In this paper, a stair-step-shaped magnetic pole structure is proposed to use in a permanent-magnet linear synchronous motor (PMLSM) for its application in an electromagnetic launch system. The aim ...of this configuration is to shape the air-gap flux density distribution produced by poles to be as close to a sine waveform as possible for the reduction of thrust ripple and the increase of motor controllability. An analytical model is derived for the PMLSMs by solving Maxwell equations and applying the superposition theorem for calculating the magnetic field, electromotive force, and thrust/torque of the motor. Magnet dimensions are then optimized using the analytical method and genetic algorithm, where the reduction of air-gap flux density harmonics is considered as the optimization target. Finally, the effectiveness of the proposed technique to enhance the motor performance is investigated by a time-stepping transient finite-element method. The results show an improvement in the optimal motor performance.
In the era of Big Data and the Internet of Things, data archiving is a key technology. From this viewpoint, magnetic recordings are drawing attention because they guarantee long‐term data storage. To ...archive an enormous amount of data, further increase of the recording density is necessary. Herein a new magnetic recording methodology, “focused‐millimeter‐wave‐assisted magnetic recording (F‐MIMR),” is proposed. To test this methodology, magnetic films based on epsilon iron oxide nanoparticles are prepared and a focused‐millimeter‐wave generator is constructed using terahertz (THz) light. Irradiating the focused millimeter wave to epsilon iron oxide instantly switches its magnetic pole direction. The spin dynamics of F‐MIMR are also calculated using the stochastic Landau–Lifshitz–Gilbert model considering all of the spins in an epsilon iron oxide nanoparticle. In F‐MIMR, the heat‐up effect of the recording media is expected to be suppressed. Thus, F‐MIMR can be applied to high‐density magnetic recordings.
A new magnetic recording methodology, “focused‐millimeter‐wave‐assisted magnetic recording (F‐MIMR)”, is demonstrated by irradiating a focused millimeter wave onto epsilon iron oxide. In F‐MIMR, the magnetic pole direction is instantly switched by the focused millimeter wave generated from terahertz light, and the heat‐up effect of the recording media is suppressed. Thus, F‐MIMR can be applied to high‐density magnetic recordings.
This study provides a detailed finding of the influence of pole and slot combinations on vibration and noise in external rotor axial flux in-wheel motors (AFWMs). Firstly, electromagnetic force ...exerted on the surface of permanent magnet is discussed and a two-dimensional fast Fourier transformation is implemented to analyse its spatial distribution and frequency characteristics. Then, a multiphysics model is developed to predict the vibration and noise and figure out the main origin from the perspective of electromagnetism. The influence of pole and slot combinations on vibration and noise is also analysed via the proposed model. Finally, the effect of load on vibration and noise in AFWMs is further investigated. It turns out that zeroth spatial order of axial electromagnetic force is the main origin of vibration and noise in axial flux motors, which is quite different from radial flux motors. Moreover, AFWMs with larger lowest common multiple (LCM) of pole number (2p) and slot number (Qs) show lower noise level and for the motors that satisfy LCM(2p,Qs) ≠ 6p, vibration and noise are greatly influenced by load. This study provides guidance for the design of low noise AFWMs.
Aims . During its all-sky survey phase, the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) X-ray telescope on board the Spectrum-Roentgen-Gamma (SRG) spacecraft scans through the ...ecliptic poles every 4 h. This extensive data set of long-duration, frequent, and consistent observations of thousands of X-ray sources is ideal for a detailed long-term X-ray-variability analysis. However, individual observations are short, are separated by long but consistent gaps, and have varying exposure times. Therefore, the identification of variable sources and the characterisation and quantification of their variability requires a unique methodology. We aim to develop and evaluate variability analysis methods for eROSITA observations, focusing on sources close to the survey poles. We also aim to detect intrinsically variable sources at any count rate and quantify the variability of low-count-rate sources. Methods . We simulate eROSITA-like light curves to evaluate and quantify the effect of survey mode observations on the measured periodogram and normalised excess variance. We introduce a new method for estimating the normalised intrinsic variance of a source based on the Bayesian excess variance (bexvar) method. Results . We determine thresholds for identifying likely variable sources while minimising the false-positive rate, as a function of the number of bins, and the average count rate in the light curve. The bexvar normalised intrinsic variance estimate is significantly more accurate than the normalised excess variance method in the Poisson regime. At high count rates, the two methods are comparable. We quantify the scatter in the intrinsic variance of a stationary pink-noise process, and investigate how to reduce it. Finally, we determine a description of the excess noise in a periodogram caused by varying exposure times throughout a light curve. Although most of these methods were developed specifically for analysing variable active galactic nuclei in the eROSITA all-sky survey, they can also be used for the variability analysis of other datasets from other telescopes, with slight modifications.
In this study, eighteen compressional P-wave seismic refraction profiles survey was conducted on the western side of the Gulf of Suez, Egypt, to map bedrock topography, which is vital information in ...foundation pole placement and design for large factory construction. The configuration of the seismic survey consists of 10 metres geophone intervals (12 and 24 channels) with a total survey length of 3150 metres survey length. The seismic compressional wave velocity distribution reveals three layers ranging from (400 to 1100 m/s), (1200 to 2000 m/s), and (2200 to 3500 m/s). According to the data, the first low-velocity layer represents unconsolidated Wadi sediments. The second layer, on the other hand, comprises consolidated Wadi sediments, while the third layer comprises fractured to intact sandstone bedrock. The thickness of the first layer is believed to be between 0.5 and 10 m, while the thickness of the second layer is between 8.5 and 25 m. Pseudo-3D model of velocity distribution was constructed, revealing the presence of several low-velocity zones at a depth ranging from 15 to 32 m. Then, the topography of the non-rippable sandstone rock mass was mapped utilizing 3-D model. Finally, the correlation between seismic refraction tomography (SRT) results and nearby well logging dataset drilled by the Egyptian Geological Survey and Mining Authority (EGSMA) matched quite well. It may be inferred that, up to a depth of 15 to 32 metres, there is a high-velocity rock layer suitable for constructing deep foundations for multiple levels of the mega factory.
Mitotic divisions depend on the timely assembly and proper orientation of the mitotic spindle. Malfunctioning of these processes can considerably delay mitosis, thereby compromising tissue growth and ...homeostasis, and leading to chromosomal instability. Loss of functional Mms19 drastically affects the growth and development of mitotic tissues in Drosophila larvae and we now demonstrate that Mms19 is an important factor that promotes spindle and astral microtubule (MT) growth, and MT stability and bundling. Mms19 function is needed for the coordination of mitotic events and for the rapid progression through mitosis that is characteristic of neural stem cells. Surprisingly, Mms19 performs its mitotic activities through two different pathways. By stimulating the mitotic kinase cascade, it triggers the localization of the MT regulatory complex TACC/Msps (Transforming Acidic Coiled Coil/Minispindles, the homolog of human ch-TOG) to the centrosome. This activity of Mms19 can be rescued by stimulating the mitotic kinase cascade. However, other aspects of the Mms19 phenotypes cannot be rescued in this way, pointing to an additional mechanism of Mms19 action. We provide evidence that Mms19 binds directly to MTs and that this stimulates MT stability and bundling.
A novel high-voltage operation featured wireless power transfer system for monitoring equipment charging on a 110-kV high-voltage transmission line based on magnetic resonant coupling is studied and ...designed in this paper. With consideration of operation environment on transmission line and electrical transmission tower, an overall scheme is proposed through installation position, coupling structure, and driving topology design. In order to improve the system's suitability in high-voltage environment, related optimization methods including constraining power flow path, improving quality factor, and coupling have been adopted. Since the coupling coils are fixed at both ends of an insulator string, a barrel-shaped high-permeability material layer is added to constrain the magnetic field distribution. Moreover, cross impacts between transmission line and the charging system are analyzed. The influence of a power frequency magnetic field on the charging system is calculated and electric distribution of the insulator string with the charging system is simulated. Analysis results indicate that cross impacts can be negligible. Experimental results verify that the transmission power can meet power supply requirements and the designed charging system can be operated stably under the high-voltage condition.
We show that the evaluation of scattering amplitudes can be formulated as a problem of multivariate polynomial division, with the components of the integration-momenta as indeterminates. We present a ...recurrence relation which, independently of the number of loops, leads to the multi-particle pole decomposition of the integrands of the scattering amplitudes. The recursive algorithm is based on the weak Nullstellensatz theorem and on the division modulo the Groebner basis associated to all possible multi-particle cuts. We apply it to dimensionally regulated one-loop amplitudes, recovering the well-known integrand-decomposition formula. Finally, we focus on the maximum-cut, defined as a system of on-shell conditions constraining the components of all the integration-momenta. By means of the Finiteness Theorem and of the Shape Lemma, we prove that the residue at the maximum-cut is parametrized by a number of coefficients equal to the number of solutions of the cut itself.
Over the last years, extreme weather events have caused extensive damages in power systems, leaving millions of customers without electricity and therefore highlighting the necessity to enhance power ...system resilience. This paper proposes a resilience constrained day-ahead unit commitment framework for increasing resiliency of a power system exposed to an extreme weather event. The weather-dependent failure probabilities of the transmission lines are taken into account in order to decide the scheduling of generators that minimizes load shedding in the most efficient way, while respecting operating limits of the system. The problem is formulated as a tri-level optimization problem that is transformed to a bi-level problem using duality theory and linearization techniques. The problem is solved as a two-stage robust optimization problem using a Column & Constraint Generation based decomposition algorithm. The master problem provides the unit commitment and the subproblem identifies the worst damage scenario due to weather event. A Sequential Monte Carlo simulation of a modified IEEE Reliability Test System and IEEE 118-bus System is applied to illustrate and validate the effectiveness of the proposed framework.
To establish a functional bipolar mitotic spindle, the centrosome expands and matures, acquiring enhanced activities for microtubule (MT) nucleation and assembly at the onset of mitosis. However, the ...regulatory mechanisms of centrosome maturation and MT assembly from the matured centrosome are largely unknown. In this study, we showed that heat shock protein (HSP) 70 considerably accumulates at the mitotic centrosome during prometaphase to metaphase and is required for bipolar spindle assembly. Inhibition or depletion of HSP70 impaired the function of mitotic centrosome and disrupted MT nucleation and polymerization from the spindle pole, and may thus result in formation of abnormal mitotic spindles. In addition, HSP70 may associate with NEDD1 and γ-tubulin, two pericentriolar material (PCM) components essential for centrosome maturation and MT nucleation. Loss of HSP70 function disrupted the interaction between NEDD1 and γ-tubulin, and reduced their accumulation at the mitotic centrosome. Our results thus demonstrate a role for HSP70 in regulating centrosome integrity during mitosis, and indicate that HSP70 is required for the maintenance of a functional mitotic centrosome that supports the assembly of a bipolar mitotic spindle.
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