1,721,023 research outputs found
Travail, compétitivité, performance. Colloque de Grenoble. 15 et 16 novembre 1990 : Jacot Jacques-Henri (dir.), Troussier François (dir.), Paris, Economica, 1 992
No full textTravail, compétitivité, performance. Colloque de Grenoble. 15 et 16 novembre 1990 : Jacot Jacques-Henri (dir.), Troussier François (dir.), Paris, Economica, 1 992. In: Formation Emploi. N.40, 1992. p. 84
Travail, compétitivité, performance. Colloque de Grenoble. 15 et 16 novembre 1990 : Jacot Jacques-Henri (dir.), Troussier François (dir.), Paris, Economica, 1 992
No full textTravail, compétitivité, performance. Colloque de Grenoble. 15 et 16 novembre 1990 : Jacot Jacques-Henri (dir.), Troussier François (dir.), Paris, Economica, 1 992. In: Formation Emploi. N.40, 1992. p. 84
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Multi-experts scheduling system for real-time applications
No full textThis thesis focuses on the decisional process of autonomous systems, and more particularly, on the way to take a decision when the time at disposal in order to assess the whole situation is shorter than necessary. Indeed, numerous systems propose solutions to the user that are more and more "intelligent", or at least more personalized and adapted to the present context. As the process of taking a decision is complex, it exists different methods of resolution based on hypothesis and/or methods being complementary and/or concurrent. The three following examples exhibit different domains where the use of several methods of resolution would be of prime interest : Financial market investments : numerous studies on the volatility of the financial markets have been performed in order to build an automatic system being able to select the content of the optimal portfolio. Its diversity should promote the financial gain while minimizing the risks of the investments. However, it is difficult to guarantee that a single method is sufficiently robust against the chaotic variations of the financial markets. Video compression became more democratic since the large usage of the World Wide Web, handheld game player and mobile phones. The compression methods mainly cut the image in different regions, named macroblocks. Various methods of compression are applied onto these regions depending on some of their characteristics : static macroblock (i.e. steady background), or macroblock containing a moving object or moving scene. The goal is to guarantee the highest compression ratio for all the macroblocks, while maintaining the visual quality without any artifacts onto the architecture used to play the video. Speech recognition is used in an increasing number of services, for example mobile phones can compose automatically the phone number of a person present in the contact names, only by pronouncing his name. It exists also different softwares which allow to transcribe under typed shapes, the stream of word dictated in a microphone. The variability of the human voices, the local accents, the regional pronunciations, and the presence of background noise into the various speech samples can affect more or less significantly one or another of the recognition methods. An "agent" is an instance which uses a methodology leading to a particular solution of a given problem. Thus, if the same problem can be solved with 5 different methods, then it exists at least 5 different agents. The use of a multi-agent system handling various resolution methods (agents), increases the knowledge of a given problem, and thus increases also the robustness of the proposed solution with regards to a single agent solution. Comparing the results of the different agents allows using the competition between them, but also their ability to cooperate in order to build a robust solution. However, the time at disposal limits the number of used agents. In the previous example, it would be possible to use only 3 methods (agents) among the 5 agents at disposal. The goal is thus to determine how to chose optimally the n = 3 used agents in order to guarantee that they contain the best solution among the 5 methods at disposal. The solution taken up in this thesis uses a "Blackboard" systems. This multi-agent system contains the list of all the agents which may be used to solve a particular problem. The main module, which is named the supervisor, is in charge to schedule the activation of the agents which should provide the optimal solution in a reduced amount of time. We have described the behavior of 4 different supervisors1 in order to highlight the advantages and drawbacks of each of them (see Fig. II.1). The supervisors use the reliability of the agents (credibility function) having proposed a solution at time t < t0, and proposes a scheduling policy for the agents at cycle time t = t0 in order to increase the robustness and reliability of the next computed solution. A scheduling is said optimal if the series of n agents having time to be executed contains the agent with the most important credibility over the m agents at disposal (2 ≤ n ≤ 6 m). We have highlighted the advantages and drawbacks of the different supervisors and described the aspects and the major constraints to take into consideration with regards to the application requirements to satisfy. Figure II.1: These plots compare the robustness of the four tested supervisors when the credibility of each agent follows a Gaussian distribution. In this example, 100 agents are used and each decisional process has been repeated 2'000 times in order to reduce the random behavior and highlights the main trend of the supervisors. The goal is to measure the robustness with which the performed scheduling can recover the optimal agent among a reduced population of agents being executed. The plot (a) highlights the number of times where the optimal solution has been found with regards to the number of active agents. Similarly, (b) shows the standard deviation with which the supervisors can find the optimal solution through the 2'000 repetitions. In order to characterize the robustness of the multi-agent system, we have modelized the credibility function of the different agents with several statistical distributions (Gaussian, Uniform, Rayleigh, bi-Gaussian). This credibility function reflects the confidence of the agents to find the most appropriate solution. The simulation results have proved that the performance of the supervisors is consistent over the different distributions used. Thus, when 50% of the agents have time to be executed, then we have shown that simpler supervisors can find the optimal solution in only 50% of the cases. In the contrary, the supervisors called "random change of less efficient", and "evolutionary evaluation" find the optimal solution in more than 85% of the cases. Consequently, using an appropriate scheduling of the agents by respects to the application requirements, allows to increase the efficiency of the proposed solution, even though the computation time is limited and does not allow to use more than n agents among the m at disposal. Moreover, depending on the application to satisfy, we have shown that the selection of the supervisor will be lead by two main constraints. On one hand, it will be necessary to satisfy the trade-off between the computation time needed to set up the scheduling and the robustness of the solution proposed by the multi-agent system after the remaining time at disposal. On the other hand, specific requirements of the application can restrict the use of one or another of the solution. For example, applications related to the spatial area, or with the avionics industry, would require that the use of a supervisor should produce a behavior perfectly reproducible when the input conditions are identical. Finally, we have illustrated the methodology described in this thesis by applying it to a practical example in the automotive field, the "Advanced Driver Assistant Systems" (ADAS). These modules are integrated into vehicles to ease the driving behavior and increase the safety of the users. The practical application performed is the detection of the lane where the vehicle is allowed to evolve, by using an embedded camera ("Lane Detection"). The goal is to maintain the optimal trajectory of the vehicle and thus, to reduce the accidents happening when performing a dangerous maneuver. Several methods to perform the lane detection exist and several have been integrated into different agents. Each one tries to bypass the detection limitations of other technics in order to solve optimally all the situations that could arise in uncontrolled environment. Thus, the aging or the lack of white lines are only few of these possible difficulties. Indeed, driving under bridges, entering into tunnels, or objects situated near the road can produce intensity change in the image that could lead to reduce the detection performance of some agents. The use of our multi-agent system increases significantly the detection robustness with regards to use a single method of detection. Moreover, it allows to guarantee the efficiency of the found solution in a wide range of situations. Thus, when using only 50% of the agents, we have shown that it is possible to select the optimal agent with a probability of about 85%, while maintaining a computation time of 50% of the agents. This performance can overcome 98% if 75% of the agents can be used. ______________________________ 1 The 4 supervisors having been tested are : a fixed scheduling of the agents ("Fixed set of agents"); a random selection of the agents ("Random selection of agents"); a random permutation of the less efficient agents ("Randomly change the less-efficient agents"); a scheduling based on the probability evolution of the agents performances ("Evolutionary evaluation of agents' pool").LP
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Conception acoustique de systèmes microtechniques
No full textConsidered as one of the most difficult complications in horology, the mechanical chiming watch, known as the striking watch, has today become one of the symbols of high craftsmanship. When it chimes the hour the sound of a striking watch must not only be harmonious to the ear of the hearer but also be identical from one watch to another. Today only a few talented watchmakers produce these watches. The resulting empiricism sometimes translates into significant differences between the sounds of these watches. One particularly complex aspect in the application of sound to a striking watch is the appreciation of the sound quality as well as the adequacy to the sound reference. This thesis aims to identify the principal influencing factors at the origin of the variances in sound from one striking watch to another and to identify those that allow the sound of one watch to conform to a recognised ideal sound. The problem is approached from two different angles. The first angle of physical reality, attempts to describe and characterise the sound produced by a watch according to physical parameters. The second angle of perceptive reality models our perception of sound. A virtual spectrum can be established by taking into account psychoacoustic aspects. This is derived from the real spectrum and allows not only a quantified measure of the perceived pitch but also an appreciation of the tone quality. The experimental work relies on the implementation of designed experiments using a functional sample. This reproduces the striking system at the same time allowing the modification of parameters necessary for the planned experiments. The physical spectrum combined with the virtual spectrum allows the identification of the principal influencing factors. Amongst these are hammer-gong pre-penetration, the contact geometry as well as the position of the hitting point and the contact time. By means of the generalised mass, it is possible to modify the perceived pitch within a significant range of frequencies which makes this factor an important element in the adequacy to the recognised ideal of sound. Finally, this work illustrates the importance that should be accorded to the implementation of measuring tools and appropriate characterisation of sound if the processes in the mechanical striking watch industry are to be mastered. Also included is a description of the factors that the watchmaker must control to ensure minimal variation from one watch to another in a production series.LP
Dimensional analysis and similitude in microsystem design and assembly
Get PDFThe effects miniaturization has on microsystems and related fields are the central subject of this work. Physical phenomena we are used to in our conventionally sized world seldom work at smaller scales. Before attempting to design a microsystem or try to perform any operation on or with it, the outcome of size reduction has to be considered. When well-known phenomena are involved it remains relatively simple to predict the outcome as a function of size. Unfortunately the behavior of microsystems is, in many cases, governed by phenomena that have been systematically and correctly neglected. In consequence our knowledge about them is limited to the point that we can't establish a relation between them and the size of the system. Dimensional analysis and theory of similitude are two engineering tools that have been long used to solve problems where analytical solutions were not available. While the first one gives us the possibility of obtaining prediction equations for our phenomena based on our initial hypothesis, the second allows us to test the validity of our findings through the use of models of convenient size. Combined they allow information and data obtained from the study of different cases where similar phenomena are involved to be extrapolated to the case under consideration. Ship engineering has benefited from those tools: the flow around a ship's hull is difficult to describe analytically and full-sized models are uneconomical to build for testing purposes alone. Since microsystems find themselves in a similar situation (some effects can't be described analytically and full-size models are difficult to work with) the use of dimensional analysis and similitude to solve different problems encountered in this domain is proposed. The subject of forces at the microsystem level is treated in detail to show how dimensional analysis can be used both qualitatively and quantitatively to help understand how forces behave at this scale.LP
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