Direct Drive Applications: Possible Replacement of Rare-Earth Permanent Magnet Motors

This paper deals with the possibility to replace rare-earth permanent magnet (PM) motors in direct drive applications. According to previous researches, there are alternatives such as surface-mounted PM motors and spoke-type motors adopting Ferrite PMs, synchronous reluctance motors, with or without the assistance of low-energy PMs. Few studies have been carried out to compare all models at once, thus it is hard to choose which type motor is to be preferred as a valid alternative of rare-earth PM motors in direct drive applications. In this paper, the representative candidates listed above are analyzed and the results are compared with that of a rare-earth PM motor, which is considered as a reference motor. Additionally, the demagnetization phenomenon of the motors with Ferrite PMs is deeply analyzed because this kind of PM may be easily demagnetized by the stator flux. Finally, both strengths and weaknesses of each alternative motors are highlighted.

Motor domain-mediated autoinhibition dictates axonal transport by the kinesin UNC-104/KIF1A

The UNC-104/KIF1A motor is crucial for axonal transport of synaptic vesicles, but how the UNC-104/KIF1A motor is activated in vivo is not fully understood. Here, we identified point mutations located in the motor domain or the inhibitory CC1 domain, which resulted in gain-of-function alleles of unc-104 that exhibit hyperactive axonal transport and abnormal accumulation of synaptic vesicles. In contrast to the cell body localization of wild type motor, the mutant motors accumulate on neuronal processes. Once on the neuronal process, the mutant motors display dynamic movement similarly to wild type motors. The gain-of-function mutation on the motor domain leads to an active dimeric conformation, releasing the inhibitory CC1 region from the motor domain. Genetically engineered mutations in the motor domain or CC1 of UNC-104, which disrupt the autoinhibitory interface, also led to the gain of function and hyperactivation of axonal transport. Thus, the CC1/motor domain-mediated autoinhibition is crucial for UNC-104/KIF1A-mediated axonal transport in vivo.

A kinesin-1 variant reveals motor-induced microtubule damage in cells

Kinesins drive the transport of cellular cargoes as they walk along microtubule tracks, however, recent work has suggested that the physical act of kinesins walking along microtubules can stress the microtubule lattice. Here, we describe a kinesin-1 KIF5C mutant with an increased ability to generate defects in the microtubule lattice as compared to the wild-type motor. Expression of the mutant motor in cultured cells resulted in microtubule breakage and fragmentation, suggesting that kinesin-1 variants with increased damage activity would have been selected against during evolution. The increased ability to damage microtubules is not due to the altered motility properties of the mutant motor as expression of the kinesin-3 motor KIF1A, which has similar single-motor motility properties, also caused increased microtubule pausing, bending, and buckling but not breakage. In cells, motor-induced microtubule breakage could not be prevented by increased α-tubulin K40 acetylation, a post-translational modification known to increase microtubule flexibility. In vitro, lattice damage induced by wild-type KIF5C was repaired by soluble tubulin and resulted in increased rescues and microtubule growth whereas lattice damage induced by the KIF5C mutant resulted in larger repair sites that made the microtubule vulnerable to breakage and fragmentation when under mechanical stress. These results demonstrate that kinesin-1 motility causes defects in and damage to the microtubule lattice in cells. While cells have the capacity to repair lattice damage, conditions that exceed this capacity result in microtubule breakage and fragmentation and may contribute to human disease.

Investigation of an Interior Micro Permanent Magnet Synchronous Motor

This study describes the development of the world’s smallest interior permanent magnet synchronous motor (IPMSM) to increase the torque density of micromotors. The research evaluates the feasibility of the miniaturization of IPMSM since recent studies in this area focus on medium to large size compressor and traction motor applications. The standard-type and spoke-type IPMSM were selected for ease of micro machining. In order to surpass the performance of an inset motor of the same size used in previous research, the interior motors were designed with a different slot pole number, permanent magnet shape and rotor structure. Two types of interior motors were manufactured and tested to compare their performance. It was shown that the spoke-type interior motor had a better output torque, while the standard-type interior motor had a lower torque ripple, and both motors matched the specifications of commercially available motors. To achieve a higher torque density, the IPMSM designs increased the slot pole number from 6 slots 4 poles to 9 slots 6 poles. The torque density of the spoke-type motor was increased by 48% compared to the inset motor. The disadvantage is that the new design has a greater number of parts and smaller size, resulting in difficulties in manufacturing and assembly.

A Fast Engineering Method for Estimating Iron Losses in Induction Type Motor Spindles Based on Equivalent Magnetic Circuit

The iron losses in the motor of motorized spindles have a significant effect on the heat generation, working efficiency, and speed-torque characteristics of motorized spindles as well as on their thermal deformation and machining accuracy. The existing finite element and analytical methods based on Maxwell’s equations are too complicated to be suitable for engineering designers. A fast engineering method for estimating iron losses in the spindle motor is presented based on equivalent magnetic circuit (EMC) where the problem of solving a complex electromagnetic field inside the spindle motor is simplified into a simple magnetic circuit calculation by the assumption that the magnetic flux density distribution of any cross section along the magnetic flux direction in the spindle motor is uniform. The EMC is combined with the Boglietti’s model. They are integrated into a developed program by compiling source codes to achieve the analysis and prediction of iron losses in the spindle motor. The results obtained from the proposed method are compared with the prototype experiment data to verify its validity. With the purpose of ensuring accurate experiment results of iron losses, a method of no load running combined with a sudden loss of power supply is proposed to eliminate the braking torque and electromagnetic losses of the spindle motor, namely to achieve the separation of the mechanical loss from the total losses.

Inertial Piezoelectric Rotary Motor Based on Low Profile Stator with Trapezoidal Waveguides

Results of numerical and experimental investigations of a novel inertial piezoelectric rotary type motor based on a low profile stator with trapezoidal waveguides. The proposed motor has a simple design and is well scalable. Moreover, the proposed design of the motor allows mount it on a printed circuit board and use it in a small-size mobile positioning and actuating systems. The structure of the stator is based on a square type hollowed steel frame with four straight trapezoidal waveguides that are used to transfer vibrations of the stator to the rotation of the rotor. Piezo ceramic plates are glued on both sides of the stator. The thickness of the assembled stator is 0.9 mm, while the total area needed for stator mounting does not exceed 625 mm2. The driving of the rotor is based on the stick-slip principle, which is induced by excitation of the second in-plane bending mode of the four bimorph plates applying two saw tooth waveform signals with a phase difference by π. The numerical and experimental investigation was carried out to validate the operation principle of the motor and to measure the mechanical and electrical characteristics. The maximum angular rotation speed of 1304 RPM was achieved at a resonance frequency of 44.81 kHz when a preload of a 7.35mN was applied.

Neuroimaging Patterns and Function in Cerebral Palsy—Application of an MRI Classification

Background: Cerebral palsy (CP) is a disorder of movement and posture and every child with CP has a unique composition of neurological symptoms, motor severity, and associated impairments, constituting the functional profile. Although not part of the CP definition, magnetic resonance imaging (MRI) sheds light on the localization, nature, and severity of brain compromise. The MRI classification system (MRICS), developed by the Surveillance of Cerebral Palsy in Europe (SCPE), describes typical MRI patterns associated with specific timing of vulnerability in different areas of the brain. The classification has proven to be reliable and easy to use.Aims: The aim of this study is to apply the MRICS on a large dataset and describe the functional profile associated with the different MRI patterns of the MRICS.Materials and Methods: Data on children with CP born in 1999–2009 with a post-neonatal MRI from 20 European registers in the JRC-SCPE Central Registry was included. The CP classification and the MRICS was applied, and The Gross Motor Function Classification (GMFCS) and the Bimanual Fine Motor Function (BFMF) classification were used. The following associated impairments were documented: intellectual impairment, active epilepsy, visual impairment, and hearing impairment. An impairment index was used to characterize severity of impairment load.Results: The study included 3,818 children with post-neonatal MRI. Distribution of CP type, motor, and associated impairments differed by neuroimaging patterns. Functional profiles associated with neuroimaging patterns were described, and the impairment index showed that bilateral findings were associated with a more severe outcome both regarding motor impairment and associated impairments than unilateral compromise. The results from this study, particularly the differences in functional severity regarding uni- and bilateral brain compromise, may support counseling and service planning of support of children with CP.

An Overview of KMP. Gorare Route Tanjung Ru-Sadai Belitung, Bangka Belitung Province

Belitung Regency is one of the regencies in Indonesia’s Bangka Belitung Province where river crossing transportation plays a vital role in transportation activities and the region’s economy. The Gorare Ferry Motor Boat is a ro-ro type motor boat serving the Tanjung Ru-Sadai route. This form of transportation is expected to be able to stimulate economic growth in the region’s more remote areas, and the government is therefore providing subsidies to support the programme. Based on productivity data from 2010 to 2013, there was a significant increase in passenger volumes and vehicle productivity. However, the pricing rate does not cover the operating costs of the ship. This study seeks to ascertain when the service will reach breakeven and no longer require subsidies. Keywords: Crossing, Transportation, Role