A Review of System Development Systems

The requirements for a system development system are defined and used as guidelines to review six such systems: SAMM, SREM, SADT, ADS / SODA, PSL/PSA and Systematics. It is found that current system development systems emphasise only validation and user verification. They can perform relatively little on automatic file optimisation, process optimisation and maintenance.postprin

Doped Mott insulators are insulators: hole localization in the cuprates

We demonstrate that a Mott insulator lightly doped with holes is still an insulator at low temperature even without disorder. Hole localization obtains because the chemical potential lies in a pseudogap which has a vanishing density of states at zero temperature. The energy scale for the pseudogap is set by the nearest-neighbour singlet-triplet splitting. As this energy scale vanishes if transitions, virtual or otherwise, to the upper Hubbard band are not permitted, the fundamental length scale in the pseudogap regime is the average distance between doubly occupied sites. Consequently, the pseudogap is tied to the non-commutativity of the two limits $U\to\infty$ ($U$ the on-site Coulomb repulsion) and $L\to\infty$ (the system size).Comment: 4 pages, 3 .eps file

Graph Convolutional Neural Networks for Web-Scale Recommender Systems

Recent advancements in deep neural networks for graph-structured data have led to state-of-the-art performance on recommender system benchmarks. However, making these methods practical and scalable to web-scale recommendation tasks with billions of items and hundreds of millions of users remains a challenge. Here we describe a large-scale deep recommendation engine that we developed and deployed at Pinterest. We develop a data-efficient Graph Convolutional Network (GCN) algorithm PinSage, which combines efficient random walks and graph convolutions to generate embeddings of nodes (i.e., items) that incorporate both graph structure as well as node feature information. Compared to prior GCN approaches, we develop a novel method based on highly efficient random walks to structure the convolutions and design a novel training strategy that relies on harder-and-harder training examples to improve robustness and convergence of the model. We also develop an efficient MapReduce model inference algorithm to generate embeddings using a trained model. We deploy PinSage at Pinterest and train it on 7.5 billion examples on a graph with 3 billion nodes representing pins and boards, and 18 billion edges. According to offline metrics, user studies and A/B tests, PinSage generates higher-quality recommendations than comparable deep learning and graph-based alternatives. To our knowledge, this is the largest application of deep graph embeddings to date and paves the way for a new generation of web-scale recommender systems based on graph convolutional architectures.Comment: KDD 201

Effect of synthesis conditions on the physiochemical properties of lauric acid coated magnetite nanoparticles

Magnetic iron oxide nanoparticles have attracted broad interests in many biomedical areas, such as magnetic resonance imaging (MRI) contrast enhancement, magnetic hyperthermia, magnetic bio-sensing, and cell labeling [1]. To avoid nanoparticle aggregation and enhance their colloidal stability, carboxylate surfactants are widely used as coating materials to form steric repulsions between nanoparticles [2]. Lauric acid is one of the classical carboxylate materials, and is already approved for use in pharmaceuticals and food industry, which makes it a very promising coating material for nanoparticles in biomedical application. [3] Various methods, like mechanical milling, microemulsion, co-precipitation, thermal decomposition, etc., have been widely attempted to prepare nanoparticles. However, it is reported that the synthesis route has great impact on the properties of nanoparticle products, such as aluminium oxide nanoparticles, cobalt ferrite nanoparticles, and so on [4, 5]. Therefore, it is worthwhile to investigate the effects of different synthesis methods on the properties of lauric acid coated magnetic iron oxide nanoparticles. The research outcome can enable the synthesis of magnetic nanoparticles with desired features. Here, lauric acid coated iron oxide nanoparticles (LAIONPs) were prepared through two methods, co-precipitation and thermal decomposition. The products were characterized by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), dynamic light scattering (DLS), thermo gravimetric analysis (TGA), and vibrating sample magnetometry (VSM). The iron-oxide-core average size could be tuned from 9 nm (CP-1), 11 nm (CP-2) to 13 nm (CP-3) by using different stirring speed of 1200 rpm, 800 rpm, and 400 rpm, respectively in co-precipitation experiments, while the core average size could be adjusted from 7 nm (TD-1), 11 nm (TD-2) to 17 nm (TD-3) by following different heating process in thermal - ecomposition experiments. (Fig. 1) The nanoparticles obtained through thermal decomposition (LAIONPs-TD) showed more uniform sizes and morphologies than the ones got from co-precipitation (LAIONPs-CP). Higher mass ratio of lauric acid in TD samples than CP samples, as indicated in TGA results (Fig. 2a and 2b), implies higher surface cover density of lauric acid surfactant on LAIONPs-TD than LAIONPs-CP. All the six LAIONPs samples exhibited superparamagnetic behavior at room temperature (Fig. 2c and 2d). The saturated magnetization (Ms) of LAIONPs increased as the particle size increased. Such a trend can be observed in the samples obtained through co-precipitation (CP-1, 54 emu/g; CP-2, 58 emu/g; and CP-3, 63 emu/g) and also in the samples obtained through thermal decomposition (TD-1, 53 emu/g; TD-2, 64 emu/g; TD-3, and 78 emu/g). For the LAIONPs with similar average core size of 11 nm, Ms value of TD-2 obtained by thermal decomposition (64 emu/g) was higher than CP-2 obtained by co-precipitation (58 emu/g). As shown in Fig. 2e, in colloidal solution with solvent of chloroform, smaller mean hydrodynamic sizes and narrower hydrodynamic size distributions were observed on IONPs-TD samples, compared with IONPs-CP samples. This work revealed the influences of two different synthesis methods on the core size, morphology, hydrodynamic size, surfactant coating mass ratio, and magnetic behavior of the final products. Our comparative study provides insights into the influence of synthesis conditions on the geometrical and magnetic properties of lauric acid coated iron oxide nanoparticles.postprin

Injection locking of spin-torque nano-oscillators

This journal issue contain selected papers from the Asia-Pacific Data Storage Conference (APDSC'13)We demonstrated the phase locking of a spin-torque oscillator (STO) to an alternating current (ac) using macrospin and micromagnetic simulations. We found that the locking properties of both approaches agree with each other. The phase difference between the STO and the injected ac stabilizes at ∆φ ≈ 90° and is not sensitive to the initial phase difference, which provides potential application of STO for microwave generation.published_or_final_versio

Natural orbits of atomic Cooper pairs in a nonuniform Fermi gas

We examine the basic mode structure of atomic Cooper pairs in an inhomogeneous Fermi gas. Based on the properties of Bogoliubov quasi-particle vacuum, the single particle density matrix and the anomalous density matrix share the same set of eigenfunctions. These eigenfunctions correspond to natural pairing orbits associated with the BCS ground state. We investigate these orbits for a Fermi gas in a spherical harmonic trap, and construct the wave function of a Cooper pair in the form of Schmidt decomposition. The issue of spatial quantum entanglement between constituent atoms in a pair is addressed.Comment: 14 pages, 4 figures, submitted to Phys. Rev.

Overhead High-Voltage Transmission-Line Current Monitoring by Magnetoresistive Sensors and Current Source Reconstruction at Transmission Tower

Session PF: Materials for ApplicationsThis paper proposes a novel current monitoring technology based on magnetic field sensing at a transmission tower for overhead high-voltage transmission lines (HVTLs), which can accurately measure phase current parameters in real time. This technology is based on the phenomenon that the magnetic field distribution at the top level of a transmission tower can reflect the operation states of the transmission lines including current amplitude and phase angle imbalances. A current source reconstruction method based on stochastic optimization strategy was developed to reconstruct the electrical parameters from the magnetic field emanated by the overhead transmission lines. This concept of current monitoring by magnetic field sensing and current source reconstruction was experimentally implemented and verified in our laboratory setup. A typical model of 500 kV three-phase transmission lines was simulated to further corroborate this technology. The reconstruction results for the 500 kV transmission lines verify the feasibility and practicality of this novel current monitoring technology based on magnetic field sensing at the top of a transmission tower for monitoring overhead transmission lines.published_or_final_versio

Electronic structure of the Fe-layer-catalyzed carbon nanotubes studied by x-ray-absorption spectroscopy

[[abstract]]X-ray-absorption near edge structure (XANES) measurements have been performed to investigate the local electronic structures of the Fe-catalyzed and stabilized carbon nanotubes (CNT) with various diameters. The intensities of the π∗- and σ∗-band and the interlayer-state features in the C K-edge XANES spectra of these CNTs vary with the diameter of the CNT. The white-line features at the C K- and Fe L3-edges suggest a strong hybridization between the C 2p and Fe 3d orbitals, which lead to an enhancement of the C K- and reduction of the Fe L3-edge features, respectively, indicative of a charge transfer from C 2p to Fe 3d orbitals. The Fe K-edge spectra reveal a p–d rehybridization effect that reduces p-orbital occupation at the Fe site.[[booktype]]紙

Determination of the microstructure of Eu-treated ZnO nanowires by x-ray absorption

100學年度杜昭宏升等參考著作[[abstract]]X-ray absorption near-edge structure (XANES), extended x-ray absorption fine structures (EXAFS), and photoluminescence measurements were used to elucidate the microstructural and photoluminescence properties of ZnO nanowires (ZnO-NWs) that had been treated with Eu by thermal diffusion. The O K- and Eu L3-edge XANES and EXAFS spectra at the Zn K- and Eu L3-edge verified the formation of Eu2O3-like layer on the surface of ZnO-NWs. X-ray diffraction, XANES and EXAFS measurements consistently suggest the lack of substitutional doping of Eu ions at the Zn ion sites in the interior of ZnO-NWs. The clear sharp and intense emission bands in the range 610–630 nm of Eu-treated ZnO-NWs originated from the intra-4f transition of Eu ions in the Eu2O3-like surface layer.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙