Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Semiconductor-based Photocatalytic Hydrogen Generation

Redox‐Based Resistive Switching Memories – Nanoionic Mechanisms, Prospects, and Challenges

Polarity discontinuities at the interfaces between different crystalline materials (heterointerfaces) can lead to nontrivial local atomic and electronic structure, owing to the presence of dangling bonds and incomplete atomic coordinations. These discontinuities often arise in naturally layered oxide structures, such as the superconducting copper oxides and ferroelectric titanates, as well as in artificial thin film oxide heterostructures such as manganite tunnel junctions. If polarity discontinuities can be atomically controlled, unusual charge states that are inaccessible in bulk materials could be realized. Here we have examined a model interface between two insulating perovskite oxides--LaAlO3 and SrTiO3--in which we control the termination layer at the interface on an atomic scale. In the simple ionic limit, this interface presents an extra half electron or hole per two-dimensional unit cell, depending on the structure of the interface. The hole-doped interface is found to be insulating, whereas the electron-doped interface is conducting, with extremely high carrier mobility exceeding 10,000 cm2 V(-1) s(-1). At low temperature, dramatic magnetoresistance oscillations periodic with the inverse magnetic field are observed, indicating quantum transport. These results present a broad opportunity to tailor low-dimensional charge states by atomically engineered oxide heteroepitaxy.

A high-mobility electron gas at the LaAlO3/SrTiO3 heterointerface

Trust: The Social Virtues and the Creation of Prosperity

A noninvasive energy-efficient FM-UWB transmitter is implemented in 65nm CMOS for stereo hearing aid applications. Different form the conventional FM-UWB transmitter, the proposed transmitter employs an 8-FSK subcarrier modulation method to enhance data rate by three times with slight increment of hardware complexity. The 8-FSK subcarrier modulation is achieved by a fast-settling PLL along with a pre-tuned relaxation VCO. The FM-UWB signal generated by an FLL-assisted ring VCO and a single-stage class AB power amplifier meets the FCC spectrum mask. The 3.5-4GHz 750kb/s transmitter consumes 1.14mW from a 1V supply, achieving an energy efficiency of 1.5nJ/bit.

A 1.14mW 750kb/s FM-UWB transmitter with 8-FSK subcarrier modulation

Bipolar resistive switching characteristics of Cu/TaOx/Pt structures

Phonemes provide an interesting alternative to pure tones in hearing tests. We propose a new smartphone-based method for self-hearing assessment using the four Korean phonemes which are similar to the English phonemes /a/, /i/, /sh/, and /s/. We conducted tests on 15 subjects diagnosed with mild to severe hearing loss and estimated their conventional pure-tone hearing thresholds from their phoneme hearing thresholds using regression analysis. The phoneme-based self-hearing assessment was found to be sufficiently reliable in estimating the hearing thresholds of hearing-impaired subjects. The difference between the hearing thresholds obtained through conventional pure-tone audiometry and those obtained using our method was 5.6 dB HL on average. The proposed hearing assessment was able to significantly reduce the mean test time compared to conventional pure-tone audiometry.

Phoneme-Based Self Hearing Assessment on a Smartphone

A method and apparatus to a hearing ability and a hearing aid using the same are described. The hearing aid outputs a sound to test a hearing ability of a user, to detect an electrical signal generated in a body of the user as a result of the output sound, amplifies the electrical signal detected by an electrode unit, and to determine an amplification ratio of a surrounding sound detected by the hearing aid based on characteristics of peaks of waveforms of the amplified signal.

Method and apparatus to test hearing ability and hearing aid apparatus using the same

We investigate the influence of Al back reflectors on the optical absorption spectra of Si nanowire (NW) arrays by using the finite-difference time-domain simulation method. A flat Al layer enhances the absorption in the NW array due to not only the reflection-induced optical path length enlargement but also reflection of light between NWs and localized surface plasmon induced optical field confinement. An Al underlayer with a grating structure allows grating-coupled surface plasmon polariton excitation and raise the optical absorption in the Si NWs. Interplay among all these factors on the optical absorption and expected solar cell performance of the NW arrays is discussed.

Dong-Wook Kim

Papers

A 1.14mW 750kb/s FM-UWB transmitter with 8-FSK subcarrier modulation

Bipolar resistive switching characteristics of Cu/TaOx/Pt structures

Phoneme-Based Self Hearing Assessment on a Smartphone

Method and apparatus to test hearing ability and hearing aid apparatus using the same

Beneficial roles of Al back reflectors in optical absorption of Si nanowire array solar cells