bluuebunny/crossref_metadata_2025 huggingface dataset:
Data driven soliton solution of the nonlinear Schrödinger equation with certain PT-symmetric potentials via deep learning
Authors: Meiyazhagan J. , Manikandan K. , Sudharsan J. B. , Senthilvelan M.
Published: May 2022

We investigate the physics informed neural network method, a deep learning approach, to approximate soliton solution of the nonlinear Schrödinger equation with parity time symmetric potentials. We consider three different parity time symmetric potentials, namely, Gaussian, periodic, and Rosen–Morse potentials. We use the physics informed neural network to solve the considered nonlinear partial differential equation with the above three potentials. We compare the predicted result with the actual result and analyze the ability of deep learning in solving the considered partial differential equation. We check the ability of deep learning in approximating the soliton solution by taking the squared error between real and predicted values. Further, we examine the factors that affect the performance of the considered deep learning method with different activation functions, namely, ReLU, sigmoid, and tanh. We also use a new activation function, namely, sech, which is not used in the field of deep learning, and analyze whether this new activation function is suitable for the prediction of soliton solution of the nonlinear Schrödinger equation for the aforementioned parity time symmetric potentials. In addition to the above, we present how the network’s structure and the size of the training data influence the performance of the physics informed neural network. Our results show that the constructed deep learning model successfully approximates the soliton solution of the considered equation with high accuracy.
Breakup mechanism of the electrically induced conical liquid bridge
Authors: Xu Xiao-Yu , Xu Zheng , Wang Xiao-Dong , Wang Li-Ding , Qin Shao-Chun , Liu Jun-Shan , Yu Yu
Published: May 2022

The breakup mechanism of a conical liquid bridge is reported based on the previously proposed electrostatic liquid loading method. The breakup criterion in terms of interface feature size is derived. Based on the criterion, the breakup mechanism can be categorized as either spontaneous breakup or stretching breakup. The evolution of interface and velocity for two breakup behaviors is subsequently investigated. For the spontaneous breakup, the remnant volume Vd depends primarily on the top radius Rt and is proportional to the square of Rt. For the stretching breakup, the remnant volume depends on the early stage of the stretching, and Vd is proportional to the cube of Rt. In addition, the influence of the stretching velocity U is examined. Results show that U has a weaker effect on the change of remnant volume than the top radius Rt for large capillary numbers. This study is helpful in understanding the liquid bridge breakup mechanism and improving the transfer printing process.
Long short-term memory-driven forecast of CO2 injection in porous media
Authors: Ekechukwu Gerald Kelechi , de Loubens Romain , Araya-Polo Mauricio
Published: May 2022

The ability to simulate the partial differential equations (PDE's) that govern multiphase flow in porous media is essential for different applications such as geologic sequestration of CO2, groundwater flow monitoring, and hydrocarbon recovery from geologic formations. These multiphase flow problems can be simulated by solving the governing PDE's numerically, using various discretization schemes such as finite elements, finite volumes, spectral methods, etc. More recently, the application of Machine Learning (ML) to approximate the solutions to PDE's has been a very active research area. However, most researchers have focused on the performance of their models within the time-space domain in which the models were trained. In this work, we apply ML techniques to approximate PDE solutions and focus on the forecasting problem outside the training domain. To this end, we use two different ML architectures, the feed forward neural network and the long short-term memory (LSTM)-based neural network, to predict the PDE solutions in future times based on the knowledge of the solutions in the past. The results of our methodology are presented on two example PDE's, namely, a form of PDE that models the underground injection of CO2 and its hyperbolic limit, which is a common benchmark case. In both cases, the LSTM architecture shows a huge potential to predict the solution behavior at future times based on prior data.
Reduced H+channel activity disrupts pH homeostasis and calcification in coccolithophores at low ocean pH
Authors: Kottmeier Dorothee M. , Chrachri Abdesslam , Langer Gerald , Helliwell Katherine E. , Wheeler Glen L. , Brownlee Colin
Published: May 2022

Significance

Coccolithophore calcification is a major ocean biogeochemical process. While this process is likely to be sensitive to acidification-driven changes in ocean carbonate chemistry, incomplete understanding of the underlying mechanisms and constraints is a major bottleneck in predicting ocean acidification effects on calcification. We report severe disruption of pH homeostasis linked to a loss of H+channel function in the coccolithophoreCoccolithus braarudiiacclimated to seawater pH values that are likely to be encountered currently in localized regions and more widely in future oceans. This disruption leads to specific defects in coccolith morphology. These findings provide mechanistic insight into how calcification in different coccolithophores is affected by changes in seawater carbonate chemistry.
Cosmogenic radiosulfur tracking of solar activity and the strong and long-lasting El Niño events
Authors: Lin Mang , Thiemens Mark H.
Published: May 2022

Reconstruction of past solar activity or high-energy events of our space environment using cosmogenic radionuclides allows evaluation of their intensities, frequencies, and potential damages to humans in near space, modern satellite technologies, and ecosystems. This approach is limited by our understanding of cosmogenic radionuclide production, transformation, and transport in the atmosphere. Cosmogenic radiosulfur (
35
S) provides additional insights due to its ideal half-life (87.4 d), extensively studied atmospheric chemistry (gas and solid), and ubiquitous nature. Here, we report multiyear measurements of atmospheric
35
S and show the sensitivity of
35
S in tracking solar activity in Solar Cycle 24 and regional atmospheric circulation changes during the 2015/2016 El Niño. Incorporating
35
S into a universal cosmogenic radionuclide model as an independent parameter facilitates better modeling of production and transport of other long-lived radionuclides with different atmospheric chemistries used for reconstructing past astronomical, geomagnetic, and climatic events.
Sound–Emotion Interaction in Poetry
Authors: Tsur Reuven , Gafni Chen
Published: May 2022

This book is a collection of studies providing a unique view on two central aspects of poetry: sounds and emotive qualities, with emphasis on their interactions. The book addresses various theoretical and methodological issues related to topics like sound symbolism, poetic prosody, and voice quality in recited poetry. The authors examine how these sound-related phenomena contribute to the generation of emotive qualities and how these qualities are perceived by readers and listeners.
The book builds upon Reuven Tsur’s theoretical research and supplements it from an experimental angle. It also engages in methodological debates with prevalent scientific approaches. In particular, it emphasises the importance of proper theory in empirical literary studies and the role of the personal traits of the reader in literary analysis.
The intended readership of this book consists mainly of literary scholars, but it might also appeal to researchers from disciplines such as linguistics, psychology, and brain science.
A matter of degree?
Authors: Reznikova Tatiana , Panina Anna , Kruglyakova Victoriya
Published: May 2022

The article studies the domain of wetness in 20 languages. In many of them the domain features two main words (e.g. German nass, feucht; Mongolian nojton, čijgleg; Moksha načkə, l’et’kə) and the difference between them tends to be described in terms of degree, i.e. ‘intensely’ versus ‘slightly wet’. Typological analysis shows that in each case the degree of humidity receives a specific interpretation depending on the noun that is being modified, so that the choice of a particular synonym is based not simply on the quantity of the fluid, but on the situation as a whole (including the source of moisture, intentional versus non-intentional event, etc.). We also discuss the additional factors relevant to the domain in the languages that have more than two words in it, that is, the additional words with a positive or a negative connotation, or moisture from contact with a liquid versus moisture absorbed from humid air.
Registration of histological brain images onto optical coherence tomography images based on shape information
Authors: Strenge Paul , Lange Birgit , Grill Christin , Draxinger Wolfgang , Danicke Veit , Theisen-Kunde Dirk , Hagel Christian , Spahr-Hess Sonja , Bonsanto Matteo M , Huber Robert , Handels Heinz , Brinkmann Ralf
Published: May 2022

Identifying tumour infiltration zones during tumour resection in order to excise as much tumour tissue as possible without damaging healthy brain tissue is still a major challenge in neurosurgery. The detection of tumour infiltrated regions so far requires histological analysis of biopsies taken from at expected tumour boundaries. The gold standard for histological analysis is the staining of thin cut specimen and the evaluation by a neuropathologist. This work presents a way to transfer the histological evaluation of a neuropathologist onto optical coherence tomography (OCT) images. OCT is a method suitable for real time in vivo imaging during neurosurgery however the images require processing for the tumour detection. The method demonstrated here enables the creation of a dataset which will be used for supervised learning in order to provide a better visualization of tumour infiltrated areas for the neurosurgeon. The created dataset contains labelled OCT images from two different OCT-systems (wavelength of 930 nm and 1300 nm). OCT images corresponding to the stained histological images were determined by shaping the sample, a controlled cutting process and a rigid transformation process between the OCT volumes based on their topological information. The histological labels were transferred onto the corresponding OCT images through a non-rigid transformation based on shape context features retrieved from the sample outline in the histological image and the OCT image. The accuracy of the registration was determined to be 200 ± 120 μm. The resulting dataset consists of 1248 labelled OCT images for each of the two OCT systems.
Higgs-Dilaton inflation in Einstein-Cartan gravity
Authors: Piani Matteo , Rubio Javier
Published: May 2022

We study the phenomenology of the Higgs-Dilaton model in the context of Einstein-Cartan gravity, focusing on the separate impact of the Holst and Nieh-Yan terms on the inflationary observables. Using analytical and numerical techniques, we show the predictions of these scenarios to display an attractor-like behaviour intrinsically related to the curvature of the field-space manifold in the metric formulation of the theory. Beyond that, the analysis of the Nieh-Yan case reveals the existence of an additional attractor solution induced by a cubic pole in the inflaton kinetic term that becomes relevant at large dilaton couplings. This constitutes a unique feature of the Einstein-Cartan formulation as compared to the metric and Palatini counterparts.
Dynamic corticomuscular multi-regional modulations during finger movement revealed by time-varying network analysis
Authors: Zhang Xiabing , Zhang Shu , Lu Bin , Wang Yifeng , Li Ning , Peng Yueheng , Hou Jingming , Qiu Jing , Li Fali , Yao Dezhong , Xu Peng
Published: May 2022

Objective. A body movement involves the complicated information exchange between the central and peripheral systems, which is characterized by the dynamical coupling patterns between the multiple brain areas and multiple muscle units. How the central and peripheral nerves coordinate multiple internal brain regions and muscle groups is very important when accomplishing the action. Approach. In this study, we extend the adaptive directed transfer function to construct the time-varying networks between multiple corticomuscular regions, and divided the movement duration into different stages by the time-varying corticomuscular network patterns. Main results. The inter dynamical corticomuscular network demonstrated the different interaction patterns between the central and peripheral systems during the different hand movement stages. The muscles transmit bottom-up movement information in the preparation stage, but the brain issues top-down control commands and dominates in the execution stage, and finally the brain’s dominant advantage gradually weakens in the relaxation stage. When classifying the different movement stages based on time-varying corticomuscular network indicators, an average accuracy above 74% could be reliably achieved. Significance. The findings of this study help deepen our knowledge of central-peripheral nerve pathways and coordination mechanisms, and also provide opportunities for monitoring and regulating movement disorders.
Corrigendum: Probiotic characterization of Bacillus subtilis SM10.1 (2021 J. Phys.: Conf. Ser.
1918 052025)
Authors: City S , Sugata M , Jan T T
Published: May 2022

Please see Article PDF for corrigendum text.
Sensitivity analysis on the influence factors of clearance axial force of a varying-speed centrifugal pump
Authors: Jin Faye , Li Na , Wei Zhicong , Wu Yanzhao , Tao Ran , Xiao Ruofu
Published: May 2022

Hydraulic axial force is an important parameter of the performance of centrifugal pump. It strongly affects the operation stability and the life-time of thrust bearing. Under the influence of flow pressure distribution, the hydraulic axial force of centrifugal pump has mainly two parts. One is the force inside impeller while the other is the force in clearance. In this case, the situation is more complex because the pump operates with varying-speed. Under the influence of rotation speed, pump head and minimum clearance width, the variation law of clearance axial force is still not fully understood. Therefore, the orthogonal experiment is conducted based on Large Eddy Simulation (LES). The local flow and hydraulic axial force in impeller shroud clearance is mainly studied. Results show that the pressure difference between impeller inlet and outlet will strongly impact the pressure distribution in clearance. Then, it affects the clearance axial force. The rotation speed and pump head are proved influential. However, range analysis shows that the minimum clearance width is the most dominant factor. It can somehow adjust the pressure distribution in clearance. The geometric design of impeller clearance will be important in reducing hydraulic axial force especially for varying-speed centrifugal pumps.
Aerodynamic performances and efficiency of axial flow fan placed in cooling system
Authors: Kawano Takashi , Fuchiwaki Masaki
Published: May 2022

One way to reduce the aerodynamic noise generated by the cooling system of construction machinery is to improve the fan efficiency and then drive the cooling fan at a lower speed. Computational Fluid Dynamics (CFD) is effective for clarifying the mechanisms of the fan efficiency, but there are few reports that capture the flow field around the axial fan blades installed in the cooling system of construction machinery, that is, in a high static pressure environment. Moreover, from the viewpoint of the three-dimensional flow field, the fan efficiency has not been sufficiently studied. In this study, the flow field of the entire cooling system including an axial cooling fan was visualized by numerical simulation using ANSYS-CFX17.0, and the effect of the flow field formed around the blades on the fan efficiency was investigated. In case of a single axial fan, increase or decrease in pressure caused by airflow collision or separation is higher than the entire cooling system. As a result, the loss becomes large. In addition, the increase in loss due to collision or separation occurs regardless of the blade span length, and its magnitude is proportional to the circumferential velocity at each point of the blade except for the blade tip.
Unsteady flow simulations in two-stage turbines of a rocket turbopump to estimate blade structural soundness for fatigue
Authors: Funazaki K. , Iwaguchi N. , Kawasaki S.
Published: May 2022

This study first aims at detailed investigations of three-dimensional unsteady flow field in the reference and optimized rocket turbine stages by performing time-accurate flow simulations based on Transient Blade Row (TBR) method or Time Transformation (TT) method in a commercial software ANSYS CFX. Although TT method is believed to enable relatively low-cost unsteady flow simulation, detailed comparisons between TT method-based and conventional unsteady flow simulations are made before TT method application to Fluid-Structural Interaction (FSI) problem. This study then makes an attempt to conduct structural analyses of the 1st and 2nd stage turbine blades under the influence of unsteady fluid forces caused by rotor-stator interaction predicted by TT method-based flow simulations. The structural analyses are executed by use of MSC Nastran. In this study, two materials are adopted as blade material. After the Fourier-series decomposition of the calculated unsteady pressure distributions, the unsteady pressure information is mapped onto the FEM (Finite Element Method)-modeled turbine blade surface as exciting aerodynamic loading. The frequency response analyses are then performed to calculate alternating stresses of the blade, from which the maximum magnitudes of alternating stress are obtained so as to discuss the rotor blade fatigue life.
Performance improvement of centrifugal compressors for automotive turbochargers using adjoint method
Authors: Honda Hironori , Kanzaka Tadashi , Oka Nobuhito , Verstraete Tom , Châtel Arnaud , Müller Lasse
Published: May 2022

A sensitivity calculation using adjoint method has a feature of low calculation cost because sensitivity information of all computational grid points can be calculated by only one numerical simulation. From this feature, it has been utilized as a calculation method of sensitivity information for a gradient-based optimization and this optimization procedure with adjoint method can be one of suitable ways for centrifugal compressor impeller which has a lot of design parameters such as meridional shape, blade angle and thickness. During the gradient-based optimization, mesh morphing, which moves the computational grid directly based on sensitivity information, is generally used for shape deformation. However, the mesh morphing is difficult to implement due to shape constraints which is particularly required for rotating blades, such as minimum blade thickness and rotationally axisymmetric shape. In this study, in order to avoid these problems, sensitivity information of each grid point was converted into that of conventional design parameters, and optimization was carried out. In order to verify the effectiveness of this method, two different optimizations were carried out for centrifugal compressor impeller. In the single-point optimization which focuses on efficiency improvement, maximum efficiency was increased by 3.5% compared to a baseline impeller. While, multi-points optimization which considers balance between flow capacity and efficiency showed that the maximum efficiency was improved by 0.6% compared to the baseline impeller while maintaining the same flow capacity.
2D structured mesh for simulations of unsteady cavitation around a plane convex hydrofoil
Authors: Puga D , Hidalgo V , Luo X
Published: May 2022

The present paper focuses on the influence of the mesh for simulations of unsteady cavitation around a plane convex hydrofoil. A two dimensional structured mesh was generated using free software Gmsh. The span wise size of the hydrofoil was 0.02 of the chord length in the computational domain. The numerical simulation was conducted by using the software OpenFOAM with the k-ω SST SAS turbulence model and the Zwart-Gerber-Belamri cavitation model. The results show that the present numerical method including two dimensional mesh strategy and the SAS turbulence model efficiently represents the unsteady cavitation behaviour around the plane convex hydrofoil, and reproduces the maximum cavity length and the cavitation oscillation compared with the experimental data and the numerical results simulated by implicit LES in a characteristic cycle.
Difference of clogging performance between radial and swept back impeller of axial pump
Authors: Kondo Y , Miura K , Miyagawa K , Nohmi M , Tsuneda T
Published: May 2022

An axial pump which is used to pump water out of a river often sucks in solid bodies such as leaves and branches. These foreign substances may clog the passage and lead to dangerous conditions such as a decline in the performance of the pump. In this investigation, we conducted the clogging experiments by putting polyester strings in an axial drain pump which has two types of impellers, a radial blade impeller and a swept back blade impeller. By visualizing behavior of the strings in the pump using a high-speed video camera, we compared the anti-clogging performance between the two impellers and investigated the mechanism of clogging. The results of these experiments showed that the pass rate of the strings that flowed into the swept back blade impeller was higher than that in the radial blade impeller. It is because strings that are caught in the leading edge of the swept back blade tend to move to the tip side and be pulled towards the suction surface. In addition to the experiments, we carried out the simulations of these experiments using a CFD-DEM (Discrete Element Method) coupling analysis. The results were in good agreement with the experiments qualitatively.
Numerical investigation of radial thrust fluctuation caused by diffuser rotating stall in a centrifugal pump
Authors: Takamine Taiki , Watanabe Satoshi
Published: May 2022

In this study, in order to understand the relation between the diffuser rotating stall and the fluctuating radial thrust, unsteady RANS simulation of a centrifugal pump was carried out. The rotating stall with single stall cell was qualitatively reproduced though the propagation speed was smaller than the experiment. The pressure amplitude caused by the rotating stall was comparable to the measured one, and the tendency that the propagation speed increases as the flow rate increases agreed with experiment. The radial thrust fluctuation due to the rotating stall was well evaluated by the simulation, and a considerable difference of phase angle between the stall cell position and the working direction of radial thrust was detected, which also agreed with experiment. On the basis of simulation result, the reason is found to be that the radial force acting on the impeller external wall at the liner ring section due to stall cell was not very small but comparable to that acting on the impeller blade and outer wall, while their working directions were roughly 100° different. This suggests that considering the leakage flow in numerical simulation is important to accurately predict the radial forces generated by rotating stall.
Mechanical property analysis of shaft tubular pump rotor with different blade angle based on fluid-structure interaction
Authors: Shen Jiawei , Pei Ji , Chen Songshan
Published: May 2022

Shaft tubular pump is widely used in large and medium-sized pumping stations with ultra-low head. But occasionally the blade cracks or even breaks, which seriously restricts the safe and stable operation of the pump station. In order to obtain the mechanical properties of the pump rotor with different blade installation angles, the fluid-structure interaction numerical simulation method is applied to analyze the structure of the pump rotor. Based on the SST k-ω model and the structured grid of the whole flow field, the three-dimensional numerical simulation of the internal flow field of the pump device is carried out by using CFX, and the reliability of the simulation is verified by model test. Then, the static analysis and modal analysis of the pump rotor structure under different working conditions are carried out by using Workbench. From the results, it can be found that the axial force increases with the increase of blade installation angle at a same flow rate. And at a same flow rate, the maximum deformation and equivalent stress increases with the increase of the blade installation angle. Finally, the change of the blade installation angle mainly affects the third and sixth order frequency which are only showed as blade vibration. Therefore, all of these results indicate that the blade installation angle has obvious influence on the mechanical property of the rotor of shaft tubular pump.
Numerical calculation and analysis of axial force of multistage centrifugal submersible pump
Authors: Dong Jian , Liang Wuke , Dong Wei
Published: May 2022

The study of axial force has been a hot spot in fluid mechanics research, and the magnitude of axial force directly affects the stability, safety, and efficiency of submersible pumps. This paper takes 200QJ50 multistage centrifugal submersible pump with spatial guide vane as the research object, simulates and numerically calculates the internal flow field of multistage submersible pump based on Standard k-ε turbulence model, a SIMPLE algorithm, and high-resolution format through CFX software, analyzes the distribution law of static pressure and velocity field of the multistage submersible pump under 0.7Qd
, 0.8Qd
, 0.9Qd
, 1.0Qd
and 1.1Qd
working conditions and compared the theoretical and simulated values of the corresponding axial force for each working condition. The results show that with the increase of the flow rate, the axial force of the multistage submersible pump shows a downward trend; the axial force generated by the first stage impeller has a larger proportion, and reaches the maximum value in the design condition; the traditional axial force calculation formula can more accurately predict the axial force under the design condition, and the error is 6%. The results of this study can provide references for the design and optimization of multistage centrifugal submersible pumps.
Multi-objective design optimization of industrial pump inducer to avoid cavitation instabilities
Authors: Masuda Itsuki , Takao Shunya , Nakamura Yushi , Miyabe Masahiro
Published: May 2022

In this paper, important four design parameters which are sweep radius, sweep angle, solidity and incidence angle were firstly extracted for the inducer shape optimization. A multi-objective optimization method was applied to the inducer and optimal design was manufactured by 3D-Printer. Pump performance tests and cavitation performance test were conducted for both baseline inducer and optimal one. In addition, internal flow at the inlet of the inducer was measured by PIV in order to investigate the onset and the scale of backflow. As the result, it was confirmed that the cavitation performance of the optimized inducer was improved by about 23% while maintaining pump efficiency. It was also clarified that the onset of backflow at partial flow rate was shifted to lower flow rate by PIV. Furthermore, the occurrence range of cavitation surge in the partial flow rate was narrowed. Based on the sensitivity analysis result, it was found that the influence of sweep radius on both cavitation performance and backflow onset was large. Moreover, some design guidelines are suggested in conclusion.
Investigation on the circumferential grooves effects in a two-stage axial flow compressor
Authors: Dou Xiangyuan , Wang Tong , Qu Xiaoyun
Published: May 2022

The performances of a two-stage industrial axial-flow compressor were tested to investigate the effects of circumferential grooves. The corresponding numerical models with four-blade cascade were set up. The numerical and test results showed that the operation range of the compressor near stall point can be extended obviously by the circumferential grooves. The internal flow field of the compressor was analysed numerically in detail, especially the tip leakage flow. It was found that stall occurred originally in the first stage and the local flow rate of the tip leakage was approximately proportional to the corresponding blade load. In addition, the local flow rate of tip leakage tended to decrease gradually along the flow direction near stall point. The tendency indicated that there were the most part of the blade load in the front of the rotor. It was proposed that the circumferential grooves could be set up at a specific stage in the multistage axial flow compressor where stall might occur originally to extend the operation range with lower manufacturing cost. Meanwhile, several circumferential grooves in the front segment of the rotor would be enough to play the effect on the stability enhancement for the axial compressor.
Effects of vortex generator on the performance of a flush-intake duct in oblique navigation
Authors: Huang C L , Chen L , Dai R
Published: May 2022

Effects of vortex generator (VG) on the flow field in a flush-intake duct for waterjet propulsion are investigated numerically under various navigation conditions. Flow’s Reynolds-averaged Navier-Stokes equations (RANS) are solved with the SST-Kω turbulence model. Four VG blades are installed at the ship bottom ahead of the intake entrance. The VG blade is rectangular shaped with a height of 0.1D, a length of 0.3D, and an angle of attack of 20°. Results show that under the forward moving condition, VG device effectively restrains the flow separation on the duct ramp side and improves the section uniformity at intake exit under low inflow velocity ratio (IVR) condition. The duct efficiency gets improved over a wide IVR range. Under the oblique moving condition, there is no separation region on the duct ramp side at low IVR, but significant vortex appears on the lip side. VG device does not introduce any obvious extra negative effects on the hydraulic performance.
A study of sediment erosion of runner seal of a Francis turbine
Authors: Yonezawa K , Watamura T
Published: May 2022

Suspended sediment particles included in working fluid of hydro turbines often cause erosion and reduce reliability and lifetime of the hydro turbine. It is important for understanding and suppressing erosion problems to understand characteristics of two-phase-flows of liquid and solid particles. In the present study, experimental and numerical studies were carried out to understand mechanisms of erosion in runner seal of a Francis turbine. The experiments were carried out using small-scale seal models. Flow patterns were visualized using coated mica flakes to understand entire flow patterns and a particle image velocimetry were also carried out to measure velocity field in a meridional cross-section. Accelerated erosion tests were also carried out and it was observed similar erosion distributions to that was observed in the actual hydro-turbine. Numerical flow simulations were also carried out to examine mechanisms of the erosion, contributions of each forces acting on the particles and appropriate parameters to capture characteristics of liquid-solid flows and erosion distribution, which were observed in experiments.
Design of a point absorber wave energy converter for an indian coast
Authors: Kumar Prashant , Singh Devesh , Paul Akshoy Ranjan , Samad Abdus
Published: May 2022

Ocean waves are considered as a potential unharnessed renewable resource being 800 times denser than wind. India has a wide coastal area of nearly 7500 km, providing a huge potential for harnessing ocean wave energy. The article aims to present the parametric optimization of a point absorber wave energy converter (PAWEC) for a location near Ennore port of India. Indian offshore condition such as significant wave height, period, and amplitude was reviewed for their minimum, maximum, and average values for several years. Hydrodynamic coefficients such as Froude-Krylov force, radiation damping, added mass, diffraction, excitation and response amplitude operator are optimized through geometric optimization of PAWEC’s float. In hydrodynamic response analysis, only heaving motion is considered and all motion is neglected for the study. Regular wave is only considered for this study. Output parameters such as structure velocity and structure response are studied for the mentioned geometry. Power-take-off (PTO) device is simulated for maximum efficiency and the float velocity response is observed. Monthly variation in the mean absorbed power and efficiency of Point absorber is calculated with respect to ocean power.
Investigation of inter-stage passive flow control for turbine performance improvement on regulated two-stage turbocharger
Authors: Zou Z , Yang M , Zhou S , Ding Z , Tian Y , Deng K
Published: May 2022

The flow field coupling effect between the HPT (high pressure turbine) and LPT (low pressure turbine) introduces a particular flow structure to the two-stage turbocharging system. Compared to the isolated turbines, the performance of these two connected turbines will inevitably be affected by each other. However, in the open state of the bypass valve, the influence of the bypass flow on this flow field coupling effect is still unknown. In this study, the inter-stage performance interaction of regulated two-stage turbocharger was investigated through the three-dimensional numerical method. With the bypass valve open, the influence of different positions of the bypass branch on the inter-stage coupling effects is investigated. The results manifest that the different positions of the bypass branch significantly change the performance of low pressure turbine and the flow interactions within the inter-stage. When the bypass branch is on the right, the LPT efficiency improves by approximately 2.2%. The detailed flow field analysis of the inter-stage pipe, volute and rotor is conducted to reveal the flow mechanism behind the inter-stage interactions. Based on this investigation, a new passive flow control scheme is proposed to ameliorate the swirling flow at the LPT inlet and improve the performance of LPT.
High durability variable geometry turbine for commercial vehicle turbochargers
Authors: Gupta B , Hoshi T , Yoshizawa H
Published: May 2022

Transportation sector constitutes a major portion in the Green House Gas (GHG) emissions of the world. Reduction of GHG emission requires the development of highly efficient Internal Combustion Engines (ICE) which are downsized using turbochargers that provide compressed air for cleaner combustion. Variable Geometry (VG) turbochargers are widely accepted for this application because of the ability of VG turbine to function at wider flow range. This ensures the supply of compressed air at low engine speeds also. However, the interaction between stator vanes and turbine rotor has been a major issue in terms of High Cycle Fatigue (HCF) of such a turbocharger. Till now, a conservative design approach constrained the maximum rotation speed to below resonance speed for vibration mode 2. But, to achieve further downsizing it would be necessary to challenge higher rotation speeds. This paper will firstly introduce the tip-timing experiment and CFD-FEA simulations used to evaluate the HCF of VG turbine, and secondly it discusses the results of new VG turbine system which achieved safe operability even at vibration mode 3, both on simulation and experiment. The tip-timing experiment was conducted at 680°C on hot gas stand test bench with optical sensors installed circumferentially around the rotor tip. These measurements have been verified and validated with the safety factor calculated from blade surface pressure data obtained from transient rotor CFD simulations.
Aerodynamic investigation on compact variable compressor for vehicular turbochargers
Authors: Yonemura Atsushi , Sakisaka Ryota , Kaneko Yudai , Morita Isao , Nagao Kenichi , Bamba Takahiro
Published: May 2022

In order to install a turbocharger which has wider operating range and higher boost pressure than a current supercharging system to an internal combustion engine (ICE) and a hybrid vehicle (HV), one development focus lies on a variable trim compressor (VTC) which can change passage area upstream a compressor wheel. In this paper, a new variable geometry device which was developed from the VTC mechanism proposed by Fujiwara et al. in 2018 is studied. The experimental result confirmed the performance enhancement associated with the design concept change and the improvement of trim actuation. In addition, the effect of the throat area ratio as design parameter in the new device on performance was numerically analysed. As a result, the optimal design value of passage area size in the VTC was around 60% and the passage area change position should be placed as close as possible to the compressor wheel.
Influence of nozzle clearance of VG turbocharger turbine on performance and internal flow
Authors: Asanaka Y , Nishimura R , Miyagwa K , Yoshida T , Ebisu M
Published: May 2022

To realize a sustainable society, it is necessary to reduce exhaust gas from automobiles and improve fuel efficiency. Turbochargers are useful for the purpose and especially variable geometry (VG) turbochargers are often installed because their nozzle blade angle can be optimally changed according to the rotational speed of the engine. To change the angle, it is needed to provide the nozzle clearance on both hub and shroud sides. In this study, CFD (Computational Flow Dynamics) calculations of a turbocharger turbine were conducted. The rotational speed of the turbine was set to 10,000 rpm. The diameter of the wheel blade is 60 mm and the height of the nozzle blade was 9.71 mm. The following were mainly investigated: the effect of the nozzle clearance position or blade angle on turbine performance, and the effect of leakage vortex from nozzle clearance on the downstream flow in the wheel domain. First, the steady-state CFD analysis on the nozzle and wheel domain was conducted. Four models of nozzle clearance were used: No Clearance (NC), Hub Clearance (HC), Shroud Clearance (SC), and Hub and Shroud Clearance (HSC). And four nozzle blade angles were used. With the Shroud Clearance model, the torque efficiency was worst with every nozzle blade angle. It was also found that the leakage flow rate from the nozzle clearance affects the loss increase in the wheel domain. Second, the unsteady-state CFD analysis on the full domain (casing + nozzle + wheel +diffuser) was conducted to investigate the leakage flow from nozzle clearance. The turbulence model was DES (Detached Eddy Simulation). Hub Clearance model and Shroud clearance model were used. The leakage vortex generated from nozzle clearance was found to flow into the wheel domain. With each nozzle model, the rotating directions of those vortexes were opposite. By the rothalpy loss investigation with the Hub Clearance model, it was confirmed that the portions of wheel domain where two leakage vortexes flow into showed larger losses than other portions. Those portions were located diagonally in two places, and they rotated in the opposite direction to the wheel rotation. On the other hand, with the Shroud Clearance model, the portions where the rothalpy loss was large were not shown regularly.
Simulation Study of Reliability Model and Optimization for Electrical Power System
Authors: Wu Qicai , Yuan Haibin
Published: May 2022

An architecture with multi-parallel and multi-standby system of aircraft electrical power system is proposed, simulation study is given. First the reliability model of parallel system is formulated, and total system reliability model is obtained. Parallel subsystem number and standby subsystems number are the two parameters of reliability model. In order to maximize the system MTBF and minimize the purchase cost of each subsystem, a novel redundancy optimization function is proposed. Simulation results are analyzed to study the impact of parameters on the system reliability. Redundancy number and configuration of typical aircraft power system is also discussed from the viewpoint of application practice. Simulation result shows that the architecture is flexible, with the options to increase or decrease subsystems of parallel or standby systems to satisfy reliability and capacity requirement.
Simulated Analysis of Liquid System for High-power Power Electronic Equipment
Authors: He Xunan , Kang YuanLi , Li Peng
Published: May 2022

Liquid cooling system mainly provides cooling to high-power power electronic equipment on civil aircraft. It is an important support that it can ensure the high-power power electronic equipment working normally. In this paper, the modeling and simulation of cooling system are carried out. And it mainly focuses on the liquid cooling plate of high-power power electronic equipment. First, three kinds of simulated conditions are confirmed, which are variable temperature of cooling liquid, variable heat load of power electronic equipment and variable flow of cooling liquid. Then according to three kinds of simulated conditions, the performance of cooling system is validated, which is benefit to the design of liquid cooling system and liquid cooling plate.
Study on Model Construction of Multi-agent Negotiation
Authors: Yang Changhui , Zhong Jiayin , Handian Pengke
Published: May 2022

In this paper, a multi-agent negotiation model will be constructed which consider the risk preference degree of the participants. And then the model is simulated. The simulation result has verified the effectiveness of the model.
3D Simulation Design of Ideal City
Authors: Zeng Min
Published: May 2022

From static and single model display to dynamic and complex scenes such as 3d animation of real estate and hotel, 3D roaming, 3D virtual city and character animation, all of these can be realized by strong technical strength. This project uses 3D Max to complete the animation production of park landscape planning, venue greening, community greening and real estate landscape. Its effect is real, three-dimensional, vivid, traditional renderings can not be compared. At the same time, a unique modeling scheme is proposed. Then, with the help of AE and PR, the animation clips are combined into videos to comprehensively show the real estate through multiple angles, giving viewers an immersive feeling.
Proposal of a New Agent-based Model and Its Validation by Simulation
Authors: Li Zhaowei , Tanaka Kenji , Zhang Jing
Published: May 2022

Transportation services are diversifying as the demand for logistics services and truck transportation increases. However, the subcontracting hierarchy has produced social problems such as excessive driver labor, dissatisfaction of recipients, and deterioration of distribution efficiency. In this study, we focused on these problems and proposed, designed, implemented, and verified a point-to-point (P2P)-type logistics platform that reflects user preferences. A P2P logistics platform is defined as a decentralized platform in which delivery schedules are made only by interactions between truck and package agents without any human intervention. This platform is based on logistics agent modeling and sacrifice volume and negotiation, and its construction and simulation are described. In addition, as a case study, the model’s effectiveness for time-insensitive cargo, the case of truck entry and exit for time-sensitive cargo, and the actual delivery and truck supply convergence were verified.
On the Modeling and Multi-objective Optimization Design of Compact Planar Ultra-wideband Impedance Transformer
Authors: Yang Nan , Wang Dong , Wang Gang
Published: May 2022

A versatile scheme for design of planar ultra-wideband impedance transformer is proposed by using fragment-type structures (FTS) for modeling and MOEA/D-GO for optimization. To improve the optimization efficiency, non-uniform FTS cells are applied. To find the optimal planar FTS transformer, two objective functions characterizing the return loss and the insertion loss of the impedance transformer, respectively, are defined on a ultra-wide bandwidth. For demonstration, a 25-ohm to 50-ohm FTS impedance transformer is designed, which acquires reflection coefficient lower than -20 dB and extra insertion loss less than 0.27 dB in ultra-wide frequency band of 0.89-5.00 GHz.
A Task Planning Simulation Method Based On Hungarian Algorithm
Authors: Gong Xunan , Li Hongmei , Yang Xuesheng
Published: May 2022

As information technology continues to evolve, the need for accuracy and efficiency in task planning in computer simulation continues to strengthen. Task planning is a key part of computer-generated resource planning. To improve the effectiveness of task planning, this paper tries to design a task planning method. Firstly, a task planning model is designed by decomposing the requirements of the task according to the task capability of the platform, describing the resources quantitatively, and extracting the constraints and objective functions. Then the Hungarian algorithm is used to solve the problem. Finally, a typical case is used to test the proposed method, which verifies the correctness and feasibility of the method.
The Analysis Method of Performance Comprehensive Performance Optimization Design for Multi-body Unmanned Boat
Authors: Han Xiaofeng , Qi Xuejia , Zhang Jincheng , Yang Songlin , Chen Shuling
Published: May 2022

In order to compare and analyze the comprehensive performance of multi-hull unmanned boats under specific conditions, this paper conducts in-depth research on the multi-objective decision-making theory and intelligent optimization algorithms of boat type design. First of all, this paper establishes the corresponding ship type and resistance database using the response surface fitting method through the drag resistance test of the ship model. Secondly, comprehensively considering the impact of the three major performances of multi-hull unmanned craft on the design of the boat’s speed, maneuverability and seakeeping, a comprehensive optimization mathematical model was established, and the comprehensive optimization design software was adapted. Then, using genetic algorithm, particle swarm algorithm, and chaos algorithm to conduct a preliminary calculation and analysis of the comprehensive performance of the two ship types. By comparing the calculation results, it is concluded that the particle swarm algorithm is the best algorithm among the three intelligent algorithms. Finally, the particle swarm algorithm is used to compare and analyze the comprehensive performance of the two ship types in the multi-hull unmanned craft. It is concluded that the overall performance of the three-hull unmanned craft is better at the same speed and displacement. This paper discusses the pros and cons of the three intelligent algorithms, compares and analyzes the calculation results of each optimization algorithm, and provides a practical way and method for the selection of multihull unmanned boats under the same speed and same displacement.