A new method for determining the magnetic properties of solid materials employed in unconventional magnetic circuits

The mechanical and thermal properties of common, solid (non-laminated) ferromagnetic materials are widely available, but the electro-magnetic characteristics of such solid materials are often undefined. Existing characterization procedures such as the toroidal ring sample test method are capable of mapping the electro-magnetic properties of solid materials quite accurately when investigating materials to be used in conventional magnetic circuits, i.e. where the flux paths and induced eddy currents follow the more common ‘radial’ characteristics as in a standard rotating machine. When solid ferromagnetic material is employed in unconventional machine structures, such as for transverse flux machines or tubular linear machines, simple toroidal test methods do not accurately represent the flux conditions in the stator material. In this paper a new testing method is proposed to accurately impose the correct flux conditions for tubular linear machines. The proposed method uses a simple experimental test setup to characterize the magnetic properties of solid, ferro-magnetic material. The basic experimental results from the new setup are compared to results from 3D finite element analysis

Design, Synthesis and Characterization of New Superconductors

Design and synthesis of new materials are a long-standing goal for chemistry, physics and material science, especially those with intriguing properties such as magnetism and superconductivity. With consideration and incorporation of the highlights in some existing design rules, we successfully designed and discovered the superconductivity in BaPt2Bi2, SrSnP and YbxPt5P. With the help of valence electron counting method, we synthesized a new intermetallic compound, BaIr2Ge2, which was then found to be non-superconducting above 1.8 K. Thus, we considered both valence electron counting and chemical pressure adjustment to reach the superconductivity of BaPt2Bi2 (Tc = 2.0 K) which crystallizes in a structure highly related to the parent compound of one of the high-temperature superconductors, BaFe2As2. According to the bonding analysis, Pt-Pt and Pt-Bi antibonding interactions are believed to be responsible to superconductivity in such system. In order to find more superconductors with Pt-Bi critical charge transfer pair, with the help from adaptive genetic algorithm, we synthesized SrPtBi2 for the first time. Theoretical calculation reveals that Pt-Bi antibonding interaction exists in SrPtBi2 but does not induce superconductivity while few Pt-Pt interaction can be found. Guided by the famous bismuthate superconductor, Ba1-xKxBiO3, we successfully observed the superconductivity in a known compound, SrSnP, at Tc = 2.3 K. The bonding analysis indicates that the Sn-P antibonding interaction and Sr-P bonding interaction are essential in releasing more electrons from Sn atom and, thus, provide more possibilities for electrons to form Cooper pair which is significant for superconductivity based on BCS theory. Due to the fact that there exist many superconducting Pt-rich materials, the ones with Pt-P charge transfer pair were also tested with the success in synthesizing APt8P2 (A = Ca and La) and YbxPt5P. APt8P2 compounds were determined to be non-superconducting above 1.8 K. The bonding analyses for them provided the evidence for structural stability. However, YbxPt5P was observed to be superconducting below Tc = 0.6 K while large heat capacity anomaly attributed to magnetism can be found below Tc which implies the possible coexistence of superconductivity and magnetism

Consideration on Eddy Current Reduction Techniques for Solid Materials Used in Unconventional Magnetic Circuits

The use of solid materials in tubular, linear machines has significant manufacturing benefits, as this removes the need for an axially laminated stator. However, this comes at the cost of extra eddy current losses. In this paper, a detailed analysis of the behavior of eddy currents in a tubular permanent magnet machine that comprises unconventional magnetic circuit is given, highlighting the importance of the field distribution and current directions, when compared with conventional magnetic circuits. This analysis is then used to identify and investigate the appropriate eddy current reduction methods for tubular machines, when a solid material stator is being used. Accurate three-dimensional models have been built and then validated on previously built testing setups. Different winding configurations have been accounted. Finally, considerations of these techniques are given when being implemented into an actual, tubular machine design, highlighting the improved performance and losses

Integrated Circuits/Microchips

With the world marching inexorably towards the fourth industrial revolution (IR 4.0), one is now embracing lives with artificial intelligence (AI), the Internet of Things (IoTs), virtual reality (VR) and 5G technology. Wherever we are, whatever we are doing, there are electronic devices that we rely indispensably on. While some of these technologies, such as those fueled with smart, autonomous systems, are seemingly precocious; others have existed for quite a while. These devices range from simple home appliances, entertainment media to complex aeronautical instruments. Clearly, the daily lives of mankind today are interwoven seamlessly with electronics. Surprising as it may seem, the cornerstone that empowers these electronic devices is nothing more than a mere diminutive semiconductor cube block. More colloquially referred to as the Very-Large-Scale-Integration (VLSI) chip or an integrated circuit (IC) chip or simply a microchip, this semiconductor cube block, approximately the size of a grain of rice, is composed of millions to billions of transistors. The transistors are interconnected in such a way that allows electrical circuitries for certain applications to be realized. Some of these chips serve specific permanent applications and are known as Application Specific Integrated Circuits (ASICS); while, others are computing processors which could be programmed for diverse applications. The computer processor, together with its supporting hardware and user interfaces, is known as an embedded system.In this book, a variety of topics related to microchips are extensively illustrated. The topics encompass the physics of the microchip device, as well as its design methods and applications

Resident research associateships. Postdoctoral and senior research awards: Opportunities for research at the Jet Propulsion Laboratory

Opportunities for research as part of NASA-sponsored programs at the JPL cover: Earth and space sciences; systems; telecommunications science and engineering; control and energy conversion; applied mechanics; information systems; and observational systems. General information on applying for an award for tenure as a guest investigator, conditions, of the award, and details of the application procedure are provided