Search

This paper presents a parallel-hybrid-excited linear vernier machine (PHE-LVM) for direct-drive oceanic wave power generation. By equipping a set of field winding in the mover yoke, hybrid excitation for the proposed PHE-LVM is realized: the air-gap flux can be flexibly controlled via adjusting the magnitude and polarity of the DC current in the field winding. With this merit, the operating performances in the wave power generation, such as the output voltage, load capacity and power factor can be improved. Firstly, the proposed PHE-LVM topology based on homopolar machine configuration is presented, with the consequent-pole PM poles mounted on the surface of the stator, while the DC field winding is wound around the mover yoke. Secondly, the operating principle of the proposed PHE-LVM is described with corresponding theoretical analysis. Thirdly, by using the 3-D finite element method, the power generation performances of the proposed PHE-LVM are evaluated. Finally, a prototype machine is also implemented and tested. Experimental results well agree with the analytical data. [ABSTRACT FROM AUTHOR]

This paper presents an experimental characterization and comparison of the performances achieved by a Tubular Linear Induction Motor (TLIM) prototype with different typologies of primary winding connections. More in detail, three different configurations have been considered, analyzed and discussed: full-pitch star, 5/6 shortened pitch star and 5/6 shortened pitch double star. For this purpose, an experimental test bench at the Sustainable Development and Energy Saving Laboratory (SDESLab), University of Palermo, Italy, has been set-up. The obtained results have allowed the identification of the best winding configuration for different applications intended for the motor. Moreover, in comparison with classic approaches that involve mathematical equations for winding design, the proposed experimental work is suitable for TLIM winding designs: indeed, more accurate results are obtained and approximation coefficients avoided. [ABSTRACT FROM AUTHOR]

This paper describes the development of a real time error measuring device for the simultaneous measurement of movement errors in straightness, yaw and roll in a linear machine stage. It was designed specifically for measuring errors in the spatial positioning of meso-scale machine tool stages. The arrangement of the optical path and design of the optical elements make it easy install the device on a linear stage. Roll, yaw and horizontal straightness error motions are sensed using the reflection of a laser beam from a plane mirror. A nonlinear measurement model was derived and simulation analysis showed this could be linearized when the measurement angle error was smaller than 0.05°. The measurement ranges of the proposed system are ±30″ for θ x , ±20″ for θ y and ±30 μm for the z-axis. The measurement precision was verified using a laser interferometer and an electronic level and the accuracy of the angular error and straightness error measurements were found to be in the range of ±0.25″ and ±0.5 μm respectively. The extended measurement uncertainties (95% confidence level) were: 0.46″ for θ x error motion; 0.46″ for θ y error motion; and 0.616 μm for straightness. [ABSTRACT FROM AUTHOR]

Free-piston engines (FPEs) are known to have a greater thermal efficiency (40–50%) than an equivalent and more conventional four-stroke reciprocating engines (30–40%). Modern FPEs are proposed for the generation of electric and hydraulic power, with a potential application in hybrid electric vehicles. The numerous FPE configurations considered to date have almost exclusively operated using a two-stroke thermodynamic cycle to improve the thermal efficiency, however it is well known that the application of two-stoke cycles can be limited by noise and exhaust gas emissions constraints. In this article, a numerical model is used to investigate the techno-feasibility of operating Newcastle University’s FPE prototype using a two- or four-stroke thermodynamic cycle. If operated as a four-stroke cycle, the linear generator must be used as both a motor and a generator resulting in a more irregular piston motion compared to corresponding operating in a two-stroke cycle. In four-stroke cycles, almost half the indicated power is consumed in overcoming the pumping losses of the motoring process. Whilst the heat release process is appears to be closer to a constant volume process when operated on two-stroke engine cycle, the peak cylinder pressure and compression ratio proved lower. In addition, a narrower power range is reported for a four-stroke cycle despite a corresponding higher thermal efficiency. [ABSTRACT FROM AUTHOR]

In this study we apply the Support Vector Machine (SVM) combined together with Distance Correlation (DC) to the forecasting of Dst index by using 80 intense geomagnetic storms ( Dst ≤ − 100 nT ) from 1995 to 2014. We also train the Neural Network (NN) and the Linear Machine (LM) to verify the effectiveness of SVM. The purpose for us to introduce DC is to make feature screening in input datasets that can effectively improve the forecasting performance of the SVM. For comparison, we estimate the correlation coefficients (CC), the RMS errors, the absolute value of difference in minimum Dst ( Δ Dst min ) and the absolute value of difference in minimum time ( Δ t Dst ) between observed Dst and predicted one. K -fold Cross Validation is used to improve the reliability of the results. It is shown that DC-SVM model exhibits the best forecasting performance for all parameters when all 80 events are considered. The CC, the RMS error, the Δ Dst min , and the Δ t Dst of DC-SVM are 0.95, 16.8 nT, 9.7 nT and 1.7 h, respectively. For further comparison, we divide the 80 storm events into two groups depending on minimum value of Dst . It is also found that the DC-SVM is better than other models in the two groups. [ABSTRACT FROM AUTHOR]

An industrial ozone generator with 35 parallel tubular electrodes attached in the same enclosure was developed. Each tubular electrode consists of a stainless steel tube behaves as a ground electrode. A borosilicate glass tube was used as a dielectric material. The aluminum granules with sharp edges were filled in all the glass tubes. The aluminum granules in all 35 tubes were connected in parallel to the HV electrode. The outer surface of the stainless steel tubes was cooled by water. The aluminum granules electrodes were used in this novel ozone generator to improve the efficiency of ozone generation. [ABSTRACT FROM AUTHOR]

Abstract: Guides in machine tools aim for high accuracy, stiffness and damping. However, these characteristics are mainly limited by the working principle. In this paper, the implementation of electromagnetic guides in linear machine tool axes is evaluated. A milling machine prototype, with the opportunity of using ball guides or electromagnetic guides in the z-axis, is employed. Primarily, working principle and properties of the electromagnetic guide are presented and analyzed. Operating behaviour, stiffness and damping of the two guiding principles are compared. The electromagnetic guide is finally assessed in the milling process and beneficial functions of the system are presented. [Copyright &y& Elsevier]