The charge density and pair correlation function of three interacting electrons confined within a two-dimensional disc-like hard wall quantum dot are calculated by full numerical diagonalization of the Hamiltonian. The formation of a Wigner-molecule in the form of equilateral triangular configuration for electrons is observed as the size of the dot is increased. PACS Numbers: 73.20.Dx, 73.61.-r

We report results obtained from six XMM–Newton observations of the Seyfert galaxy 1H 0419–577. The source was observed in a wide range of different flux levels, allowing its long–term spectral variability to be studied in detail as already reported by Pounds et al (2004a; 2004b). Here we show that the X–ray spectrum is well described by a simple two– component model comprising a power law with ...

Plint (IMechE 182 (1):300–306,1967) reported a reduced coefficient of friction with increasing roller sizes in EHL traction measurements. In this study, similar scale effect has been observed when comparing measured curves at the same operating conditions between ball-on-disc rig and twin-disc machine different geometrical sizes. This studied numerically for point contacts radii curvature Rx ba...

We present a unified semi-quantitative model for the disc-jet coupling in black hole X-ray binary systems. In the process we have compiled observational aspects from the existing literature, as well as performing new analyses. We argue that during the rising phase of a black hole transient outburst the steady jet known to be associated with the canonical ’low/hard’ state persists while the X-ra...

ABSTRACT We present a rapid timing analysis of optical (HiPERCAM and ULTRACAM) X-ray (NICER) observations the transient Swift J1858.6−0814 during 2018 2019. The light curves show relatively slow, large amplitude (∼1 mag in gs) ‘blue’ flares (i.e. stronger at shorter wavelengths) on time-scales ∼minutes as well fast, small (∼0.1 ‘red’ longer ∼seconds. are consistent with reprocessing optically t...

We consider hard-disc mixtures with disc sizes within ratio 2?1, that is, the small exactly fits in hole between four large discs. For each prescribed stoichiometry of and discs, densest packings are rigorously determined via a computer-assisted proof. The density is maximal for 1:1 stoichiometry: discs then form square grid interstitial site which nests. When there an excess made single phase ...

The hard disk drive industry has been under great cost pressures. Manufacturing has achieved very high levels of efficiencies and there is hardly any room for reducing costs any further by improving manufacturing. An area worth exploring is the design of the hard drives to further reduce the costs. Modular design helps in developing designs that will be amenable to cost reductions by identifyin...

We study the problem of ordering a collection of n numbers such that the maximum sum of k successive numbers is minimized. The problem occurs in the design of video servers and in-home hard disk recorders used for storage of video files. By alternately assigning the successive data blocks of a video file to the different zones of a hard disk one can guarantee a higher transfer rate over a given...

Contrary to the conventional method of disturbance observers (DOB) where Q-filter is designed to be a low-pass filter with unity DC gain, the optimal H1 method has been proposed to design the Q-filter and applied in the servo control system of hard disk drives in track following. Simulation and implementation results have shown that the resultant H1 DOB improves low-frequency disturbance attenu...

Piezoelectric nanopositioning actuators are widely employed in many applications, including the hard disk drives [1–3], gyroscopes [4] and the scanning probe microscopes [5]. Besides the precise position control, high-bandwidth tracking control is crucial for the applications of piezoelectric actuators, since, for example, it will allow hard disk drives to meet the demand for higher data storag...