Evolutionary cell biology: Functional insight from “Endless forms most beautiful”

In animal and fungal model organisms, the complexities of cell biology have been analyzed in exquisite detail and much is known about how these organisms function at the cellular level. However, the model organisms cell biologists generally use include only a tiny fraction of the true diversity of eukaryotic cellular forms. The divergent cellular processes observed in these more distant lineages are still largely unknown in the general scientific community. Despite the relative obscurity of these organisms, comparative studies of them across eukaryotic diversity have had profound implications for our understanding of fundamental cell biology in all species and have revealed the evolution and origins of previously observed cellular processes. In this Perspective, we will discuss the complexity of cell biology found across the eukaryotic tree, and three specific examples of where studies of divergent cell biology have altered our understanding of key functional aspects of mitochondria, plastids, and membrane trafficking

Monitoring and damping unbalanced magnetic pull due to eccentricity fault in induction machines: A review

© 2017 IEEE. Condition monitoring can diagnose the inception of fault mechanisms in induction motors, thus avoiding failure and expensive repairs. Therefore, there is a strong need to develop an efficient condition monitoring. The main target is to achieve a relatively low cost and/or non-invasive system which is still powerful in terms of monitoring for online detection of developing faults. The presented paper addresses rotor eccentricity faults and studies conventional monitoring techniques for induction motors. In order to reduce the unbalanced magnetic pull (UMP) in case of an eccentric rotor, the eccentricity-generated additional airgap flux waves should be reduced. The radial forces in an induction motor are calculated, and the characteristics of unbalanced magnetic pull are described

Analysis of rectangular EV inductive charging coupler

© 2017 IEEE. The number of commercial electric vehicles has increased significantly in recent years. However, there are still limited recharging facilities for EVs. Wireless charging offers an alternative way to recharge with more flexibility and convenience. The wireless transformer/coupler is the key component in electric vehicle wireless charging. The maximum power transfer capability is limited by the coupler. In order to reach desired power transfer level, the parameters of the wireless transformer should be analyzed. The wireless power transfer system design also requires accurate coupler parameters. In this paper, rectangular pads with different size of ferrite bars were analyzed in finite element analysis software. The prototype was built to valid the simulation result

Design and comparison of 11 kV multilevel voltage source converters for local grid based renewable energy systems

Because the availability of renewable energy is highly variable and the power demand by the consumers could have a very different characteristic, it is very desirable to connect a renewable generation system to the grid. In this respect, the 11 kV multilevel Voltage Source Converter (VSC) has no heavy transformer and is the cost effective solution to interfacing a renewable generation system to the local grid directly. This paper presents the design and comparison of a Five-Level Neutral Point Clamped (5L-NPC), a Five-Level Flying Capacitor (5L-FC), a Five-Level Series Connected H-Bridge (5L-SCHB), an Eleven-Level Neutral Point Clamped (11L-NPC), an Eleven-Level Flying Capacitor (11L-FC), and an Eleven-Level Series Connected H-Bridge (5L-SCHB) VSC for an 11 kV local grid based converter. The cost of power semiconductors and capacitors, modulation schemes and harmonic spectra of the converters are the bases for comparison. © 2011 IEEE

Development of a claw pole permanent magnet motor with a molded low-density soft magnetic composite stator core

SMC (soft magnetic composite) materials and SMC electrical machines have undergone significant development in the past decade. For the molding of the SMC core, if a high productivity low pressure press is used, the manufacturing cost can be dramatically reduced. However, the magnetic properties of the SMC core and the machine performance are highly dependant on the mass density of the core. This paper presents the development of a claw pole permanent magnet motor with a low mass density SMC stator core molded at low pressure which can replace the existing single phase induction motor in a dish washer pump. The developed SMC motor has been prototyped and tested. Both the parameter computation and performance prediction are validated by the experimental results. These show that the low mass density SMC core is suitable for low cost mass production of SMC electrical machines. © 2009 IEEE

Sequential model predictive control of three-phase direct matrix converter

© 2019 by the authors. The matrix converter (MC) is a promising converter that performs the direct AC-to-AC conversion. Model predictive control (MPC) is a simple and powerful tool for power electronic converters, including the MC. However, weighting factor design and heavy computational burden impose significant challenges for this control strategy. This paper investigates the generalized sequential MPC (SMPC) for a three-phase direct MC. In this control strategy, each control objective has an individual cost function and these cost functions are evaluated sequentially based on priority. The complex weighting factor design process is not required. Compared with the standard MPC, the computation burden is reduced because only the pre-selected switch states are evaluated in the second and subsequent sequential cost functions. In addition, the prediction model computation for the following cost functions is also reduced. Specifying the priority for control objectives can be achieved. A comparative study with traditional MPC is carried out both in simulation and an experiment. Comparable control performance to the traditional MPC is achieved. This controller is suitable for the MC because of the reduced computational burden. Simulation and experimental results verify the effectiveness of the proposed strategy

Development of Composite Honeycomb and Solid Laminate Reference Standards to Aid Aircraft Inspections

The rapidly increasing use of composites on commercial airplanes coupled with the potential for economic savings associated with their use in aircraft structures means that the demand for composite materials technology will continue to increase. Inspecting these composite structures is a critical element in assuring their continued airworthiness. The FAA's Airworthiness Assurance NDI Validation Center, in conjunction with the Commercial Aircraft Composite Repair Committee (CACRC), is developing a set of composite reference standards to be used in NDT equipment calibration for accomplishment of damage assessment and post-repair inspection of all commercial aircraft composites. In this program, a series of NDI tests on a matrix of composite aircraft structures and prototype reference standards were completed in order to minimize the number of standards needed to carry out composite inspections on aircraft. Two tasks, related to composite laminates and non-metallic composite honeycomb configurations, were addressed. A suite of 64 honeycomb panels, representing the bounding conditions of honeycomb construction on aircraft, were inspected using a wide array of NDI techniques. An analysis of the resulting data determined the variables that play a key role in setting up NDT equipment. This has resulted in a prototype set of minimum honeycomb reference standards that include these key variables. A sequence of subsequent tests determined that this minimum honeycomb reference standard set is able to fully support inspections over the fill range of honeycomb construction scenarios. Current tasks are aimed at optimizing the methods used to engineer realistic flaws into the specimens. In the solid composite laminate arena, we have identified what appears to be an excellent candidate, G11 Phenolic, as a generic solid laminate reference standard material. Testing to date has determined matches in key velocity and acoustic impedance properties, as well as, low attenuation relative to carbon laminates. Furthermore, comparisons of resonance testing response curves from the G11 Phenolic prototype standard was very similar to the resonance response curves measured on the existing carbon and fiberglass laminates. NDI data shows that this material should work for both pulse-echo (velocity-based) and resonance (acoustic impedance-based) inspections. Additional testing and industry review activities are underway to complete the validation of this material

Effect of mutual coupling on torque production in switched reluctance motors

In many cases, the normal operation of switched reluctance machines requires excitation of two or more phases simultaneously. When multiple phases are conducting simultaneously, the flux paths from each phase will overlap, which may lead to localized saturation. In such cases, the flux linkage must be considered a function not just of the current in the test winding but of all excited windings. The degree of mutual coupling between phases influences the per-phase magnetization curves and torque characteristics. In machines with even phase numbers, the degree of mutual coupling between phases varies due to discontinuities in the phase polarity arrangement. From nonlinear finite element simulations, it is possible to compare the i - loop diagrams under single-phase and multiphase excitations, and hence the torque produced. The mutual flux linkage from each phase can be calculated separately for each rotor position using the frozen permeability method, to further analyze the mutual coupling effects. For a given excitation current profile, the torque can be maximized by careful arrangement of the phase polarities