bluuebunny/crossref_metadata_2025 huggingface dataset:
Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) activity is required for V(D)J recombination
Authors: Chen Chun-Chin , Chen Bo-Ruei , Wang Yinan , Curman Philip , Beilinson Helen A. , Brecht Ryan M. , Liu Catherine C. , Farrell Ryan J. , de Juan-Sanz Jaime , Charbonnier Louis-Marie , Kajimura Shingo , Ryan Timothy A. , Schatz David G. , Chatila Talal A. , Wikstrom Jakob D. , Tyler Jessica K. , Sleckman Barry P.
Published: May 2021

A whole-genome CRISPR/Cas9 screen identified ATP2A2, the gene encoding the Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) 2 protein, as being important for V(D)J recombination. SERCAs are ER transmembrane proteins that pump Ca2+ from the cytosol into the ER lumen to maintain the ER Ca2+ reservoir and regulate cytosolic Ca2+-dependent processes. In preB cells, loss of SERCA2 leads to reduced V(D)J recombination kinetics due to diminished RAG-mediated DNA cleavage. SERCA2 deficiency in B cells leads to increased expression of SERCA3, and combined loss of SERCA2 and SERCA3 results in decreased ER Ca2+ levels, increased cytosolic Ca2+ levels, reduction in RAG1 and RAG2 gene expression, and a profound block in V(D)J recombination. Mice with B cells deficient in SERCA2 and humans with Darier disease, caused by heterozygous ATP2A2 mutations, have reduced numbers of mature B cells. We conclude that SERCA proteins modulate intracellular Ca2+ levels to regulate RAG1 and RAG2 gene expression and V(D)J recombination and that defects in SERCA functions cause lymphopenia.
Norfluoxetine inhibits TREK-2 K2P channels by multiple mechanisms including state-independent effects on the selectivity filter gate
Authors: Proks Peter , Schewe Marcus , Conrad Linus J. , Rao Shanlin , Rathje Kristin , Rödström Karin E.J. , Carpenter Elisabeth P. , Baukrowitz Thomas , Tucker Stephen J.
Published: May 2021

The TREK subfamily of two-pore domain K+ (K2P) channels are inhibited by fluoxetine and its metabolite, norfluoxetine (NFx). Although not the principal targets of this antidepressant, TREK channel inhibition by NFx has provided important insights into the conformational changes associated with channel gating and highlighted the role of the selectivity filter in this process. However, despite the availability of TREK-2 crystal structures with NFx bound, the precise mechanisms underlying NFx inhibition remain elusive. NFx has previously been proposed to be a state-dependent inhibitor, but its binding site suggests many possible ways in which this positively charged drug might inhibit channel activity. Here we show that NFx exerts multiple effects on single-channel behavior that influence both the open and closed states of the channel and that the channel can become highly activated by 2-APB while remaining in the down conformation. We also show that the inhibitory effects of NFx are unrelated to its positive charge but can be influenced by agonists which alter filter stability, such as ML335, as well as by an intrinsic voltage-dependent gating process within the filter. NFx therefore not only inhibits channel activity by altering the equilibrium between up and down conformations but also can directly influence filter gating. These results provide further insight into the complex allosteric mechanisms that modulate filter gating in TREK K2P channels and highlight the different ways in which filter gating can be regulated to permit polymodal regulation.
Coercivity in the Mg-doped CeCo3 permanent magnet: grain size and anisotropy variation effects
Authors: Guan Weizheng , Zhang Zhengming , Wang Dunhui , Du Youwei
Published: May 2021

Understanding the microstructure–coercivity relationship is essential not only because of its theoretical significance, but also for the application value of designing high performance magnets. As one of the latest found permanent magnets, Mg-doped CeCo3 alloys have attracted wide attention due to their lots of advantages such as strong ferromagnetism, large magnetocrystalline anisotropy, low cost, and good hydrogenation property. However, the potential of coercivity in the Ce1−x
Mg
x
Co3 magnet has not been fully excavated, which restricts the practical application to a certain extent. In this work, the effects of grain size and anisotropy variation on coercivity have been investigated systematically by using micromagnetic simulation. It has been shown that the coercivity exhibits nonlinear size-dependence and can reach ∼1.45 T in the sample with a grain size around 320 nm. In addition, the random variation of magnetocrystalline anisotropy caused by the precipitated Co phase in the small grain would lead to the fluctuation of coercivity. Our work can provide guidelines for the design and implementation of permanent magnets.
Stability analysis of hydro-turbine governing system based on machine learning
Authors: Chen Yuansheng , Tong Fei
Published: May 2021

Hydro-turbine governing system is a time-varying complex system with strong non-linearity, and its dynamic characteristics are jointly affected by hydraulic, mechanical, electrical, and other factors. Aiming at the stability of the hydro-turbine governing system, this paper first builds a dynamic model of the hydro-turbine governing system through mechanism modeling, and introduces the transfer coefficient characteristics under different load conditions to obtain the stability category of the system. BP neural network is used to perform the machine study and the predictive analysis of the stability of the system under different working conditions is carried out by using the additional momentum method to optimize the algorithm. The test set results show that the method can accurately distinguish the stability category of the hydro-turbine governing system (HTGS), and the research results can provide a theoretical reference for the operation and management of smart hydropower stations in the future.
Increasing the accuracy of processing thin-walled box-shaped parts
Authors: Danilenko E A , Yamnikov A S
Published: May 2021

The paper describes the development of a procedure for increasing the accuracy of processing thin-walled parts. The paper proposes a new method for fixing and processing thin-walled box-shaped parts, during which the coordinate of the workpiece base side position is measured using an RMP40 sensor before and after the application of clamping forces, followed by compensation for processing on a CNC milling machine. A special control program that takes into account elastic deformations has been developed. A comparative analysis of dimensions performance showed that the accuracy of coordinate dimensions performance taking into account the compensation of elastic deformations is higher than without compensation.
Automation of control the state of graphic collections and of content selection for design tasks in the printing
Authors: Proskuriakov N E , Yakovlev B S , Arkhangelskaia N N , Dementyeva K V
Published: May 2021

Results of pilot studies of use of average color for problems of support of graphic collections in current state and selection of graphics for the color parameters set by the user – search of duplicates of images, selection of graphics due to data entry of color in the RGB format and also search of illustrations in the set color range or the specific image are provided. Based on the conducted researches it was established that under certain conditions the indicator of average color of the image rather precisely finds duplicates of illustrations and can be applied to selection of the same images. The research showed that the JPG format, despite the low opportunities in transfer of color, can be considered the optimum format for search of duplicates of digital images. Also, it was defined that BMP, TIFF, PNG behave equally in tasks of finding of duplicates, optimum deviations from average color for the solution of this task were revealed.
Investigation of the rotational motion stability of the aist small spacecraft prototype according to the measurements of the earth’s magnetic field
Authors: Sedelnikov A V , Taneeva A S , Khnyryova E S , Kamaletdinova M V , Martynova E D
Published: May 2021

The paper deals with the rotational motion stabilization of the AIST small spacecraft prototype under the influence of a magnetic moment. According to the measurements of the Earth’s magnetic field by onboard measuring instruments, the angular velocity of small spacecraft rotation has significantly decreased over several years of active existence in a near-earth orbit. At the same time, attempts to actively control the angular velocity by magnetic executors were unsuccessful. In this investigation, approximate solution regions for the magnetic moment are obtained from the condition of the rotational motion stability around the center of mass of the AIST small spacecraft prototype. These regions can be further analyzed for compliance with the operation of the onboard equipment of a small spacecraft.
Combined Nonlinear Control of Non-Affine MIMO System with Input and State Delays
Authors: Eremin E L , Nikiforova L V , Shelenok E A
Published: May 2021

The article studies algorithms synthesis of a multiply connected system for controlling non-affine plants, the state variables of which are not available for direct measurement. It is shown that the decentralized control law constructed on the basis of the hyperstability criterion eliminates the influence of non-linearities and compensates external and parametric perturbations in the tracking multiply connected system with the required accuracy.
Numerical study of flow in a plane suddenly expanding channel based on Wilcox and two-fluid turbulence models
Authors: Malikov Z M , Nazarov F Kh , Omonov Z J , Abdukhamodov S K
Published: May 2021

The article presents the results of a numerical study of the flow structure in a flat channel in the zone of its sudden expansion. The calculations are based on the two-fluid turbulence model and the Wilcox turbulence model. The stationary solution of the problem was obtained by the establishment method, for which non-stationary equations of hydrodynamics were used. The paper investigates the velocity fields and turbulent stresses of the flow, as well as the drag coefficient in different sections of the channel. The main calculations were performed on a uniform grid with 300 × 90 nodes. For the difference approximation of the original equations, the control volume method of the second order in space is used. The correctness of the results was confirmed for Reynolds numbers Re = 36000 by comparison with experimental data found in the literature.
Impact assessment of the supply chain based on the theory of fuzzy sets
Authors: Mochalin S M , Radionova V A
Published: May 2021

The next questions were considered: creation of performance evaluation system as part of the automated software complex designed to improve the activities functioning of the business structures. These business structures are complex regarding their structure as well as liaison communications in a supply chain. Proposed model for the efficiency assessement was created while using the theory of fuzzy sets on the software basis in the MATLAB environment. Conducted investigations have shown that this developed model allows to create supply chains that are optimal in terms of its structure and efficiency; it equally formalizes the decision-making procedure and reduces the error probabilities when it comes to the supply chain management.
Simulation of purposeful movement in the transport network
Authors: Purtov A
Published: May 2021

A conceptual model of purposeful movement on the oriented graph of the route of the road network is presented. To determine the purpose of the movement and to stimulate the participants of the movement, two functions for calculating losses are proposed. For routing used the samples. The graph of one of the routes of Omsk was constructed using the technology of geoinformation systems. The simulation model has been developed on Java Script. A brief description of the simulation model and the experimenter’s window is given. The new results of experiments showing the influence of the target parameters, loss functions, the samples on the time and cost of moving along the route are presented. The complex relationships between the input and output data of the model are shown. The results obtained are considered from the point of view of the general problems of organizing a purposeful movement, such as goal selection, decision-making, coordination of the interests of the organizers and participants of the movement. The conclusion is made about the possibility of using the developed methods and tools for the analysis of purposeful movement in different spheres of activity.
On generic complexity of theories of finite algebraic structures
Authors: Rybalov Alexander
Published: May 2021

This article is devoted to investigation of generic complexity of universal and elementary theories of finite algebraic structures with universal set with more than one element of finite predicate signature with equality. We prove that there are no polynomial strongly generic algorithm, recognizing any such theory, provided P = BPP and P ≠ NP (P ≠ PSPACE). The author is supported by Russian Science Foundation, grant 19-11-00209.
Geometric model of the pursuit problem on a plane for the case of sets of targets and pursuers
Authors: Dubanov A A
Published: May 2021

This article examines a kinematic model of a group pursuing several targets by the method of parallel approach. The model is based on the fact that pursuers try to adhere to pre-designed trajectories. The pursuers’ trajectories have curvature constraints. The initial directions of the pursuers’ velocities are arbitrary, which changes the well-known method of parallel approach. In our model, targets are chased by the pursuers simultaneously. This is due to the change in the lengths of the predicted trajectories in such a way as to synchronize the time to reach the target. The change in the lengths of the predicted trajectories occurs due to an increase in the radius of curvature in the initial segment of the trajectory.
Model of the method of parallel approximation on the surface
Authors: Dubanov A A , Ausheev T V
Published: May 2021

The article considers the kinematic model of pursuit, transferred from plane to surface, by the method of parallel approach. Simulation of iterative pursuit processes is a topical continuation of autonomous unmanned vehicles. The aim of the article is to develop a model in which the trajectory of the pursuer is the result of following the predicted routes at each discrete moment in time. The research was carried out in the computer mathematics system Math CAD on a surface defined by a point basis. Situations with different initial states were simulated. Detailed results in the form of animated images based on materials, program codes can be found on the authors’ website and channel.
A Sierpiński triangle geometric algorithm for generating stronger structures
Authors: Zhikharev L A
Published: May 2021

In the twenty-first century, in the era of 3D printers and advanced technologies for the production of complex parts, it becomes possible to create objects that have a fractal structure. This gives relevance to the attempts of applying the knowledge of fractal geometry. This paper presents effectiveness confirmation and feasibility studies of using a fractal algorithm for making stronger structures. The algorithm is based on the Sierpiński fractal. The essence of the algorithm is to increase the buckling strength of the rods by fixing their midpoints. This principle makes it possible to create complex flat and three-dimensional structures, as well as to solve some engineering problems. Analytical strength calculations were run in Wolfram Mathematica, whilst Solid Works, a CAD and CAE program, were used to compute the strength.
Methodology formation of the training sample short-term forecasting electricity load for an energy supply company using data mining technologies
Authors: Khomutov S O , Khamitov R N , Gritsay A S , Serebryakov N A
Published: May 2021

For effective management of the power system operation mode the predictive information about hourly electrical load of all consumers is required. Forecasting errors, as a rule, lead to a decline of the technological and economic indicators of the power system operation, due to unreasonable changes of the generating equipment operating mode, as well as the selection of a non-optimal scheme of electrical networks. This article is devoted to improving the accuracy of short-term load forecasting of delivery points cluster of energy sales company with the use artificial neural networks. One of the most important conditions for achieving high prediction accuracy is the quality of the data sample required for training and testing neural network algorithms for short-term loading forecast. The proposed methodology is based on the authors’ analysis uses the factors influencing the hourly power loading. The proposed methodology is based on the authors’ analysis uses the factors influencing the hourly power loading as well as methods for improving the convergence of learning algorithms for artificial neural networks.
Load Model Identification using Steady-state Measurements for Power System Control
Authors: Pankratov A V , Zhuykov A K , Polishchuk V I , Postoyankova K Yu , Shuvalova A A
Published: May 2021

Power system control requires verified models of all its elements: generators, transformers, transmission lines, and power system loads. To identify load model parameters, the measurement data are used. The paper discusses the possibility of using steady-state measurements instead staged field test data. This requires taking into account an unobvious effect-the network response. The network response is due to the probabilistic nature of the power and voltage changes and the correlation between them. The network response effect is demonstrated using a probabilistic load model and a simple power supply scheme.
Mathematical model of the condensation process in the crankcase space of a piston engine warmed up under negative temperatures of a cold climate
Authors: Kaminsky V N , Kostyukov A V , Kolunin A V , Materi I V
Published: May 2021

In recent years, there has been a trend of increasing activities in the development of polar territories. Negative temperatures are a characteristic feature of the North. Negative temperatures have a negative impact on the state of power installations of land, air and water transport, mobile, stationary power plants and small-scale mechanization facilities. The engine is least adapted unit for operation in such conditions. There is a chain of negative factors that consistently provides a connection between the state of the lubrication systems and the negative temperatures, in which the equipment is operated. Condensation processes are a primary link in this chain. The existence of condensation processes in the crankcase space when a piston engine is warmed up at negative temperatures is experimentally proved. The percentage of engine oil watering and the dew point temperature of crankcase gases are determined in the conditions of a full-scale experiment. However, the high labor intensity and significant financial costs of organizing such experiments require the search for other methods of testing. A mathematical representation of reality, which allows you to obtain objective and adequate experimental data information, can be one of the ways to solve this problem.
The use of light fractional composition fuels in the electric flame jet of a diesel engine
Authors: Kaminsky V N , Kostyukov A V , Kolunin A V , Materi I V
Published: May 2021

In recent years, there has been an increased interest in the development of the polar territories of our planet. A large number of minerals on land and in the shelves attracts the attention of our contemporaries. Development of these territories with a harsh climate is possible by using modern vehicles and mechanisms that ensure the exploration of sediment layers, extraction of deposits, transportation of rocks and raw materials. The most common mode of transportation in these conditions are motorized vehicles. One of the most important aspects in the operation of automotive equipment in conditions of temperatures below freezing point in a cold climate is the startup of the diesel engine after a long period of parking. The industry produces auxiliary equipment. In this regard, heat generators are widely used. There are individual and group heaters of various types, including flame and infrared heaters that can provide support in the pre-starting procedure. In addition, there are means to facilitate the start-up. The reliable start of a diesel engine is influenced by factors such as the temperature of the air charge, the operating torque of the crankshaft, the conditions of fuel spraying, the activity of heat exchange processes and the tightness of the mating of the cylinder-piston group parts. The use of fuels of light fractional composition with an electric flame jet or the so-called gas-electric flame jet can constitute an effective solution to the problem.
Investigation of the combined process of isothermal crimping with a set of thickenings at the ends of pipe blanks
Authors: Pasynkov A A , Larin S N , Gurova O Yu
Published: May 2021

The article discusses the production of cylindrical hollow workpieces with different cross-sections along the height. The difference in cross-sections is ensured by crimping. During the crimping, the ends of the blanks are thickening. The operation under consideration is carried out in a hot state with local heating of the workpiece elements with a slow movement of the tool. It occurs due to the material grade of the workpiece, which is very demanding in terms of the deformation conditions. Simulation of the studied combined process has been carried out, during which the influence of the parameters of the main operations (deformation rate, heating parameters, friction) on the possibility of obtaining products with specified geometric characteristics has been established.
Study of the machining quality of CMC ceramic composite during high-speed grinding
Authors: Rechenko D S , Kamenov R U
Published: May 2021

Ceramic matrix composites (CMC) are now an increasingly popular choice of materials used to manufacture critical parts for a variety of engineering applications. Due to the complex heterogeneous structure of CMC and the high hardness of at least one of the components (fiber or matrix)-processing such materials becomes an extremely difficult task. In addition, the heterogeneous structure and brittleness of CMC leads to different material removal mechanisms during machining, resulting in unique surface defects that reduce the quality of the machined surface. This article deals with the issues of ensuring the quality of the machined surface of samples made of SiC/SiC ceramic composite with ceramic matrix, by selecting the characteristics of the grinding tool and cutting modes during high-speed grinding.
Development of polymer composite materials and structures with their subsequent utilization after the mission
Authors: Trushlyakov V I , Russkikh G S , Blesman A I , Davydovich D Yu , Iordan Yu V , Fateev P D
Published: May 2021

The article considers the transfer of utilization technologies for detachable elements of the launch vehicle (LV) structures during the launch at the powered phase after their detachment at the unpowered phase of the descent trajectory to the utilization of tanks for fuel and lubrication materials (FLM) delivered to outlying regions of the Arctic. Opposed to detachable LV structures, utilization of FLM tanks is carried out under ground conditions by burning fuel elements prepared from FLM tank structures in conventional boilers and domestic heating furnaces. The research task has been set considering the possibility of implementing the requirements in the design and construction of polymeric composite material (PCM) to manufacture combustible tanks for the FLM storage. The requirements have been formulated for the production stages of combustible PCM and utilization system including the definition of design and construction parameters of PCM. The results of preliminary experimental studies in terms of determining the combustibility of the proposed PCM and their strength characteristics have shown the possibility of developing combustible structures.
New way to increase the profitability of railway transportation of viscous petroleum products at low air temperatures
Authors: Vorobiev A A , Moiseev V I , Samarkina I K , Komarova T A , Krutko A A , Sedykh D A , Fedorov I V , Ksenofontova V A
Published: May 2021

The article deals with the main problems associated with the transportation and unloading of viscous petroleum products by rail at low temperatures. Taking into account the analysis of the applied technologies and modeling of the ongoing processes in the ANSYS program, a solution to the problems that arise is proposed by using a tank car with a steam-heating casing or by applying thermal insulation to the upper part of the tank. To ensure the tightness of the drain device of the tank car and to avoid the occurrence of environmental disasters, the modernization of its design is proposed.
Influence of technological regimes of plasma chemical deposition on texture formation in aluminum nitride films
Authors: Baranova L V , Strunin V I
Published: May 2021

Textured polycrystalline aluminum nitride films were grown by magnetron sputtering of an aluminum target in a mixture of argon and nitrogen, followed by the formation of a film on sitall substrates. The influence of the pressure of the working gases, the power dissipated on the target, and the ratio of the Ar / N2 gas fluxes on the texture of the aluminum nitride films are investigated. The phase composition and degree of crystallinity of the obtained films were determined using scanning electron microscopy and X-ray diffraction. The results of studies of the phase composition and parameters of the crystal structure of aluminum nitride films are presented: the size of the coherent scattering regions, the predominant orientation of the crystallites in the growing film, and the degree of crystallinity. It is noted that the films are predominantly oriented along the (111) and (002) planes. The degree of crystallinity of the A1N films varied from 10 to 30% depending on the conditions of the deposition process. The relative microdeformation of the lattice (Δd/d), depending on the parameters, ranged from 1.7·10−3 to 6.9·10−3. The size of the crystallites is affected by the microdeformation of the lattice, with its increase by 4 times, the size of the crystallites decreased by 3.6 times from 29 to 8 nm.
The features of organic soil dielectric characteristics in the Arctic region
Authors: Suslov K N , Yashchenko A S
Published: May 2021

The results of measurements of the complex dielectric permittivity of the Arctic region organic soil are presented. The trends in the change of the soil CDP with varying soil moisture and temperature are described. We compared measure data with the values calculated by the Dobson model for sandy and silty clay soil. It was found that the experimental and model data differ markedly.
On physical reliability of constitutive relations in plasticity for plane processes with bend point
Authors: Abirov R A
Published: May 2021

We focus our attention on the physical reliability of plasticity at complex loading. It is important for reliable solution of boundary-value problems. The results of experiments on complex loading in the form of trajectory in the form of two-element trajectories for weakly hardened material are considered in this issue. An analysis of physical reliability of the simplest versions of plasticity theories for describing active processes of complex loading with bend point is given here. We provide analysis and recommendations as to preferable applications of classical theories for plane complex loading modes. It is shown that neglecting the loading process geometry lead to considerable errors in theoretical calculations.
Numerical calculation of the natural vibration frequencies of thermo-elastic rods taking into account the effect of the temperature gradient
Authors: Kikvidze O G , Sakhvadzeand G G , Sakhvadze G Zh
Published: May 2021

Elastic rod elements are considered, the axial line of which in the natural state is a flat curve and remains a flat curve after loading. The following assumptions are used: the normal cross-sections, which are flat before deformation, remain flat and normal to the deformed thermo-elastic axial line after deformation; the temperature field is stationary and non-uniform. Nonlinear equations of motion of the rod are obtained, taking into account the rotational inertia of cross-section and the extensibility of the axial line.
Optimization of the rubber element of the rubber-metal hinge of a tracked system
Authors: Korostelev S A , Korostelev D S
Published: May 2021

The paper presents the formulation of the problem of optimal design of rubber bush of the track link and its solution. The search for the optimal design is based on the results of calculating the stress-strain state of the rubber ring caused by the assembly of the rubber-metal hinge and loads during subsequent operation. As an objective function, the specific energy of deformation of the rubber was chosen. The dimensions of the rubber ring of the rubber-metal hinges in the undeformed state are taken as variable parameters. Formulation of the optimization problem imposes constraints on the design parameters in the form of inequations. The solution of the problem of optimal design and the results of durability tests are presented.
Effects of slag on cement hydration by electrical resistivity characterization
Authors: Xiao Chengyi , Lv Quanhong , Jiang Xingjiao , Xiao Lianzhen
Published: May 2021

Non-contact resistivity measurement was used to characterize the early hydration characteristics of cement paste with different contents of slag, combined with other traditional methods such as hydration heat, compressive strength. The results show that the maximum compressive strength of sample P0.4SL20 was 34.4 MPa and 45.2 MPa at 3 d and 7 d, respectively. The addition of slag could reduce the hydration heat of slurry, which makes the second hydration exothermic peak shift to the left. The characteristic points on electrical resistivity differential curve with different slag contents had good correspondence with the corresponding characteristic points on hydration heat release curve of samples with different slag contents. A good linear relationship between electrical resistivity and compressive strength was shown as f
c(3d) = 5.23992P(3d)-12.31066. The electrical resistivity method can be used to characterize the influence of slag on the hydration process of cement paste and predict its compressive strength.
The concrete application of lightning protection technology of electrical automation system in water conservancy and hydropower project
Authors: ZhaoChunLei
Published: May 2021

the development of science and technology has promoted the continuous progress of water conservancy and hydropower projects. Advanced equipment and advanced technology are widely used in water conservancy and hydropower projects, which improves the working efficiency and working level of staff in two directions, and also brings great economic benefits to the water conservancy and hydropower projects. Among them, electrical automation technology is widely used in water conservancy and hydropower projects as the basis of quality guarantee, therefore, correspondent research on it should be strengthened. The application of lightning protection technology in electrical automation system of water conservancy project is to provide guarantee for the stable operation of the electrical automation system of water conservancy project. This paper analyzes the lightning protection technology of electrical automation system used in water conservancy project from the practical point of view, and analyzes the main points of application of electrical automation in water conservancy and hydropower projects in detail.
Analysis of connection structure of prefabricated reinforced concrete exterior wall panels
Authors: Jian Tang , zhaofeng Zheng , minsi Chen , huihui Hu , yaru Sun
Published: May 2021

By analyzing and discussing the connection structure related to the fabricated reinforced concrete external wall panel, including the material, technology, connection principle and form method of the external wall panel, the design principles of the fabricated reinforced concrete external wall panel connection structure are summarized.
Research on the method based on the combination of BETC and BIM
Authors: Zhiqiang Chen
Published: May 2021

The virtual simulation model building (BIM) of civil engineering is used more and more widely. Based on the platform of “cost workshop” of civil engineering and the BETC method of “BIM virtual construction + actual engineering information + industry standard comparison”, this paper emphasizes the integration of “virtual construction technology”, “information pricing technology” and “industry standard requirements” of civil engineering. This method is conducive to the research of civil engineering BIM Technology and the development of cost information.
Research on BIM Technology in Smart City
Authors: Wu Bei , Chang Runwu , Zhang Jiamin , Sun Haowei , Luan Wenjie , Li Nan
Published: May 2021

With the vigorous development of green and intelligent concepts and technologies in China’s urban construction, BIM can no longer meet the tasks of data processing and management of a large number of information flows in green ecological urban areas. CIM (Urban Information Model), as an information means, has gradually become the engine power of future urban construction. Through the application of information technology and communication technology, smart cities can collect, analyze and integrate the key information of the core system of urban operation, and then make intelligent response to the needs of people’s livelihood, environmental protection, public safety and urban services, create a better life and promote the harmonious and sustainable development of cities. CIM refines the granularity of data to an electromechanical accessory and a door inside a single building in a city, and upgrades the traditional static digital city into a digital twin city with perceptibility, dynamic online and virtual-real interaction, providing a data foundation for agile management and fine governance of the city.
Modeling of Wake Effects in Steady State Mixing Plane Simulations of a High Lift Turbine Cascade with Different Combinations of Wake Passing Frequency and Wake Orientation
Authors: Führing A. , Kožulović D. , Bode C. , Franke M.
Published: May 2021

Due to operation at low Reynolds numbers, low pressure turbines of aircraft engines mostly show large laminar boundary layers and transitional separation bubbles which considerably change their viscous losses when interacting with impinging wakes. The change of loss depends on several wake parameters, among others on wake passing frequency and wake orientation. In the present work, these parameters are expressed in terms of Strouhal number and flow coefficient and their influence is investigated by means of unsteady Reynolds-averaged Navier-Stokes (RANS) simulations. Different combinations of both wake parameters which are typical of aircraft engine conditions, are prescribed upstream of a high lift turbine cascade, while the Reynolds number and Mach number are kept constant. The solver TRACE by DLR and MTU Aero Engines together with the γ −
Re
Θ transition model by Langtry and Menter has been used. Further, the wake profile is representative for upstream turbine profiles and is prescribed by a correlation framework which has been calibrated in previous work. A newly developed quasi-unsteady wake model (QUWM) is applied in order to model the effects of periodically passing wakes in steady state simulations involving mixing plane interfaces. It is shown that the gap between unsteady and steady state simulations is narrowed significantly by the QUWM while still maintaining quick turnaround times that are crucial in industrial flow solver applications.
Sweep-angle effect on low-order acoustic prediction for low-speed fans
Authors: Zarri Alessandro , Christophe Julien , Moreau Stéphane , Schram Christophe
Published: May 2021

The low-speed fans that are used for automotive engine cooling contribute to a significant part of the global noise emitted by the vehicle. Automotive engine cooling manufacturers are therefore interested in developing low-order noise prediction methodologies that include the radiated sound in pre-design optimization cycles. Two among the most influential broadband noise mechanisms characterizing the automotive axial cooling-fans spectra in operating conditions are the turbulence-impingement noise and the trailing-edge noise. We modelled them through the application of a semi-analytical method called Amiet’s airfoil theory, appropriately adapted via a strip-theory approach, in order to take the rotating motion into account. In modern fan designs, the fan blades are strongly forward-swept, meaning that the blade edges are not always perpendicular to the tangential-to-rotation velocity vector. This is particularly true at the tip of the blades where the sweep angle often reaches its maximum value, and where most of the noise is expected. Sweep was shown to reduce the noise emitted by isolated airfoils, but its effect on rotating machines is not yet well understood. Its prediction requires an extension to the classical Amiet’s theory, which has been implemented in this work, permitting to assess the importance of varying sweep on the acoustic far-field radiation. Amiet’s theory is therefore applied for the two noise mechanisms mentioned above, starting from steady CFD simulations, reproducing the ventilator geometry operating at its maximum-efficiency condition. In contrast with the classical unswept formulation, the predicted results considering the sweep variation along the blade span better compare with the experimental measured ones in the VKI anechoic chamber, especially for high frequencies.
Cavitation analysis of a Delft twisted hydrofoil using multi-process cavitation model
Authors: Miki Takahito , Fujiyama Keita , Tsuda Shin-Ichi , Irie Tomohiro
Published: May 2021

Cavitation is essentially formed of a combination of multiple processes. Most of the conventional cavitation models consider these in a single model, and the conservation equation for void fraction of cavitation bubbles is solved. To understand the relationship between cavitation and turbomachinery performance, not only void fraction, but also states of cavitation bubbles such as number and radius may become useful data. The multi-process cavitation model proposed by Tsuda and Watanabe is one of the solutions. This model has been implemented into commercial CFD software scFLOW. To validate the implemented cavitation model, cavitation around a Delft twisted hydrofoil was analyzed, and the result was compared with past studies. From a parametric study of the bubble growth coefficient in this cavitation model, it was found that 0.2 for expansion and 0.05 – 0.1 for shrinkage are appropriate. Cavitation shedding frequency and cavity volume agreed well with the past studies by using those coefficients. Since the multi-process cavitation model provides detailed cavitation bubble states, a new index is proposed to detect bubbly regions and its distribution compares well with experimental data. This implies that the multi-process cavitation model will help us to predict cavitation noise and erosion risk as well as to understand the mechanism of the cavitation phenomenon.
Numerical investigation of the effect of leakage flow on cavitation in centrifugal pump
Authors: Moganaradjou Yashwant , Phukan Anindita Apurbaa , Vengadesan S , Chatterjee Dhiman
Published: May 2021

Numerical studies on pumps emphasize mainly on modelling the interactions between the impeller and the volute to obtain an accurate understanding of the physics involved. However, the importance of modelling leakage paths, which is known to have a significant influence on the flow structure in the pump, necessitates an in-depth analysis. This activity is undertaken in this paper by investigating a specific case of a centrifugal pump. Numerical studies have been conducted on the pump modelled with and without leakages for the design condition. The sliding mesh method is used to obtain single phase pressure pulsations data at some important locations in the volute and the leakage path, and transient Multiple Reference Frame (MRF) modelling is utilized to conduct the cavitation analysis. It is observed that for the case under study, the pressure pulsations pattern and the cavitation behaviour varies significantly due to the inclusion of leakage paths in the analysis.
Improvement in accuracy of engine cycle simulations by using a turbocharger prediction model instead of measured efficiency map
Authors: Misono Y , Kuboyama T , Moriyoshi Y , Yamada T
Published: May 2021

In the downsizing concept, the turbocharger (T/C) is one of the key devices for improving thermal efficiency and exhaust emissions of internal combustion engines for automobiles. In order to maximize the supercharged engine performance, the size of the T/C applied for the given engine system has been optimized by using a 1-D engine cycle simulation. For this reason, T/C performance prediction model for engine cycle simulation is required to be accurate over a wide operating range. In the conventional T/C performance prediction model, the turbine performance was predicted by extrapolating from the efficiency map measured under steady flow. However, the accuracy of the extrapolation method is uncertain, and it has been pointed out that the prediction accuracy is low in the low load operations. In this study, a 1-D T/C model developed based on hydrodynamics and thermodynamics was used. Using the 1-D T/C model, a grid efficiency map over the entire operating range was calculated and the grid map was applied to 1-D engine cycle simulation. The accuracy of the T/C model was verified by comparing the experimentally measured efficiency under steady flow.
Analysis of Flow Models for Aerostatic Thrust Bearings with Porous Material
Authors: Schimpf A. , Gu Y. , Böhle M.
Published: May 2021

The numerical determination of static characteristics of bearings allows a cost-efficient and fast pre-design. In this study, two flow models for aerostatic thrust bearings with pressurized porous material are presented and analyzed. The models are based on the coupling of the Reynolds equation for lubricants (REL) and the determination of pressure drop through porous material by Darcy’s law. The simplified model is based on the assumption of a one-dimensional axial flow through porous media. The extended model considers the three-dimensional flow in the porous body. The analysis includes pressurized air from 4 to 9 bar(a) with nominal clearance of 5 to 60 µm. Commercial CFD software was used to verify the results. The extended model allows a more accurate prediction about the performance in the critical gap range. In total, the results show good agreement with CFD within a short computation time.
Experimental performance of a pump and the related vortices in a pump intake of a model pump station
Authors: Guo Miao , Zou Huijun , Chen Baoyu , Zuo Zhigang , Liu Shuhong
Published: May 2021

In order to quantitatively study the relationship between the performance of a pump and the related hydraulic phenomena in a pump intake of a model pump station, a model test was carried out in the present paper. The results show that when the dimensionless water level (water level/diameter of the pipeline: W/d) WL*≥5.46, the influence of the water level on the performance of the pump can be ignored, and the operation of the pump is stable. When WL*=5.15, the performance of the pump decreases deeply, the dimensionless flow rate (actual flow rate/reference flow rate under standard working condition) Q* can be as low as 0.79, and the pump becomes noisy. Finally, when WL *<5.15, although the impeller is still rotating and the input power is unchanged, the pump no longer pumps water.
Study on S-shape instabilities and pressure pulsations in reversible pump-turbines: Conflictive mechanisms behind a varying rotor-stator distance and development of a new guide vane design for improving transient behavior during turbine start-up and in case of load-rejection
Authors: Lenarcic M. , Gehrer A.
Published: May 2021

Increasing demands towards a more flexible and reliable operation of backbone systems for electrical grid stability has been leading to an upsurge of pumped-storage in the last years. As technological requirements concerning reversible pump-turbines have been undergone substantial transformations with respect to operational stability and noise emission, hydraulic designs are prompted to change according to market needs and requirements. One of the main factors threatening the mechanical structure of components represents the unstable operation in pump and turbine mode. Instabilities are typically accompanied by an intense increase in pressure pulsations that can be a main reason for vibration issues and resonance excitations in reversible pump-turbines. Avoiding instabilities during operation is, therefore, one of the major targets for competitive designs. This paper emphasizes the relevance of a thorough analysis of S-shape instabilities and provides an explanation of their underlying mechanisms based on analytical, numerical and experimental methods. It also addresses conflictive mechanisms behind a varying rotor-stator distance that could occur in terms of operational stability and rotor-stator interaction. The introduction of a new 3D-shaped guide vane design represents a further key outcome of this study. With respect to a varying rotor-stator distance, special attention has been paid to the description of influencing factors for turbine stability and pressure pulsations using three rescaled versions of an existing guide vane design. Series of model tests have been conducted on a test rig at ANDRITZ in Linz, Austria, revealing whether a measure is competitive based on the layout of a 2x330MW variable-speed pump-turbines plant.
LUMEN Turbopump: Preliminary Thermal Model
Authors: Saraf Anirudh Mukund , Traudt Tobias , Oschwald Michael
Published: May 2021

The DLR LUMEN (Liquid Upper stage deMonstrator ENgine) rocket engine comprises of two separate turbopumps, one each for Liquid Oxygen (LOX) and Liquified Natural Gas (LNG) supply. In both turbopumps, an identical bearing block separates the pump section from the turbine section. In the current design, the bearing block features an oil-jet lubrication system to cool and lubricate the bearings during operation. Cryogenic conditions at the pump-interface and high temperature conditions at turbine-interface impose thermal constraints on the selection of a suitable lubricant for the bearing assembly and the design of the lubrication system.

As a starting point to address this challenge, this paper presents a preliminary uncoupled finite element thermal model of the LUMEN LOX turbopump. The thermal model investigates the thermal behavior of the housing and rotor components in the bearing housing from start-up to shutdown of the turbopump. The model employs thermal worst case conditions to establish the operational thermal envelope of the turbopump system. Spatial and temporal evolution of the temperature at critical points within the bearing housing are reported.

The model, albeit the uncertainties rooted from its empirical nature, provides beneficial insight into the thermal characteristics of the turbopump assembly. This serves as a first estimate of the thermal constraints for the selection of lubricant oil.