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To assess unsteady vortex interaction between rim seal purge flow and upstream stator, numerical ‎investigations were conducted under different purge flow rates. The vortex distributions for the stator and ‎cavity were investigated and the interaction processes near the cavity exit, in particular the vorticity ‎change resulting from the ingress and egress, were analyzed. Results show the intensity of hub passage ‎vortex (HPV) and hub trailing shedding vortex (HTSV) at stator exit is decreased as a consequence of ‎enhancing blockage effects caused by the egress flow. However, when the purge flow rate increases, ‎from stator exit to downstream of cavity exit, the reduction in the intensity of two vortices is weakened as ‎the extrusion of egress flow thins their vortex tubes. The vortex inside the cavity is generated as the ‎combined effect of relative rotation of cavity walls and non-uniform circumferential pressure mainly ‎imposed by upstream stator. The ingress leads the positive axial vorticity near the stator hub to ingest into ‎the cavity and eject into the main passage due to the blockage of purge flow. Furthermore, the interaction ‎between the ingress of the mainstream and purge flow produces local negative axial vorticity. The egress ‎flow carries negative axial vorticity mainly originated from the rotational cavity wall, and enters into the ‎main flow passage near the rotating hub, then locations of HPV and HTSV move to the mid-span slightly ‎with the extrusion of egress flow‎.

The paper presents a new approach to designing the stator of a multistage centrifugal pump, which has a simple structure, satisfactory operating parameters, and is easy to manufacture. The stator is distinguished by its lack of a classic diffuser part, with the shape of its crossover being similar to a segment of a spherical surface. This solution was patented in 1989, but to date it is not well known and practically not used. The paper attempts to identify the flow phenomena in such a stator and also to examine the impact of the design features of the stator on the pump's operating parameters. Both experimental methods and numerical modelling were used in the research. [ABSTRACT FROM AUTHOR]

Generally, the high-fidelity finite element models of aero-engines comprise millions of degrees of freedom (DOFs). Although they can provide precise predictions of structural dynamics, the computational cost will be often unaffordable if appropriate dimension reduction techniques are not adopted. The homogenization of the substructure, also termed as the physical replacement, reduces the model scale by simplifying the unnecessary details of the substructure, thus speeding up the dynamic analysis of the whole engine. In this study, we design the physical replacements for the stators of an aero-engine based on the long-wave assumption. These replacements have the same wave features as the stators in long-wave cases while possessing fewer DOFs. The core steps include the analytical description of the stators and the corresponding physical replacement design through two homogenizations. Specifically, we first investigate the wave characteristics of the stators using the wave finite element method and find two dominant waves: flexural and flexural–torsional coupled waves. The first homogenization introduces two analytical Timoshenko beams to describe the two wave motions of the stators. These two analytical beams are subsequently solidified into physical replacements with I, box, and open cross-sections in the second homogenization. The mechanical and geometric parameters are identified through a combination of the static analysis and the genetic algorithm (GA). The search processes are of great efficiency, because all the descriptions are analytical. Results show that the relative errors of the natural frequencies between the pristine stators and the physical replacements associated with the nodal diameters 6–15 are less than 5%. [ABSTRACT FROM AUTHOR]

Many motile bacteria swim and swarm toward favorable environments using the flagellum, which is rotated by a motor embedded in the inner membrane. The motor is composed of the rotor and the stator, and the motor torque is generated by the change of the interaction between the rotor and the stator induced by the ion flow through the stator. A stator unit consists of two types of membrane proteins termed A and B. Recent cryo-EM studies on the stators from mesophiles revealed that the stator consists of five A and two B subunits, whereas the low-resolution EM analysis showed that purified hyperthermophilic MotA forms a tetramer. To clarify the assembly formation and factors enhancing thermostability of the hyperthermophilic stator, we determined the cryo-EM structure of MotA from Aquifex aeolicus (Aa-MotA), a hyperthermophilic bacterium, at 3.42 Å resolution. Aa-MotA forms a pentamer with pseudo C5 symmetry. A simulated model of the Aa-MotA 5 MotB 2 stator complex resembles the structures of mesophilic stator complexes, suggesting that Aa-MotA can assemble into a pentamer equivalent to the stator complex without MotB. The distribution of hydrophobic residues of MotA pentamers suggests that the extremely hydrophobic nature in the subunit boundary and the transmembrane region is a key factor to stabilize hyperthermophilic Aa-MotA. • The Na-type stator of Aquifex aeolicus , a hyperhermophile, comprises MotA and MotB. • The structure of the hyperthermophilic Aa-MotA was determined at 3.42 Å. • Aa-MotA can form a pentameric ring assembly without MotB. • A simulated structure of Aa-stator is equivalent to known A 5 B 2 stator structures. • Extremely hydrophobic nature of Aa-MotA may be a key for its hyperthermostability. [ABSTRACT FROM AUTHOR]

In the article, the analytical dependences of modelling the cell cross-sectional area between two adjacent blades of a rotary blade pump and capacity for a pump with fixed and rotating stators are given, and analytical dependences are derived to model the power necessary to overcome the friction forces of the blades. The forces acting on the radially placed blade of a rotary pump with a fixed stator (non-rotating or stationary) and a rotating stator are analyzed. Design and technological parameters that influence the pump capacity and power are taken into account. The power required for the movement of the pump blade without taking into account the compression of the air has the opposite character of the change as to the pump capacity The capacity of a rotary pump with a rotating stator is three times higher than that of a stationary stator. The rotary pump with a rotating stator, with six radially spaced blades, consumes 0.854 [ kW ] less power to overcome the blade friction of 1 313 [ kW ]. The results of modelling of the pump work are given.

The article is devoted to the analysis of thermometric methods of control and diagnosis of the state of compression of the stator core of the turbogenerator (TG), which have found the greatest application. It is shown that ensuring effective and high-quality control of powerful electric machines, especially power plant generators, today is an integral part of ensuring the reliability and trouble-free operation of their work. As a result of the analysis, it is shown that ensuring high reliability of operation of the generating equipment is practically impossible without their equipping with modern means of control capable to work in real-time. Bibl. 34, fig. 4.

This article proposes a hybrid analytical modeling procedure for the performance parameter estimation of synchronous reluctance machine, including its operation in the region of magnetic saturation. The proposed model better estimated the torque profile through improved translation and stepped transition of rotor flux barriers. The non-linear operation is simulated by considering the global saturation and estimating the machine’s operating point on the magnetization curve of the core material. The procedure formulation focuses on improving the accuracy and rapidness of the iterative design process. The obtained results are validated against an already established design analysis technique, finite-element analysis, and the frequency spectrum analysis of practical machine results. With the improved accuracy and the least requirement of simulation runtime and computational resources, the modeling procedure can be utilized as an initial design iteration tool. [ABSTRACT FROM AUTHOR]

Aiming at the problem of large vibration of a high-subside stator inner cavity curve vane pump, the force analysis of the vane at the transition curve is carried out, and the functional relationship between the vane turning angle θ, the large arc radius R, the small arc radius r and the sliding friction is established. The particle swarm algorithm is used to optimize the solution of the objective function, and the optimized parameter values are brought into the MATLAB simulation program to obtain the optimized stator curve profile diagram. The dynamic performance of the vane pump before and after optimization is simulated using ADAMS. The results show that: the acceleration of the vane pump slide is significantly reduced; the friction between the slide and the slide groove is significantly reduced; the contact force between the slide and the stator is significantly reduced; the impact vibration of the optimized vane pump is significantly reduced; and the dynamic performance of the vane pump is improved. [ABSTRACT FROM AUTHOR]

The present paper investigates the aerodynamic performance of a cantilevered tandem stator based on experiments conducted within a high speed annular test rig at the Technische Universitaet Berlin. A tandem blade in this context describes a double rowed stator configuration where the turning of the incoming flow is split up between two blades arranged in succession. For evaluation purposes, a conventional single bladed stator is used as reference. To provide machine relevant boundary conditions of cantilevered stator assemblies, the moving hub wall is recreated by a rotating disk. Overall, the tandem stator is able to achieve higher flow turning while keeping the total pressure losses below those of a single stator. It is found that the tandem stator in general behaves similar to the conventional stator. When installed in cantilevered fashion, both stator types benefit considerably in terms of loss reduction. Without the hub clearance and therefore absence of the clearance flow, each of the configurations suffered from severe corner separation. The tandem stator responds more sensitively to change in clearance height. [ABSTRACT FROM AUTHOR]

Copyright of Energy Policy Journal / Polityka Energetyczna is the property of Mineral & Energy Economy Research Institute of the Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, we apply dimensional analysis to the optimization of radial magnetic torque couplers. Our goal is to find the design that maximizes the torque potential in a given package size. We consider two types of torque coupler: the permanent-magnet (a.k.a. synchronous) torque coupler, in which both the inner and outer rotors contain permanent magnets; and the variable-reluctance torque coupler, in which the inner rotor contains permanent magnets and the outer rotor contains soft-magnetic teeth. Both types of torque coupler are defined by the same set of independent geometric and material parameters. First, the Buckingham $\Pi $ theorem is used to find the minimal set of dimensionless parameters required for design optimization. Then, using a combination of 2-D and 3-D finite-element analysis, we find and characterize the optimal designs. We explicitly consider torque couplers with eight stable magnetic equilibria (i.e., 45° of rotation between stable equilibria), but the methodology can be repeated for other configurations. [ABSTRACT FROM AUTHOR]

In this paper, an artificial intelligence (AI) system is created in order to overcome difficulties in extracting information about electrical generator stator condition from data generated during offline electrical testing. The proposed AI system will enable classification of generators and that way expose urgency for any service activity. The logic used in expert decision-making is implemented in a fuzzy expert system and tested on a database of 82 generators in Serbia's power plants. This way an objective tool is made to overcome deficiency in sharp, discrete criteria or lack of criteria in international standards. Analysis and fuzzy system rule base will be based on conclusions from official reports about each generator condition and valid international standards and recommendations. The presented methodology is used for condition-based management (CBM) and risk-based management (RBM) of generators. [ABSTRACT FROM AUTHOR]

Vibrio has a polar flagellum driven by sodium ions for swimming. The force-generating stator unit consists of PomA and PomB. PomA contains four transmembrane regions and a cytoplasmic domain of approximately 100 residues, which interacts with the rotor protein, FliG, to be important for the force generation of rotation. The 3D structure of the stator shows that the cytosolic interface (CI) helix of PomA is located parallel to the inner membrane. In this study, we investigated the function of CI helix and its role as stator. Systematic proline mutagenesis showed that residues K64, F66 and M67 were important for this function. The mutant stators did not assemble around the rotor. Moreover, the growth defect caused by PomB plug deletion was suppressed by these mutations. We speculate that the mutations affect the structure of the helices extending from TM3 and TM4 and reduce the structural stability of the stator complex. This study suggests that the helices parallel to the inner membrane play important roles in various processes, such as the hoop-like function in securing the stability of the stator complex and the ion conduction pathway, which may lead to the elucidation of the ion permeation and assembly mechanism of the stator. [ABSTRACT FROM AUTHOR]

Introduction. Vibration cavitation homogenizers are increasingly used in various industries, including the pharmaceutical industry – for the preparation of creams, gels to give them a homogeneous composition, and more recently for the extraction of valuable substances from plant materials. As we have shown earlier, a comparison of the extraction of dioscin from fenugreek seeds, carried out in devices of various designs, under the same conditions for organizing the process showed that the most effective method was the extraction method in a vibro-cavitation field. Obviously, this is due to the fact that cavitation reduces the diffusion resistance of the process and, thus, increases the intensity of the process of transferring the mass of a substance from the solid phase to the solution. However, the extraction process in apparatus of this type is complex and is accompanied by crushing of seeds, which leads to a change in the dispersed composition of the solid phase.Aim. Conduct a theoretical and experimental analysis of the process of grinding hay fenugreek seeds particles in a vibrocavitation homogenizer, accompanied by the extraction of biologically active substances, as well as obtaining dependences that allow evaluating the contribution of grinding to the formation of the dispersed composition of the meal in this apparatus and determining the average particle size as a result of crushing. In earlier works, using the example of the extraction of dioscin from fenugreek seeds, it was shown that an increase in the rotor speed increases the yield of biologically active substances. However, fine grinding of raw materials often leads to the formation of a sediment layer that pollutes the solution with ballast substances and complicates its purification, and also reduces the yield of biologically active substances, therefore, the study of this process is necessary to control the dispersed composition in order to ensure the highest extraction efficiency in devices of this type.Materials and methods. The first stage of the study was the theoretical analysis of the grinding process, since it is a special case of a large class of processes in which the dispersed composition of the solid phase is not constant. Therefore, in this work, for the mathematical description of particle grinding, a model is used that takes into account the kinetic features of the process under consideration. An experimental study of the extraction of valuable components from plant raw materials was carried out in a laboratory setup with a vibro-cavitation homogenizer of periodic action. As a raw material, we used fenugreek seeds purchased from LLC «Stoing», Moscow (Russia), which we used for research. Commodity analysis showed the compliance of raw materials with the requirements of the GF XIV edition. The initial, aqueous solution of ethanol (volume concentration 60 %) with fenugreek seeds was loaded into glass 6, in a volume of 0.2 liters, then the rotor of the apparatus was brought into rotation and brought to a given rotation frequency. The experiments were carried out at a rotation frequency of 1000, 3000 and 5000 rpm (16.7; 50 and 83.3) 1/s. At each value of the rotor speed, the process time varied in the range from 0 to 50 minutes, and the process was carried out for 60, 120, 180, 240 and 300 seconds. Studies carried out for 5 minutes or more showed that the dispersed composition of the meal practically does not change over time, but significantly depends on the rotor speed. Thus, after 5 minutes, a certain stabilization of the dispersed composition occurs and further residence of the material in the apparatus does not lead to a noticeable change in the dispersed composition. After each experiment, the meal was taken, dried, and sieve analysis of the dispersed composition was carried out.Results and discussion. Based on the results obtained by processing the experimental data according to the equation, the values of the average probability of particle crushing were calculated and, as it turned out, it practically does not depend on time, but depends only on the rotor speed. The dependence of the change in the average probability of particle grinding at different rotor speed was obtained. The analysis of these results showed that the value of the average probability of particle grinding in the cavitation homogenizer increases with an increase in the rotor speed, which is quite expected, since the frequency of contacts of particles with the working organs of the apparatus increases. In addition, the obtained dependence for the average probability of particle crushing is linear. This Expression quite accurately describes the values of the change in time of the relative mass of particles in the working range n = 16.7 – 83.3 1/s. Taking these values into account, the experimental and calculated results are in good agreement.Conclusions. The proposed approach and the results obtained can be used to assess the dispersed composition of particles obtained in other designs of devices of similar action.

Incompliance of the settings of the system to control actual values of the parameters of a variable frequency induction electric drive may sometimes result in complete non-operability of a variable frequency electric drive as well as in the considerable reduction of the dynamic quality parameters. Such parameters as active rotor resistance, rotor inductance, and inductance of the magnetization circuit are available for the immediate measuring. They are not identified in terms of the acceptance tests, and the values presented in catalogues and reference books are calculated ones that may differ considerably from the real values of a certain machine. Despite constant studies by the researchers, a task to identify electromagnetic parameters of the equivalent circuit of an induction motor is still important and topical. The objective of the paper is to develop a method of online-identification of the electromagnetic parameters of an induction motor making it possible to implement accurate regulator adjustment of the frequency control system in terms of operational changes in the driving motor parameters. For the first time, the paper analyzes a steady mode of induction motor operation which does not apply T-network of the equivalent circuit of an induction motor. An approach has been proposed relying on the equation of an induction motor in three-phase fixed coordinate system obtained on the basis of the theory of generalized electromechanical converter.

Background. The actual problem in the development of new types of aviation products is the creation of angular displacement sensors with high stability, measurement accuracy and reliability. Materials and methods. The methods of integral and differential calculus, the theory of electric circuits and electromagnetic field were used to solve the problems. The computer-aided design system KOMPAS was used in the design of sensor structures. Results. As a result of this work, a three-channel angular displacement sensor and two versions of the secondary converter have been developed. The substitution diagram of transformer angular displacement sensor on the basis of which the expression defining dependence of output EMF value on angular displacement of the sensor rotor is obtained.

Powered by ion transport across the cell membrane, conserved ion-powered rotary motors (IRMs) drive bacterial motility by generating torque on the rotor of the bacterial flagellar motor. Homologous heteroheptameric IRMs have been structurally characterized in ion channels such as Tol/Ton/Exb/Gld, and most recently in phage defense systems such as Zor. Functional stator complexes synthesized from chimeras of PomB/MotB (PotB) have been used to study flagellar rotation at low ion-motive force achieved via reduced external sodium concentration. The function of such chimeras is highly sensitive to the location of the fusion site, and these hybrid proteins have thus far been arbitrarily designed. To date, no chimeras have been constructed using interchange of components from Tol/Ton/Exb/Gld and other ion-powered motors with more distant homology. Here, we synthesized chimeras of MotAB, PomAPotB, and ExbBD to assess their capacity for cross-compatibility. We generated motile strains powered by stator complexes with B-subunit chimeras. This motility was further optimized by directed evolution. Whole-genome sequencing of these strains revealed that motility-enhancing residue changes occurred in the A-subunit and at the peptidoglycan binding domain of the B-unit, which could improve motility. Overall, our work highlights the complexity of stator architecture and identifies the challenges associated with the rational design of chimeric IRMs., Importance: Ion-powered rotary motors (IRMs) underpin the rotation of one of nature's oldest wheels, the flagellar motor. Recent structures show that this complex appears to be a fundamental molecular module with diverse biological utility where electrical energy is coupled to torque. Here, we attempted to rationally design chimeric IRMs to explore the cross-compatibility of these ancient motors. We succeeded in making one working chimera of a flagellar motor and a non-flagellar transport system protein. This had only a short hybrid stretch in the ion-conducting channel, and function was subsequently improved through additional substitutions at sites distant from this hybrid pore region. Our goal was to test the cross-compatibility of these homologous systems and highlight challenges arising when engineering new rotary motors., Competing Interests: The authors declare no conflict of interest.

To assess unsteady vortex interaction between rim seal purge flow and upstream stator, numerical investigations were conducted under different purge flow rates. The vortex distributions for the stator and cavity were investigated and the interaction processes near the cavity exit, in particular the vorticity change resulting from the ingress and egress, were analyzed. Results show the intensity of hub passage vortex (HPV) and hub trailing shedding vortex (HTSV) at stator exit is decreased as a consequence of enhancing blockage effects caused by the egress flow. However, when the purge flow rate increases, from stator exit to downstream of cavity exit, the reduction in the intensity of two vortices is weakened as the extrusion of egress flow thins their vortex tubes. The vortex inside the cavity is generated as the combined effect of relative rotation of cavity walls and nonuniform circumferential pressure mainly imposed by upstream stator. The ingress leads the positive axial vorticity near the stator hub to ingest into the cavity and eject into the main passage due to the blockage of purge flow. Furthermore, the interaction between the ingress of the mainstream and purge flow produces local negative axial vorticity. The egress flow carries negative axial vorticity mainly originated from the rotational cavity wall, and enters into the main flow passage near the rotating hub, then locations of HPV and HTSV move to the mid-span slightly with the extrusion of egress flow. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The design of water-lubricated journal bearings and the results of bench tests of a turbine generator rotor that ended in bearing damage are described. A program module has been developed for mathematical modeling of rotor oscillation with rubbing against the bearing. This process was modeled for different values of the flexibility and damping in the supports and of the sliding friction coefficient at rubbing points. Considerable attention was given to the potential risk of an accident developing into a catastrophic failure, determined by the development of asynchronous rolling of rotor over the stator elements (stator). The risk of rotor rubbing against the stator is the development of the forces of contact interaction of the rotor with the stator causing the self-excited vibrations of the rotor–supports system. The nature of these forces is related to the appearance of sliding friction at the rotating rotor-to-stator contact point. The contact interaction forces caused by the rotor-stator rubbing are governing ones as compared to other vibration excitation forces. A short time interval for development of the asynchronous rolling determines its explosive nature. It has been demonstrated that an increase in flexibility and damping of the supports does not facilitate the development of a pattern of the rotor contact interaction with a bearing—asynchronous rolling, which is dangerous to the construction integrity. With flexible supports and energy losses in the dampers, the vibrations with rubbing give rise to synchronous rolling generation with pressure forces acting on the bearings, which will not be dangerous to the construction until the machinery protection system operates in response to excessive peak-to-peak vibrations. ADP-2400 shock absorbers, whose dynamic impact properties had been determined in a shock-testing machine, were selected as dampers for the supports. With more rigid bearings and no damping, the rubbing induces the asynchronous rotor rolling over the bearing with pressure forces acting on the bearings that are dangerous for their integrity. [ABSTRACT FROM AUTHOR]

Recently, the use of switched reluctance motors (SRMs) has considerably increased due to technological developments of systems and devices requiring more control. More so, peculiar features of SRMs such as robustness, reliability, low cost construction makes it ideal for applications in ventilation systems, pumps and systems that require high speed. However, SRMs have the problem of torque ripples and high acoustic noise from design and development stage. The torque ripples experienced by the SRM ensues as the rotor tries to align itself to an excited phase on the stator. Therefore, the aim of this paper is to design and develop a 3 phase, 6/4 switched reluctance motor in order to reduce the issues of torque ripple and acoustic noise. Finite element analysis software (Ansys-Maxwell) was used to carry out the nonlinear electromagnetic transient analysis of the motor while the control topology used was simulated using the MATLAB software. The design stages involved suitable assumptions which were made for the stator design, winding design and rotor design. The results from the analysis and performance of the motor have been presented in the work. The magnetic field plot of the developed motor does not present saturation effect on any part. [ABSTRACT FROM AUTHOR]

This study investigates the potential gains in operating volume flow rate and static efficiency of an induced draught axial flow fan system. These gains are achieved through pressure recovery, i.e. the conversion of dynamic pressure at the fan exit into static pressure. Pressure recovery is achieved using downstream diffusers, stator blade rows, and combinations of these. Three different diffuser lengths are considered. Of the shortest diffusers, a conical diffuser increases the operating volume flow rate by 3.2 % and the fan static efficiency by 9.8 % (absolute). A longer conical diffuser increases it by 3.9 % and 11.9 %, respectively. Of the longest diffusers, an annular diffuser increases the flow rate by 5.5 % and the fan static efficiency by 16.8 %. [ABSTRACT FROM AUTHOR]

We developed a robust bead assay for studying flagellar motor behavior of Pseudomonas aeruginosa. Using this assay, we studied the dynamics of the two stator systems in the flagellar motor. We found that the two sets of stators function differently, with MotAB stators providing higher total torque and MotCD stators ensuring more stable motor speed. The motors in wild-type cells adjust the stator compositions according to the environment, resulting in an optimal performance in environmental exploration compared to that of mutants with one set of stators. The bead assay we developed in this investigation can be further used to study P. aeruginosa chemotaxis at the level of a single cell using the motor behavior as the chemotaxis output. [ABSTRACT FROM AUTHOR]

The stator ventilation duct is the main path for fluid flowing to cool the stator bar and the core. Considering the complexity of the ventilation system, the investigation on the relationship between the air motion law in the ventilation duct and its surface heat transfer coefficient is crucial for the accurate calculation of the temperature field. Therefore, this paper takes the 150 MW air-cooled turbo-generator as a research object. Firstly, a new calculation model of the stator taking the air gap under rotor rotation state, and the yoke back into account is proposed to calculate the heat transfer coefficient in inner surface of stator ventilation duct. The relationship among the velocity vector, temperature of fluid and heat transfer coefficient in the ventilation duct is analyzed. Secondly, the temperature field of the new model calculated by finite volume method is compared with the measured values to verify the accuracy of calculation method. Finally, the influence of the varied rotational velocity on the heat transfer coefficient is investigated. The correction coefficient of the heat transfer coefficient related to the velocity is proposed. The calculation of the heat transfer coefficient and the correction of the fitting formula can provide theoretical guidance for the ventilation design of generators. [ABSTRACT FROM AUTHOR]

Generally, the high-fidelity finite element models of aero-engines comprise millions of degrees of freedom (DOFs). Although they can provide precise predictions of structural dynamics, the computational cost will be often unaffordable if appropriate dimension reduction techniques are not adopted. The homogenization of the substructure, also termed as the physical replacement, reduces the model scale by simplifying the unnecessary details of the substructure, thus speeding up the dynamic analysis of the whole engine. In this study, we design the physical replacements for the stators of an aero-engine based on the long-wave assumption. These replacements have the same wave features as the stators in long-wave cases while possessing fewer DOFs. The core steps include the analytical description of the stators and the corresponding physical replacement design through two homogenizations. Specifically, we first investigate the wave characteristics of the stators using the wave finite element method and find two dominant waves: flexural and flexural–torsional coupled waves. The first homogenization introduces two analytical Timoshenko beams to describe the two wave motions of the stators. These two analytical beams are subsequently solidified into physical replacements with I, box, and open cross-sections in the second homogenization. The mechanical and geometric parameters are identified through a combination of the static analysis and the genetic algorithm (GA). The search processes are of great efficiency, because all the descriptions are analytical. Results show that the relative errors of the natural frequencies between the pristine stators and the physical replacements associated with the nodal diameters 6–15 are less than 5%.

Nowadays, induction motor (IM) is extensively used in industry, including mechanical and electrical applications. However, three main types of IM faults have been discussed in the literature, bearing, stator, and rotor. Importantly, stator and rotor (S/R) faults represent approximately 50%. Traditional condition monitoring (CM) and fault diagnosis (FD) methods require a high processing cost and much experience knowledge. To tackle this challenge, artificial intelligent (AI) based CM and FD techniques are extensively developed. However, there have been many review research papers for intelligent CM and FD machine learning methods of rolling elements bearings of IM in the literature. Whereas there is a lack in the literature, and there are not many review papers for both S/R intelligent CM and FD. Thus, the proposed study's main contribution is in reviewing the CM and FD of IM, especially for the stator and the rotor, based on AI methods. The paper also provides discussions on the main challenges and possible future works. [ABSTRACT FROM AUTHOR]

The bacterial flagellar motor (BFM) is a rotary molecular motor embedded in the cell membrane of numerous bacteria. It turns a flagellum which acts as a propeller, enabling bacterial motility and chemotaxis. The BFM is rotated by stator units, inner membrane protein complexes that stochastically associate to and dissociate from individual motors at a rate which depends on the mechanical and electrochemical environment. Stator units consume the ion motive force (IMF), the electrochemical gradient across the inner membrane that results from cellular respiration, converting the electrochemical energy of translocated ions into mechanical energy, imparted to the rotor. Here, we review some of the main results that form the base of our current understanding of the relationship between the IMF and the functioning of the flagellar motor. We examine a series of studies that establish a linear proportionality between IMF and motor speed, and we discuss more recent evidence that the stator units sense the IMF, altering their rates of dynamic assembly. This, in turn, raises the question of to what degree the classical dependence of motor speed on IMF is due to stator dynamics vs. the rate of ion flow through the stators. Finally, while long assumed to be static and homogeneous, there is mounting evidence that the IMF is dynamic, and that its fluctuations control important phenomena such as cell-to-cell signaling and mechanotransduction. Within the growing toolbox of single cell bacterial electrophysiology, one of the best tools to probe IMF fluctuations may, ironically, be the motor that consumes it. Perfecting our incomplete understanding of how the BFM employs the energy of ion flow will help decipher the dynamical behavior of the bacterial IMF.

The present paper investigates the aerodynamic performance of a cantilevered tandem stator based on experiments conducted within a high speed annular test rig at the Technische Universitaet Berlin. A tandem blade in this context describes a double rowed stator configuration where the turning of the incoming flow is split up between two blades arranged in succession. For evaluation purposes, a conventional single bladed stator is used as reference. To provide machine relevant boundary conditions of cantilevered stator assemblies, the moving hub wall is recreated by a rotating disk. Overall, the tandem stator is able to achieve higher flow turning while keeping the total pressure losses below those of a single stator. It is found that the tandem stator in general behaves similar to the conventional stator. When installed in cantilevered fashion, both stator types benefit considerably in terms of loss reduction. Without the hub clearance and therefore absence of the clearance flow, each of the configurations suffered from severe corner separation. The tandem stator responds more sensitively to change in clearance height.

The bacterial flagellar motor (BFM) is a rotary molecular motor embedded in the cell membrane of numerous bacteria. It turns a flagellum which acts as a propeller, enabling bacterial motility and chemotaxis. The BFM is rotated by stator units, inner membrane protein complexes that stochastically associate to and dissociate from individual motors at a rate which depends on the mechanical and electrochemical environment. Stator units consume the ion motive force (IMF), the electrochemical gradient across the inner membrane that results from cellular respiration, converting the electrochemical energy of translocated ions into mechanical energy, imparted to the rotor. Here, we review some of the main results that form the base of our current understanding of the relationship between the IMF and the functioning of the flagellar motor. We examine a series of studies that establish a linear proportionality between IMF and motor speed, and we discuss more recent evidence that the stator units sense the IMF, altering their rates of dynamic assembly. This, in turn, raises the question of to what degree the classical dependence of motor speed on IMF is due to stator dynamics vs. the rate of ion flow through the stators. Finally, while long assumed to be static and homogeneous, there is mounting evidence that the IMF is dynamic, and that its fluctuations control important phenomena such as cell-to-cell signaling and mechanotransduction. Within the growing toolbox of single cell bacterial electrophysiology, one of the best tools to probe IMF fluctuations may, ironically, be the motor that consumes it. Perfecting our incomplete understanding of how the BFM employs the energy of ion flow will help decipher the dynamical behavior of the bacterial IMF. [ABSTRACT FROM AUTHOR]

Variable-pitch multifinned seals (VPMS) have not hitherto found wide use in the steam turbines produced in Russia, although they are quite often used outside of Russia. In modernizing the existing and designing new steam turbines, rotor blades with an integrally machined shroud are used, which opens the possibility to manufacture multirow peripheral seals. In this connection, the question about selecting the optimal VPMS configuration becomes of important practical significance. The results obtained in this study made it possible to experimentally estimate the extent to which different combination of fin pitches on the rotor and stator influence the VPMS discharge characteristics and to elaborate practical recommendations on using them. The minimal leak flow was recorded for the VPMS models with a 2-mm-wide pitch on the rotor. Comparative experimental investigations of VPMS models with 3- and 4-mm-wide spacers on the rotor and 4- and 5-mm-wide spacers on the stator were carried out as applied to the shroud seals of large-capacity steam turbines. The model pair with the 4- and 5-mm-wide spacers on the rotor and stator, i.e., with the pitches equal to 4.8 and 5.8 mm on the rotor and stator, respectively, can be regarded as the most optimal of those investigated in this work. It has been shown experimentally that, with all other things being equal, the leak in VPMSs is by 22–25% smaller than it is in straight-flow seals. By using VPMS, it becomes possible to avoid rubbing of the rotor against the stator under the conditions of relative radial and axial rotor displacements in transient modes of operation. In addition, the aerodynamic forces in VPMS able to excite a low-frequency shaft line self-oscillation are approximately equal to 60% of the similar forces occurring in the conventional radial clearance seals. In view of this circumstance, VPMS can be recommended for use instead of the standard tip shroud seals in the high- and intermediate-pressure cylinders in new and modernized steam turbines. [ABSTRACT FROM AUTHOR]

The bacterial flagellar motor (BFM) is a nanomachine that rotates the flagellum to propel many known bacteria. The BFM is powered by ion transit across the cell membrane through the stator complex, a membrane protein. Different bacteria use various ions to run their BFM, but the majority of BFMs are powered by either proton (H+) or sodium (Na+) ions. The transmembrane (TM) domain of the B-subunit of the stator complex is crucial for ion selectivity, as it forms the ion channel in complex with TM3 and TM4 of the A-subunit. In this study, we reconstructed and engineered thirteen ancestral sequences of the stator B-subunit to evaluate the functional properties and ionic power source of the stator proteins at reconstruction nodes to evaluate the potential of ancestral sequence reconstruction (ASR) methods for stator engineering and to test specific motifs previously hypothesized to be involved in ion-selectivity. We found that all thirteen of our reconstructed ancient B-subunit proteins could assemble into functional stator complexes in combination with the contemporary Escherichia coli MotA-subunit to restore motility in stator deleted E. coli strains. The flagellar rotation of the thirteen ancestral MotBs was found to be Na+ independent which suggested that the F30/Y30 residue was not significantly correlated with sodium/proton phenotype, in contrast to what we had reported previously. Additionally, four among the thirteen reconstructed B-subunits were compatible with the A-subunit of Aquifex aeolicus and able to function in a sodium-independent manner. Overall, this work demonstrates the use of ancestral reconstruction to generate novel stators and quantify which residues are correlated with which ionic power source.

Este trabalho teve por objetivo analisar a germinação de sementes de Senegalia polyphylla (DC.) Britton & Rose (Fabaceae) atacadas por bruquíneos (Coleoptera: Chrysomelidae: Bruchinae). Frutos dessa espécie foram coletados em São Gonçalo do Rio Preto, MG. As sementes indenes e as danificadas por bruquíneos foram submetidas aos testes de germinação em cinco tratamentos, com 100 sementes cada. O melhor percentual de germinação foi obtido nas sementes sadias e lixadas. As sementes sadias embebidas em água apresentaram baixo percentual de germinação. O ataque de bruquíneos proporcionou redução na taxa de germinação, mas não impediu que esse processo ocorresse nas sementes danificadas.

A horizontal impact crusher provides for high­quality grinding of grain materials and getting the finished product equalized by particle size distribution to 98 percent. The effectiveness of the crusher is determined by the following parameters: rotor speed, operating clearance, intensity and full filling of the crushing chamber, the duration of impact on the original product, the design features of the working bodies and the geometric design of their corrugated surfaces. (Research purpose) To determine the design parameters of a horizontal rotary crusher for feed grains. (Materials and methods) The influence of the stator flute number on the quality of the crushed product has been studied by three indicators: the grinding degree, the grinding module, the actual effectiveness of the grinding process. It has been found that as the flute number increases, the grinding module and the degree of grinding change insignificantly, and the actual effectiveness of grinding decreases. In this case, the finished product corresponds to coarse grinding. A comparative experiment has been conducted with two design variants of the working surfaces with one stator contradiction to check the effectiveness of changing the shape of the rotor and stator flutes. (Results and discussion) It has been determined that the geometrical parameters of flute working elements of a horizontal rotary crusher can be calculated using the proposed model of theoretical calculation based on the type of material crushed and zootechnic requirements. An angular shape of the rotor grooves also has a positive effect on the overall performance of the grinding process. (Conclusions) The authors present theoretical substantiation of the design features of cutting flute working surfaces of a horizontal rotary crusher and the calculation of the rotor diameter. They have proposed a model for calculating these parameters basing on the type of crushed grain crops. They have experimentally compared various design forms and the number of stator contradictions with respect to the quality of the products obtained. The main manufacturing parameters of rotor grooves have been calculated for the most common grain crops (wheat, barley, oats, and corn) and their optimal values have been theoretically substantiated.

The paper presents a brief analysis of the conducted researches of the asynchronous executive motors and the induction motor, as well as the design of the asynchronous executive motor with a hollow perforated rotor. The basic relationships for determining the geometry of the rotor that directly influences the energy performance of the electric machine are also presented. The calculations to determine the geometry of the windows, located within a part of the active length of the stator package in the zone adjacent to the solid frontal area of the surface of the barrel from the side of its end face that is opposite to the bottom of the rotor barrel. In an asynchronous motor with a hollow perforated rotor improvement of energy performance (increase of maximum torque, efficiency and cosj of the engine) is achieved. These advantages are provided by the fact that the windows in the hollow rotor barrel are located within the part of the active length of the stator package in the zone adjacent to the solid frontal section of the rotor barrel surface on its end face that is opposite to the bottom of the barrel. In accordance with the design of the hollow rotor, the bottom of the barrel of one of the ends acts as superconducting short-circulating ring, therefore the ratio of increase in resistance (caused by the transverse edge effect) depends on the distribution of the rotor currents in the area adjacent to the solid frontal portion of the surface of the barrel on end that is opposite to the bottom of the barrel. In the analysis of current density distribution in a hollow rotor with the axial length L', all electric constant and geometric dimensions that are taken into account in the calculation are known values. Arbitrarily set constants are the primary currents and the rotational frequency of the rotor. With the rotation speed increase, due to the presence of the windows on one end face of the rotor and to the impact of the bottom of the barrel on the other one, the elementary currents of the rotor within the active length of the machine boring would be directed mainly in the axial direction, including the cases of comparatively small slippage that corresponds to the small frequency of the alternating magnetization of the rotor material. I. e. a certain part of the active surface of the rotor on the end that is opposite to the bottom of its barrel would not function as the frontal part of the winding while reducing the frequency of currents in the rotor material. This provides an increase in the active component of the rotor current that is proportional to the electromagnetic torque of the motor. Correspondingly, the frontal parts of equivalent winding of the hollow rotor (through which the currents do not generate torque) would not be spread at high rotational speeds to the area of the active length of the machine.

The bacterial flagellar motor (BFM) is a nanomachine that rotates the flagellum to propel many known bacteria. The BFM is powered by ion transit across the cell membrane through the stator complex, a membrane protein. Different bacteria use various ions to run their BFM, but the majority of BFMs are powered by either proton (H+) or sodium (Na+) ions. The transmembrane (TM) domain of the B-subunit of the stator complex is crucial for ion selectivity, as it forms the ion channel in complex with TM3 and TM4 of the A-subunit. In this study, we reconstructed and engineered thirteen ancestral sequences of the stator B-subunit to evaluate the functional properties and ionic power source of the stator proteins at reconstruction nodes to evaluate the potential of ancestral sequence reconstruction (ASR) methods for stator engineering and to test specific motifs previously hypothesized to be involved in ion-selectivity. We found that all thirteen of our reconstructed ancient B-subunit proteins could assemble into functional stator complexes in combination with the contemporary Escherichia coli MotA-subunit to restore motility in stator deleted E. coli strains. The flagellar rotation of the thirteen ancestral MotBs was found to be Na+ independent which suggested that the F30/Y30 residue was not significantly correlated with sodium/proton phenotype, in contrast to what we had reported previously. Additionally, four among the thirteen reconstructed B-subunits were compatible with the A-subunit of Aquifex aeolicus and able to function in a sodium-independent manner. Overall, this work demonstrates the use of ancestral reconstruction to generate novel stators and quantify which residues are correlated with which ionic power source. [ABSTRACT FROM AUTHOR]