Stator Assembly Research Articles

BB0326 is responsible for the formation of periplasmic flagellar collar and assembly of the stator complex in Borrelia burgdorferi.

Borrelia burgdorferi is a highly motile spirochete due to its periplasmic flagella. Unlike flagella of other bacteria, spirochetes' periplasmic flagella possess a complex structure called the collar, about which little is known in terms of function and composition. Using various approaches, we have identified a novel protein, BB0326, as a key component of the collar. We show that a peripheral portion of the collar is diminished in the Δbb0326 mutant and restored in the complemented bb0326+ cells, leading us to rename BB0326 as periplasmic flagellar collar protein A or FlcA. The ΔflcA mutant cells produced fewer, abnormally tilted and shorter flagella, as well as diminished stators, suggesting that FlcA is crucial for flagellar and stator assemblies. We provide further evidence that FlcA interacts with the stator and that this collar-stator interaction is essential for the high torque needed to power the spirochete's periplasmic flagellar motors. These observations suggest that the collar provides various important functions to the spirochete's periplasmic flagellar assembly and rotation.

Time for a motor check.

Two studies now provide structural insights into the stator–rotor interaction, stator assembly and stator maintenance of the bacterial flagellum.

Perbaikan Proses Produksi Menggunakan ECRS Based Line Balancing pada Lini Perakitan Stator 4

PT. XYZ is one of the manufacturing companies in Indonesia. The company produces water pumps. An important component in the water pump is the stator. The observation results in the Stator Assembly line 4 show that low line efficiency occurs because the production process has not run optimally. So that an improvement in the production process is important to do on this line. One method to improve the production process is ECRS based line balancing. By still considering the concept of line balancing, line efficiency can be improved through improving the production process. Through the improvement of the production process, there was a decrease in the number of work stations from 10 work stations to 9 work stations, improvement of line layout and 7th work station (Heating Air Dryer), also an increase in line efficiency from 74.72% to 81.09%.

Computationally Efficient Strand Eddy Current Loss Calculation in Electric Machines

A fast finite element (FE) based method for the calculation of eddy current losses in the stator windings of randomly wound electric machines is presented in this paper. The method is particularly suitable for implementation in large-scale design optimization algorithms where a qualitative characterization of such losses at higher speeds is most beneficial for identification of the design solutions that exhibit the lowest overall losses including the ac losses in the stator windings. Unlike the common practice of assuming a constant slot fill factor s <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> for all the design variations, the maximum s <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</sub> in the developed method is determined based on the individual slot structure/dimensions and strand wire specifications. Furthermore, in lieu of detailed modeling of the conductor strands in the initial FE model, which significantly adds to the complexity of the problem, an alternative rectangular coil modeling subject to a subsequent flux mapping technique for determination of the impinging flux on each individual strand is pursued. Rather than pursuing the precise estimation of ac conductor losses, the research focus of this paper is placed on the development of a computationally efficient technique for the derivation of strand eddy current losses applicable in design optimization, especially where both the electromagnetic and thermal machine behavior are accounted for. A fractional-slot concentrated winding permanent magnet synchronous machine is used for the purpose of this study due to the higher slot leakage flux and slot opening fringing flux of such machines, which are the major contributors to strand eddy current losses in the windings. The analysis is supplemented with an investigation on the influence of the electrical loading on ac winding loss effects for this machine design, a subject that has received less attention in the literature. Experimental ac loss measurements on a 12-slot 10-pole stator assembly will be discussed to verify the existing trends in the simulation results.

Effect of the MotA(M206I) Mutation on Torque Generation and Stator Assembly in the Salmonella H+-Driven Flagellar Motor.

The bacterial flagellar motor is composed of a rotor and a dozen stators and converts the ion flux through the stator into torque. Each stator unit alternates in its attachment to and detachment from the rotor even during rotation. In some species, stator assembly depends on the input energy, but it remains unclear how an electrochemical potential across the membrane (e.g., proton motive force [PMF]) or ion flux is involved in stator assembly dynamics. Here, we focused on pH dependence of a slow motile MotA(M206I) mutant of Salmonella The MotA(M206I) motor produces torque comparable to that of the wild-type motor near stall, but its rotation rate is considerably decreased as the external load is reduced. Rotation assays of flagella labeled with 1-μm beads showed that the rotation rate of the MotA(M206I) motor is increased by lowering the external pH whereas that of the wild-type motor is not. Measurements of the speed produced by a single stator unit using 1-μm beads showed that the unit speed of the MotA(M206I) is about 60% of that of the wild-type and that a decrease in external pH did not affect the MotA(M206I) unit speed. Analysis of the subcellular stator localization revealed that the number of functional stators is restored by lowering the external pH. The pH-dependent improvement of stator assembly was observed even when the PMF was collapsed and proton transfer was inhibited. These results suggest that MotA-Met206 is responsible for not only load-dependent energy coupling between the proton influx and rotation but also pH-dependent stator assembly.IMPORTANCE The bacterial flagellar motor is a rotary nanomachine driven by the electrochemical transmembrane potential (ion motive force). About 10 stators (MotA/MotB complexes) are docked around a rotor, and the stator recruitment depends on the load, ion motive force, and coupling ion flux. The MotA(M206I) mutation slows motor rotation and decreases the number of docked stators in Salmonella We show that lowering the external pH improves the assembly of the mutant stators. Neither the collapse of the ion motive force nor a mutation mimicking the proton-binding state inhibited stator localization to the motor. These results suggest that MotA-Met206 is involved in torque generation and proton translocation and that stator assembly is stabilized by protonation of the stator.

Autonomous control mechanism of stator assembly in the bacterial flagellar motor in response to changes in the environment.

The bacterial flagellar motor is composed of a rotor and a transmembrane ion channel complex that acts as a stator unit. The ion channel complex consists of at least three structural parts: a cytoplasmic domain responsible for the interaction with the rotor, a transmembrane ion channel that forms a pathway for the transit of ions across the cytoplasmic membrane, and a peptidoglycan-binding (PGB) domain that anchors the stator unit to the peptidoglycan (PG) layer. A flexible linker connecting the ion channel and the PGB domain not only coordinates stator assembly with its ion channel activity but also controls the assembly of stator units to the motor in response to changes in the environment. When the ion channel complex encounters the rotor, the N-terminal portion of the PGB domain adopts a partially stretched conformation, allowing the PGB domain to reach and bind to the PG layer. The binding affinity of the PGB domain for the PG layer is affected by the force applied to its anchoring point and to the type of ionic energy source. In this review article, we will present current understanding of autonomous control mechanism of stator assembly in the bacterial flagellar motor.

Fabrication and Assembly Method for Synchronous Reluctance Machines

In this paper, a comprehensive manufacturing and assembly process of synchronous reluctance machines (SynRMs) is presented. One stator and two transversally laminated anisotropic (TLA) SynRM rotors are manufactured using cold-roll nongrain-oriented steel. To enhance the performance of the designed SynRM, a TLA segmented SynRM rotor is fabricated using cold-roll grain-oriented steel. The application of nonconventional photochemical machining to produce machine laminations is presented. Different stages of manufacturing, stator and rotor assembly techniques, rotor balancing procedure as well as specialized components used at various stages of the process are described. Performance characteristics such as static torque–angle curves are obtained experimentally to verify the accuracy of design, manufacturing, and assembly.

Trapped Cylindrical Flow With Multiple Inlets for Savonius Vertical Axis Wind Turbines

Savonius vertical axis wind turbines (VAWTs) typically suffer from low efficiency due to detrimental drag production during one half of the rotational cycle. The present study examines a stator assembly created with the objective of trapping cylindrical flow for application in a Savonius VAWT. While stator assemblies have been studied in situ around Savonius rotors in the past, they have never been isolated from the rotor to determine the physics of the flow field, raising the likelihood that a moving rotor could cover up deficiencies attributable to the stator design. The flow field created by a stator assembly, sans rotor, is studied computationally using three-dimensional (3D) numerical simulations in the commercial computational fluid dynamics (CFD) package Star-CCM+. Examination of the velocity and pressure contours at the central stator plane shows that the maximum induced velocity exceeded the freestream velocity by 65%. However, flow is not sufficiently trapped in the stator assembly, with excess leakage occurring between the stator blades due to adverse pressure gradients and momentum loss from induced vorticity. A parametric study was conducted on the effect of the number of stator blades with simulations conducted with 6, 12, and 24 blades. Reducing the blade number resulted in a reduction in the cohesiveness of the internal swirling flow structure and increased the leakage of flow through the stator. Two unique energy loss mechanisms have been identified with both caused by adverse pressure gradients induced by the stator.

A large-diameter hollow-shaft cryogenic motor based on a superconducting magnetic bearing for millimeter-wave polarimetry.

In this paper, we present the design and measured performance of a novel cryogenic motor based on a superconducting magnetic bearing (SMB). The motor is tailored for use in millimeter-wave half-wave plate (HWP) polarimeters, where a HWP is rapidly rotated in front of a polarization analyzer or polarization-sensitive detector. This polarimetry technique is commonly used in cosmic microwave background polarization studies. The SMB we use is composed of fourteen yttrium barium copper oxide (YBCO) disks and a contiguous neodymium iron boron (NdFeB) ring magnet. The motor is a hollow-shaft motor because the HWP is ultimately installed in the rotor. The motor presented here has a 100 mm diameter rotor aperture. However, the design can be scaled up to rotor aperture diameters of approximately 500 mm. Our motor system is composed of four primary subsystems: (i) the rotor assembly, which includes the NdFeB ring magnet, (ii) the stator assembly, which includes the YBCO disks, (iii) an incremental encoder, and (iv) the drive electronics. While the YBCO is cooling through its superconducting transition, the rotor is held above the stator by a novel hold and release mechanism. The encoder subsystem consists of a custom-built encoder disk read out by two fiber optic readout sensors. For the demonstration described in this paper, we ran the motor at 50 K and tested rotation frequencies up to approximately 10 Hz. The feedback system was able to stabilize the rotation speed to approximately 0.4%, and the measured rotor orientation angle uncertainty is less than 0.15°. Lower temperature operation will require additional development activities, which we will discuss.

The role of a cytoplasmic loop of MotA in load-dependent assembly and disassembly dynamics of the MotA/B stator complex in the bacterial flagellar motor.

The proton-driven flagellar motor of Salmonella enterica can accommodate a dozen MotA/B stators in a load-dependent manner. The C-terminal periplasmic domain of MotB acts as a structural switch to regulate the number of active stators in the motor in response to load change. The cytoplasmic loop termed MotAC is responsible for the interaction with a rotor protein, FliG. Here, to test if MotAC is responsible for stator assembly around the rotor in a load-dependent manner, we analyzed the effect of MotAC mutations, M76V, L78W, Y83C, Y83H, I126F, R131L, A145E and E155K, on motor performance over a wide range of external load. All these MotAC mutations reduced the maximum speed of the motor near zero load, suggesting that they reduce the rate of conformational dynamics of MotAC coupled with proton translocation through the MotA/B proton channel. Dissociation of the stators from the rotor by decrease in the load was facilitated by the M76V, Y83H and A145E mutations compared to the wild-type motor. The E155K mutation reduced the number of active stators in the motor from 10 to 6 under extremely high load. We propose that MotAC is responsible for load-dependent assembly and disassembly dynamics of the MotA/B stator units.

Dynamic Analysis of a Novel Moving Magnet Linear Actuator

A novel moving magnet linear actuator is proposed for linear oscillations in the linear resonant compressors for household refrigerators. This paper provides stator and armature design including CAD model and geometric parameters. Furthermore, the working principle of the proposed actuator is explained. The stator assembly is composed of two reversely wound coils, which are electrically excited with single phase ac power and oscillates the radially magnetized armature. With the help of the electromechanical analytical model, the dynamic parameters such as stroke, velocity, and acceleration of the armature are derived. Additionally, the time-dependent current model of the stator winding is proposed. An experimental setup is used to validate these responses at the resonance excitation frequency with the help of sensors. The system kinetics are discussed to estimate the spring, damping, inertial, and magnetic forces. A simulation is executed to estimate the time-domain responses of these dynamic parameters and the effects of excitation frequency are discussed. The force models are experimentally validated at the resonance frequency excitation. In order to evaluate the performance of the proposed actuator, a comparison of the performance parameters, such as efficiency, stroke, current, and mass flow rate is demonstrated with the conventional rotary as well as the linear motors for linear compressor application.

Load- and polysaccharide-dependent activation of the Na+-type MotPS stator in the Bacillus subtilis flagellar motor

The flagellar motor of Bacillus subtilis possesses two distinct H+-type MotAB and Na+-type MotPS stators. In contrast to the MotAB motor, the MotPS motor functions efficiently at elevated viscosity in the presence of 200 mM NaCl. Here, we analyzed the torque-speed relationship of the Bacillus MotAB and MotPS motors over a wide range of external loads. The stall torque of the MotAB and MotPS motors at high load was about 2,200 pN nm and 220 pN nm, respectively. The number of active stators in the MotAB and MotPS motors was estimated to be about ten and one, respectively. However, the number of functional stators in the MotPS motor was increased up to ten with an increase in the concentration of a polysaccharide, Ficoll 400, as well as in the load. The maximum speeds of the MotAB and MotPS motors at low load were about 200 Hz and 50 Hz, respectively, indicating that the rate of the torque-generation cycle of the MotPS motor is 4-fold slower than that of the MotAB motor. Domain exchange experiments showed that the C-terminal periplasmic domain of MotS directly controls the assembly and disassembly dynamics of the MotPS stator in a load- and polysaccharide-dependent manner.

Measurement and control system design for the assembly of stator can

Stator can assembly is one of difficult issues in the manufacturing of AP1000 nuclear reactor coolant pumps. A new measurement and control system is developed to ensure precise assembly of the ultrathin stator can with large length to thickness ratio on the stator core. The system includes three parts: hydraulic pressure measurement and control, deformation measurement of the can and displacement measurement of valve core. Since deformation of the can is hard to measure, a new method by measuring the bulge displacement of the can is proposed. With the help of the system, the loading path can be accurately controlled and the deformation can be precisely measured. The system provides possibility for the detailed study of assembly process. Finally, the feasibility of the system in the experiment rig of a reduced scale is verified.

Mechanism of Stator Assembly and Incorporation into the Flagellar Motor.

In many cases, conformational changes in proteins are related to their functions, and thereby inhibiting those changes causes functional defects. One way to perturb such conformational changes is to covalently link the regions where the changes are induced. Here, I introduce an example in which an intramolecular disulfide crosslink in the stator protein of PomB, introduced based on its crystal structure, reversibly inhibits the rotation of the flagellar motor, and I detail how we analyzed that phenotype. In this Chapter, first I describe how we monitor the motility inhibition and restoration by controlling disulfide bridge formation, and secondly how we detect intramolecular disulfide crosslinks, which are sometimes difficult to monitor by mobility shifts on SDS-PAGE gels.

Modeling and Analysis of Drift Error in a MSSG with Double Spherical Envelope Surfaces

To improve the sensing accuracy of the newly developed magnetically suspended sensitive gyroscope (MSSG), it is necessary to analyze the causes of drift error. This paper build the models of disturbing torques generated by stator assembly errors based on the geometric construction of the MSSG with double spherical envelope surfaces, and further reveals the generation mechanism of the drift error. Then the drift error from a single stator magnetic pole is calculated quantitatively with the established model, and the key factors producing the drift error are further discussed. It is proposed that the main approaches in reducing the drift error are guaranteeing the rotor envelope surface to be an ideal spherical and improving the controlling precision of rotor displacement. The common problems associated in a gyroscope with a spherical rotor can be effectively resolved by the proposed method.

Modeling and Analysis of Drift Error from Stator of A MSSG with Double Spherical Envelope Surfaces

For the newly developing magnetically suspended sensitive gyroscope (MSSG) with double spherical envelope surfaces, it is necessary to analyze the causes of drift error to improve sensing accuracy. This paper builds the models of disturbing torques generated by stator assembly and process errors based on the geometric construction and running regularity of the MSSG, and further reveals the generation mechanism of the drift error. Then the drift error from a single stator magnetic pole is calculated quantitatively with the established model, and the key factors producing the drift error are further discussed. It is proposed that the main approaches in reducing the drift error from stator are guaranteeing the rotor envelope surface to be an ideal spherical and improving the controlling precision of rotor displacement. The common problems associated in a gyroscope with a spherical rotor can be effectively resolved by the proposed method. This analysis provides a reference for the structure optimization and error compensation of a MSSG.

Development of a Brushless DC Generator for the Micro Solar-Thermal Power Generation System for Societal Applications

This paper describes the work performed on the design and development of 1KW Brushless DC generator: armature stator and permanent magnet rotor assembly for a Micro Solar Thermal Power Generation System for societal applications. A Solar Thermal Electricity generating system is an emerging renewable energy technology, where we generate the thermal energy by concentrating the direct solar radiation at high temperature. The resulting thermal energy is used in a thermodynamic cycle to produce electricity, by running a turbine which rotates the generator to produce electricity. The brushless dc generator armature design is a three phase star connected winding housed in the magnetic core. The magnetic circuit of the stator is designed to meet the required power output. The rotor assembly has high energy rare earth permanent magnets to produce required flux for the voltage generation. The armature stator and permanent magnet rotor is modeled in two dimensional finite element based electromagnetic software to validate the flux density at the airgap, tooth and back iron. The proto model generator is realized and tested for its performance with load.

Intensification of biogas production using pretreatment based on hydrodynamic cavitation

The present work investigates the application of hydrodynamic cavitation (HC) for the pretreatment of wheat straw with an objective of enhancing the biogas production. The hydrodynamic cavitation reactor is based on a stator and rotor assembly. The effect of three different speeds of rotor (2300, 2500, 2700rpm), wheat straw to water ratios (0.5%, 1% and 1.5% wt/wt) and also treatment times as 2, 4 and 6min have been investigated in the work using the design of experiments (DOE) approach. It was observed that the methane yield of 31.8ml was obtained with untreated wheat straw whereas 77.9ml was obtained with HC pre-treated wheat straw confirming the favourable changes during the pre-treatment. The combined pre-treatment using KOH and HC gave maximum yield of biogas as 172.3ml. Overall, it has been established that significant enhancement in the biogas production can be obtained due to the pretreatment using HC which can also be further intensified by combination with chemical treatment.

Developing a Vortical Stator Assembly to Improve the Performance of Drag-Type Vertical-Axis Wind Turbines

AbstractIn this study, a vortical stator assembly (VSA) was developed to improve the rotor performance, surrounding a drag-type, vertical-axis wind turbine (VAWT). A rotor with six half-tube blades was employed. The VSA consisted of a number of guide vanes, which were to guide the air tangentially into the VSA. The design was to generate a vortical flow inside the VSA, to reduce the negative torque of the returning rotor blade, and to increase the air speed into the rotor. Wind tunnel model tests were conducted to investigate how the VSAs affected rotor performance. Four VSAs were developed in this study, employing 4, 6, 8 and 12 guide vanes that were 24cm in width, and one 6-guide-vane VSA employing guide vane widths of 12, 18, 24 and 30cm. Results indicated that VSAs can substantially augment the rotor performance, depending on the number and length of guide vanes. The 6-guide-vane VSA produced the largest effect on the rotor performance, and the optimal VSA diameter was approximately 1.82 times the rotor diameter. At an air speed of 6m/s, the optimal VSA helps to increase the free-running rotational speed by 318%, the torque output by 200%, and the maximal power output by 910%.

FliL associates with the stator to support torque generation of the sodium-driven polar flagellar motor of Vibrio.

Flagellar motors generate torque to rotate flagellar filaments and drive bacterial cells. Each motor is composed of a rotor and many stators. The stator is a force-generating complex that converts ion flux into torque. Previous reports have suggested that the membrane protein FliL is located near the stator and is involved in torque generation. We investigated the role of FliL in the sodium-driven polar flagellar motor of Vibrio alginolyticus. Our results revealed that FliL is a cytoplasmic membrane protein and is located at the base of flagellum. The deletion of fliL did not affect the cell morphology or flagellation but resulted in a significant decrease of swimming speed, especially at a higher load thus suggesting that FliL is important for torque generation at high load conditions. Furthermore, the polar localization of the stator was decreased in a ΔfliL mutant, but the sodium-dependent assembly of the stator complex was still retained. The polar localization of FliL was lost in the absence of the stator complex, indicating that FliL interacts directly or indirectly with the stator. Our results suggest that FliL is localized along with the stator in order to support the motor functioning for swimming at high load conditions by maintaining the stator assembly.