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Sharrock [1][2] derived a law about the time-dependent coercivity for hard magnetic materials Hc(t)=H0{1−[kBT/KV×ln(At/0.693)]1/2}(1) Conventional micromagnetics using the Landau-Lifshitz (LL) equations, with a thermal fluctuation field and temperature-dependent parameters included, can take the thermal activation into account; however, the energy minimum cannot be achieved.
Microwave assisted magnetic recording (MAMR) technology, with microwave generated by the spin transfer oscillator (STO) as energy assisted source, is potential for future magnetic recording technique.
One recent focus in spintronics is the observation of giant magnetoresistance (GMR) in organic spin-valve (OSV). Sandwiched by two ferromagnetic (FM) layers, organic semiconductor (OSC) was incorporated into the spin-valve structure to take advantage of its low spin-orbit interaction so that the coherence of spin-polarized carriers can be preserved over an extended time. The observation of GMR in...
Spin-torque oscillator (STO) with reference layer (REF) has been proposed to be an efficient way to excite oscillation at low current density [1-2]. A well-controlled STO is the center part of microwave assisted magnetic recording (MAMR); however, in the recording process, the STO is exposed in an alternative external head field in addition to the applied current [3-4]. To assist the writing in MAMR,...
Microwave assisted magnetic recording (MAMR) is a promising candidate to achieve the areal density above 1Tb/in2 [1]. Nowadays CoX/Pt multilayer is chosen as the media for STO MAMR due to its ultrahigh interfacial anisotropy [2]. In this paper, a micromagnetic model is utilized for recording simulation on high anisotropy (Hk >25 kOe) CoX/Pt media, with Voronoi polycrystalline built up based on...
The CoX/Pt multilayer (X here represents the doping element to form grain boundary) is considered as the potential future medium owing to its high interfacial perpendicular anisotropy [1] utilized in magnetic assisted magnetic recording (MAMR) [2]. Meanwhile, microwave assisted reversal in Co/ Pt and Co/Pd has been reported in experiments [3,4]. The magnetic property and its writability of the CoX/Pt...
This paper proposes a methodology to assess cyber-related risks and to identify critical assets both at power grid and substation levels. The methodology is based on a two-pass engine model. The first pass engine is developed to identify the most critical substation(s) in a power grid. A mixture of Analytical hierarchy process (AHP) and (N-1) contingent analysis is used to calculate risks. The second...
Driving tasks are vulnerable to the effects of sleep deprivation and mental fatigue, diminishing driver's ability to respond effectively to unusual or emergent situations. Physiological and brain activity analysis could help to understand how to provide useful feedback and alert signals to the drivers for avoiding car accidents. In this study we analyze the insurgence of mental fatigue or drowsiness...
This paper presents an algorithm that stabilizes video and reduces rolling shutter distortions using a six-parameter affine model that explicitly contains parameters for translation, rotation, scaling, and skew to describe transformations between frames. Rolling shutter distortions, including wobble, skew and vertical scaling distortions, together with both translational and rotational jitter are...
This paper introduces a new way to detect and improve the vulnerability of bulk power systems against the intrusion and malicious acts of cyber hackers. For this aim, detecting the most vulnerable part of the power grid to hacker attack is needed. The method for finding the most vulnerable substation inside the grid (fist pass model) and then finding the most critical asset inside that substation...
This paper considers two problems in sparse filter design, the first involving a least-squares constraint on the frequency response, and the second a constraint on signal-to-noise ratio relevant to signal detection. It is shown that both problems can be recast as the minimization of the number of non-zero elements in a vector subject to a quadratic constraint. A solution is obtained for the case in...
This paper presents a method for designing sparse FIR filters by means of a sequence of p-norm minimization problems with p gradually decreasing from 1 toward 0. The lack of convexity for p < 1 is partially overcome by appropriately initializing each subproblem. A necessary condition of optimality is derived for the subproblem of p-norm minimization, forming the basis for an efficient local search...
The performance of several unstructured peer-to- peer (P2P) content discovery techniques over ad hoc networks was analyzed in this work. They include: query flooding, expanding ring search, random walk and Bloom filter(BF)-based probabilistic routing. The chosen performance metrics are the query success rate, the route stretch and the search cost. Mathematic analysis is conducted to predict their...
When heterogeneous congestion control protocols that react to different pricing signals (e.g. packet loss, queueing delay, ECN marking etc.) share the same network, the current theory based on utility maximization fails to predict the network behavior. Unlike in a homogeneous network, the bandwidth allocation now depends on router parameters and flow arrival patterns. It can be non-unique, inefficient...
A computer simulator of the excitation and recovery process of the human heart is described which consists of three main parts: the heart model editor, the simulation calculator, and the display unit. Action potential waveforms and other physiological parameters such as the conduction speed and the refractory period can be arbitrarily modified and assigned to different kinds of model cells. A variety...
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