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1.
PAPER CURRENT
Cyclic (Alkyl)(Amino)Carbenes (CAACs): Stable Carbenes on the Rise (2014)
Publication Date: 2014-12-18
Description: Accounts of Chemical ResearchDOI: 10.1021/ar5003494
Print ISSN: 0001-4842
Electronic ISSN: 1520-4898
Topics: Chemistry and Pharmacology
2.
PAPER CURRENT
Electronic Structure and Optical Signatures of Semiconducting Transition Metal Dichalcogenide Nanosheets (2014)
Publication Date: 2014-12-18
Description: Accounts of Chemical ResearchDOI: 10.1021/ar500303m
Print ISSN: 0001-4842
Electronic ISSN: 1520-4898
Topics: Chemistry and Pharmacology
3.
PAPER CURRENT
Modeling and robust H-infinite control of a novel non-contact ultra-quiet Stewart spacecraft (2014)
Publication Date: 2014-12-18
Description: Publication date: February–March 2015 Source:Acta Astronautica, Volume 107 Author(s): Yufei Xu , He Liao , Lei Liu , Yue Wang This paper presents the modeling and robust H∞ control of a novel ultra-quiet spacecraft which employs the non-contact Stewart platform to actively control its support module (SM) and payload module (PM). The SM and PM are mechanically separated such that the disturbances and vibrations from the SM can be perfectly suppressed. However, this novel spacecraft has internal instability. To overcome the instability, this paper derives the dynamics model of the non-contact Stewart spacecraft using Newton–Euler approach at first. Then, the mixed sensitivity robust H∞ control is developed to guarantee both the attitude stability and precision pointing. Finally, simulation studies are provided to validate the effectiveness of the proposed approach.
Print ISSN: 0094-5765
Electronic ISSN: 1879-2030
Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
4.
PAPER CURRENT
Flight results: Reliability and lifetime of the polymeric 3D-printed antenna deployment mechanism installed on Xatcobeo & Humsat-D (2014)
Publication Date: 2014-12-18
Description: Publication date: February–March 2015 Source:Acta Astronautica, Volume 107 Author(s): José Antonio Vilán Vilán , Fernando Aguado Agelet , Miguel López Estévez , Alberto González Muiño The aim of this article is to announce the results for the antenna deployment mechanism on the Cubesat [1,4] Xatcobeo picosatellite which launched on 13th February, 2012 from the Kourou space port aboard the new VEGA rocket. It was also launched as part of Humsat-D on 21st November, 2013 aboard Dnepr. The main feature of the device is its extremely light weight, achieved by using polymeric materials and additive manufacturing. Analysis was not only made of detailed characteristics but also of the advantages of using this combination, its validity after almost two years of perfect operation in orbit on Xatcobeo, and its latest operational success on Humsat-D. The results show that it deployed as expected in orbit and that it continues to operate correctly on both missions, not only in terms of the deployment mechanism but also the materials used. The analysis focuses on the mechanism׳s operational reliability and long useful lifetime.
Print ISSN: 0094-5765
Electronic ISSN: 1879-2030
Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
5.
PAPER CURRENT
A three-scale model for ionic solute transport in swelling clays incorporating ion–ion correlation effects (2014)
Publication Date: 2014-12-18
Description: Publication date: January 2015 Source:Advances in Water Resources, Volume 75 Author(s): Tien Dung Le , Christian Moyne , Marcio A. Murad A new three-scale model is proposed to describe the movement of ionic species of different valences in swelling clays characterized by three separate length scales (nano, micro, and macro) and two levels of porosity (nano- and micropores). At the finest (nano) scale the medium is treated as charged clay particles saturated by aqueous electrolyte solution containing monovalent and divalent ions forming the electrical double layer. A new constitutive law is constructed for the disjoining pressure based on the numerical resolution of non-local problem at the nanoscale which, in contrast to the Poisson–Boltzmann theory for point charge ions, is capable of capturing the short-range interactions between the ions due to their finite size. At the intermediate scale (microscale), the two-phase homogenized particle/electrolyte solution system is represented by swollen clay clusters (or aggregates) with the nanoscale disjoining pressure incorporated in a modified form of Terzaghi’s effective principle. At the macroscale, the electro-chemical–mechanical couplings within clay clusters is homogenized with the ion transport in the bulk fluid lying in the micro pores. The resultant macroscopic picture is governed by a three-scale model wherein ion transport takes place in the bulk solution strongly coupled with the mechanics of the clay clusters which play the role of sources/sinks of mass to the bulk fluid associated with ion adsorption/desorption in the electrical double layer at the nanoscale. Within the context of the quasi-steady version of the multiscale model, wherein the electrolyte solution in the nanopores is assumed at instantaneous thermodynamic equilibrium with the bulk fluid in the micropores, we build-up numerically the ion-adsorption isotherms along with the constitutive law of the retardation coefficients of monovalent and divalent ions. In addition, the constitutive law for the macroscopic swelling pressure is reconstructed numerically showing patterns of attractive forces between particles for bivalent ions for particular ranges of bulk concentrations. The three-scale model is applied to numerically simulate ion diffusion in a compacted clay liner underneath a sanitary landfill. Owing to the distinct constitutive behavior of the swelling pressure and partition coefficient for each ionic species, different compaction regimes and diffusion/adsorption patterns, with totally different characteristic time scales, are observed for sodium and calcium migration in the clay liner.
Print ISSN: 0309-1708
Electronic ISSN: 1872-9657
Topics: Geography , Geosciences
Published by Elsevier
6.
PAPER CURRENT
Urban flood modelling combining top-view LiDAR data with ground-view SfM observations (2014)
Publication Date: 2014-12-18
Description: Publication date: January 2015 Source:Advances in Water Resources, Volume 75 Author(s): Vorawit Meesuk , Zoran Vojinovic , Arthur E. Mynett , Ahmad F. Abdullah Remote Sensing technologies are capable of providing high-resolution spatial data needed to set up advanced flood simulation models. Amongst them, aerial Light Detection and Ranging (LiDAR) surveys or Airborne Laser Scanner (ALS) systems have long been used to provide digital topographic maps. Nowadays, Remote Sensing data are commonly used to create Digital Terrain Models (DTMs) for detailed urban-flood modelling. However, the difficulty of relying on top-view LiDAR data only is that it cannot detect whether passages for floodwaters are hidden underneath vegetated areas or beneath overarching structures such as roads, railroads, and bridges. Such (hidden) small urban features can play an important role in urban flood propagation. In this paper, a complex urban area of Kuala Lumpur, Malaysia was chosen as a study area to simulate the extreme flooding event that occurred in 2003. Three different DTMs were generated and used as input for a two-dimensional (2D) urban flood model. A top-view LiDAR approach was used to create two DTMs: (i) a standard LiDAR-DTM and (ii) a Filtered LiDAR-DTM taking into account specific ground-view features. In addition, a Structure from Motion (SfM) approach was used to detect hidden urban features from a sequence of ground-view images; these ground-view SfM data were then combined with top-view Filtered LiDAR data to create (iii) a novel Multidimensional Fusion of Views-Digital Terrain Model (MFV-DTM). These DTMs were then used as a basis for the 2D urban flood model. The resulting dynamic flood maps are compared with observations at six measurement locations. It was found that when applying only top-view DTMs as input data, the flood simulation results appear to have mismatches in both floodwater depths and flood propagation patterns. In contrast, when employing the top-ground-view fusion approach (MFV-DTM), the results not only show a good agreement in floodwater depth, but also simulate more correctly the floodwater dynamics around small urban feature. Overall, the new multi-view approach of combining top-view LiDAR data with ground-view SfM observations shows a good potential for creating an accurate digital terrain map which can be then used as an input for a numerical urban flood model.
Print ISSN: 0309-1708
Electronic ISSN: 1872-9657
Topics: Geography , Geosciences
Published by Elsevier
7.
PAPER CURRENT
Experimental investigation of asymptotic state for anisotropic sand (2014)
Publication Date: 2014-12-18
Description: Abstract The asymptotic behavior of soil under constant strain increment ratio is a topic of current research interest. In this paper, the effect of anisotropy on the asymptotic behavior of sand is investigated. A new device is developed for testing soil samples along paths with constant strain increment ratio. This triaxial test apparatus with hydraulic loading systems is particularly suitable to study the asymptotic behavior of soil. An extensive testing program was carried out on specimens prepared with different sedimentation directions. The effect of anisotropy on the asymptotic stress ratio is shown. Experimental results show that the inherent anisotropy of compressibility has a greater effect on the asymptotic ratio than the strength anisotropy. Finally, an equation is formulated to quantitatively determine the relation between the asymptotic stress ratio and strain increment ratio for anisotropic sand, and its effectiveness is confirmed experimentally.
Print ISSN: 1861-1125
Electronic ISSN: 1861-1133
Topics: Geosciences
Published by Springer
8.
PAPER CURRENT
System driven technology selection for future European launch systems (2014)
Publication Date: 2014-12-18
Description: Publication date: February–March 2015 Source:Acta Astronautica, Volume 107 Author(s): P. Baiocco , G. Ramusat , A. Sirbi , Th. Bouilly , F. Lavelle , T. Cardone , H. Fischer , S. Appel In the framework of the next generation launcher activity at ESA, a top-down approach and a bottom-up approach have been performed for the identification of promising technologies and alternative conception of future European launch vehicles. The top-down approach consists in looking for system-driven design solutions and the bottom-up approach features design solutions leading to substantial advantages for the system. The main investigations have been focused on the future launch vehicle technologies. Preliminary specifications have been used in order to permit sub-system design to find the major benefit for the overall launch system. The development cost, non-recurring and recurring cost, industrialization and operational aspects have been considered as competitiveness factors for the identification and down-selection of the most interesting technologies. The recurring cost per unit payload mass has been evaluated. The TRL/IRL has been assessed and a preliminary development plan has been traced for the most promising technologies. The potentially applicable launch systems are Ariane and VEGA evolution. The main FLPP technologies aim at reducing overall structural mass, increasing structural margins for robustness, metallic and composite containment of cryogenic hydrogen and oxygen propellants, propellant management subsystems, elements significantly reducing fabrication and operational costs, avionics, pyrotechnics, etc. to derive performing upper and booster stages. Application of the system driven approach allows creating performing technology demonstrators in terms of need, demonstration objective, size and cost. This paper outlines the process of technology down selection using a system driven approach, the accomplishments already achieved in the various technology fields up to now, as well as the potential associated benefit in terms of competitiveness factors.
Print ISSN: 0094-5765
Electronic ISSN: 1879-2030
Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
9.
PAPER CURRENT
Multivariate statistical methodologies applied in biomedical Raman spectroscopy: Assessing the validity of partial least squares regression using simulated model datasets. (2014)
Publication Date: 2014-12-18
Description: Analyst, 2014, Accepted ManuscriptDOI: 10.1039/C4AN02167C, PaperMark Edward Keating, Haq Nawaz, Franck Bonnier, Hugh ByrneAbstract Raman spectroscopy is fast becoming a valuable analytical tool in a number of biomedical scenarios, most notably disease diagnostics. Importantly, the technique has also shown increasing promise in the...The content of this RSS Feed (c) The Royal Society of Chemistry
Print ISSN: 0003-2654
Electronic ISSN: 1364-5528
Topics: Chemistry and Pharmacology
10.
PAPER CURRENT
Meandering Bed Development Time: Formulation and Related Experimental Testing (2014)
Publication Date: 2014-12-18
Description: Publication date: Available online 24 November 2014 Source:Advances in Water Resources Author(s): Andrew D. Binns , Ana Maria Ferreira da Silva This paper concerns the prediction of the bed development time of alluvial meandering streams. It is assumed that the stream centreline follows a sine-generated curve; the banks are rigid; the flow is turbulent and subcritical; and the width-to-depth ratio is “large”. The bed is flat at the beginning of an “experiment”. The bed development consists of the formation of large-scale, laterally adjacent pool-bar complexes strictly induced by the stream curvature. The paper is to be viewed as an extension of previous work by the writers, who have introduced an equation for the aforementioned bed development time, albeit with a proportionality factor that remains a not yet known function of the stream initial deflection angle. The objective of this paper is to reveal this function, and thus bring the equation for the bed development time into a form suitable for practical applications. This is achieved on the basis of a series of experiments carried out by the writers in three sine-generated meandering streams of varying sinuosity, as well as data from the literature. The paper concludes with examples of application of the resulting equation to real rivers.
Print ISSN: 0309-1708
Electronic ISSN: 1872-9657
Topics: Geography , Geosciences
Published by Elsevier