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Institution

École Polytechnique Fédérale de Lausanne

FacilityLausanne, Switzerland
About: École Polytechnique Fédérale de Lausanne is a facility organization based out in Lausanne, Switzerland. It is known for research contribution in the topics: Population & Catalysis. The organization has 44041 authors who have published 98296 publications receiving 4372092 citations. The organization is also known as: EPFL & ETHL.


Papers
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Journal ArticleDOI
TL;DR: This paper gives an introduction to Blast and demonstrates, through two case studies, how it can be applied to program verification and test-case generation.
Abstract: Blast is an automatic verification tool for checking temporal safety properties of C programs. Given a C program and a temporal safety property, Blast either statically proves that the program satisfies the safety property, or provides an execution path that exhibits a violation of the property (or, since the problem is undecidable, does not terminate). Blast constructs, explores, and refines abstractions of the program state space based on lazy predicate abstraction and interpolation-based predicate discovery. This paper gives an introduction to Blast and demonstrates, through two case studies, how it can be applied to program verification and test-case generation. In the first case study, we use Blast to statically prove memory safety for C programs. We use CCured, a type-based memory-safety analyzer, to annotate a program with run-time assertions that check for safe memory operations. Then, we use Blast to remove as many of the run-time checks as possible (by proving that these checks never fail), and to generate execution scenarios that violate the assertions for the remaining run-time checks. In our second case study, we use Blast to automatically generate test suites that guarantee full coverage with respect to a given predicate. Given a C program and a target predicate p, Blast determines the program locations q for which there exists a program execution that reaches q with p true, and automatically generates a set of test vectors that cause such executions. Our experiments show that Blast can provide automated, precise, and scalable analysis for C programs.

617 citations

Journal ArticleDOI
TL;DR: In this article, an ionic liquid electrolyte composed of 1-methyl-3-propylimidazolium iodide, 1-ethyl-3]-dimethyl-polypyridyl ruthenium dicyanamide, and lithium iodide (LiI) was combined with an amphiphilic polypyrinyl-rushenium sensitizer to obtain a solar cell based on a solvent-free electrolyte that had an efficiency of 6.6% at an irradiance of air mass 1.5 and >7.1
Abstract: An ionic liquid electrolyte composed of 1-methyl-3-propylimidazolium iodide, 1-methyl-3-ethylimidazolium dicyanamide, and lithium iodide (LiI) was combined with an amphiphilic polypyridyl ruthenium sensitizer to obtain a solar cell based on a solvent-free electrolyte that had an efficiency of 6.6% at an irradiance of air mass 1.5 (AM 1.5, 100 mW cm -2 ) and >7.1% at lower light intensities. This is the first time such a high efficiency was obtained for dye-sensitized solar cells with pure ionic liquid electrolytes. A thin-layer electrochemical cell was used to determine the redox potential of sensitizers anchored on TiO 2 nanocrystalline film by square-wave voltammetry. Laser transient absorbance measurements revealed that a significant enhancement of the device efficiency, after adding LiI to the ionic liquid electrolyte, could be ascribed to an increase in the electron injection yield and dye regeneration rate.

617 citations

Journal ArticleDOI
TL;DR: The concept of using eutectic melts to produce solvent-free liquid redox electrolytes to produce mesoscopic DSCs is introduced and excellent stability and an unprecedented efficiency of 8.2% under air-mass 1.5 global illumination are reached.
Abstract: The presence of organic solvents in solar cells has hindered the application of devices, especially in flexible cells. Now, by mixing three solid salts, a solvent-free liquid electrolyte for dye-sensitized solar cells has been discovered that shows both excellent efficiency and stability. Low-cost excitonic solar cells based on organic optoelectronic materials are receiving an ever-increasing amount of attention as potential alternatives to traditional inorganic photovoltaic devices. In this rapidly developing field, the dye-sensitized solar cell1 (DSC) has achieved so far the highest validated efficiency of 11.1% (ref. 2) and remarkable stability3. However, the cells with the best performance use volatile solvents in their electrolytes, which may be prohibitive for outdoor solar panels in view of the need for robust encapsulation. Solvent-free room-temperature ionic liquids4,5,6,7,8,9,10,11 have been pursued as an attractive solution to this dilemma, and device efficiencies of over 7% were achieved by using some low-viscosity formulations containing 1-ethyl-3-methylimidazolium thiocyanate8, selenocyanate9, tricyanomethide10 or tetracyanoborate11. Unfortunately, apart from tetracyanoborate, all of these low-viscosity melts proved to be unstable under prolonged thermal stress and light soaking. Here, we introduce the concept of using eutectic melts to produce solvent-free liquid redox electrolytes. Using a ternary melt in conjunction with a nanocrystalline titania film and the amphiphilic heteroleptic ruthenium complex Z907Na (ref. 10) as a sensitizer, we reach excellent stability and an unprecedented efficiency of 8.2% under air-mass 1.5 global illumination. Our results are of importance to realize large-scale outdoor applications of mesoscopic DSCs.

617 citations

Journal ArticleDOI
TL;DR: In this article, the similarity solutions describing the steady plane (flow and thermal) boundary layers on an exponentially stretching continuous surface with an exponential temperature distribution are examined both analytically and numerically.
Abstract: The similarity solutions describing the steady plane (flow and thermal) boundary layers on an exponentially stretching continuous surface with an exponential temperature distribution are examined both analytically and numerically. The mass- and heat-transfer characteristics of these boundary layers are described and compared with the results of earlier authors, obtained under the more familiar power-law boundary conditions.

617 citations

Journal ArticleDOI
TL;DR: A new reconstruction procedure that retrieves both the specimen's image and the illumination profile was recently demonstrated with hard X-ray data and is presented in greater details to illustrate its practical applicability with a visible light dataset.

616 citations


Authors

Showing all 44420 results

NameH-indexPapersCitations
Michael Grätzel2481423303599
Ruedi Aebersold182879141881
Eliezer Masliah170982127818
Richard H. Friend1691182140032
G. A. Cowan1592353172594
Ian A. Wilson15897198221
Johan Auwerx15865395779
Menachem Elimelech15754795285
A. Artamonov1501858119791
Melody A. Swartz1481304103753
Henry J. Snaith146511123155
Kurt Wüthrich143739103253
Richard S. J. Frackowiak142309100726
Jean-Paul Kneib13880589287
Kevin J. Tracey13856182791
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023234
2022704
20215,247
20205,644
20195,432
20185,094