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Many bacteria swim in liquid or swarm on surface using the flagellum rotated by a motor driven by specific ion flow. The motor consists of the rotor and stator, and the stator converts the energy of ion flow to mechanical rotation. However, the ion pathway and the mechanism of stator rotation coupled with specific ion flow are still obscure. Here, we determined the structures of the sodium-driven stator of Vibrio, namely PomAB, in the presence and absence of sodium ions and the structure with its specific inhibitor, phenamil, by cryo-electron microscopy. The structures and following functional analysis revealed the sodium ion pathway, the mechanism of ion selectivity, and the inhibition mechanism by phenamil. We propose a model of sodium ion flow coupled with the stator rotation based on the structures. This work provides insights into the molecular mechanisms of ion specificity and conversion of the electrochemical potential into mechanical functions. [ABSTRACT FROM AUTHOR]

Rotation of the bacterial flagellum, the first identified biological rotary machine, is driven by its stator units. Knowledge gained about the function of stator units has increasingly led to studies of rotary complexes in different cellular pathways. Here, we report that a tetrameric PilZ family protein, FlgX, is a structural component underneath the stator units in the flagellar motor of Campylobacter jejuni. FlgX forms a stable tetramer that does not bind cyclic di-GMP (c-di-GMP), unlike other canonical PilZ domain-containing proteins. Cryoelectron tomography and subtomogram averaging of flagellar motors in situ provide evidence that FlgX interacts with each stator unit and plays a critical role in stator ring assembly and stability. Furthermore, FlgX is conserved and was most likely present in the common ancestor of the phylum Campylobacterota. Overall, FlgX represents a divergence in function for PilZ superfamily proteins as well as a player in the key stator-rotor interaction of complex flagellar motors. [ABSTRACT FROM AUTHOR]

Abstract MotY homologs are present in a variety of monotrichous bacterial strains and are thought to form an additional structural T ring in flagellar motors. While MotY potentially plays an important role in motor torque generation, its impact on motor output dynamics remains poorly understood. In this study, we investigate the role of MotY in P. aeruginosa, elucidating its interactions with the two sets of stator units (MotAB and MotCD) using Förster resonance energy transfer (FRET) assays. Employing a newly developed bead assay, we characterize the dynamic behavior of flagellar motors in motY mutants, identifying MotY as the key functional protein to affect the clockwise bias of naturally unbiased motors in P. aeruginosa. Our findings reveal that MotY enhances stator assembly efficiency without affecting the overall assembly of the flagellar structure. Additionally, we demonstrate that MotY is essential for maintaining motor torque and regulating switching rates. Our study highlights the physiological significance of MotY in fine-tuning flagellar motor function in complex environments.

Many bacteria swim in liquids and move over solid surfaces by rotating flagella. The bacterial flagellum is a supramolecular protein complex that is composed of about 30 different flagellar proteins ranging from a few to tens of thousands. Despite structural and functional diversities of the flagella among motile bacteria, the flagellum commonly consists of a membrane-embedded rotary motor fueled by an ion motive force across the cytoplasmic membrane, a universal joint, and a helical propeller that extends several micrometers beyond the cell surface. The flagellar motor consists of a rotor and several stator units, each of which acts as a transmembrane ion channel complex that converts the ion flux through the channel into the mechanical work required for force generation. The rotor ring complex is equipped with a reversible gear that is regulated by chemotactic signal transduction pathways. As a result, bacteria can move to more desirable locations in response to environmental changes. Recent high-resolution structural analyses of flagella using cryo-electron microscopy have provided deep insights into the assembly, rotation, and directional switching mechanisms of the flagellar motor complex. In this review article, we describe the current understanding of the structure and dynamics of the bacterial flagellum. [ABSTRACT FROM AUTHOR]

MotY homologs are present in a variety of monotrichous bacterial strains and are thought to form an additional structural T ring in flagellar motors. While MotY potentially plays an important role in motor torque generation, its impact on motor output dynamics remains poorly understood. In this study, we investigate the role of MotY in P. aeruginosa, elucidating its interactions with the two sets of stator units (MotAB and MotCD) using Förster resonance energy transfer (FRET) assays. Employing a newly developed bead assay, we characterize the dynamic behavior of flagellar motors in motY mutants, identifying MotY as the key functional protein to affect the clockwise bias of naturally unbiased motors in P. aeruginosa. Our findings reveal that MotY enhances stator assembly efficiency without affecting the overall assembly of the flagellar structure. Additionally, we demonstrate that MotY is essential for maintaining motor torque and regulating switching rates. Our study highlights the physiological significance of MotY in fine-tuning flagellar motor function in complex environments. [ABSTRACT FROM AUTHOR]

Wind energy is a prominent renewable energy source, and Vertical Axis Wind Turbines (VAWTs) offer distinct advantages, including adaptability to changing wind directions and reduced noise levels. This paper conducts a numerical investigation into the impact of flat and curved stator blades on VAWTs, specifically the Savonius turbine, under 2D, viscous, turbulent, and steady flow conditions. Four stator blade configurations were examined, including no stator blades, smooth stator blades, twisted stator blades (Case A), and both blades being concave (Case B). The study reveals that curved stator blades enhance VAWT performance, with Case B exhibiting the most efficient performance. The results show pressure distribution on the turbine blades is non-uniform, with high and low-pressure zones, predominantly on the windward side. The presence of stator blades enhances pressure on all turbine blades, with Case B exhibiting the most optimal pressure distribution. Detailed observation of streamline and velocity distribution reveals improved flow lines for Case B, leading to more effective turbine blade performance. Case B consistently produces the highest turbine torque, with a maximum value of approximately 2.1 N·m achieved at Re = 15750. The torque demonstrates a positive correlation with increasing Reynolds numbers. The study further introduces a non-dimensional torque ratio analysis, where Case B attains 7.59 times higher torque than the reference case at Reynolds number 15750. The sensitivity of torque increase with respect to Reynolds number change highlights that Case B (with a slope of torque increase at around 4.5e-04) is the most responsive within the studied Reynolds number range.

The bacterial flagellar motor consists of a rotor and stator units and is driven by ion flow through the stator. The activation of the ion flow is coupled with the anchoring of the stator units to the peptidoglycan layer by the stator B-subunit around the rotor. Gram-negative bacteria, such as Salmonella and Vibrio, change the conformation of the N-terminal helix of the periplasmic domain of the B-subunit to anchor the stator units. However, a recent high-speed atomic force microscopic study has suggested that the periplasmic domain of MotS, the stator B-subunit of the sodium (Na+)-driven stator of Bacillus subtilis, a gram-positive bacterium, unfolds at low external Na+ concentrations and folds at high Na+ concentrations to anchor the stator units. Here, we report the crystal structures of MotS68–242, a periplasmic fragment of MotS, from B. subtilis at high and low Na+ concentrations. We also performed far-UV CD spectroscopic analysis of the wild-type MotS68–242 and MotS78–242 proteins and mutant variants of MotS68–242 under high and low Na+ concentrations and found that the N-terminal disordered region of MotS68–242 shows a Na+-dependent coil–helix transition. We propose a mechanism of the Na+-dependent structural transition of Bs-MotS to anchor the stator units.

Aiming at the phenomenon that a high-power torque converter is susceptible to cavitation, which leads to performance degradation, first, a transient flow field model of the torque converter is established, and CFD simulation and experimental research on the torque converter are carried out to find out the speed ratio region where cavitation occurs in the torque converter as well as the rule of occurrence of cavitation, and then the cavitation identification method based on the difference between the inlet and outlet flow of the torque converter is proposed. Then, the transient flow process inside the torque converter is analyzed, and it is pointed out that the angle between the inlet angle of the stator and the outlet angle of the turbine of the torque converter, i.e., the fluid inflow injection deviation angle is an important factor affecting the cavitation phenomenon. By adjusting the key parameters of the stator blade bone line, the fluid inflow deviation angle of the torque converter stator is optimized, so that the speed ratio range of cavitation under large load conditions is greatly reduced from the original 0–0.5 (50%) to 0–0.15 (15%). Meanwhile, in terms of test performance, the nominal torque of the torque converter is greatly improved under the premise of ensuring that the performance is basically unchanged, in which the nominal torque of the test zero speed is increased by 28.7%, and the cavitation of the torque converter has been greatly improved. [ABSTRACT FROM AUTHOR]

ABSTRACT The bacterial predator Bdellovibrio bacteriovorus is considered to be obligatorily prey (host)-dependent (H-D), and thus unable to form biofilms. However, spontaneous host-independent (H-I) variants grow axenically and can form robust biofilms. A screen of 350 H-I mutants revealed that single mutations in stator genes fliL or motA were sufficient to generate flagellar motility-defective H-I strains able to adhere to surfaces but unable to develop biofilms. The variants showed large transcriptional shifts in genes related to flagella, prey-invasion, and cyclic-di-GMP (CdG), as well as large changes in CdG cellular concentration relative to the H-D parent. The introduction of the parental fliL allele resulted in a full reversion to the H-D phenotype, but we propose that specific interactions between stator proteins prevented functional complementation by fliL paralogs. In contrast, specific mutations in a pilus-associated protein (Bd0108) mutant background were necessary for biofilm formation, including secretion of extracellular DNA (eDNA), proteins, and polysaccharides matrix components. Remarkably, fliL disruption strongly reduced biofilm development. All H-I variants grew similarly without prey, showed a strain-specific reduction in predatory ability in prey suspensions, but maintained similar high efficiency in prey biofilms. Population-wide allele sequencing suggested additional routes to host independence. Thus, stator and invasion pole-dependent signaling control the H-D and the H-I biofilm-forming phenotypes, with single mutations overriding prey requirements, and enabling shifts from obligate to facultative predation, with potential consequences on community dynamics. Our findings on the facility and variety of changes leading to facultative predation also challenge the concept of Bdellovibrio and like organisms being obligate predators.IMPORTANCEThe ability of bacteria to form biofilms is a central research theme in biology, medicine, and the environment. We show that cultures of the obligate (host-dependent) “solitary” predatory bacterium Bdellovibrio bacteriovorus, which cannot replicate without prey, can use various genetic routes to spontaneously yield host-independent (H-I) variants that grow axenically (as a single species, in the absence of prey) and exhibit various surface attachment phenotypes, including biofilm formation. These routes include single mutations in flagellar stator genes that affect biofilm formation, provoke motor instability and large motility defects, and disrupt cyclic-di-GMP intracellular signaling. H-I strains also exhibit reduced predatory efficiency in suspension but high efficiency in prey biofilms. These changes override the requirements for prey, enabling a shift from obligate to facultative predation, with potential consequences on community dynamics.

To solve the problem in which it is difficult to consider the complex transposition structure of the stator winding in the stator fluid-solid coupling analysis of a large synchronous condenser, a three-dimensional stator fluid-solid coupling model considering the transposition structure of the stator winding is established in this paper. Based on the heat transfer characteristics of the transposition insulation in the slot portion and involute insulation in the end portion, a non-uniform grid division method is proposed to solve the three-dimensional fluid-solid coupling model. Then, taking a 300 Mvar synchronous condenser as an example, the stator fluid distribution and temperature distribution were calculated and analyzed, and the results were compared with the non-transposition model and short-circuit type test data. The results show that the transposition structure affects the temperature distribution trend, temperature value and location of the highest temperature of the stator winding. The calculated results obtained using the transposition model were closer to the test data. Finally, the stator temperatures under no-load, over-excited, and no-excited operating conditions were calculated and compared. The results show that the stator temperature distribution trends and values are significantly affected by operating conditions. The stator temperature under the over-excited condition was the highest, and that under the no-load condition was the lowest.

In machine learning, the extraction of features is necessary for intelligent motor fault diagnosis. In industrial applications, it is necessary to identify the optimal number of features to differentiate various types of fault characteristics with less computational complexity and cost. However, motor fault diagnosis for real-time applications has challenges in capturing characteristics due to variations in speed, load, force, run-to-failure state as well as the type of the motor and its parts. The deep learning techniques that automatically extract features and perform classification have algorithmic complexity. In this work, the authors address these challenges by: 1) selecting and ensembling optimal time-domain features that are capable of identifying motor faults using current signals of the permanent magnet synchronous motor (PMSM) in bearing; and 2) investigating the feature ensemble constituting optimal features for robust fault diagnosis in the PMSM bearing as well as the stator and bearing of squirrel cage induction motor (SCIM) for various conditions. The optimal features mean absolute value, simple sign integral, and waveform length yields 99.8% and 100% for bearing fault and stator fault diagnosis, respectively, in PMSM. These features show 100% accuracy for identification of fault in SCIM and 98.2% accuracy in the run-to-failure state.

In high-speed motors, there is a huge amount of heat generation from core and winding losses, which may result in thermal failures or motor performance deterioration. In the prevention of heat accumulation, efficient cooling technology is critical for smooth and reliable motor movement. This paper summarizes the diverse application of high-speed motor and thermal requirements, such as in electrical devices, turbo-machinery, and high-precision machine tools. Three paths of case convection—cooling, internal ventilation cooling and spindle core cooling—are analyzed. Methods for configuring thermal resistance and improving cooling efficiency are summarized. Among them, coolant flow characteristics and flow channel shapes, gas supply ventilation systems, and methods to reduce air resistance, as well as axial cooling and integrated heat pipe structures, are extensively investigated. Finally, the development prospects of high-speed motor cooling are also forecasted. At present, the primary research directions are to reduce the heat generated by the heat source, utilize the latent heat of the coolant, optimize the cooling flow path of the shell, design an axial air-cooling circulation system, and enhance the heat dissipation of the spindle. [ABSTRACT FROM AUTHOR]

There are various secondary flow types in turbodrill's blade cascades, and all kinds of secondary flow have a significant effect on flow loss. In this paper, the stator cascade of φ160 mm turbodrill is taken as the research object, and the CFD method is used to analyze the secondary flow and its evolution. The origin and evolution mechanism of secondary flow is explained from the flow mechanism. The results show that when the working rotary speed is lower than the design rotary speed, the secondary flows are composed of suction surface separation vortex, horseshoe vortex, and passage vortex coexisting. The intensity of secondary flows increases with the decrease of rotary speed. When the working rotary speed is near the design rotary speed, the secondary flows include horseshoe vortex, passage vortex, and corner vortex. When the working rotary speed is higher than the design rotary speed, the secondary flows consist of pressure surface separation vortex and suction surface trailing edge separation vortex. Regardless of rotary speed, secondary flow intensity in the shroud region is greater than the hub region, which has a greater influence on the mainstream. In addition, compared with high rotary speeds, secondary flow intensity is greater at low rotary speeds, resulting in greater flow losses. [ABSTRACT FROM AUTHOR]

Introduction. The performance and reliability of gerotor hydraulic machines depend on the geometry of the cycloidal gearing profile. The existing methods of calculating and optimizing the profile parameters are cumbersome, multicriteria and difficult for practical application. Therefore, the problem of creating the methodology for calculating the parameters of the gerotor machine profile suitable for engineering calculations at the stage of conceptual design is a challenge. In this regard, the objective of this work was to modernize the methodology for designing the geometry of the profiles of the end section of hypocycloidal gears used in gerotor hydraulic machines, and to analyze the possibilities of their optimization during preliminary design. In the course of the study, the Mathcad computer mathematics system was used; numerical experiments were carried out to study the influence of geometric profile parameters on the performance and operability of the gerotor hydraulic machine, based on the data obtained and analyzed; recommendations for the design of optimal profiles of the end section of gerotor hydraulic machines were developed.Materials and Methods. Materials included known methods of profile parameters calculation, based on application of classical formulas of hypocycloidal equidistant used for outlining profiles of teeth of working elements of gerotor machines. The basic research method was modeling the gerotor machine profile using Mathcad computer mathematics system. Calculated data were obtained for the selected ranges of varying parameters, processed through the univariate regression analysis.Results. An algorithm for analyzing the tooth profile smoothness was developed. Two target parameters were defined: the cross-sectional area of the end profile, which affects the productivity; the smallest reduced radius of contact that determines operability of the working body. A technique for calculating the target parameters at the early stage of design was proposed. A number of optimal values of profile parameters according to the criteria of productivity and operability of gerotor machine was obtained. The dependences providing the optimum values of profile parameters at the stage of designing were constructed.Discussion and Conclusion. The developed methodology makes it possible to obtain an assessment of the performance and operability of the gerotor hydraulic machine at the design stage of the working body. The research results can be used in mechanical engineering when designing gerotor hydraulic machines in order to improve their technical and operational characteristics.

Permanent magnet brush DC motor is widely used in the automotive field. "Carbon sink Plan" requires the further reduction of automotive energy consumption, so the optimization problem of motor efficiency is becoming increasingly prominent. Based on vehicle cooling fan with permanent magnet brush DC motor as the research object, in view of the motor inefficiencies, using the finite element analysis software Maxwell, through simulation and parametric analysis of the rotor lamination length, laminated slots, winding wire diameter, winding pitch, winding circle number influences the performance of motor, combined with the simulation results and actual production conditions, determine the feasible motor efficiency optimization scheme. According to the optimization scheme, the sample is made and measured. The test data show that the motor efficiency is improved by 4.8%, and the optimization effect of motor efficiency is obvious. [ABSTRACT FROM AUTHOR]

The authors of the article describe and analyze the processes of functioning of a synchronous electric motor-generator (EDG). A review of mathematical descriptions of synchronous EDG is presented. A simplified mathematical description is proposed that makes it possible to simulate the process of functioning of the hybrid propulsion system (GSU) in typical modes of movement of wheeled vehicles (CTS). The functional dependences of the current, power and torque on the rotor speed of the synchronous EDG of the Toyota Prius car are presented. The goal is to develop a simplified mathematical description of a synchronous electric motor–generator of a car with a hybrid power plant. The method or methodology of the work is a numerical method based on the finite – difference scheme of the Park method, using a special numerical-iterative method of composing equations of motion. Results – a simplified mathematical description has been developed, which allows to determine the functional dependencies necessary for the analysis of the functioning of the CCC with GSU. The scope of the results. It is advisable to apply the results obtained when modeling the processes of functioning of a synchronous electric motor-generator of a hybrid power plant of wheeled vehicles.

Aiming at the phenomenon that a high-power torque converter is susceptible to cavitation, which leads to performance degradation, first, a transient flow field model of the torque converter is established, and CFD simulation and experimental research on the torque converter are carried out to find out the speed ratio region where cavitation occurs in the torque converter as well as the rule of occurrence of cavitation, and then the cavitation identification method based on the difference between the inlet and outlet flow of the torque converter is proposed. Then, the transient flow process inside the torque converter is analyzed, and it is pointed out that the angle between the inlet angle of the stator and the outlet angle of the turbine of the torque converter, i.e., the fluid inflow injection deviation angle is an important factor affecting the cavitation phenomenon. By adjusting the key parameters of the stator blade bone line, the fluid inflow deviation angle of the torque converter stator is optimized, so that the speed ratio range of cavitation under large load conditions is greatly reduced from the original 0–0.5 (50%) to 0–0.15 (15%). Meanwhile, in terms of test performance, the nominal torque of the torque converter is greatly improved under the premise of ensuring that the performance is basically unchanged, in which the nominal torque of the test zero speed is increased by 28.7%, and the cavitation of the torque converter has been greatly improved.

Studi ini menganalisa aplikasi mesin permanen magnet fluks aksial sebagai generator. Tipe generator magnet permanen flux aksial yang dianalisa yaitu single stator double rotor axial-flux. Tujuan dari studi ini adalah menganalisa pengaruh penambahan inti stator terhadap performa generator. Metode yang digunakan adalah simulasi menggunakan aplikasi FEEM 4.2. untuk mengamati parameter rapat fluks magnet (Br) dan fluks magnet (ϕ) pada celah udara, back-emf (E-rms) generator, dan kapasitas daya nyata (S) pada generator tanpa inti stator (coreless stator) dan penambahan ferrite pada belitan stator dengan variabel pemasangan magnet pada rotor (PM). Celah udara (δ) antara stator dan rotor konstan pada jarak 2 mm dengan variabel kedalaman pemasangan magnet permanen pada piringan rotor. Hasilnya penambahan inti ferrite pada stator meningkatkan fluks, back-emf dan daya generator sebesar 27,9%, 28,5%, 28,9% dan 35,9% untuk pemasangan magnet permanen pada kedalaman berturut-turut 0%, 5%, 10% dan 50%. Penambahan inti ferrite pada belitan stator generator magnet permanen fluks aksial signifikan meningkatkan Br, Φ, E-rms dan S.

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The current standard considers the efficiency of electric motors only in terms of power efficiency and does not pay attention to the so-called economic efficiency - the power factor that affects the loss of electricity in the motor supply network and depends on its energy excellence. This ill-considered approach to establishing the energy efficiency class is a significant shortcoming of the European standard and requires its refinement. The single-phase power supply network in housing and communal services has led to the fact that modern motor compressor units of refrigerators, air conditioners, etc. are equipped with single-phase asynchronous electric motors. An innovative single-phase asynchronous AC motor for motor-compressor units of household appliances is considered in the paper. The stator winding of it is composed of two identical series-connected coils enclosed in half-slots of the stator with a spacious offset of 900 . The phase shift of the currents in the coils is provided by a capacitor connected in parallel to one of the coils. The proposed motor is technological in production, has higher specific power and energy efficiency than existing models and meets the IE-3 class energy efficiency. Equivalent electrical circuit and vector diagram of currents for this motor have been developed and shown. They are intended for its mathematical simulation, calculation of static operating characteristics, analysis of dynamic properties at operation in the electric drive system, and also at the level of design work. [ABSTRACT FROM AUTHOR]

In high-speed motors, there is a huge amount of heat generation from core and winding losses, which may result in thermal failures or motor performance deterioration. In the prevention of heat accumulation, efficient cooling technology is critical for smooth and reliable motor movement. This paper summarizes the diverse application of high-speed motor and thermal requirements, such as in electrical devices, turbo-machinery, and high-precision machine tools. Three paths of case convection—cooling, internal ventilation cooling and spindle core cooling—are analyzed. Methods for configuring thermal resistance and improving cooling efficiency are summarized. Among them, coolant flow characteristics and flow channel shapes, gas supply ventilation systems, and methods to reduce air resistance, as well as axial cooling and integrated heat pipe structures, are extensively investigated. Finally, the development prospects of high-speed motor cooling are also forecasted. At present, the primary research directions are to reduce the heat generated by the heat source, utilize the latent heat of the coolant, optimize the cooling flow path of the shell, design an axial air-cooling circulation system, and enhance the heat dissipation of the spindle.

Vibration and torque ripple of the permanent magnet generator axis cause excessive wearing up of the generator, noise, efficiency reduction. The article theoretically considers the possibility of eliminating the oscillation of the rotation torque of the permanent magnets generator at constant load due to mutual compensation of the interaction of coils with the field of permanent magnets in the case of certain symmetry of this field. This effect is called pi resonance. For a given class of model functions of the magnetic field density of permanent magnets, it is shown that full compensation occurs with a certain number of coils (Ns) and magnets (Nr), while for other combinations of {Ns, Nr} the interaction is in the nature of oscillations. Pi resonance tables are given for a number of model field density functions represented by Fourier series up to the fifth power. Pi resonance is primarily realized in the case of a small difference in the values of Nr and Ns, which corresponds to the location near the main diagonal of the pi resonance table, as well as at the values of Nr, Ns corresponding to prime numbers. The number of configurations {Nr, Ns} providing pi resonance (compensation of parasitic torques) is the largest for the sinusoidal magnetic flux density and decreases if the magnetic flux density function is approximated by a high-degree Fourier series. It is shown that in the absence of coil cores, pi resonance is possible at Nr = Ns. An additional possibility of pi resonance is shown when placing coils on opposite sides of the rotor. A simplified method of investigating the system (without integrating the equation for the induction current) is substantiated. The results can be used in the design of permanent magnets generators and motors.

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]

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]

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]

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.

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]

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]

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%.

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]

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.