Active corrosion of carbon steel in reinforced concrete occurs when the chloride ion concentration exceeds the chloride threshold (CT). CT is affected by many physical and chemical parameters including primary variables (pH, corrosion potential, breakdown potential, and temperature) and secondary variables (cemenet composition, concreete porosity, and water/cement ratio). A Kohonen-self organized map (KSOM) and regression artificial neural network (ANN) coupled methodology was developed to find the missing values of independent variables in the sparse database and for quantitatively evaluating the effects of these variables on CT values that are expressed in %TotalCl/cem (or %FreeCl/cem), and [Cl<sup>-</sup>]/[OH<sup>-</sup>].
Luminescence extraction has played a tremendous role in improving the efficiency of solar photovoltaics. This has been assisted by the development of a highly reflective rear mirror. At the same time, thermophotovoltaic efficiency has shown to benefit from a rear mirror. The low-energy, unabsorbed photons in the thermophotovoltaic cells can be reflected by the mirror, thereby assisting in photon regeneration. In both cases, it has been shown that device efficiency has an increasing return with improvement rear mirror reflectivity. However, the realization of broadband mirrors with reflectivity >98% has remained elusive. Here, we demonstrate a mirror that can achieve broadband 99.3% reflectivity, for thermophotovoltaic cells. The design concept can be equally extended to photovoltaic cells as well, thereby enhancing the efficiencies closer to the thermodynamic limits.
Force feedback coupled with a real-time physically realistic graphic display provides a human operator with an artificial sense of presence in a virtual environment. Furthermore, it allows a human operator to interact with the virtual environment through "touch". We describe a haptic simulation system that allows a human operator to perform real-time interaction with soft 3D objects that go through large global deformations. We model and simulate such a global deformation using geometrically nonlinear finite element methods (FEM). We also introduce an efficient method that computes the force feedback, in real-time, by simulating the collision between the virtual "proxy" and the deformable object. To perceptually satisfy a human operator, haptics requires a much higher update frequency (at least 1000 Hz) than graphics. We update the graphics using full simulation and interpolate the fully simulated states at a higher frequency to render haptics. The interpolation is made possible by intentionally delaying the display (both graphics and haptics) by one full simulation cycle.
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXT"Hangman" Porphyrins for the Assembly of a Model Heme Water ChannelChen-Yu Yeh, Christopher J. Chang, and Daniel G. NoceraView Author Information Department of Chemistry, 6-335 Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge, Massachusetts 02139 Cite this: J. Am. Chem. Soc. 2001, 123, 7, 1513–1514Publication Date (Web):January 30, 2001Publication History Received1 September 2000Revised7 November 2000Published online30 January 2001Published inissue 1 February 2001https://pubs.acs.org/doi/10.1021/ja003245khttps://doi.org/10.1021/ja003245krapid-communicationACS PublicationsCopyright © 2001 American Chemical SocietyRequest reuse permissionsArticle Views2142Altmetric-Citations130LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (2)»Supporting Information Supporting Information SUBJECTS:Anions,Bioinorganic chemistry,Cations,Noncovalent interactions,Pyrroles Get e-Alerts
Excess energy–volume and cohesive energy density coefficients have been calculated for the hexane + perfluoro-hexane, water + DMSO, water + tert-butanol, water + methanol, water + acetonitrile, and methanol + DMSO Systems. These parameters are compared with other constant pressure excess functions of mixing for these binary systems, and it is proposed that they represent additional criteria for the classification of liquid mixtures.
The SBU approach facilitated the development of permanently porous MOFs with unique properties, chemistry, and applications.
Techwire Using the URL at the [end][1] of this item, readers can immediately offer feedback and suggestions on this topic. I t has always been a dream of materials researchers [[HN1][2]] to design a new material completely on paper, optimizing the composition and processing steps in order to
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
This paper describes two approaches for estimating sensible heat flux, using surface renewal and similarity concepts. One approach depends on a temperature structure function parameter and is valid in the inertial sublayer. The other approach depends on the temperature standard deviation and operates when measurements are made above the canopy top, either in the roughness or inertial sublayer. The approaches were tested over grass, rangeland grass, wheat, grape vineyard, and nectarine and olive orchards. It is shown that the free convection limit expression for the standard deviation method holds for slightly unstable conditions. When surface homogeneity and fetch requirements are not fully met in the field, the results show that the equations based on surface renewal principles are more robust and accurate than equations exclusively based on similarity backgrounds. It is likely that the two methods are less sensitive to site‐specific adjustment of the similarity relationships unless the canopy is rather heterogeneous. Under unstable conditions, the free convection limit equation, which depends on the temperature standard deviation, can provide online sensible heat flux estimates using affordable battery‐powered data logger with temperature data as the only input. The approach performed well when measuring above the canopy in the roughness and inertial sublayers, thus suggesting that the method is useful for long‐term monitoring over growing vegetation.
New hafnocene triarylstannyl complexes were prepared and were shown to undergo clean thermal decompositions via alpha-aryl-elimination to produce the corresponding stannylene and a hafnocene aryl complex. The rate of the decomposition is highly dependent on the nature of the ancillary ligand, with the stabilities of the CpCp*Hf(SnPh(3))X compounds following the order X = NMe(2) > Np (alpha-agostic) > OMe > Cl > Me. Mechanistic information suggests that alpha-aryl-elimination may be viewed as a concerted process involving nucleophilic attack of the migrating aryl group onto the electrophilic metal center.
The Peer-to-Peer (P2P) architectures that are most prevalent in today's Internet are decentralized and unstructured. Search is blind in that it is independent of the query and is thus not more effective than probing randomly chosen peers. One technique to improve the effectiveness of blind search is to proactively replicate data. We evaluate and compare different replication strategies and reveal interesting structure: Two very common but very different replication strategies - uniform and proportional - yield the same average performance on successful queries, and are in fact worse than any replication strategy which lies between them. The optimal strategy lies between the two and can be achieved by simple distributed algorithms. These fundamental results o.er a new understanding of replication and show that currently deployed replication strategies are far from optimal and that optimal replication is attainable by protocols that resemble existing ones in simplicity and operation.
The electron irradiation induced TiCl4 deposition on a gold polycrystalline foil and on a Au (100) single crystal in ultra-high vacuum conditions is reported. Titanium chloride ultrathin films are prepared at 250−300 K by irradiation of the substrate with 1 keV electrons in a background pressure of TiCl4 of 1 × 10-8 to 5 × 10-7 Torr. The deposited films are characterized by AES, XPS, and temperature-programmed desorption (TPD). We can grow titanium chloride films of the maximum thickness of about 25 Å under our experimental conditions. The film consists of 3−4 layers of TiCl2 with 1 monolayer of TiCl4 chemisorbed on its surface. A comparison is made with the titanium chloride film grown on MgCl2 ultrathin films by electron irradiation induced TiCl4 deposition as previously reported. This film is very similar to the titanium chloride film deposited on Au and can be described as few layers of TiCl2 deposited on a defective MgCl2-x film. One monolayer of TiCl4 is chemisorbed on the TiCl2 surface.
