Identifying Web Tables - Supporting a Neglected Type of Content on the Web

The abundance of the data in the Internet facilitates the improvement of extraction and processing tools. The trend in the open data publishing encourages the adoption of structured formats like CSV and RDF. However, there is still a plethora of unstructured data on the Web which we assume contain semantics. For this reason, we propose an approach to derive semantics from web tables which are still the most popular publishing tool on the Web. The paper also discusses methods and services of unstructured data extraction and processing as well as machine learning techniques to enhance such a workflow. The eventual result is a framework to process, publish and visualize linked open data. The software enables tables extraction from various open data sources in the HTML format and an automatic export to the RDF format making the data linked. The paper also gives the evaluation of machine learning techniques in conjunction with string similarity functions to be applied in a tables recognition task.Comment: 9 pages, 4 figure

Simple and robust predictive direct control of DFIG with low constant switching frequency and reduced torque and flux ripples

For conventional direct torque control (CDTC) methods, there are usually undesired torque and flux ripples mainly for two reasons. First, the vectors selected are not necessary the best. Secondly, one-step delay influence in digital implementation causes additional torque and flux ripples. This paper proposes a novel predictive direct torque control (PDTC) strategy of the doubly fed induction generator (DFIG). The proposed strategy aims to reduce torque and flux ripples effectively at low constant switching frequency by appropriately arranging two active vectors followed by one zero vector within one control period. Furthermore, one-step delay is compensated using a mode-based prediction scheme. Finally, the control system is simplified through further analysis of the transient slope of torque and flux without performance degradation. Simulation results validate the proposed strategy with excellent steady-state and transient performance, which makes it very suitable for wind power generation. © 2011 IEEE

Unified nonequilibrium dynamical theory for exchange bias and training effects

We investigate the exchange bias and training effects in the FM/AF heterostructures using a unified Monte Carlo dynamical approach. This real dynamical method has been proved reliable and effective in simulating dynamical magnetization of nanoscale magnetic systems. The magnetization of the uncompensated AF layer is still open after the first field cycling is finished. Our simulated results show obvious shift of hysteresis loops (exchange bias) and cycling dependence of exchange bias (training effect) when the temperature is below 45 K. The exchange bias fields decrease with decreasing the cooling rate or increasing the temperature and the number of the field cycling. With the simulations, we show the exchange bias can be manipulated by controlling the cooling rate, the distributive width of the anisotropy energy, or the magnetic coupling constants. Essentially, these two effects can be explained on the basis of the microscopical coexistence of both reversible and irreversible moment reversals of the AF domains. Our simulated results are useful to really understand the magnetization dynamics of such magnetic heterostructures. This unified nonequilibrium dynamical method should be applicable to other exchange bias systems.Comment: Chin. Phys. B, in pres

Orbit angular momentum MIMO with mode selection for UAV-assisted A2G networks

As an emerging solution for line-of-sight (LOS) wireless communications, in air-to-ground (A2G) channels, the unmanned aerial vehicle (UAV), and allowing the dynamic and flexible network deployments enables the supplement or/and replacement of the terrestrial base stations (BSs). However, in conventional multiple-input-multiple-output (MIMO) systems, high-speed communications are significantly limited by channel crosstalks and spectrum scarcities. An orbit angular momentum (OAM) wireless network, allowing co-existence of multiple physical channels within the same frequency band, offers new degrees of freedom to address this dilemma. In this paper, we investigate the UAV-based A2G radio vortex wireless networks and study its channel model. Then we propose a branch and bound search-based mode selection (BBS-MS) scheme, which uses the spatial distribution characteristics of vortex beams to optimize the spectrum efficiency (SE). Theoretical derivations and numerical results demonstrate that our developed BBS-MS scheme can obtain the optimal performance, which outperforms conventional OAM-based MIMO systems. Also, it possesses a lower complexity compared with exhaustive searches

Solid Phase Extraction and Spectrophotometric Determination of Gold with 5-(2-Hydroxy-4-nitrophenylazo)-rhodanine as Chromogenic Reagent

This paper presents the synthesis and application of 5-(2-hydroxy-4-nitrophenylazo)-rhodanine (HNAR) as a new chromogenic reagent for the determination of gold. Based on the rapid reaction of gold with HNAR and the solid phase extraction of the coloured chelate with a reversed phase polymer-based C18 cartridge, a highly sensitive, selective and rapid method for the determination of gold has been developed. In the presence of 0.05–0.5 mol L–1 of phosphoric acid solution and emulsifier-OP medium,HNAR reacted with gold to forma red chelate of a molar ratio 1:3 (gold to HNAR). This chelate was enriched by the solid phase extraction with a polymer-based C18 cartridge and the retained chelate was eluted from the cartridge with dimethyl formamide (DMF).Anenrichment factor of 100 was achieved. In DMF medium, the molar absorptivity of the chelate was found to be 1.51 × 105 L mol–1 cm–1 at 496 nm. Beer’s law was obeyed in the range of 0.01~2 μg mL–1. The relative standard deviation for eleven replicates with a concentration of 0.5 μgL–1 level was 2.31%. The detection limit based on three times the standard deviation was 0.01 μg L–1 in the original sample. This method was applied to the determination of gold with good results.Keywords: Gold, solid phase extraction, spectrophotometry, 5-(2-hydroxy-4-nitrophenylazo)-rhodanine

Dynamics aspect of subbarrier fusion reaction in light heavy ion systems

Subbarrier fusion of the 7Li + 12C reaction is studied using an antisymmetrized molecular dynamics model (AMD) with an after burner, GEMINI. In AMD, 7Li shows an \alpha + t structure at its ground state and it is significantly deformed. Simulations are made near the Coulomb barrier energies, i.e., E_{cm} = 3 - 8 MeV. The total fusion cross section of the AMD + GEMINI calculations as a function of incident energy is compared to the experimental results and both are in good agreement at E_{cm} > 3 MeV. The cross section for the different residue channels of the AMD + GEMINI at E_{cm} = 5 MeV is also compared to the experimental results.Comment: Talk given by Meirong Huang at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

Δ\Delta-scaling and Information Entropy in Ultra-Relativistic Nucleus-Nucleus Collisions

The $\Delta$-scaling method has been applied to ultra-relativistic p+p, C+C and Pb+Pb collision data simulated using a high energy Monte Carlo package, LUCIAE 3.0. The $\Delta$-scaling is found to be valid for some physical variables, such as charged particle multiplicity, strange particle multiplicity and number of binary nucleon-nucleon collisions from these simulated nucleus-nucleus collisions over an extended energy ranging from $E_{lab}$ = 20 to 200 A GeV. In addition we derived information entropy from the multiplicity distribution as a function of beam energy for these collisions.Comment: 4 pages, 4 figures, 1 table; to appear in the July Issue of Chin. Phys. Lett.. Web Page: http://www.iop.org/EJ/journal/CP

Airport taxi situation awareness with a macroscopic distribution network analysis

This paper proposes a framework for airport taxi situation awareness to enhance the assessment of aircraft ground movements in complex airport surfaces. Through a macroscopic distribution network (MDN) of arrival and departure taxi processes in a spatial-temporal domain, we establish two sets of taxi situation indices (TSIs) from the perspectives of single aircraft and the whole network. These TSIs are characterized into five categories: aircraft taxi time indices (ATTIs), surface instantaneous flow indices (SIFIs), surface cumulative flow indices (SCFIs), aircraft queue length indices (AQLIs), and slot resource demand indices (SRDIs). The coverage of the TSIs system is discussed in detail based on the departure and arrival reference aircraft. A real-world case study of Shanghai Pudong airport demonstrates significant correlations among some of the proposed TSIs such as the ATTIs, SCFIs and AQLIs. We identify the most crucial influencing factors of the taxi process and propose two new metrics to assess the taxi situation at the aircraft and network levels, by establishing taxi situation assessment models instead of using two systems of multiple TSIs. The findings can provide significant references to decision makers regarding airport ground movements for the purposes of air traffic scheduling and congestion control in complex airports