Nouri J. M. , Guerrato D. , Stosic N. , Yan Y. 
Published: September 2021

Abstract
The application of LDV and PIV systems to measure the flow variation in the suction port of a new designed optical screw compressor has been found to be very successful. Time-resolved mean velocity measurements were made over a time window of 1° (Δθ) at a rotor speed of 1000 rpm, a pressure ratio of 1 and a gas temperature of 55°C. The LDV investigation on the suction port has shown a very stable and slow flow with almost no influence of the rotor motions everywhere except close to rotors at Z=-10mm where the rotor motions start to show its influence and formed a more complex flow with a wavy axial flow profile. The PIV results confirmed flow trend measured by LDV and showed no influence of rotors’ movement on the mean flow structure. The PIV results within the vertical plane also showed relatively strong horizontal stream flow vectors upstream of the inlet suction port and became almost vertically downwards at the inlet port. Despite the current success, further improvements have been recommended to give better optical accessibility as close as possible to the rotors entrance.
Theoretical study on the leakage characteristics of Disc-Seal Single Screw Pump used in oily sludge waste heat source absorption refrigeration system
Authors: Wang Z L , Shi H W , Wang S Y , Wang Z M , Hao M M , Wang J 
Published: September 2021

Abstract
The disc-seal single screw pump (DSSP) used in the field of oily sludge transport has a huge advantage. However, there is no research on the leakage characteristics of the DSSP at present, which makes its application limited. Therefore, the mathematical calculation model of leakage amount of each leakage channel was established in this paper according to the geometric model of the leakage channel. By using this mathematical model, the influence rule of working parameters on the leakage characteristics was analyzed. The results show that the total leakage amount per unit time of the DSSP varies periodically with the rotation of the screw, and the total leakage per unit time of the DSSP will increase with the increase of outlet pressure and screw rotation velocity. When the dynamic viscosity coefficient of the medium increases, the corresponding leakage will be reduced, in which the transmission medium dynamic viscosity is the main factor affecting the total leakage of the DSSP. The study of the leakage characteristics of the DSSP can provide a theoretical basis for the optimal design of its structure in the future.