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31.
Morin G Juillot F Casiot C Bruneel O Personné JC Elbaz-Poulichet F Leblanc M Ildefonse P Calas G 《Environmental science & technology》2003,37(9):1705-1712
The oxidation of Fe(II) in acid mine drainage (AMD) leads to the precipitation of Fe(III) compounds which may incorporate toxic elements, such as arsenic (As), within their structure or adsorb them at their surface, thus limiting their mobility. The present work provides evidence for spatial and seasonal variations of microbial activity that influence arsenite oxidation and As immobilization in the heavily contaminated AMD from the Carnoulès mine, Gard, France ([As III] = 80 to 280 mg x L(-1) in the acidic spring draining the waste-pile). In the first tens of meters of the AMD, the rapid oxidation of Fe(II) leads to the coprecipitation of large amounts of As with Fe(III) in bacterial mats. XRD, XANES, and SEM analyses of sediments and stromatolite samples revealed the unusual formation of As(III)-rich compounds, especially nanocrystalline tooeleite, Fe6(AsO3)4(SO4)(OH)4 x 4H2O, a rare ferric arsenite sulfate oxy-hydroxide mineral, together with XRD-amorphous mixed As(III)/As(V)-Fe(III) oxy-hydroxide compounds. In the wet season, the suspended sediments of the upstream zone essentially consist of tooeleite associated with am-As(III)-Fe(III) oxy-hydroxides, while am-As(V)-Fe(III) oxy-hydroxides, having As:Fe molar ratios as high as 0.6-0.8, dominate in the dry season. Comparing natural and bioassay samples revealed that the formation of As(III)-rich compounds in the wet season may be related to the metabolic activity of bacterial strains able to oxidize Fe(II) but not As(III). One of these strains, having an Acidithiobacillus ferrooxidans genotype, has been isolated from the Carnoulès AMD. In contrast, the formation of As(V)-rich compounds in the dry season can be related to both biotic and abiotic oxidation of As(III) to As(V). Some Thiomonas strains isolated from the Carnoulès AMD were shown to be able to catalyze the oxidation of As(III) to As(V) in solution. Therefore, they can promote the formation of mixed As(V)-Fe(III) oxy-hydroxides, provided enough Fe(II) oxidizes. These results yield a better understanding of natural processes at this site and may help in designing efficient As-removal processes. 相似文献
32.
Dugué Nicolas Lamirel Jean-Charles Chen Yue 《Neural computing & applications》2021,33(19):12939-12956
Neural Computing and Applications - This paper focuses on using feature salience to evaluate the quality of a partition when dealing with hard clustering. It is based on the hypothesis that a good... 相似文献
33.
Jacques Angel Alain Boissier Sylvain Lallemant Franois Leblanc Bertrand Pcout Jacob W. Lin James Tung 《Journal of the Society for Information Display》2003,11(3):533-538
Abstract— As the need for high‐resolution ultra‐low‐power bistable displays grows, it is important to rapidly implement the mass‐production manufacturing of BiNem® LCDs. The cost‐effective approach for BiNem® manufacturing is based on using STN manufacturing process technologies since BiNem® and STN displays have a similar internal structure. The key differences between BiNem® and STN displays from a manufacturing point of view will be discussed. We show that industrial STN manufacturing equipment can be used to produce BiNem® LCDs at competitive costs. Reflective e‐book display modules with VGA resolution are produced in the pilot‐production series. 相似文献
34.
This paper presents a simple and general modeling primitive, called a block, based on a generalized cuboid shape. Blocks are laid out and connected together to constitute the base shape of complex objects, from which is extracted a control mesh that can contain both smooth and sharp edges. The volumetric nature of the blocks allows for easy topology specification, as well as CSG operations between blocks. The surface parameterization inherited from the block faces provides support for texturing and displacement functions to apply surface details. A?variety of examples illustrate the generality of our blocks in both interactive and procedural modeling contexts. 相似文献
35.
David Balloy Jean-Charles Tissier Marie-Laurence Giorgi Marc Briant 《Metallurgical and Materials Transactions A》2010,41(9):2366-2376
The corrosion mechanisms by liquid aluminum of three industrial materials have been studied: unalloyed steel (UAS), and ferritic
and modified pearlitic cast irons (FCI and PCI, respectively). The behavior of these materials when in contact with liquid
aluminum is different. Aluminum diffuses deep into the UAS and forms intermetallic compounds with iron at the surface and
in the steel matrix. At the surface, only Fe2Al5 and FeAl3 are found. In the matrix, FeAl2 also is formed in agreement with the equilibrium Fe-Al diagram. From the matrix to FeAl2, the Al content in the ferrite increases progressively until Al saturation is reached. At this step, black elongated precipitates
(Al4C3 and/or graphite) appear. Graphite lamellas present in both FCI and PCI constitute an efficient barrier to the Al diffusion.
The high silicon content of the FCI leads to the formation of a phase free from Al and saturated in Si. For the PCI, a thin
layer rich in Al and Si, which is formed between the matrix and Fe2Al5, limits the diffusion of atoms. The effects of Cr and P added in the PCI also are discussed. 相似文献
36.
Jean-Charles Delvenne Ruggero Carli Sandro Zampieri 《Systems & Control Letters》2009,58(10-11):759-765
Let a set of communicating agents compute the average of their initial positions, where every agent is restricted to communicate to a given small number of other agents (average consensus problem). We prove that the optimal topology of communication is given by a de Bruijn graph. Consensus is then reached in finitely many steps. This solution is valid when the number of agents is an exact power of the out-degree of the communication graph. We introduce an algebraic tool, the shifted Kronecker product, and a more general family of strategies, also based on a de Bruijn communication graph. Those strategies are compared to Cayley strategies in terms of the speed of convergence. We also show that quantized communication between the agents still allows finite convergence, to a consensus, which is not in general the average of the initial positions. 相似文献
37.
38.
Heuristic construction knowledge generated while contracting is seldom recorded and transferred to other workers. Experiences of past mistakes as well as efficient work practices are crucial means for saving money, time, and improving the safety and quality of construction. With the rising costs of construction and the increased demand of time constraints on contractor schedules, few members of the construction industry can afford to waste time and resources on errors or ineffective work practices. The Constructability Lessons Learned Database (CLLD) prototype described in this paper is a leading edge method of automatically gathering, systematically organizing and efficiently applying vital construction information to a contractor's daily activities. This paper presents a review of previous and current attempts at database constructability programs, uses of constructability feedback systems, challenges to develop and utilize such systems, and an overview of the design and development of the CLLD prototype. The overview describes knowledge elicitation techniques used to gather constructability knowledge, the design of the system (organizing and classifying construction information for efficient retrieval and expansion), and system's implementation, validation, and operation. The conclusion discusses future extensions of the CLLD concept in the construction industry. 相似文献
39.
At 75/25 concentration ratio, bisphenol a polycarbonate (PC)/styreneacry-lonitrile copolymer (SAN) blend has poor impact resistance compared to PC/ABS. A rubber phase methacrylate-butadiene-styrene (MBS) of core/shell type was dispersed in PC/SAN blend. The morphology of the unmodified and modified blend was investigated. The influence of the acrylonitrile ratio in the SAN on the microstructure was studied. It clearly shows that core/shell resides at the interface between PC and SAN. It seems that core/shell particles enhance the adhesion between the different phases. Their presence influences the interface mobility; i.e., the coalescence of the dispersed phase observed in pure PC/SAN is considerably reduced when the MBS particles are added. The impact resistance of the samples was correlated with the morphology. 相似文献
40.
Tremblay R. E.; Masse B.; Perron D.; Leblanc M.; Schwartzman A. E.; Ledingham J. E. 《Canadian Metallurgical Quarterly》1992,60(1):64
Three alternative models concerning the causal links between early disruptive behavior, poor school achievement, and delinquent behavior or antisocial personality were tested with linear structural equation modeling. Ss were boys and girls followed from 1st grade to age 14 yrs. Disruptive behavior was assessed in Grade 1; school achievement was assessed in Grades 1 and 4; delinquent behavior and antisocial personality were assessed at age 14 yrs. With regard to self-reported delinquent behavior at age 14 yrs, results indicate that the best model for boys was a direct causal link between Grade 1 disruptive behavior and delinquent behavior. Poor school achievement was not a necessary causal factor. For girls, none of the tested models were a good fit to the delinquent behavior data. As for delinquent personality, results indicate that, for boys and girls, poor school achievement was a necessary component of the causal path between Grade 1 disruptive behavior and age 14 delinquent personality. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献