An Improved Differential Evolution Algorithm for Maritime Collision Avoidance Route Planning

High accuracy navigation and surveillance systems are pivotal to ensure efficient ship route planning and marine safety. Based on existing ship navigation and maritime collision prevention rules, an improved approach for collision avoidance route planning using a differential evolution algorithm was developed. Simulation results show that the algorithm is capable of significantly enhancing the optimized route over current methods. It has the potential to be used as a tool to generate optimal vessel routing in the presence of conflicts

Novel Z2 Topological Metals and Semimetals

© 2016 American Physical Society.We report two theoretical discoveries for Z2 topological metals and semimetals. It is shown first that any dimensional Z2 Fermi surface is topologically equivalent to a Fermi point. Then the famous conventional no-go theorem, which was merely proven before for Z Fermi points in a periodic system without any discrete symmetry, is generalized so that the total topological charge is zero for all cases. Most remarkably, we find and prove an unconventional strong no-go theorem: all Z2 Fermi points have the same topological charge νZ2=1 or 0 for periodic systems. Moreover, we also establish all six topological types of Z2 models for realistic physical dimensions.postprin

Enhanced Coagulation of Titanium Tetrachloride Aided by the Modified Compound Bioflocculant

© 2015 American Society of Civil Engineers. The compound bioflocculant (CBF) was modified by graft copolymerization of acrylic amide and dimethyl diallyl ammonium chloride, and the novel copolymer was denoted as MCBF. The effect of MCBF used as coagulant aid with titanium tetrachloride (TiCl4) was investigated for both high and low molecule weight natural organic matter (NOM) removal. Floc characteristics were studied using a laser diffraction particle-sizing device. Results indicated that the monomers were successfully grafted onto the CBF, and the molecule weight and zeta potential of CBF were greatly improved. The MCBF with TiCl4 exhibited synergistic effect by promoting NOM removal, especially at low TiCl4 doses. Additionally, using MCBF as a coagulant aid with TiCl4 can significantly increase the floc growth rate, size, strength, and broken-floc recoverability. The effect of MCBF on fractal dimension of flocs generated by TiCl4 depended on NOM properties. Both coagulation performance and floc properties were significantly affected by dosing sequence

Coagulation performance and floc characteristics of polytitanium tetrachloride and titanium tetrachloride compared with ferric chloride for coal mining wastewater treatment

© 2015 Elsevier B.V. Abstract The production and discharge of large volumes of wastewater during coal mining activities are one of the major environmental issues in Australia. Therefore, it is crucial to develop and optimise effective treatment processes for the safe disposal of coal mining wastewater (CMWW). In this study, we investigated the performance of a recently developed polytitanium tetrachloride (PTC) coagulant and compared with the performance of titanium tetrachloride (TiCl4) and the commonly used ferric chloride (FeCl3) coagulant for the treatment of CMWW from one of the coal mining sites in Australia. The use of Ti-based coagulants is particularly attractive for the CMWW treatment due to the advantage of being able to recycle the sludge to produce functional titanium dioxide (TiO2) photocatalyst; unlike the flocs formed using conventional coagulants, which need to be disposed in landfill sites. The results showed that both PTC and TiCl4 performed better than FeCl3 in terms of turbidity, UV254 and inorganic compounds (e.g. aluminium, copper or zinc) removal, however, PTC performed poorly in terms of dissolved organic carbon removal (i.e. less than 10%). While charge neutralisation and bridging adsorption were the main coagulation mechanisms identified for TiCl4 treatment; sweep coagulation and bridging adsorption seemed to play a more important role for both PTC and FeCl3 treatments. The flocs formed by PTC coagulation achieved the largest floc size of around 900 μm with the highest floc growth rate. Both Ti-based coagulants (i.e., PTC and TiCl4) showed higher strength factor than FeCl3, while TiCl4 coagulant yielded the flocs with the highest recovery factor. This study indicates that Ti-based coagulants are effective and promising coagulants for the treatment of CMWW

Radial Growth of Qilian Juniper on the Northeast Tibetan Plateau and Potential Climate Associations

There is controversy regarding the limiting climatic factor for tree radial growth at the alpine treeline on the northeastern Tibetan Plateau. In this study, we collected 594 increment cores from 331 trees, grouped within four altitude belts spanning the range 3550 to 4020 m.a.s.l. on a single hillside. We have developed four equivalent ring-width chronologies and shown that there are no significant differences in their growth-climate responses during 1956 to 2011 or in their longer-term growth patterns during the period AD 1110–2011. The main climate influence on radial growth is shown to be precipitation variability. Missing ring analysis shows that tree radial growth at the uppermost treeline location is more sensitive to climate variation than that at other elevations, and poor tree radial growth is particularly linked to the occurrence of serious drought events. Hence water limitation, rather than temperature stress, plays the pivotal role in controlling the radial growth of Sabina przewalskii Kom. at the treeline in this region. This finding contradicts any generalisation that tree-ring chronologies from high-elevation treeline environments are mostly indicators of temperature changes

Solar influenced late Holocene temperature changes on the northern Tibetan Plateau

Considerable efforts have been made to extend temperature records beyond the instrumental period through proxy reconstructions, in order to further understand the mechanisms of past climate variability. Yet, the global coverage of existing temperature records is still limited, especially for some key regions like the Tibetan Plateau and for earlier times including the Medieval Warm Period (MWP). Here we present decadally-resolved, alkenone-based, temperature records from two lakes on the northern Tibetan Plateau. Characterized by marked temperature variability, our records provide evidence that temperatures during the MWP were slightly higher than the modern period in this region. Further, our temperature reconstructions, within age uncertainty, can be well correlated with solar irradiance changes, suggesting a possible link between solar forcing and natural climate variability, at least on the northern Tibetan Plateau. © 2013 The Author(s).published_or_final_versio

Understanding the nature of "superhard graphite"

Numerous experiments showed that on cold compression graphite transforms into a new superhard and transparent allotrope. Several structures with different topologies have been proposed for this phase. While experimental data are consistent with these models, the only way to solve this puzzle is to find which structure is kinetically easiest to form. Using state-of-the-art molecular-dynamics transition path sampling simulations, we investigate kinetic pathways of the pressure-induced transformation of graphite to various superhard candidate structures. Unlike hitherto applied methods for elucidating nature of superhard graphite, transition path sampling realistically models nucleation events necessary for physically meaningful transformation kinetics. We demonstrate that nucleation mechanism and kinetics lead to $M$-carbon as the final product. $W$-carbon, initially competitor to $M$-carbon, is ruled out by phase growth. Bct-C$_4$ structure is not expected to be produced by cold compression due to less probable nucleation and higher barrier of formation

Neuropilin 1 is an entry factor that promotes EBV infection of nasopharyngeal epithelial cells

Epstein-Barr virus (EBV) is implicated as an aetiological factor in B lymphomas and nasopharyngeal carcinoma. The mechanisms of cell-free EBV infection of nasopharyngeal epithelial cells remain elusive. EBV glycoprotein B (gB) is the critical fusion protein for infection of both B and epithelial cells, and determines EBV susceptibility of non-B cells. Here we show that neuropilin 1 (NRP1) directly interacts with EBV gB 23-431. Either knockdown of NRP1 or pretreatment of EBV with soluble NRP1 suppresses EBV infection. Upregulation of NRP1 by overexpression or EGF treatment enhances EBV infection. However, NRP2, the homologue of NRP1, impairs EBV infection. EBV enters nasopharyngeal epithelial cells through NRP1-facilitated internalization and fusion, and through macropinocytosis and lipid raft-dependent endocytosis. NRP1 partially mediates EBV-activated EGFR/RAS/ERK signalling, and NRP1-dependent receptor tyrosine kinase (RTK) signalling promotes EBV infection. Taken together, NRP1 is identified as an EBV entry factor that cooperatively activates RTK signalling, which subsequently promotes EBV infection in nasopharyngeal epithelial cells. © 2014 Macmillan Publishers Limited. All rights reserved.published_or_final_versio

An activity-based integrated land-use transport model for urban spatial distribution simulation

This research develops an activity-based integrated land use/transport interaction model based on the concepts – activities (mainly, households and employment activities), activity location and relocation for Chinese regions. It consists of a residential and employment location sub-model, a transport sub-model and an implicit real estate rent adjustment sub-model. The model is developed to model the urban activity distribution evolution, predict urban spatial development trends and examine various planning decision implications. It spatially distributes household and employment activity change of a study area by zone based on the current activity distribution, land use policies and the accessibilities of the zones. The model is subsequently calibrated to predict the distribution of households and employment activities in Beijing metropolitan area in 2025. Model results show that the resident and employment densities are still high in central Beijing in 2025, and most zones’ resident densities are higher than their employment densities. However, there is also significant population density increase along the 6th ring road, indicating the relocation trend of the residents and businesses to the outskirts. This is consistent with the government objectives to decentralize activities within the central urban area. The paper also suggests that the model should be used mainly in examining the possible differences arising from the adoption of different policies though predicting future of a city distribution proves feasible