Design of a small disc-type coreless permanent magnet brushed DC actuator

Purpose Design of small disc-type permanent magnet (PM) brushed DC motors for servomechanisms is challenging. The purpose of this paper is to propose a special coreless double-sided structure. This easy to manufacture motor has two set of shifted concentrated windings on both sides of the rotor. All of the coils in each winding are simply connected in series. A simple arcless commutator, which shares the features of both the usual commutators and slip rings, is connected to each winding at only two points. Design/methodology/approach By replacing the PMs with an equivalent current density, main design equations of the motor have been derived through the solving of scalar Poisson equation. A radial division technique has been used to take the radial variations into account. This provides the ability of considering various shapes of coils and PMs. A novel iterative algorithm has been proposed to design a motor with high torque capability, compared to other coreless counterparts. Some design variables are obtained based on an independent optimization problem, which maximizes the active portion of windings. The other variables are calculated in such a way that the design requirements are satisfied. Findings The feasibility and capability of the new structure have been proved by prototyping a sample motor. Comparing the design outputs with the results of the 3D finite element analysis and experimental tests shows a good agreement. This verifies the accuracy of the proposed design method. Originality/value A new structure for PM brushed DC motors and a novel algorithm for its design has been developed.

A bronze mirror with Aphrodite and Eros from Nicomedia in Bithynia (northwestern Turkey)

The Archeological and Ethnographical Museum of Kocaeli has in its collection a small, disc–shaped bronze mirror decorated with a relief scene, whose protagonist is the goddess Aphrodite. The scene shows Aphrodite seated left of centre on a rock. She is accompanied by two figures, a female who stands on a pedestal in front of her and her young son, Eros, who is behind her. This formerly unpublished object was found in Nicomedia in Bithynia, and has been dated to the fourth century BC. This paper will give a detailed presentation of the mirror relief scene, focus on its art–historical contextualisation and argue a first century BC. date for this object.

Computed Tomographic Diagnosis of Intracranial Granulomatous Lesions and Clinical Correlation

Background: The evaluation of intracranial granulomatous lesions with emphasis particularly on tuberculoma and neurocysticercosis. Intracranial granulomatous lesions especially tuberculosis and neurocysticercosis are potentially lethal diseases and therefore prompt diagnosis and treatment are imperative. Cysticercosis of the brain is a disease entity that is a easily demonstrable by CT and is confined to the endemic areas in majority of cases. Aim: To identify and the role of computed tomography (CT) in diagnosing intracranial granulomatous lesions and to correlate the findings with clinical health care. Materials and Methods: This study was done at Ganesh Shankar Vidyarthi Medical (GSVM) College, Kanpur, Uttar Pradesh, India during the period 2002 to 2003. The patients admitted with seizures were included after considering the exclusion of metabolic causes and infective causes. 50 cases of documented antecedent history suggestive of raised intracranial tension and seizure (focal or generalized) were evaluated and referred for CT scanning from out patients department and in patients department in Lala Lajpat Rai (LLR) and associated hospitals and GSVM College, Kanpur, India. Results: We prospectively noted in our study that more than half of the patients with chronic granulomatous lesions presented with raised intracranial tensions. Seizure was one of the most commonest presenting complaint in patients with neurocysticercosis diagnosis. Presumptive diagnosis of tuberculoma and neurocysticercosisis was based on clinical and other ancillary criteria. Associated family history and extracerebral tuberculosis are the important criteria for presumptive diagnosis of tuberculoma. Solitary lesions were more frequent CT finding in both tuberculoma and neurocysticercosis. Majority of tuberculomas and neurocysticercosis observed were supratentorial in location, regardless of their clinical presentation. Lesions were isodense or hyperdense on plain CT scan and showed peripheral enhancement with intravenous contrast injection. The lobulated masses represent coalesced small disc and rings forming a large tuberculoma. Conclusion: In our study we have tried to evaluate intracranial granulomatous lesions with emphasis particularly on tuberculoma and neurocysticercosis.

Evolution of α Centauri b’s protoplanetary disc

ABSTRACT With hydrodynamical simulations we examine the evolution of a protoplanetary disc around α Centauri B including the effect of the eccentric orbit binary companion α Centauri A. The initially circular orbit disc undergoes two types of eccentricity growth. First, the eccentricity oscillates on the orbital period of the binary, Porb, due to the eccentricity of the binary orbit. Secondly, for a sufficiently small disc aspect ratio, the disc undergoes global forced eccentricity oscillations on a time-scale of around $20\, P_{\rm orb}$. These oscillations damp out through viscous dissipation leaving a quasi-steady eccentricity profile for the disc that oscillates only on the binary orbital period. The time-averaged global eccentricity is in the range 0.05–0.1, with no precession in the steady state. The periastrons of the gas particles are aligned to one another. The higher the disc viscosity, the higher the disc eccentricity. With N-body simulations we examine the evolution of a disc of planetesimals that forms with the orbital properties of the quasi-steady protoplanetary disc. We find that the average magnitude of the eccentricity of particles increases and their periastrons become misaligned to each other once they decouple from the gas disc. The low planetesimal collision velocity required for planet formation suggests that for planet formation to have occurred in a disc of planetesimals formed from a protoplanetary disc around α Centauri B, said disc’s viscosity must be have been small and planet formation must have occurred at orbital radii smaller than about $2.5\, \rm au$. Planet formation may be easier with the presence of gas.

Ultralow Profile, Low Passive Intermodulation, and Super-Wideband Ceiling Mount Antennas for Cellular and Public Safety Distributed Antenna Systems

This paper presents an ultralow profile, low passive intermodulation (PIM), and super-wideband in-building ceiling mount antenna that covers both the cellular and public safety ultra high frequency (UHF) band for distributed antenna system (DAS) applications. The proposed antenna design utilizes a modified 2-D planar discone design concept that is miniaturized to fit into a small disc-shaped radome. The 2-D planar discone has an elliptical-shaped disc monopole and a bell-shaped ground plane, a stub at the shorting path, with asymmetrical structure and an additional proximity coupling patch to maximize the available electrical path to support the 350 MHz band range. The proposed design maximizes the radome area with a reduction of about 62% compared to similar concept type antennas. Besides, the proposed design exhibits an improved radiation pattern with null reduction compared to a typical dipole/monopole when lies at the horizontal plane. A prototype was manufactured to demonstrate the antenna performance. The VSWR and radiation pattern results agreed with the simulated results. The proposed antenna achieves a band ratio of 28.57:1 while covering a frequency range of 350–10000 MHz. The measured passive intermodulation levels are better than −150 dBc (2 × 20 Watts) for 350, 700 and 1920 MHz bands.

The thermal-radiative wind in low-mass X-ray binary H1743−322 – II. Iron line predictions from Monte Carlo radiation transfer

ABSTRACT We show the best current simulations of the absorption and emission features predicted from thermal-radiative winds produced from X-ray illumination of the outer accretion disc in binary systems. We use the density and velocity structure derived from a radiation hydrodynamic code as input to a Monte Carlo radiation transport calculation. The initial conditions are matched to those of the black hole binary system H1743−322 in its soft, disc dominated state, where wind features are seen in Chandra grating data. Our simulation fits well to the observed line profile, showing that these physical wind models can be the origin of the absorption features seen, rather than requiring a magnetically driven wind. We show how the velocity structure is the key observable discriminator between magnetic and thermal winds. Magnetic winds are faster at smaller radii, whereas thermal winds transition to a static atmosphere at smaller radii. New data from XRISM (due for launch 2022 January) will give an unprecedented view of the physics of the wind launch and acceleration processes, but the existence of static atmospheres in small disc systems already rules out magnetic winds which assume self-similar magnetic fields from the entire disc as the origin of the absorption features seen.

Self-Assembly in Ganglioside‒Phospholipid Systems: The Co-Existence of Vesicles, Micelles, and Discs

Ganglioside lipids have been associated with several physiological processes, including cell signaling. They have also been associated with amyloid aggregation in Parkinson’s and Alzheimer’s disease. In biological systems, gangliosides are present in a mix with other lipid species, and the structure and properties of these mixtures strongly depend on the proportions of the different components. Here, we study self-assembly in model mixtures composed of ganglioside GM1 and a zwitterionic phospholipid, 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC). We characterize the structure and molecular dynamics using a range of complementary techniques, including cryo-TEM, polarization transfer solid state NMR, diffusion NMR, small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and calorimetry. The main findings are: (1) The lipid acyl chains are more rigid in mixtures containing both lipid species compared to systems that only contain one of the lipids. (2) The system containing DOPC with 10 mol % GM1 contains both vesicles and micelles. (3) At higher GM1 concentrations, the sample is more heterogenous and also contains small disc-like or rod-like structures. Such a co-existence of structures can have a strong impact on the overall properties of the lipid system, including transport, solubilization, and partitioning, which can be crucial to the understanding of the role of gangliosides in biological systems.

Additional contributions to the knowledge of Philippine predatory mites mainly of the subfamilies Cunaxinae and Cunaxoidinae (Acari: Prostigmata: Cunaxidae)

A new species of cunaxid mite belonging to the subfamily Cunaxinae, Cunaxa minidiscondyla sp. nov., is described from the Philippines. This species is distinctive by the presence of a small disc-shaped apophysis dorsodistally on the palp telofemur, two spine-like setae on the palp genu, a long spine-like seta on the palp tibiotarsus, an ill-defined propodosomal shield, the absence of a median hysterosomal shield, long hysterosomal setae, and basifemoral and telofemoral chaetotaxy of 4-4-3-1 and 5-5-4-4, respectively. The previously unknown female of Lupaeus longisetus (Cunaxoidinae) and unknown male of Dactyloscirus trifidus (Cunaxinae) are described. A supplementary description is provided for Scutopalus clavatus (Cunaxoidinae) which is recorded for the first time in the Philippines on coconut leaves infested with the scale insect, Aspidiotus rigidus. New locality and habitat data are given for some species of the aforementioned subfamilies, as well as the subfamilies Bonzinae and Orangescirulinae.