Bit Patterned Media (BPM) for magnetic recording provides a route to thermally stable data recording at >1 Tb/in 2 and circumvents many of the challenges associated with extending conventional granular media technology. Instead of recording a bit on an ensemble of random grains, BPM is comprised of a well ordered array of lithographically patterned isolated magnetic islands, each of which stores one bit. Fabrication of BPM is viewed as the greatest challenge for its commercialization. In this article we describe a BPM fabrication method which combines rotary-stage e-beam lithography, directed self-assembly of block copolymers, self-aligned double patterning, nanoimprint lithography, and ion milling to generate BPM based on CoCrPt alloy materials at densities up to 1.6 Td/in 2 (teradot/inch 2 ). This combination of novel fabrication technologies achieves feature sizes of <10 nm, which is significantly smaller than what conventional nanofabrication methods used in semiconductor manufacturing can achieve. In contrast to earlier work which used hexagonal closepacked arrays of round islands, our latest approach creates BPM with rectangular bitcells, which are advantageous for integration of BPM with existing hard disk drive technology. The advantages of rectangular bits are analyzed from a theoretical and modeling point of view, and system integration requirements such as provision of servo patterns, implementation of write synchronization, and providing for a stable head-disk interface are addressed in the context of experimental results. Optimization of magnetic alloy materials for thermal stability, writeability, and tight switching field distribution is discussed, and a new method for growing BPM islands from a specially patterned underlayer -referred to as "templated growth" -is presented. New recording results at 1.6 Td/in 2 (roughly equivalent to 1.3 Tb/in 2 ) demonstrate a raw error rate <10 -2 , which is consistent with the recording system requirements of modern hard drives. Extendibility of BPM to higher densities, and its eventual combination with energy assisted recording are explored.Index Terms-Bit patterned media, hard disk drive, block copolymer, self-assembly, double patterning, e-beam lithography, sequential infiltration synthesis, nanoimprint lithography, templated growth, thermal annealing, Co alloys, magnetic multilayers, interface anisotropy, magnetic recording, write synchronization, prepatterned servo, areal density.

In this paper, an efficient and reliable neural active power filter (APF) to estimate and compensate for harmonic distortions from an AC line is proposed. The proposed filter is completely based on Adaline neural networks which are organized in different independent blocks. We introduce a neural method based on Adalines for the online extraction of the voltage components to recover a balanced and equilibrated voltage system, and three different methods for harmonic filtering. These three methods efficiently separate the fundamental harmonic from the distortion harmonics of the measured currents. According to either the Instantaneous Power Theory or to the Fourier series analysis of the currents, each of these methods are based on a specific decomposition. The original decomposition of the currents or of the powers then allows defining the architecture and the inputs of Adaline neural networks. Different learning schemes are then used to control the inverter to inject elaborated reference currents in the power system. Results obtained by simulation and their real-time validation in experiments are presented to compare the compensation methods. By their learning capabilities, artificial neural networks are able to take into account time-varying parameters, and thus appreciably improve the performance of traditional compensating methods. The effectiveness of the algorithms is demonstrated in their application to harmonics compensation in power systems.Index Terms-Active power filter (APF), adaptive control, artificial neural networks (ANNs), harmonics, selective compensation, three-phase electric system.

Directed self-assembly (DSA) of block copolymers (BCPs) is a leading strategy to pattern at sublithographic resolution in the technology roadmap for semiconductors and is the only known solution to fabricate nanoimprint templates for the production of bit pattern media. While great progress has been made to implement block copolymer lithography with features in the range of 10-20 nm, patterning solutions below 10 nm are still not mature. Many BCP systems self-assemble at this length scale, but challenges remain in simultaneously tuning the interfacial energy atop the film to control the orientation of BCP domains, designing materials, templates, and processes for ultra-high-density DSA, and establishing a robust pattern transfer strategy. Among the various solutions to achieve domains that are perpendicular to the substrate, solvent annealing is advantageous because it is a versatile method that can be applied to a diversity of materials. Here we report a DSA process based on chemical contrast templates and solvent annealing to fabricate 8 nm features on a 16 nm pitch. To make this possible, a number of innovations were brought in concert with a common platform: (1) assembling the BCP in the phase-separated, solvated state, (2) identifying a larger process window for solvated triblock vs diblock BCPs as a function of solvent volume fraction, (3) employing templates for sub-10-nm BCP systems accessible by lithography, and (4) integrating a robust pattern transfer strategy by vapor infiltration of organometallic precursors for selective metal oxide synthesis to prepare an inorganic hard mask.

This paper reports the design, fabrication and control of arrayed microelectromechanical systems (MEMS)-based actuators for distributed micromanipulation by generation and control of an air-flow force field. The authors present an original design of pneumatic microactuator, improving reliability and durability of a distributed planar micromanipulator described in the previous study. The fabrication process is based on silicon-on-insulator (SOI) wafer and HF (hydroflouric acid) vapor release, which also significantly increases the production yield of the 560 microactuator array device of 35 35 mm 2 . Minimization of the electrostatic actuation pull-in voltage through suspension shaping fabrication was also studied, and successfully validated for electrical efficiency improvement. A distributed control method to achieve good conveyance performance and reduce motion control instability was investigated. An emulation approach was chosen to validate a decentralized control strategy on the distributed active surface in order to conduct a proof-of-concept of a future smart structure, integrating sensors, intelligence, and microactuators. Thus, a centralized/decentralized control flow, inspired by autonomous mobile robot principles, was applied. It was modeled and implemented using C-programming language. Experimental and characterization results validate the control method for feedback micromanipulation with good velocity and load capacity performance.[1605]