Deviation warnings of ferries based on artificial potential field and historical data

Ferries are usually used for transporting passengers and vehicles among docks, and any deviation of the course can lead to serious consequences. Therefore, transportation ferries must be watched closely by local maritime administrators, which involves much manpower. With the use of historical data, this article proposes an intelligent method of integrating artificial potential field with Bayesian Network to trigger deviation warnings for a ferry based on its trajectory, speed and course. More specifically, a repulsive potential field-based model is first established to capture a customary waterway of ferries. Subsequently, a method based on non-linear optimisation is introduced to train the coefficients of the proposed repulsive potential field. The deviation of a ferry from the customary route can then be quantified by the potential field. Bayesian Network is further introduced to trigger deviation warnings in accordance with the distribution of deviation values, speeds and courses. Finally, the proposed approach is validated by the historical data of a chosen ferry on a specific route. The testing results show that the approach is capable of providing deviation warnings for ferries accurately and can offer a practical solution for maritime supervision. © IMechE 2019

Rock-salt SnS and SnSe: Native Topological Crystalline Insulators

Unlike time-reversal topological insulators, surface metallic states with Dirac cone dispersion in the recently discovered topological crystalline insulators (TCIs) are protected by crystal symmetry. To date, TCI behaviors have been observed in SnTe and the related alloys Pb$_{1-x}$Sn$_{x}$Se/Te, which incorporate heavy elements with large spin-orbit coupling (SOC). Here, by combining first-principles and {\it ab initio} tight-binding calculations, we report the formation of a TCI in the relatively lighter rock-salt SnS and SnSe. This TCI is characterized by an even number of Dirac cones at the high-symmetry (001), (110) and (111) surfaces, which are protected by the reflection symmetry with respect to the ($\bar{1}$10) mirror plane. We find that both SnS and SnSe have an intrinsically inverted band structure and the SOC is necessary only to open the bulk band gap. The bulk band gap evolution upon volume expansion reveals a topological transition from an ambient pressure TCI to a topologically trivial insulator. Our results indicate that the SOC alone is not sufficient to drive the topological transition.Comment: 5 pages, 5 figure

Synthesis of new dendritic chiral binol ligands and their applications in enantioselective lewis acid catalyzed addition of diethylzinc to aldehydes

2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Micromagnetic simulations of current-induced magnetization switching in Co/Cu/Co nanopillars

Author name used in this publication: S. Q. Shi2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Climate and soil moisture content during development ofthe frst palaeosol in the southern Loess Plateau

The scientific problems concerning Quaternary soil water content and the water cycle have not been researched. This study examined the soil water content and depth of distribution of gravitational water in the south Loess Plateau during development of the first palaeosol layer (S1) by methods such as field investigation, electron microscopy, energy spectrum analysis, chemical analysis, and so on. The purpose was to reveal the climate, water balance and vegetation type at the time when S1 developed. The depth of migration of CaCO3 and Sr were 4.2 m below the upper boundary of the S1 palaeosol, and the depth of weathered loess beneath the argillic horizon was 4.0 m. Ferri‐argillans developed well in the argillic horizon and their depth of migration was 1 m below the argillic horizon. These findings suggest that the climate during the last interglacial was subtropical and humid, and the soil‐water balance was positive. Gravitational water was present to a depth of least 4.2 m from the top of S1, and the water content was adequate for tree growth. The chemical weathering index showed that this palaeosol has been moderately weathered

Current-induced magnetization dynamics in Co/Cu/Co nanopillars

Author name used in this publication: S. Q. Shi2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Structure-Induced Reversible Anionic Redox Activity in Na Layered Oxide Cathode

Anionic redox reaction (ARR) in lithium- and sodium-ion batteries is under hot discussion, mainly regarding how oxygen anion participates and to what extent oxygen can be reversibly oxidized and reduced. Here, a P3-type Na0.6[Li0.2Mn0.8]O2 with reversible capacity from pure ARR was studied. The interlayer O-O distance (peroxo-like O-O dimer, 2.506(3) Å), associated with oxidization of oxygen anions, was directly detected by using a neutron total scattering technique. Different from Li2RuO3 or Li2IrO3 with strong metal-oxygen (M-O) bonding, for P3-type Na0.6[Li0.2Mn0.8]O2 with relatively weak Mn-O covalent bonding, crystal structure factors might play an even more important role in stabilizing the oxidized species, as both Li and Mn ions are immobile in the structure and thus may inhibit the irreversible transformation of the oxidized species to O2 gas. Utilization of anionic redox reaction (ARR) on oxygen has been considered as an effective way to promote the charge-discharge capacity of the layered oxide cathodes for lithium- or sodium-ion batteries. The detailed mechanism of ARR, in particular how crystal structure affects and coordinates with the ARR, is not yet well understood. In the present work, a combination of X-ray and neutron total scattering measurements has been performed to study the structure of the prototype P3-type layered Na0.6[Li0.2Mn0.8]O2 with pure ARR. Unique structural characteristics, rather than prevailing knowledge of covalency of metal-oxygen, enable the stabilization of the crystal structure of Na0.6[Li0.2Mn0.8]O2 along with the ARR. This work suggests that reversible ARR can be manipulated by proper structure designs, thus to achieve high lithium or sodium storage in layered oxide cathodes. For P3-type Na0.6[Li0.2Mn0.8]O2 with relatively weak Mn-O covalent bonding, crystal structure factors play an important role in stabilizing the oxidized species, inhibiting the irreversible transformation of the oxidized species to O2 gas. The finding is important for better design of layered oxide positive materials with higher reversible capacity via the introduction of a reversible anionic redox reaction

Current transport property of n-GaN/n-6H-SiC heterojunction: Influence of interface states

Heterostructures of n-GaNn-6H-SiC grown by hydride vapor phase epitaxy (HVPE) and molecular-beam epitaxy (MBE) are characterized with the current-voltage (I-V), capacitance-voltage (C-V), and deep level transient spectroscopy (DLTS) techniques. Using different contact configurations, the I-V results reveal a rectifying barrier in the n-GaNn-6H-SiC heterostructures. When GaN is negatively biased, the current is exponentially proportional to the applied voltage with the built-in barrier being 0.4-1.1 eV for the HVPE samples and 0.5 eV for the MBE sample. DLTS measurements reveal intense band-like deep level states in the interfacial region of the heterostructure, and the Fermi-level pinning by these deep level defects is invoked to account for the interfacial rectifying barrier of the heterostructures. © 2005 American Institute of Physics.published_or_final_versio

In vitro callus induction and plant regeneration from mature seed embryo and young shoots in a giant sympodial bamboo, Dendrocalamus farinosus (Keng et Keng f.) Chia et H.L. Fung

The method for callus induction, adventitious shoot induction and plant regeneration derived from mature embryos of the seed and young shoots in Dendrocalamus farinosus was examined. For young shoots, the lowest callus induction frequency (21.0 to 29.7%) was obtained and the induced callus became brown and perished after two weeks. For mature embryos of the seed, an efficient protocol for callus induction, adventitious shoot induction and plant regeneration was developed. The best callus induction medium for mature embryos was observed to be Murashige and Skoog (MS) supplemented with 2.0 mg l-1 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in combination with 0.2 mg l-1 kinetin (Kn) plus 0.4 mg l-1 indole-3-butyric acid (IBA). Callus induction frequency was 95%. The highest adventitious shoot induction frequency (91.2 ± 2.18%) was obtained on MS medium supplemented with 2.5 mg l-1 kn plus 0.5 mg l-1 indole-3-acetic acid (IAA). The regenerated adventitious shoots were rooted in vitro on MS medium with 0.4 mg l-1 IBA plus 0.25 mg l-1 IAA. Rooted plantlets successfully acclimatized to the greenhouse and 90.1% survived after being transplanted to plastic pots (measuring 30 cm in  diameter) with garden soil.Key words: Callus culture, plant regeneration, making-pulp use, Dendrocalamus farinosus

Tuning the vertical location of helical surface states in topological insulator heterostructures via dual-proximity effects

In integrating topological insulators (TIs) with conventional materials, one crucial issue is how the topological surface states (TSS) will behave in such heterostructures. We use first-principles approaches to establish accurate tunability of the vertical location of the TSS via intriguing dual-proximity effects. By depositing a conventional insulator (CI) overlayer onto a TI substrate (Bi2Se3 or Bi2Te3), we demonstrate that, the TSS can float to the top of the CI film, or stay put at the CI/TI interface, or be pushed down deeper into the otherwise structurally homogeneous TI substrate. These contrasting behaviors imply a rich variety of possible quantum phase transitions in the hybrid systems, dictated by key material-specific properties of the CI. These discoveries lay the foundation for accurate manipulation of the real space properties of TSS in TI heterostructures of diverse technological significance