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Search Results: 1 - 10 of 65 matches for " Meriam Triki "
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Progress towards an accurate determination of the Boltzmann constant by Doppler spectroscopy
Cyril Lemarchand,Meriam Triki,Beno?t Darquié,Christian J. Bordé,Christian Chardonnet,Christophe Daussy
Physics , 2010, DOI: 10.1088/1367-2630/13/7/073028
Abstract: In this paper, we present significant progress performed on an experiment dedicated to the determination of the Boltzmann constant, k, by accurately measuring the Doppler absorption profile of a line in a gas of ammonia at thermal equilibrium. This optical method based on the first principles of statistical mechanics is an alternative to the acoustical method which has led to the unique determination of k published by the CODATA with a relative accuracy of 1.7 ppm. We report on the first measurement of the Boltzmann constant by laser spectroscopy with a statistical uncertainty below 10 ppm, more specifically 6.4 ppm. This progress results from improvements in the detection method and in the statistical treatment of the data. In addition, we have recorded the hyperfine structure of the probed saQ(6,3) rovibrational line of ammonia by saturation spectroscopy and thus determine very precisely the induced 4.36 (2) ppm broadening of the absorption linewidth. We also show that, in our well chosen experimental conditions, saturation effects have a negligible impact on the linewidth. Finally, we draw the route to future developments for an absolute determination of with an accuracy of a few ppm.
Evidence for speed-dependent effects in NH3 self-broadened spectra: towards a new determination of the Boltzmann constant
Meriam Triki,Cyril Lemarchand,Beno?t Darquié,Papa Lat Tabara Sow,Vincent Roncin,Christian Chardonnet,Christophe Daussy
Physics , 2012, DOI: 10.1103/PhysRevA.85.062510
Abstract: In this paper we present an accurate analysis of the shape of an isolated rovibrational ammonia line from the strong nu2 band around 10 $\mu$m, recorded by laser absorption spectroscopy. Experimental spectra obtained under controlled temperature and pressure, are confronted to various models that take into account Dicke narrowing or speed-dependent effects. Our results show clear evidence for speed-dependent broadening and shifting, which had never been demonstrated so far in NH3. Accurate lineshape parameters of the nu2 saQ(6,3) line are obtained. Our current project aiming at measuring the Boltzmann constant, kB, by laser spectroscopy will straight away benefit from such knowledge. We anticipate that a first optical determination of kB with a competitive uncertainty of a few ppm is now reachable.
A revised uncertainty budget for measuring the Boltzmann constant using the Doppler Broadening Technique on ammonia
Cyril Lemarchand,Sinda Mejri,Papa Lat Tabara Sow,Meriam Triki,Sean K. Tokunaga,Stephan Briaudeau,Christian Chardonnet,Beno?t Darquié,Christophe Daussy
Physics , 2013, DOI: 10.1088/0026-1394/50/6/623
Abstract: We report on our on-going effort to measure the Boltzmann constant, kB, using the Doppler Broadening Technique. The main systematic effects affecting the measurement are discussed. A revised error budget is presented in which the global uncertainty on systematic effects is reduced to 2.3 ppm. This corresponds to a reduction of more than one order of magnitude compared to our previous Boltzmann constant measurement. Means to reach a determination of kB at the part per million accuracy level are outlined.
Accurate determination of the Boltzmann constant by Doppler spectroscopy: Towards a new definition of the kelvin
Beno?t Darquié,Sinda Mejri,Papa Lat Tabara Sow,Cyril Lemarchand,Meriam Triki,Sean Tokunaga,Christian J. Bordé,Christian Chardonnet,Christophe Daussy
Physics , 2015, DOI: 10.1051/epjconf/20135702005
Abstract: Accurate molecular spectroscopy in the mid-infrared region allows precision measurements of fundamental constants. For instance, measuring the linewidth of an isolated Doppler-broadened absorption line of ammonia around 10 $\mu$m enables a determination of the Boltzmann constant k B. We report on our latest measurements. By fitting this lineshape to several models which include Dicke narrowing or speed-dependent collisional effects, we find that a determination of k B with an uncertainty of a few ppm is reachable. This is comparable to the best current uncertainty obtained using acoustic methods and would make a significant contribution to any new value of k B determined by the CODATA. Furthermore, having multiple independent measurements at these accuracies opens the possibility of defining the kelvin by fixing k B, an exciting prospect considering the upcoming redefinition of the International System of Units.
Dispositifs info-communicationnels: questions de médiations documentaires, sous la direction; Viviane Couzinet - DOI: 10.3395/reciis.v3i4.306en
Meriam Marouki
RECIIS : Electronic Journal of Communication, Information & Innovation in Health , 2009,
Per una convivenza ragionevole
Fathi Triki
Rivista Internazionale di Filosofia e Psicologia , 2011,
Abstract: Towards a Reasonably Grounded Coexistence - Under what conditions can people of different countries and parts of the world get along? The paper tries to work out an answer to this question which avoids taking a totalitarian perspective on the world or on the relationships between people. The author sets out the conditions for the construction of a form of peaceful coexistence in which human rights are respected and life is free from violence, racism and neo-colonization. The possible basis for the creation of this new system is the idea of reasonableness (Raisonnabilité), which relies on the Aristiotelian concept of phronesis, as well as to al-Farabi’s and Ibn Khaldun’s notion of al-ta′aqul. Author’s position puts forward derives from the conjunction of these points of view and consists in a notion of raisonnabilité that aims at giving back to reason its ethical, political and esthetical functions, recovering its humane and humanistic dimensions.
Published White House Internal Memos: Legal Transparency or Subtle Electoral Canvassing? La publication officielle des rapports internes de la Maison Blanche : transparence légale ou subtile stratégie électorale ?
Mounir Triki
Revue LISA / LISA e-journal , 2009, DOI: 10.4000/lisa.2085
Abstract: Dans quelle mesure la manipulation du genre est-elle une stratégie utile à des fins pragmatiques ? Les rapports internes de la Maison Blanche et les décrets officiels présentent un intérêt d’analyse stimulant : celui de l’affiliation générique . D’un c té, ce sont des exemples de discours officiels, d’où leur vocabulaire légal. D’autre part, le fait qu’ils sont publiés et non tenus secrets signifie que le bureau de presse de la Maison Blanche y voit une utilité politique certaine en les rendant public, d’où la présence d’une coloration propagandiste subtile des messages. Afin d’illustrer ce jeu générique , l’étude des rapports internes de G.W. Bush sur la politique des Indiens d’Amérique est au c ur de notre réflexion. Il est intéressant de noter que la période de publications de ces écrits co ncide curieusement avec des événements politiques de grande importance, servant ainsi des ambitions plus ou moins voilées.
Toward E-Knowledge Based Complaint Management
Samiha Mjahed,Abdelfatteh Triki
International Arab Journal of e-Technology , 2009,
Abstract: Service failure and recovery is a well-established area of services research. Research has shown that service recovery is critically important from a managerial perspective in terms of maintaining customer relationships. Yet few firms excel at handling service failures. There is a growing number of managers who claim that customers tend to be dissatisfied with their service recovery effort. Their employees cannot improve service processes when they experience recovery situations and their companies still do not learn from service failure. [19] attribute the service recovery ineffectiveness to the competing interests of managing employees, customers and processes. We agree with their contention that to address these criticisms, complaint management must acknowledge and find new approaches to achieve consistency and to correct the misalignment of interests that can exist between the actions of the organisation and the needs of its customers and employees. We believe that search in the customer knowledge management literature represents one effective means to enhance a firm ability to implement a cohesive service recovery strategy.A comprehensive based knowledge creation system framework where the Socialization, Externalization, Combination and Internalization (SECI) modes, and various ‘ba’ proposed by Nonaka and Konno are introduced for complaint management. Empirical research, involving a case study is presented to illustrate the proposed framework. This framework is believed to pave the way for e-knowledge based complaint management.
The Effect of Board and Ownership Structure on the Efficiency of Banks in Tunisia: The Stochastic Frontier Approach
Salima Taktak,Mohamed Triki
International Journal of Business and Management , 2012, DOI: 10.5539/ijbm.v7n16p139
Abstract: The corporate governance problem is likely to be worse in banks due to their attributes (greater opaqueness than other industries, greater government regulation...) that weaken many traditional governance mechanisms. The purpose of this research is to explore the governance characteristics of the Tunisian listed banks and to detect the impact of the internal governance mechanisms on their efficiency during the period 2002-2009. Our findings indicate that the structure and the size of the board of directors and the ownership structures present divergent effects on the banks efficiency. Then, empirical results show that Tunisian listed banks display a middle efficiency level of 81.60% during the period 2002-2006. The deterioration of the efficiency level is owed to big public bank; in fact, private banks are more efficient than the public ones.
New Stability Estimates for the Inverse Medium Problem with Internal Data
Mourad Choulli,Faouzi Triki
Mathematics , 2015, DOI: 10.1137/140988577
Abstract: A major problem in solving multi-waves inverse problems is the presence of critical points where the collected data completely vanishes. The set of these critical points depend on the choice of the boundary conditions, and can be directly determined from the data itself. To our knowledge, in the most existing stability results, the boundary conditions are assumed to be close to a set of CGO solutions where the critical points can be avoided. We establish in the present work new weighted stability estimates for an electro-acoustic inverse problem without assumptions on the presence of critical points. These results show that the Lipschitz stability far from the critical points deteriorates near these points to a logarithmic stability.
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