bluuebunny/crossref_metadata_2025 huggingface dataset:
Two phase (water/air) suction performance of turbopump inducer
Authors: Nasu K , Kitabata T , Tanaka Y , Watanabe S , Matsunaga Y , Ohashi S , Sakata A
Published: May 2022

In the present study, the gas-liquid two-phase flow performance of a turbopump with an inducer has been experimentally investigated. In the performance evaluation test, the air bubbles is released from dissolved air at the upstream valve to realize two-phase flow. By this method, a homogeneous bubbly flow is expected just after the valve. The amount of dissolved oxygen (DO) is an important parameter, and the experiment is carried out under the conditions of DO≅50%, 100%, 200%, where DO[%] indicates the relative amount of DO against the saturated value at the atmospheric condition. Under each DO condition, the experiment is performed at various water flow rates. As a result, a clear trend that the higher DO is, the worse the performance becomes, is observed. It is found that the mechanism for the head drop of the pump differs between at high and low flow rates. At the high flow rate, the performance does not deteriorate up to relatively high volumetric flow rate ratio of air and water. The cause of performance deterioration seems to be the increased number and/or size of bubbles released at the upstream valve. On the other hand, at the low flow rate, the performance deteriorates at relatively low air-water flow rate ratio. Although the air water volume flow ratio is low, the bubbles can precipitate in inlet flow recirculation and back flow vortices, which seems to cause the performance deterioration.
Dynamic characteristics and stability evaluation of cavitation-induced flow instability in a conical diffuser
Authors: Nakajima Kazushi , Tsutaya Kazufusa , Kubo Masashi , Miyagawa Kazuyoshi
Published: May 2022

It is known that cavitation surge, which is a self-excited vibration caused by cavitation volume fluctuation, may occurs in a draft tube of a water turbine when it is operated under overload. In this study, a cavitation surge was generated by a swirling flow into a Venturi tube, and its dynamic characteristics and stability were evaluated using a one-dimensional model and a transfer matrix. In addition, the variation of the cavitation volume was calculated using the binarization process with a high speed camera and compared with CFD. As a result, it is possible to evaluate the period of the cavitation volume fluctuation by the binarization process, but it is difficult to evaluate its volume quantitatively. The magnitudes of the cavitation compliance and the mass flow gain factor decrease with the increase of the cavitation coefficient. The magnitudes of the mass flow gain factor also tend to decrease with decreasing swirl number. The phase of the mass flow gain factor tends to delay as the cavitation coefficient increases. It is found that the phase of the mass flow gain factor and the cavitation compliance are also important parameters for the stability.
Experimental transient cavitation bubbles in a conical-frustum shaped tube
Authors: Wang Zhichao , Liu Shuhong , Zuo Zhigang , Pan Zhao
Published: May 2022

Extreme flow acceleration in the water can induce large cavitation bubbles in the hydraulic machinery, and cause liquid column separations in the pipeline. The abrupt collapse of these large bubbles produces strong pressure oscillation and causes catastrophic destruction instantaneously. Considering the complexity of the shapes of pipelines in engineering, we experimentally study the transient bubble dynamics in a conical-frustum shaped tube by a modified tube-arrest method in the present paper. Three shapes of cavitation bubbles are observed during the transient processes: (A) conical-frustum shaped bubbles originated from the bottom; (B) hemispherical bubbles originated from the side wall; (C) conical-frustum shaped bubbles originated from the liquid bulk. It is seen that the locations of the cavitation bubbles strongly depend on the geometries and the surface roughness of the tube, and the nucleation status of the bulk liquid.
Investigation on axial thrust behavior of balance piston system for a rocket pump
Authors: Sakai Kento , Iwase Bungo , Matsumoto Keisuke , Miyagawa Kazuyoshi , Kawasaki Satoshi
Published: May 2022

High stability in axial direction is required for rocket pumps operated under extremely low-temperature and high-pressure conditions, turbopumps therefore uses balance piston (BP) system for balancing their axial thrust. The BP system is stable under quasi-static conditions. However, BP system might become dynamically unstable under some condition. Thus it is fundamental for stability evaluation of turbopumps to predict static/dynamic characteristics in axial direction of BP system. Furthermore, we focus on characteristic change by cavitation which often occurs in the pump inlet. In this paper, an experimental study of a model turbopump which had an unshrouded impeller equipped with BP system was carried out. We experimented it with an active magnetic bearing (AMB) test facility in order forcibly to oscillate it with an optional amplitude and frequency. In addition, we examined characteristics of BP system by three-dimensional computational fluid dynamics (3D-CFD) simulations. The results of 3D-CFD simulations were in good agreement with these tendency of BP system, and were effective in predicting its static/dynamic characteristics. Some cases showed that dynamic characteristic of BP system became unstable by growth of cavitation, therefore we suggest that the influence of cavitation must also be considered in the design of turbopump.
Numerical characterization of turbine blade dynamic properties via proper orthogonal decomposition
Authors: Kang S , Kim Y , Song D , Cho H , Shin S
Published: May 2022

Forced vibration analysis is an essential process during the design of a turbine blade and requires enormous computational expense because of its complicated numerical procedures with large size matrices. This paper focuses on the application of the proper orthogonal decomposition (POD). It is under the spotlight for its usefulness on the reduced order model (ROM) construction. POD applications include nonlinear static, modal analysis, and forced vibration (harmonic response) analysis of the turbine blade. Performance of POD-ROM is examined for various operating conditions, and effect of the number of POD modes used is also investigated. With the sufficient number of POD modes, accurate results of turbine blade response are obtained with drastically reduced computational resources.
Motion analysis of a power unit moored with a cable for tidal power generation (2D calculation considering fluid forces acting on the unit and cable)
Authors: Nakanishi Y , Funami Y , Yano T
Published: May 2022

The power unit with counter-rotating propellors has been proposed for a tidal power generation. The unit has the potential to be moored with a cable because of inherent equilibrium of the rotational moments acting on the counter-rotating propellors. On the other hand, the flow condition of a tidal current is not steady, therefore, the motion and the posture of the power unit should be investigated for the stability of the power generation in terms of the fluid dynamics. In this study, the two-dimensional motion of the power unit and the cable modelled with rigid elements connected each other with pivots are analyzed as the combination of translational and rotational motions with the constraint of the connected elements. The time-dependent position, angle and relative velocity of each calculation element were obtained to validate the usefulness of the proposed method.
Power augmentation in H-Type Darrieus wind turbine using wind lens
Authors: Verma Shalini , Mansi  , Paul Akshoy Ranjan
Published: May 2022

The need for clean, sustainable and cost-effective energy sources leads to the installation of wind turbines with advanced technologies. One of the main parameters which govern the productivity of any wind turbine is its power generation capacity. The higher the incoming wind speed, the more the power generation, but the challenges faced by wind turbine is in low wind speeds. Hence, it becomes important to boost the efficiency of wind turbine with modified designs for lower wind urban regions. The prime objective is to boost the power production of a conventional two-bladed VAWT with the application of convergent-divergent type wind lens. Ansys CFX is employed for numerical analysis of flow around the rotor of straight bladed H-Darrieus turbine. Different turbulence models are analysed and SST k-ω model is well validated with experimental result. Power coefficient values are evaluated at a range of 0.5 to 3 tip speed ratios in both cases. Simulation result is validated with experimental results in terms of power coefficient. Computational result is validated with 4% error and 2% error for simple VAWT and VAWT with wind lens respectively. The results show an enhancement of 2.6 times the power coefficient values of conventional VAWT.
Influence of blade leading edge shape on hydraulic and suction performance of a mixed-flow pump
Authors: Kim Yong-In , Yang Hyeon-Mo , Lee Kyoung-Yong , Choi Young-Seok
Published: May 2022

The shape of the blade leading edge (LE) is a design variable that cannot theoretically affect the inlet flow characteristics under the definition of the velocity triangle. However, the LE is the first to encounter the working fluid in terms of streamwise direction. Depending on its shape, not only the local flow characteristics but also the performance can be affected. In this study, a numerical analysis of the hydraulic and suction performance for a mixed-flow pump was performed with different shapes of the blade LE. The blade was prepared with four sets according to the ellipse ratio (ER), including a square (ER=0), round (1), elliptic (2), and parabolic (5) shape. As the shape of the blade LE was square, the flow streamline was immediately separated from the blade surface, showing a significant drop in the hydraulic performance. As the blade LE was designed in a round, elliptic, or parabolic shape instead of a square shape, the hydraulic performance did not show a noticeable difference. On the other hand, in the prediction of suction performance, the square LE obtained the best characteristics. As the LE shape gradually became a parabolic shape, the cavity blockage was reduced, and the suction performance was also improved.
A numerical investigation of cryogenic cavitation flow in LNG submerged pump
Authors: Suh Jun-Won , Yang Hyeon-Mo , Lee Kyoung-Yong , Hong Jin-Hee , Choi Young-Seok
Published: May 2022

The cryogenic centrifugal submersible pump is one of the core equipment of the technology and serves to pressurize and transport the fluid with the centrifugal force generated from the impeller by rotation. Due to the structural characteristics of the working fluid and multi-stage, problems such as cavitation and axial thrust negatively affect the life, noise, vibration, and performance of the pump, so it must be considered. For this reason, this research aimed to investigate a low-pressure LNG pump for an LNG fuel supply system with a general specific speed. The main components were designed based on the previous studies and CFturbo. The numerical analysis method was established and the performance prediction was conducted using commercial CFD packages. The three-dimensional Reynolds-averaged Navier-Stokes equations were discretized to analyze the internal flow field. First, the reliability of the turbulence model was proved through Hord’s experiment in the 0.357-inch ogive. Second, the steady and unsteady simulations were conducted between the single-passage and full-passage conditions in the inducer. Third, the corresponding analysis was investigated to identify problems with existing model features and find improvement directions.
Effect of diffuser vane slit on rotating stall behavior and pump performance in a centrifugal pump
Authors: Takao Shunya , Konno Shinichi , Ejiri Shinichiro , Miyabe Masahiro
Published: May 2022

In the previous study of a centrifugal pump with a vaned diffuser, it was confirmed that the flowrate at the onset of rotating stall was shifted to the lower flowrate by slitting the diffuser vanes. As the CFD result, it was found that the jet flow from pressure-side to suction-side impinges backflow near the suction surface and it suppresses to expand toward the diffuser inlet. However, it is difficult to say that the optimized shape and slitting position have been sufficiently studied. Therefore, in this study, we investigated the effect of slitting on the pump performance and internal flow by adding another slitting to the diffuser vane with slit. In order to clarify the suppression effect of the jet flow in detail, the effect of adding slits at two locations was verified. The pump performance was compared for these diffusers. The effect of slitting on the diffuser vanes on the occurrence of rotating stall was clarified by the experimental and numerical study.
A study of counter-rotating impulse turbine for wave energy conversion-effect of middle vane thickness on the performance-
Authors: Ogawa T , Takao M , Alam M M A , Okuhara S , Kinoue Y
Published: May 2022

In an oscillating water column (OWC) based wave energy device, a water column that oscillates due to the sea wave motion generates a bi-directional airflow in an air chamber, and finally, the bi-directional airflow driven air turbine converts the pneumatic energy into mechanical energy. The counter-rotating impulse turbine for bi-directional airflow has been proposed by M. E. McCormick of the United States Naval Academy in 1978. In a previous study, the authors investigated the effect of the turbine geometry on the performance of a counter-rotating impulse turbine for bi-directional airflow, and it was clarified that the efficiency of the turbine is higher than an impulse turbine with a single rotor for bi-directional airflow in a range of high flow coefficient. Moreover, this impulse turbine has a disadvantage that the efficiency in a range of low flow coefficient is remarkably low due to the deterioration of the flow between the two rotors. In this study, in order to make the counter-rotating impulse turbine practically compatible, the thickness of the middle vanes installed between the two rotors was changed, and the effect of the thickness on the turbine performance was investigated by the computational fluid dynamics (CFD) analysis. As a result, it was found that the efficiency of the counter-rotating impulse turbine with middle vanes increases as the thickness of the middle vanes decreased.
Analysis of an optimized radial impulse turbine for an OWC wave energy converter
Authors: Saad Mina , García-Diaz Manuel , Pereiras Bruno
Published: May 2022

OWC concept is one of the most spread technologies among wave energy converters due to several reasons. However, this technology has always deal with the problem of the inherent bidirectional flow. Many solutions have been adopted such as a flow rectification system combined with a unidirectional turbine, several types of bidirectional turbines such as Wells turbine or impulse turbine. In this work, it is shown the performance of an optimized geometry for a radial impulse turbine, which improvement is based on the re-designing of the blades and settling angles of the vanes. A CFD model, validated against results from the bibliography, has been used to simulate both a new and a previous geometry taken as reference. The results of both turbines have been analysed in terms of the loss coefficients for each element in order to analyse the advantages of the new geometry. It has been found that the new geometry exceeds the efficiency of the previous geometry by 5%, being this gain based on the fact that sacrificing the rotor’s efficiency could lead to a great improvement in the performance of the guide vanes, reducing their loss and, in turn, lifting the turbine’s efficiency despite reducing the rotor’s one.
Effect of adding ceramic thermal barrier coating on the turbocharger efficiency, external and internal heat transfer
Authors: Mohammad Mahadhir , Chiong Meng Soon , Tan Feng Xian , Rajoo Srithar , Md Sah Muhammad Hanafi
Published: May 2022

Turbocharger is a device installed on an internal combustion engine to boost its thermal efficiency. A turbocharger consists of three main components, namely the turbine, central housing, and compressor. The common material for commercial turbine housing is cast iron, for its lower cost yet resilience at elevated temperature. Given the high exhaust temperature a turbocharger is exposed to, energy loss in the form of heat transfer is inevitable. It is known to H turbine efficiency by up to 30%. This research aims to determine the turbocharger efficiency in the presence of thermal barrier coating (TBC) on the inner surface of turbine volute. Particularly, this work will focus on the internal and external heat transfer of the turbine and its impact on efficiency. The subject turbocharger is a commercial single-scroll vaneless unit commonly used in gasoline passenger vehicle. Yttria-Stabilized Zirconia (YSZ) is chosen as the TBC material, due to high melting point (around 2700°C), good thermal insulation property and very low thermal expansion compared to other ceramic materials. The YSZ was applied to the inner surface of turbine volute via plasma coating technique. However, due to the large disparity in thermal expansion between YSZ and cast iron, the TBC is prone to cracking at elevated exhaust temperature. Thus, an Inconel 718 turbine housing, with closer thermal expansion to YSZ, was refabricated for the use of this study The turbocharger performance was experimentally measured on the LoCARtic turbocharger gas stand. The turbine inlet temperature (TIT) was varied at 150, 350, 550, 650 and 750°C, while the compressor operating condition was maintained throughout the testing for equivalent comparison. From the result, the turbocharger efficiency drops when TIT is increased, and the turbine pressure ratio becomes lower. Overall, the external heat transfer loss is found to reduce 7% to 40% and no significant difference noticed on the internal heat transfer.
Research on the application of ADN propulsion module for satellites
Authors: Ji Jialong , Liu Guoxi , Fang Zhongjian , Song Fei
Published: May 2022

The novel technology of the liquid Ammonium Dinitramide(ADN) propulsion is researched for its higher working performance and safer characteristics. Based on the safe performance, the design of ADN propulsion system for satellites is also presented in this paper. At the same time, the research on ADN propulsion system module is presented in this paper, including the developing processes method, the interface analysis, and the assemblage in satellites. Two examples are described here besides an ADN propulsion module applied in orbit. From the research we can know that ADN propulsion technology is fit for satellites, and the modularization of ADN propulsion system is a better developing mode for small satellites, which can simplify the developing process of propulsion system and crafts. In the end, the further application object and further work of ADN propulsion module for satellites is stated.
Evaluation of the multiple sensor optical fiber probe methods for the measurement of local bubble parameters accordng to bubble shape
Authors: Moon Jeongmin , Kim Taeho , Jeong Jae Jun , Yun Byongjo
Published: May 2022

It is necessary to evaluate a multiple sensor probe methods according to the bubble shape for the measurement of local bubble parameters. For this, numerical simulation and air-water benchmark experiments were performed with the double-sensor and four-sensor probes. It was found that the velocity measurement errors of the probes were 5.3% and 4.2%, respectively. In terms of Sauter mean diameter (D
32), its measurement performance is affected by the type of the probe and bubble shape. The double-sensor probe showed reasonable measurement accurancy of the D
32 for the spherical shape bubble. However, as the bubble shape is distorted from the sphere, the D32 measurement error increases. The four-sensor probe has a relatively large error compared to that of the double sensor probe under the bubbly flow with small size. While, when the D
32 is larger than 2 mm, the four sensor probe shows excellent measurement performance regardless of the bubble shape.
Characteristics of non-equilibrium condensing flow in three-dimensional supersonic rectangular nozzles
Authors: Haque S , Matsuo S , Kaeriyama H
Published: May 2022

Fluid flow inside a supersonic nozzle with a rectangular cross-section induces secondary flow due to the shape of the upper wall curvature. The secondary flow forms longitudinal vortices near the wall of the nozzle corner which destabilizes the nozzle outlet flow due to the early transition of the flow from laminar to turbulent. It is known that non-equilibrium homogeneous condensation occurs in a supersonic rectangular nozzle due to the rapid expansion of the condensable fluid with large latent heat such as water vapor. Homogeneous condensation takes place through the formation of water nuclei from its vapor when foreign nuclei are absent in the flow. The irreversibility of the non-equilibrium condensation process causes loss in flow transportation energy in the form of total pressure loss. Although numerous researches have been conducted about the effect of non-equilibrium condensation process in supersonic nozzles, however, the interactions between nozzle shape, non-equilibrium condensation, and longitudinal vortices have not been studied convincingly. Therefore, numerical simulations have been carried out for two supersonic three-dimensional rectangular nozzles in order to understand the effect of nozzle shape and non-equilibrium condensation on the longitudinal vortices at the nozzle corner. Furthermore, total pressure distribution in the nozzle was analysed to understand the effect of degree of supersaturation and expansion rate on the total pressure loss. In this research, characteristics of simulated flow fields including total pressure loss were in good agreement with the published literature.
Design and Simulation Analysis of Wide-range Current Transformer with Adaptively Adjustable Air Gap Length
Authors: Lu Bing , Chen Xiwen , Xu Zhongda , Nie Gaoning , Tang Xiaojun
Published: May 2022

This paper proposes a wide-range current transformer structure with adaptively adjustable air gap length. The length of the air gap of the iron core of this structure can be automatically adjusted with the current harmonic ratio of the secondary side of the current transformer, so that the current transformer has good anti-saturation characteristics; on the other hand, the output voltage value of the detection winding can be adjusted after proportional calculation. The secondary side current is compensated to ensure the accuracy of its measurement. At the end of the article, the structure of the current transformer is simulated and analyzed. The calculation results show that the measurement error of the secondary side current after compensation can reach the design requirements of the 0.2-level standard current transformer during the change of the primary current from 100% to 350%. This structure can effectively broaden the range of the current transformer and improve its measurement accuracy.
Matched Interface and Boundary Method for the Helmholtz Equation with a Discretization by 4th-order 17-point FD Scheme
Authors: Zhu Xiaoling , Cheng Dongsheng , Long Guangqing
Published: May 2022

We generalize the MIB (matched interface and boundary) method for solving the Helmholtz equation with a rotated 17-point 4th-order FD(finite difference) scheme, which is non-compact, and has to use the points outside of the computational region. An optimal combination of difference schemes are employed to discretize the Helmholtz equation both on the standard coordinate system and the 45° rotated one. The combination weights are obtained via minimizing the numerical dispersion. Numerical experiments show that the rotated 17-point FD scheme with the MIB method is 4th-order in accuracy, and is effective in supressing numerical dispersion.
Effect of Gap and Diameter Ratio on Vortex-induced Forces for Cylinders in Tandem at Re=100
Authors: Annapeh H F , Kurushina V
Published: May 2022

The article investigates fluctuations of the vortex-induced loads related to the effects of gap and diameter ratio on the mean drag and lift coefficients of the downstream cylinder, when two circular stationary cylinders of different diameters are arranged in a tandem configuration. The study is performed with the method of computational fluid dynamics for the low Reynolds number of 100. The benchmarking of the numerical model is followed by the parametric investigation with the variation of: a) the ratio of diameters of the upstream to downstream cylinder (d/D), in order to observe the effects associated with relative sizes of structures; b) the gap-to-diameter ratio (G/D), in order to observe the combined effects of varying these geometrical quantities. The results demonstrate a rapid change in the mean drag and lift coefficient values at the gap-to-diameter ratio between 2.0 and 3.0 at the diameter ratios of 0.7 and 1.0.
Solitary Wave Solutions for a Generalized KdV Equation with High Power Nonlinearities
Authors: Wu Rui , Cheng Qian , Xu Yinan , Zhu Minting , Yan Yongsheng , Li Rui , Zhang Xiao , Shen Wanqing
Published: May 2022

In current paper, a generalized KdV equation with high order nonlinearities has been investigated by the expansion and the ansatz method. The obtained solutions can be classified as periodic soliton solution, kink solution, triangular soliton solution, Bell-shaped soliton solution and multi-soliton solution. Finally, by selecting some appropriate parameters, the results are demonstrated graphically that can be applied to describe the real world phenomenon.

2010 MSC: 35C07, 35C08, 35G20, 35Q53.
Global Attractivity of Solutions of Nonlinear Delay Difference Equations
Authors: Zhao Jing , Kong Xiangming , Wang Yu , Wang Chunxiao
Published: May 2022

The asymptotic behavior of solutions of delay difference equations is an important research topic in the field of qualitative analysis of difference equations and the key to grasp the evolution trend of various dynamic systems As we all know, most difference equations cannot find exact solutions Therefore, it is necessary to study the asymptotic behavior of the solution of the delay difference equation by indirect method. In this paper, improved the form of the equation in the existing reference, a single delay is changed into a multi delay equation, and the conditions required for the theorem to be established are weakened, so that the theorem can be applied to a wider range and still holds under the original conditions sufficient conditions for the asymptotic behavior of solutions independent of delay are obtained. The conclusion is proved by constructor method and counter proof method The relevant results in the existing literature are extended and improved to make the results more general. The results are applied to a kind of hematopoietic stem cell model. The asymptotic behavior of the solution is intuitively displayed in the form of chart to verify the conclusion.
A Low-temperature-coefficient Bandgap Voltage Reference for Sar Adc
Authors: Hu Daqian , Qiao Jiaqi , Yang Xiaoxu , Zhao Peng , Song Yang
Published: May 2022

The paper verifies a curvature-compensated bandgap reference circuit, which generates 1.2V bandgap voltage. Bandgap voltage comprises two parts: proportional to absolute temperature (PTAT) voltage from the bandgap core and complementary to absolute temperature (CTAT) voltage from the p-n junction. Simulation results across corners show that the temperature coefficient of this architecture can be less than 3ppm/°C by using the current compensation. Test results prove that the temperature coefficient achieves 5ppm/°C. The proposed bandgap consumes a power of 2mW and occupies an area of 0.15mm2 in the 0.18μm CMOS process.
New Feature for Evaluating Depth of Partial Decarburized Layer Based on Cepstrum Filter Banks
Authors: Yan Zhengxiang , Sun Guangmin , Liu Xiucheng , Li Yu , He Cunfu , Xing Zhixiang
Published: May 2022

Decarburization refers to a phenomenon that the content of carbon in metal is reduced, and this could be advantageous or detrimental depending on the usage scenario. In this paper, a new feature, called Barkhausen frequency scale cepstrum coefficients (BFCCs), which was based on the cepstrum was proposed to evaluate the depth of the decarburized layer. The Genetic algorithm was used to optimize the parameters of the BFCCs feature. In the experiment part, the regression precision was compared under BFCCs and MBN envelope features using multiple linear regression (MLR) and BP neural network (BP). The regression experiment result was measured by mean absolute error (MAE) and shows the good representative ability of BFCCs for the depth of the decarburized layer.
High Harmonic Generation from Oriented Asymmetric Molecules in the Presence of Static Electric Field
Authors: Silaev A A , Romanov A A , Vvedenskii N V
Published: May 2022

We investigate the high harmonic generation during the interaction of the femtosecond laser field with oriented asymmetric diatomic molecules in the presence of an external static electric field. Based on the numerical solution of the time-dependent Schrödinger equation for the model one-electron system, we calculate the high harmonic generation spectrum for a wide range of static-field strengths. The possibilities for visualizing low-frequency (terahertz and mid-infrared) radiation using time-delay measurements of even high harmonics intensities are discussed.
Simulation of High Harmonic Generation in Xenon Based on Time-Dependent Density-Functional Theory
Authors: Romanov A A , Silaev A A , Sarantseva T S , Frolov M V , Vvedenskii N V
Published: May 2022

The high harmonic generation (HHG) in xenon is studied by using the time-dependent density-functional theory for active 4th and 5th atomic shells. The HHG spectra are calculated for different intensities and carrier-envelope phases of a laser pulse. The HHG spectrum shows enhancement at the frequency region near 100 eV, where the HHG yield is by more than an order of magnitude higher than in the single-active electron approximation. The high accuracy of the obtained results is confirmed by comparing the calculated HHG spectra with experimental results.
Effects of Low-Level Laser Irradiation on Mammalian Cell Cultures: Comparative Experimental Studies with Different Types of Lasers at 1260-1270 nm
Authors: Khokhlova A , Zolotovskii I , Sokolovski S , Saenko Yu , Rafailov E , Stoliarov D , Pogodina E , Gilmutdinova A , Svetukhin V , Fotiadi A
Published: May 2022

The effects observed under near-infrared laser irradiation of mammalian cells have been demonstrated to depend to a large extent on the type of irradiation source. In our experiments, we have measured concentration of reactive oxygen species in cell cultures of different origin (rodent and human, cancerous and non-cancerous) exposed to the radiation of low-level lasers at 1265 nm. Surprisingly, the radiation effects of narrowband laser occur to be more pronounced compared with those provided by the lasers of broader linewidth. Also, we have found that the aggressive types of cancer require a more accurate selection of irradiation parameters and laser operation regime.
Research of Surface Plasmonic Resonance at The Silicon Nano-Silver Interface in the Information Recording Unit of the Diagnostic Complex Intest
Authors: Mogilnaya T Y , Vasiliev A M , Pagava L L , Botikov A G
Published: May 2022

The research presents a study of the fundamental possibility of realizing the contactless recording of information a complex for express diagnostics of an organism for the presence of infectious agents, which was called diagnostic complex “Intest”. The mathematical model of the interaction of the laser radiation with the surface of the crystal was built. Calculations were performed in the COMSOL 5.5 software package. The results of the optimization calculations showed at what crystal parameters it is possible to implement contactless recording
Phase Transitions in Quantum Complex Networks
Authors: Alodjants A.P. , Yu. Bazhenov A. , Nikitina M. M.
Published: May 2022

In this work we examine a superradiant (SR) and/or ferromagnetic (FM) - paramagnetic (PM) phase transitions problem in quantum materials which may be established by Barabási-Albert (BA) scale-free network that possesses power law degree distribution and specific degree correlations. We represent quantum material by means of Dicke-Ising model, that describes the interaction between a spin-1/2 (two-level) system and external classical (magnetic) and quantized (transverse) fields. To describe PM-FM and SR phase transitions we introduce three order parameters: the total (topologically) weighted as well as un-weighted z-spin components, and the normalized transverse field amplitude, which correspond to the spontaneous magnetization in z- and x-directions, respectively. We have shown that SR state occurs as a result of the interaction between the ordering of the spins in the z− and x-directions and depends on assortativity or disassortativity of the network medium. We have shown that non-trivial topological behavior associated with large fluctuations of network parameters inherent to assortative networks reduces of PM-FM phase transition temperature, while dissasortative networks exhibit high temperature phase transitions. Our findings demonstrate new opportunities to design of quantum materials which may be implemented for current quantum technologies at relatively high temperatures.
Process optimization of WEDM D2 steel based on orthogonal test and response surface method
Authors: Zhou Changwu , Zhao Liangliang
Published: May 2022

D2 steel can be used to manufacture cold working molds with large cross sections, complex shapes, high impact forces and high wear resistance requirements. Cutting speed is an important process index of WEDM. In order to study the influence of WEDM process parameters on the cutting speed of D2 die steel and explore the process parameters at the maximum cutting speed, In this experiment, the electrical parameters pulse width, pulse interval and servo voltage were selected as test factors, and the cutting speed process indexes were analyzed and optimized by orthogonal test and response surface analysis method. Experimental results show that: the influence of main electrical parameters on cutting speed is consistent; the effects of pulse width, pulse interval and servo voltage on cutting speed decrease successively; the optimum process parameters obtained after optimization are consistent, pulse width 8μs, pulse interval 10μs, servo voltage 38V.
Simulation analysis and experimental study on impact fall test of forklift overhead guard
Authors: Peng Xuefeng , Zhao Jianbo , Liu Yetao , Dai Zongmiao
Published: May 2022

This paper introduces the safety performance test standards and requirements of forklift overhead guard. According to the requirements of the impact fall test in the standard, an explicit dynamic calculation model of the impact of overhead guard under load was established based on the LS-DYNA display central difference method, and the field impact test of the overhead guard designed in this paper was carried out. The results show that the hourglass energy of the impact falling simulation test is less than 5% of the total energy, which conforms to the law of energy conservation, so the simulation model can be considered correct. At the same time, the simulation analysis results are consistent with the field impact falling test results. The connection position of riser and position of base bolting appear failure fracture, and the structural strengthening suggestions are given.
Study on the improvement of performance of proton exchange membrane Fuel Cell by Magnetic effect
Authors: Lang Xianji , Wu Zhicong , Li Rurun , Wu Maoliang
Published: May 2022

Oxygen and water are the main components of proton reaction, and the gradient magnetic field can affect their physical and chemical properties. The performance of PEMFC with gradient magnetic field on anode side was studied. On this basis, the performance of the battery under different battery temperature and hydrogen flow rate was tested. The experimental results show that the electric efficiency of PEMFC can be improved, the degradation of battery performance can be inhibited, and the service life of PEMFC can be extended under the same environmental variables. The experimental results can provide some reference value for improving PEMFC performance.
DEKF-based SOC estimation study for lithium batteries
Authors: Chen Yuhang , Xiong Hongjun , Guo Yi
Published: May 2022

In view of the low estimation accuracy of single extended Kalman filter algorithm (EKF) and the influence of the initial value of state of charge (SOC), the double extended Kalman filter algorithm (DEKF) is used for online estimation of battery model parameters and SOC based on the establishment of second-order RC equivalent circuit model. A 36V 32A·h lithium iron phosphate battery pack is used as the research object, and experiments are designed for the actual battery conditions. The experimental results show that the DEKF algorithm has better convergence and adaptability under different conditions than a single EKF algorithm with inaccurate initial values of SOC, and the error is controlled within 5%, which proves the feasibility and effectiveness of the algorithm.
Study on Processing Technology of Aluminium-based silicon carbide material for Shafting Installation
Authors: Li Lin , Li Hao , Zhang Bin , Wang Tianming , Yu Junyu , Mao Lei , Wei Jialin , Huang Ning , Chen Lei
Published: May 2022

Aluminium-based silicon carbide (SiCp/Al) composites are widely used in spacecraft structures due to their excellent properties. Aiming at the high-precision machining requirements of thin-walled shell components installed in SiCp/Al shafting in aerospace field. The structural characteristics of thin-walled shell components are analysed. Combined with material characteristics and mechanical properties, a single clamping vertical horizontal conversion machining scheme is formulated. Match the right machine tools and PCD tools. Then the metal cutting process is simulated by AdvantEdge, and the tool structure parameters and cutting process parameters are optimized. Finally, the process route suitable for installing housing components is formulated, with dimension accuracy of H6, cylindricity of 0.003mm and coaxiality of 0.006mm, which solves the difficult problem of machining high-precision shaft mounting housing.
Ride comfort analysis of electric vehicle using hub motor as dynamic absorber
Authors: Zhao Pingping , Fan Zhimin
Published: May 2022

To resolve the problems of adding unsprung mass and worsening ride comfort of hub motor drive electric vehicles, a new drive system with hub motor as dynamic absorber is studied and proposed. The mathematical models of the new hub motor drive system and the centralized motor drive system are established, and their ride comfort is compared and analyzed. The impact of dynamic absorber parameters on ride comfort of the new hub motor drive system is analyzed, and the parameter sensitivity is calculated. The results show that the body acceleration, suspension dynamic deflection, wheel dynamic load of the new hub motor drive system are better than those of the centralized motor drive system, and the dynamic absorber parameters have a great effect on the electric vehicle performance.
Test and Measurement Data Analysis of Fuel Consumption Measurement and Control System of Floating Ball Engine
Authors: Xu Dong
Published: May 2022

Fuel consumption is an important index to evaluate the fuel economy of automobile engine, and it is one of the important measurement parameters in engine test research. This paper uses the engine eddy current test bench to carry out the repeatability verification test, measurement accuracy and accuracy verification test, and engine bench test of the designed and developed floating ball fuel consumption meter. The data obtained from the test are analyzed to verify the floating ball fuel consumption. performance indicators of the instrument.
Evaluation of measurement uncertainty of the orthogonal deviation angle of the target mirror based on AMCM
Authors: Huang Qiangxian , Guo Xiaoqian , Li Hongli , Zhang Zuyang , Chen Zhiwen
Published: May 2022

The combination of the three-dimensional (3D) target mirror and laser interferometers can achieve 3D precision measurement, and the orthogonality between the target mirror has a significant impact on the accuracy of the measurement system. In order to ensure the accuracy of the measurement system, it is necessary to measure the orthogonal deviation angle of the 3D target mirror and evaluate the uncertainty to verify whether the machining accuracy of the target mirror meets the requirements. In this paper, to test the orthogonality of the X-Y reflection planes of the 3D target mirror, which is glued by three plane mirrors, the evaluation methods of measurement uncertainty of the orthogonal deviation angle θxy
are studied. The measurement model of uncertainty evaluation is built based on the quantitative characteristics analysis method, and the evaluation results of measurement uncertainty are obtained based on the adaptive Monte Carlo method (AMCM). Moreover, the evaluation results are compared with those evaluation results obtained respectively based on the traditional assessment method of measurement uncertainty (called as GUM method) and Monte Carlo method (MCM). Through the comparison of the evaluation results, it can be concluded that the best estimate of the orthogonal deviation angle θxy
is about -3.09”, the corresponding standard uncertainty is about 0.69”, and the machining accuracy of the X-Y reflection planes of the target mirror meets the requirements. Moreover, the AMCM evaluation results is reliable, and AMCM is more convenient and efficient than GUM and MCM methods. The research work provides valuable reference for solving practical measurement evaluation problems.
Coordinated Control of Path Following and Yaw Stability for Distributed Drive Autonomous Vehicle
Authors: Liu Zhikun , Yin Dejun , Guo Ruiming
Published: May 2022

This paper researches a coordinated control approach of path following and yaw motion stability for distributed drive autonomous electric vehicle. In the upper-level controller, a linear time-varying model predictive control algorithm is used to obtain the front wheel steering angle to guarantee the vehicle to drive along the planned path. Meanwhile, the sliding mode control theory is aimed to calculate the external yaw moment to ensure the vehicle yaw stability. In the low-level controller, this research proposes the particle swarm optimization algorithm to execute the torque distribution control. The Matlab/Simulink simulation results indicate that the coordinated control strategy can not only effectively improve the accuracy of path following, but also guarantee yaw motion stability of the autonomous vehicles.
Beam dynamics challenges in linear colliders based on laser-plasma accelerators
Authors: Schroeder C.B. , Benedetti C. , Bulanov S.S. , Terzani D. , Esarey E. , Geddes C.G.R.
Published: May 2022

In this paper we discuss design considerations and beam
dynamics challenges associated with laser-driven plasma-based
accelerators as applied to multi-TeV-scale linear colliders. Plasma
accelerators provide ultra-high gradients and ultra-short bunches,
offering the potential for compact linacs and reduced power
requirements. We show that stable, efficient acceleration with beam
quality preservation is possible in the nonlinear bubble regime of
laser-plasma accelerators using beam shaping. Ion motion, naturally
occuring for dense beams (i.e., low emittance and high energy)
severely damps transverse beam instabilities. Coulomb scattering by
the background ions is considered and it is shown that the strong
focusing in the plasma strongly suppresses scattering-induced
emittance growth. Betatron radiation emission from the transverse
motion of the beam in the plasma will result in beam power loss and
energy spread growth; however for sub-100 nm emittances, the beam
power loss and energy spread growth will be sub-percent for
multi-TeV-class plasma linacs.
Positron sources: from conventional to advanced accelerator concepts-based colliders
Authors: Chaikovska I. , Chehab R. , Kubytskyi V. , Ogur S. , Ushakov A. , Variola A. , Sievers P. , Musumeci P. , Bandiera L. , Enomoto Y. , Hogan M.J. , Martyshkin P.
Published: May 2022

Positron sources are the key elements for the future and
current lepton collider projects such as ILC, CLIC, SuperKEKB,
FCC-ee, Muon Collider/LEMMA, etc., introducing challenging critical
requirements for high intensity and low emittance beams in order to
achieve high luminosity. In fact, due to their large production
emittance and constraints given by the target thermal load, the main
collider parameters such as the peak and average current, the
emittances, the damping time, the repetition frequency and
consequently the luminosity are determined by the positron beam
characteristics. In this paper, the conventional positron sources
and their main properties are explored for giving an indication to
the challenges that apply during the design of the advanced
accelerator concepts. The photon-driven positron sources as the
novel approach proposed, primarily for the future linear colliders,
are described highlighting their variety and problematic.
On possibility of low-emittance high-energy muon source based on plasma wakefield acceleration
Authors: Shiltsev V.
Published: May 2022

Plasma wakefield acceleration (PWA) channels are
characterized by very high accelerating gradients and very strong
focusing fields. We propose to employ these properties for effective
production of low emittance high energy muon beams, consider muon
beam dynamics in the PWFA cell and analyze various options and
potential of the PWA-based muon sources.
Improving flood impact estimations
Authors: Sieg Tobias , Thieken Annegret H
Published: May 2022

A reliable estimation of flood impacts enables meaningful flood risk management and rapid assessments of flood impacts shortly after a flood. The flood in 2021 in Central Europe and the analysis of its impacts revealed that these estimations are still inadequate. Therefore, we investigate the influence of different data sets and methods aiming to improve flood impact estimates. We estimated economic flood impacts to private households and companies for a flood event in 2013 in Germany using (a) two different flood maps, (b) two approaches to map exposed objects based on OpenStreetMap and the Basic European Asset Map, (c) two different approaches to estimate asset values, and (d) tree-based models and Stage-Damage-Functions to describe the vulnerability. At the macro scale, water masks lead to reasonable impact estimations. At the micro and meso-scale, the identification of affected objects by means of water masks is insufficient leading to unreliable estimations. The choice of exposure data sets is most influential on the estimations. We find that reliable impact estimations are feasible with reported numbers of flood-affected objects from the municipalities. We conclude that more effort should be put in the investigation of different exposure data sets and the estimation of asset values. Furthermore, we recommend the establishment of a reporting system in the municipalities for a fast identification of flood-affected objects shortly after an event.