PERMANENT magnet generators, MAGNETIC alloys, AMORPHOUS alloys, MAGNETIC materials, PERMANENT magnets, AMORPHOUS substances, and MAGNETIC cores

This paper deals with the design, prototyping, and testing of a high-speed permanent magnet generator with a stator magnetic core made of amorphous magnetic material (AMM) for aerospace applications. The target operative speed range is 30 000–60 000 rpm with an output power range between 50 and 300 kW. Two types of winding are examined and compared: tooth-coil and distributed. Special attention is dedicated to the rotor dynamics aspects of the solid disk magnet rotor assembly. The multidisciplinary design process is described. Electromagnetic calculations are provided for different operative conditions where the magnetic field and loss distribution are determined. Based on the design results, a full-size prototype rated at 120 kW and 60 000 rpm rotational speed featuring a stator core made of AMM has been developed and tested. The test results proved the high efficiency achievable with the described technical solutions. It has been proved that the use of AMMs in high-speed electrical machines enables to minimize losses in the stator magnetic core by five to seven times in comparison with traditional materials. [ABSTRACT FROM AUTHOR]

WIRELESS power transmission, ELECTRIC vehicle batteries, FINITE volume method, PLUG-in hybrid electric vehicles, THERMAL analysis, COMPUTATIONAL fluid dynamics, HEAT, and DISC brakes

By employing Wireless Power Transfer (WPT), the complexities of wire utilization are eliminated in charging electric devices, especially Electric Vehicles (EVs) and Plug-in Hybrid Electric Vehicles (PHEVs). WPT can be used in both stationary and dynamic modes to charge battery of EVs and PHEVs. There are few magnetic structures that are used as transmitter and receiver sides of WPT to improve the efficiency. A first of its kind, this paper conducted a temperature analysis for three substantial pads including Double-D Pad (DDP), Double-D Quadrature Pad (DDQP), and Bipolar Pad (BPP). For this, the electromagnetic finite element method and finite volume computational fluid dynamics were employed simultaneously. After the two-way solution of the electromagnetic and thermal energy equations, the temperature distribution in all the components of the primary and secondary pads was obtained in the aligned and misaligned positions. In doing so, the material characteristics were considered as temperature-dependent. Finally, with DDP as a transmitter; and DDP, DDQP, and BPP as receivers, prototyping was conducted to verify the analytical results, and to validate that the procedure employed in this study is capable of being applied to conventional and innovative types of WPT magnetic structures. • Thermal analysis of three substantial pads is conducted for wireless power transfer. • Electromagnetic finite element and finite volume approaches are employed simultaneously. • Temperature distribution in all components of primary and secondary pads is obtained. • Current method can be used for common and novel types of wireless power transfer structures. [ABSTRACT FROM AUTHOR]

DIRECT currents, AREA measurement, REACTION time, ELECTRIC inductance, VOLT-ampere reactive, PULSE width modulation transformers, ELECTRIC inverters, and TESTING laboratories

Failure of the commutation process is a serious malfunction in line-commutated high-voltage direct current (HVdc) converters, which mainly occurs due to inverter ac faults and may lead to outage of the HVdc system. In this paper, an improved strategy is developed that functions based on the SIEMENS HVdc control system under normal conditions and switches to a designed commutation failure inhibition module (CFIM) during an inverter ac fault. From the response speed point of view, since the designed CFIM does not require any proportional-integral controller, the inverter control system has a quick performance in prevention of the commutation failure. This is achieved by direct measurement of the overlap area using the waveforms of the valves anode–cathode and commuting voltages. In addition, from the accuracy aspect, the proposed method has a superior performance in comparison with the existing strategies. It is because of the fact that by direct measurement of the overlap area, variations of both direct current and the commutation inductance are considered, and hence, the unnecessary increase of the inverter reactive power consumption during the fault and the repetitive commutation failures are prevented. The practical performance and feasibility of the proposed strategy is validated through the laboratory testing, using the real-time Opal-RT hardware prototyping platform. The experimental results demonstrate that the proposed strategy can effectively inhibit the commutation failure or repetitive commutation failures under different fault types by considering the lowest possible reactive power consumption. [ABSTRACT FROM AUTHOR]

SOFTWARE-defined networking (Computer network technology), INFORMATION sharing, and MEASUREMENT errors

Software Defined Networking (SDN) is the latest networking paradigm that espouses the separation of the control plane from the data plane for increased flexibility in the routing of flows through the network. Closely associated with SDN is OpenFlow, the most widely used protocol governing the information exchange between the data plane (switching devices) and the control plane (controller). The ease of implementing and testing new schemes in SDN has prompted many researchers to adopt the experimental and prototyping approach to validate their ideas. While the experimentation approach in validation has merits, analytical modelling provides valuable insights by making explicit the dependence of SDN performance on chosen parameters of interest. However, there is no exact queueing analysis of SDN with OpenFlow switches. In this paper, (i) we propose a queueing model of an OpenFlow–based SDN that takes into account classful treatment of packets arriving at a switch and (ii) provide an exact analysis of the proposed queueing model. In tandem, these two aspects have not been accurately modelled (if at all) by the handful of research done in this area. The proposed queueing model is validated by simulation and measurements on a test network and the prediction errors for simulation and measurements are lower than 2% and 10.5% respectively. [ABSTRACT FROM AUTHOR]

MAINTENANCE, ERROR correction (Information theory), PREDICTION models, CELLULAR aging, LITHIUM-ion batteries, and FUEL cells

This paper proposes a novel error correction grey prediction model for degradation prediction of renewable energy storages. The proposed approach uses an error correction factor ψ to eliminate the inherent error of the original grey model (GM), and at the same time retain the original simplicity and fast prototyping. In addition, due to the uncertainty and complexity of failure mechanisms, a trigonometric residual modification is considered in order to well-describe the influence of operating conditions or cyclic fluctuation on the renewable energy storages. Two experimental case studies, including lithium-ion battery and fuel cell aging tests, are performed to validate the performance of the proposed method. In particular, the accuracy of the proposed method is investigated for different prediction horizon lengths, in order to further demonstrate its effectiveness and robustness. It is worth mentioning that the proposed method can ensure the accuracy of the remaining useful life estimation in the case of long-term forecasting, and thus, the maintenance management and corrective action of renewable energy storages can be scheduled earlier, leading to more effective cost minimization and risk mitigation. [ABSTRACT FROM AUTHOR]

ARDUINO (Microcontroller), SPECTRAL irradiance, SOLAR spectra, SOLAR cells, PHOTOVOLTAIC cells, LIGHT emitting diodes, and SOLAR thermal energy

Solar simulators are a fundamental instrument to characterize solar cells parameters, as they can reproduce the operating conditions under which the solar cells are going to work. However, these systems are frequently big, heavy, and expensive, and a small solar simulator could be a good contribution to test small prototyping devices manufactured in research labs, especially if it could manage the irradiation at any wavelength interval in a custom way. We have designed, developed, and calibrated a small solar simulator made entirely with LEDs, no optics inside, and electronically controlled through a PC using an Arduino microcontroller. The whole structure is 3-D printed in black PLA plastic. The electrical current through the LEDs, and thus the spectral irradiance of the simulator, is controlled with a very intuitive LabVIEW interface. As our calibration proves, we have built an easily reproducible and low-cost Class AAA solar simulator in a central illumination area of 1 cm2, according to the IEC60904-9 standard. This means that the homogeneity in that area is under a 2% deviation in spatial terms, below 0.5% in temporal terms, and is a factor of a 3% close to the AM1.5G sun reference spectrum. The system can be built and used in any research lab to get quick tests of new small solar cells of any material. [ABSTRACT FROM AUTHOR]

CRYPTOCURRENCIES and GEOGRAPHY

These companies didn't have to compete with Google and Amazon because of the constraints the Chinese government would put on those companies if they were operating in China, so the China-native companies have gotten huge. The second point I would make is that, to a certain extent, the big three companies are China companies, but if you look at the patterns of their acquisitions, they are increasingly trying to acquire companies outside of China. The three China behemoths are definitely China-centered, but they are acquiring companies outside of China which, perhaps in stealth, can extend their capabilities outside. In China, prototyping cycles happen much faster than they do in the United States, which is why it's no accident that a company like DJI came from China and rocked the United States drone industry; it's because DJI is a hardware company. [Extracted from the article]