bluuebunny/crossref_metadata_2025_split huggingface dataset:
Corrosion behavior of 2A12 aluminum alloy in neutral salt spray environment with different Al‐clad removing processes
Authors: Liu H. C. , Xu H. P. , Zhu L. Q. , Liu J. Z. , Ye X. B. , Hu B. R. 
Published: August 2011

AbstractIn the process of assembling and machining, the aluminum alloy components will directly expose to aggressive environment once Al‐clad is destroyed. As such, it is meaningful to investigate the corrosion behavior of 2A12 aluminum alloy in neutral salt spray environment after removing Al‐clad coating with different processes. In this work, the corrosion behaviors of the aluminum alloy were evaluated by the changes in morphology, composition, and maximum mean corrosion depth. The results show that the corrosion rate of 2A12 aluminum alloy was very high in the first 24 h, and then decreased with test duration. Among all the Al‐clad removing processes, the one at higher temperature (90–100 °C) for shorter time (3–4 min) exhibit the best performance in the presence of inhibitor and sanding. The three possible reasons include effect of inhibitor adsorbing, role of sanding, impact of higher temperature, and shorter time.
Corrosion behavior of low‐alloy steel in the presence of Desulfovibrio caledoniensis
Authors: Cetin D. , Aksu M. L. 
Published: August 2011

AbstractSulfate‐reducing bacteria (SRB) are shown to be common inhabitants of oil reservoirs. Desulfovibrio caledoniensis isolated from a production well was used in this study. After an incubation period of 1 month with the SRB culture, two layers of corrosion products with different compositions were detected on the test coupons. The Tafel plots showed that the corrosion potential exhibited a cathodic shift and the corrosion rates increased with the incubation time. The analysis of the Nyquist diagrams revealed that the diffusion process begins to dominate with time in bacteria containing medium. These results are in good accordance with the Tafel data.
Microbiologically influenced corrosion of X60 carbon steel in CO2‐saturated oilfield flooding water
Authors: Fan M.‐M. , Liu H.‐F. , Dong Z.‐H. 
Published: August 2011

AbstractThe corrosion behavior of X60 carbon steel in CO2‐saturated oilfield flooding water inoculated with sulfate‐reducing bacteria (SRB) was investigated using polarization curves and electrochemical impedance spectroscopy (EIS). With the propagation of SRB in the flooding water, the pH values of flooding water increased quickly in the initial 2 days and remained relatively steady during the later stage. Polarization curves showed that the corrosion current density decreased during the first 10 days due to the protection of corrosion products and SRB‐biofilms, and then increased possibly due to the partial detachment of the corrosion products and the biofilms. EIS analysis also showed that the charge transfer resistance increased initially and then decreased with exposure time. In the beginning of corrosion, the anodic dissolution of X60 steel was dominated by CO2. After the formation of SRB‐biofilms, part of FeCO3 corrosion products was converted to incompact FeS precipitates by SRB bio‐mineralization. Thus, the dispersed iron sulfide in SRB‐biofilms and X60 steel base may constitute a galvanic couple, accelerating the localized corrosion of the steel base in the flooding water.
Reactivity Ratio Estimation from Cumulative Copolymer Composition Data
Authors: Kazemi Niousha , Duever Thomas A. , Penlidis Alexander 
Published: August 2011

AbstractThe goal is to present an alternative technique for reactivity ratio estimation in copolymerization. Typically, reactivity ratios are estimated using the instantaneous copolymer composition equation, based on low conversion copolymer composition data. However, using experimental data from the full copolymerization trajectory would, in principle, be more advantageous, and shy away from commonly used restrictive assumptions. Estimation using cumulative copolymerization data and models eliminates the difficulties associated with stopping reactions at low conversion, while one gains to study the full polymerization trajectory. The error‐in‐variables‐model (EVM) method is used for parameter estimation. Two cumulative model forms, the analytical integration of the differential composition equation and the one resulting from the direct numerical integration of this equation, are employed. Using these two types of models improves the reactivity ratio estimation and, in particular, the latter model form is a more reliable and direct method of estimating reactivity ratios. magnified image
A Kinetic Investigation of Removal of Residual Monomers From Polymer LatexesViaPost‐polymerization and Nitrogen Stripping Methods
Authors: Kechagia Zoi , Kammona Olga , Pladis Prokopis , Alexopoulos Aleck H. , Kiparissides Costas 
Published: August 2011

AbstractIn the present study, a comprehensive experimental investigation on the removal of residual monomers and other volatile organic compounds (VOCs) from polymer latexesviapost‐polymerization and nitrogen stripping is reported. Both techniques are applied to poly(methyl methacrylate) (PMMA), poly(butyl acrylate) (PBuA), and poly(methyl methacrylate/butyl acrylate) P(MMA/BuA) latexes. The effects of various process parameters (e.g., temperature, oxidant and reductant types and concentrations, addition time of the oxidant/reductant redox system for the post‐polymerization process and nitrogen flow rate, agitation rate, and temperature for the physical stripping process) and latex properties (e.g., particle size, wt.‐% of polymer solids and copolymer composition) on the monomer removal process efficiency are experimentally assessed. Finally, the two methods are applied in a simultaneous or sequential mode, to further improve the VOCs removal efficiency.magnified image
FE/BE coupling for an acoustic fluid–structure interaction problem. Residual a posteriori error estimates
Authors: Domínguez Catalina , Stephan Ernst P. , Maischak Matthias 
Published: August 2011

SUMMARYIn this paper, we developed an a posteriori error analysis of a coupling of finite elements and boundary elements for a fluid–structure interaction problem in two and three dimensions. This problem is governed by the acoustic and the elastodynamic equations in time‐harmonic vibration. Our methods combined integral equations for the exterior fluid and FEMs for the elastic structure. It is well‐known that because of the reduction of the boundary value problem to boundary integral equations, the solution is not unique in general. However, because of superposition of various potentials, we consider a boundary integral equation that is uniquely solvable and avoids the irregular frequencies of the negative Laplacian operator of the interior domain. In this paper, two stable procedures were considered; one is based on the nonsymmetric formulation and the other is based on a symmetric formulation. For both formulations, we derived reliable residual a posteriori error estimates. From the estimators we computed local error indicators that allowed us to develop an adaptive mesh refinement strategy. For the two‐dimensional case we performed an adaptive algorithm on triangles, and for the three‐dimensional case we used hanging nodes on hexahedrons. Numerical experiments underline our theoretical results. Copyright © 2011 John Wiley & Sons, Ltd.
A computational procedure for prebending of wind turbine blades
Authors: Bazilevs Y. , Hsu M.‐C. , Kiendl J. , Benson D.J. 
Published: August 2011

SUMMARYPrebending of wind turbine blades constitutes a viable engineering solution to the problem of tower clearance, that is, ensuring that during wind turbine operation there is sufficient distance between the rotor blades and the tower to avoid collision. The prebent shape of the blade must be such that when the turbine rotor is subjected to wind and inertial loads, the blades are straightened into their design configuration. In this paper, we propose a method for accurate prediction of the prebent shape of wind turbine blades. The method relies on a stand‐alone aerodynamics simulation that provides the wind loads on a rigidly spinning rotor, followed by a series of structural mechanics simulations to determine the stress‐free prebent shape of the blade. This procedure involves only one‐way coupling between the fluid and structural mechanics, which avoids the challenges of solving the coupled fluid–structure interaction problem. The proposed methodology, which has no limitations on the blade geometry and structural modeling, is successfully applied to prebending of a 63‐m offshore wind turbine blade. Copyright © 2011 John Wiley & Sons, Ltd.
Coupling of nonlocal and local continuum models by the Arlequin approach
Authors: Han Fei , Lubineau Gilles 
Published: August 2011

SUMMARYThe objective of this work is to develop and apply the Arlequin framework to couple nonlocal and local continuum mechanical models. A mechanically‐based model of nonlocal elasticity, which involves both contact and long‐range forces, is used for the ‘fine scale’ description in which nonlocal interactions are considered to have non‐negligible effects. Classical continuum mechanics only involving local contact forces is introduced for the rest of the structure where these nonlocal effects can be neglected. Both models overlap in a coupling subdomain called the ‘gluing area’ in which the total energy is separated into nonlocal and local contributions by complementary weight functions. A weak compatibility is ensured between kinematics of both models using Lagrange multipliers over the gluing area. The discrete formulation of this specific Arlequin coupling framework is derived and fully described. The validity and limits of the technique are demonstrated through two‐dimensional numerical applications and results are compared against those of the fully nonlocal elasticity method. Copyright © 2011 John Wiley & Sons, Ltd.
Diagnosis and management of early‐onset dementia
Authors: Davies R Rhys , Doran Mark , Larner Andrew J 
Published: August 2011

AbstractThe casemix of an early‐onset dementia clinic is different from that usually seen by old age psychiatrists or geriatricians and includes frontotemporal lobar degeneration, prion disease and genetically determined dementia as well as Alzheimer's disease. This brief review summarises the causes, diagnostic considerations and management of early‐onset dementias based on the authors' experience of working in a neurology‐led cognitive function clinic at a regional neuroscience centre. Copyright © 2011 Wiley Interface Ltd
Synthesis and characterization of new π‐conjugated polymers containing 1,8‐naphthyridine in the main chain: Role of the 1,8‐naphthyridine unit in π‐conjugated polymers
Authors: Koizumi Take‐Aki , Kato Shinichirou , Yamamoto Takakazu 
Published: August 2011

AbstractAlternating π‐conjugated copolymers of 1,8‐naphthyridine‐2,6‐diyl (1,8‐Nap) with 9,9‐dioctylfluorene‐2,7‐diyl (P(Flu‐Ph‐1,8‐Nap)) and 2,5‐didodecyloxy‐1,4‐phenylene (P(ROPh‐Ph‐1,8‐Nap)) have been synthesized by Pd‐catalyzed organometallic polycondensation. The copolymers showed UV‐vis absorption peaks at around 390 nm in o‐dichlorobenzene. The polymers were photoluminescent both in o‐dichlorobenzene and in the solid state. In o‐dichlorobenzene, the emission peaks of P(Flu‐Ph‐1,8‐Nap) and P(ROPh‐Ph‐1.,8‐Nap) appeared at λEM = 440 and 471 nm, with quantum yields of 87% and 66%, respectively. Electrochemical data revealed that 1,8‐Nap behaved as a typical electron‐accepting unit. When P(Flu‐Ph‐1,8‐Nap) was treated with 10‐camphorsulfonic acid, the emission peak shifted to λEM = 598 nm. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Dual crosslinked phenylethynyl end‐capped sulfonated polyimides via the ethynyl and sulfonate groups promoted by PEG
Authors: Gong Chenliang , Luo Qiang , Li Yanfeng , Giotto Marcus , Cipollini Ned E. , Yang Zhiwei , Weiss R. A. , Scola Daniel A. 
Published: August 2011

AbstractTypically, phenylethynyl (PE) end‐capped oligomides require a temperature of 370 °C for 1 h to develop a crosslinked system. A published method using poly(ethylene glycol)s (DM‐PEG‐250 and PEG‐400) as cosolvents with NMP was effective in crosslinking the ethynyl end‐caps at 250 °C/3 h in nonsulfonated oligomides. The application of this novel crosslinked method to PE end‐capped sulfonated oligomides was effective but caused a secondary crosslinked network via the sulfonic acid groups and ethylene glycol solvents. The solid‐state 13C NMR spectral data on 13C‐labeled end‐caps in the PE‐3F‐SPI‐3 oligomide provide evidence for the ethynyl to ethynyl and ethylene oxide sulfonate ester dual crosslinked structure. Infrared spectroscopy of model compounds also provides evidence for the presence of crosslinked sulfonate ester and appended sulfonate ester side chains. 13C NMR also provided quantitative data on the extent of the ethynyl to ethynyl crosslinking reaction and sulfonate ester crosslinks and side chains. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
The effect of structural variations on aromatic polyethers for high‐temperature PEM fuel cells
Authors: Morfopoulou Christina , Andreopoulou Aikaterini K. , Kallitsis Joannis K. 
Published: August 2011

AbstractThree series of new aromatic polyether sulfones bearing phenyl, p‐tolyl or carboxyl side groups, respectively, and polar pyridine main chain groups were developed. Most of the polymeric materials presented high molecular weights and excellent solubility in common organic solvents. More importantly, they formed stable, self‐standing membranes that were thoroughly characterized in respect to their thermal, mechanical and oxidative stability, their phosphoric acid doping ability and ionic conductivity. Particularly, the copolymers bearing side p‐tolyl or carboxyl groups fulfill all necessary requirements for application as proton electrolyte membranes in high temperature fuel cells, which are glass transition temperatures higher than 220 °C, thermal stability up to 400 °C, oxidative stability, high doping levels (DLs) and proton conductivities of about 0.02 S/cm. Initial single fuel cell results at high temperatures, 160 °C or 180 °C, using a copolymer bearing p‐tolyl side groups with a relatively low DLs around 200 wt % and dry H2/Air feed gases, revealed efficient power generation with a current density of 0.5 A/cm2 at 500 mV. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Influence of thermal history and humidity on the ionic conductivity of nanoparticle‐filled solid polymer electrolytes
Authors: Fullerton‐Shirey Susan K. , Ganapatibhotla Lalitha V. N. R. , Shi Wenjin , Maranas Janna K. 
Published: August 2011

AbstractThe crystallinity and conductivity of nanoparticle‐filled solid polymer electrolytes (SPEs) are investigated as a function of thermal history and water content. Our objective is to evaluate how performance is affected by the conditions under which the SPEs are handled and tested. The samples consist of polyethylene oxide (PEO), LiClO4, and Al2O3 nanoparticles. At low humidity, SPEs at ether oxygen to lithium ratios of 8:1 do not crystallize immediately; instead, 3 days are required for crystallization to occur, and this does not depend strongly on the presence of nanoparticles. The conductivity is improved by the addition of nanoparticles at low humidity, but only at an ether oxygen to lithium ratio of 10:1, which corresponds to the eutectic concentration. At high humidity, the recrystallization time is delayed for 3 weeks, and the conductivity increases in both filled and unfilled SPEs beyond that of the low humidity samples. Although we observe that water amplifies the influence of nanoparticles on conductivity, we also find that nanoparticles inhibit water uptake—but only in the presence of lithium. Because Li+ strongly absorbs water, this result suggests that nanoparticles may interact directly with Li+ ions to prevent water uptake. In filled samples at the eutectic concentration (10:1), more water is absorbed compared to the nanoparticle‐filled 8:1 samples, even though less lithium is present. This suggests that nanoparticles may segregate to lithium‐poor regions in the 10:1 samples, and this scenario is supported by the morphology that would be expected at the eutectic concentration. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1496–1505, 2011
The dimerization interface of the glycoprotein Ibβ transmembrane domain corresponds to polar residues within a leucine zipper motif
Authors: Wei Peng , Liu Xin , Hu Miao‐Hui , Zuo Li‐Min , Kai Ming , Wang Rui , Luo Shi‐Zhong 
Published: August 2011

AbstractExperiments with the transmembrane (TM) domains of the glycoprotein (GP) Ib‐IX complex have indicated that the associations between the TM domains of these subunits play an important role in the proper assembly of the complex. As a first step toward understanding these associations, we previously found that the Ibβ TM domain dimerized strongly in Escherichia coli cell membranes and led to Ibβ TM‐CYTO (cytoplasmic domain) dimerization in the SDS‐PAGE assay, while neither Ibα nor IX TM‐CYTO was able to dimerize. In this study, we used the TOXCAT assay to probe the Ibβ TM domain dimerization interface by Ala‐ and Leu‐scanning mutagenesis. Our results show that this interface is based on a leucine zipper‐like heptad repeat pattern of amino acids. Mutating either one of polar residues Gln129 or His139 to Leu or Ala disrupted Ibβ TM dimerization dramatically, indicating that polar residues might form part of the leucine zipper‐based dimerization interface. Furthermore, these specific mutational effects in the TOXCAT assay were confirmed in the thiol‐disulfide exchange and SDS‐PAGE assays. The computational modeling studies further revealed that the most likely leucine zipper interface involves hydrogen bonding of Gln129 and electrostatic interaction of the His139 side chain. Correlation of computer modeling results with experimental mutagenesis studies on the Ibβ TM domain may provide insights for understanding the role of the association of TM domains on the assembly of GP Ib‐IX complex.
Diamond ultra‐microelectrode arrays for achieving maximum Faradaic current with minimum capacitive charging
Authors: Yang Nianjun , Smirnov Waldemar , Hees Jakob , Hoffmann René , Kriele Armin , Obloh Harald , Müller‐Sebert Wolfgang , Nebel Christoph E. 
Published: August 2011

AbstractAll‐diamond ultra‐microelectrode arrays (UMEAs) were fabricated using standard photolithography processes. The array consists of typically 45 ultra‐microelectrodes with a diameter of 10 µm and with a center‐to‐center spacing of 60 µm. The quasi‐reference and counter electrodes are made from conductive diamond and integrated on a 5 × 5 mm2 chip. The arrays with different surface terminations were characterized using cyclic voltammetry and the redox couple of ${\rm Fe(CN)}_{{\rm 6}}^{{{{\rm 3}{-} } \mathord{\left/ {\vphantom {{{\rm 3}{-} } {4{-} }}} \right. \kern-\nulldelimiterspace} {4{-} }}} $ as probes. A peak‐shaped voltammogram was detected on electrochemically hydrogen‐terminated surface if scanned with a slow scan rate (e.g. 20 mV/s), resulting in a higher ratio of the Faradaic current (signal) to capacitive charging current (background current). A sensitive and reproducible detection of hydrogen peroxide was achieved by using the UMEA. The net‐charge for the oxidation of hydrogen peroxide at 0.4 V (vs. C) is linear with the concentration of hydrogen peroxide in the range of 6.5–650 µM. The detection limit is 2.0 µM, which is 100 times better than that obtained on the macro‐sized boron‐doped diamond electrode.
Persistent ocean monitoring with underwater gliders: Adapting sampling resolution
Authors: Smith Ryan N. , Schwager Mac , Smith Stephen L. , Jones Burton H. , Rus Daniela , Sukhatme Gaurav S. 
Published: August 2011

AbstractOcean processes are dynamic and complex and occur on multiple spatial and temporal scales. To obtain a synoptic view of such processes, ocean scientists collect data over long time periods. Historically, measurements were continually provided by fixed sensors, e.g., moorings, or gathered from ships. Recently, an increase in the utilization of autonomous underwater vehicles has enabled a more dynamic data acquisition approach. However, we still do not utilize the full capabilities of these vehicles. Here we present algorithms that produce persistent monitoring missions for underwater vehicles by balancing path following accuracy and sampling resolution for a given region of interest, which addresses a pressing need among ocean scientists to efficiently and effectively collect high‐value data. More specifically, this paper proposes a path planning algorithm and a speed control algorithm for underwater gliders, which together give informative trajectories for the glider to persistently monitor a patch of ocean. We optimize a cost function that blends two competing factors: maximize the information value along the path while minimizing deviation from the planned path due to ocean currents. Speed is controlled along the planned path by adjusting the pitch angle of the underwater glider, so that higher resolution samples are collected in areas of higher information value. The resulting paths are closed circuits that can be repeatedly traversed to collect long‐term ocean data in dynamic environments. The algorithms were tested during sea trials on an underwater glider operating off the coast of southern California, as well as in Monterey Bay, California. The experimental results show improvements in both data resolution and path reliability compared to previously executed sampling paths used in the respective regions. © 2011 Wiley Periodicals, Inc.
Performance evaluation of 1‐point‐RANSAC visual odometry
Authors: Scaramuzza Davide 
Published: August 2011

AbstractMonocular visual odometry is the process of computing the egomotion of a vehicle purely from images of a single camera. This process involves extracting salient points from consecutive image pairs, matching them, and computing the motion using standard algorithms. This paper analyzes one of the most important steps toward accurate motion computation, which is outlier removal. The random sample consensus (RANSAC) has been established as the standard method for model estimation in the presence of outliers. RANSAC is an iterative method, and the number of iterations necessary to find a correct solution is exponential in the minimum number of data points needed to estimate the model. It is therefore of utmost importance to find the minimal parameterization of the model to estimate. For unconstrained motion [six degrees of freedom (DoF)] of a calibrated camera, this would be five correspondences. In the case of planar motion, the motion model complexity is reduced (three DoF) and can be parameterized with two points. In this paper we show that when the camera is installed on a nonholonomic wheeled vehicle, the model complexity reduces to two DoF and therefore the motion can be parameterized with a single‐point correspondence. Using a single‐feature correspondence for motion estimation is the lowest model parameterization possible and results in the most efficient algorithm for removing outliers, which we call 1‐point RANSAC. To support our method, we run many experiments on both synthetic and real data and compare the performance with state‐of‐the‐art approaches and with different vehicles, both indoors and outdoors. © 2011 Wiley Periodicals, Inc.