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排序方式: 共有960条查询结果,搜索用时 46 毫秒
951.
Ramón Fernández-Ruiz Román Andrés Ernesto de Jesús Pilar Terreros 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010
Quantitative determination of Zr in the system constituted by quartz microspheres functionalized with two kinds of organometallic compounds has been studied due to the importance of the correct quantization of the Zr from a catalytic point of view. Two parallel approximations were done, i.e. acid leaching and direct solid quantization. To validate the acid leaching TXRF measures, ICP-MS analysis were carried out. The results obtained by means of the optimization of the quantitative direct solid procedure show that, with a previous particle size distribution modification, TXRF obtain the same analytical results as ICP-MS and TXRF by acid leaching way but without previous chemical acid manipulation. This fact implies an important improvement for the analysis time, reagents costs and analysis facility and it proves again the versatility of TXRF to solve analytical problems in an easy, quick and accurate way. Additionally and for the direct solid TXRF measurements, a deeper study was done to evaluate the intrinsic analytical parameters of the Zr TXRF analysis of this material. So, the influence of the particle size distributions (modified by means of a high power ultrasound probe) with respect to uncertainty and detection limits for Zr were developed. The main analytical conclusion was the strong correlation between the average particle sizes and the TXRF analytical parameters of Zr measurements, i.e. concentration, accuracy, uncertainty and detection limits. 相似文献
952.
Uniform Uncertainty Principle and Signal Recovery via Regularized Orthogonal Matching Pursuit 总被引:16,自引:0,他引:16
This paper seeks to bridge the two major algorithmic approaches to sparse signal recovery from an incomplete set of linear
measurements—L1-minimization methods and iterative methods (Matching Pursuits). We find a simple regularized version of Orthogonal Matching
Pursuit (ROMP) which has advantages of both approaches: the speed and transparency of OMP and the strong uniform guarantees
of L1-minimization. Our algorithm, ROMP, reconstructs a sparse signal in a number of iterations linear in the sparsity, and the
reconstruction is exact provided the linear measurements satisfy the uniform uncertainty principle.
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This study presents an interval de Novo programming (IDNP) approach for the design of optimal water-resources-management systems under uncertainty. The model is derived by incorporating the existing interval programming and de Novo programming, allowing uncertainties represented as intervals within the optimization framework. The developed IDNP approach has the advantages in constructing optimal system design via an ideal system by introducing the flexibility toward the available resources in the system constraints. A simple numerical example is introduced to illustrate the IDNP approach. The IDNP is then applied to design an inexact optimal system with budget limit instead of finding the optimum in a given system with fixed resources in a water resources planning case. The results demonstrate that the developed method efficiently produces stable solutions under different objectives. Optimal supplies of good-quality water are obtained in considering different revenue targets of municipal–industrial–agricultural competition under a given budget. 相似文献
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Dr. Bjarne Kreitz Dr. Patrick Lott Prof. Dr. Felix Studt Prof. Dr. Andrew J. Medford Prof. Dr. Olaf Deutschmann Prof. Dr. C. Franklin Goldsmith 《Angewandte Chemie (International ed. in English)》2023,62(39):e202306514
The study presents an ab-initio based framework for the automated construction of microkinetic mechanisms considering correlated uncertainties in all energetic parameters and estimation routines. 2000 unique microkinetic models were generated within the uncertainty space of the BEEF-vdW functional for the oxidation reactions of representative exhaust gas emissions from stoichiometric combustion engines over Pt(111) and compared to experiments through multiscale modeling. The ensemble of simulations stresses the importance of considering uncertainties. Within this set of first-principles-based models, it is possible to identify a microkinetic mechanism that agrees with experimental data. This mechanism can be traced back to a single exchange-correlation functional, and it suggests that Pt(111) could be the active site for the oxidation of light hydrocarbons. The study provides a universal framework for the automated construction of reaction mechanisms with correlated uncertainty quantification, enabling a DFT-constrained microkinetic model optimization for other heterogeneously catalyzed systems. 相似文献
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