630 research outputs found

    Safer hybrid workspace using human-robot interaction while sharing production activities

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    In a near future, human and industrial manipulator will work together sharing a common workspace and production activities leading to a potential increase of accident. The research project concerns the adaptation of industrial robot already installed in a flexible manufacturing system in order to make it more interactive with human. The aim concerns the reduction of potential risk of injuries while working with an industrial robot. This paper presents a new inexpensive, non-intrusive, non-invasive, and non-vision-based system, for human detection and collision avoidance. One method investigated for improving safety concerns planning of safe path. This system recognizes human activities and locates operator's position in real time through an instrumented safety helmet. This safety helmet includes an IMU (Inertial Measurement Unit) and an indoor localization system such as RSSI (Received Signal Strength Indication) using industrial wireless equipment. A hybrid workspace including a flexible manufacturing system has been designed in order to practice experiments in an industrial-like environment

    Determination of two-photon exchange amplitudes from elastic electron-proton scattering data

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    Using the available cross section and polarization data for elastic electron-proton scattering, we provide an extraction of the two-photon exchange amplitudes at a common value of four-momentum transfer, around Q^2 = 2.5 GeV^2. This analysis also predicts the e^+ p / e^- p elastic scattering cross section ratio, which will be measured by forthcoming experiments.Comment: 4 pages, 5 figures, updated error analysi

    A Smart Safety Helmet using IMU and EEG sensors for analysis of worker’s fatigue

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    It is known that head gesture and mental states can reflect some human behaviors related to a risk of accident when using machine-tools. The research works presented in this paper aim to reduce the number of injury and thus increase worker safety. Instead using camera, this paper presents a Smart Safety Helmet (SSH) in order to track head gestures and mental states of worker able to recognize anomalous behavior. Information extracted from SSH is used for computing risk level of accident (a safety level) for preventing and reducing injury or accidents. The SSH system is an inexpensive, non-intrusive, non-invasive, and non-vision-based system, which consists of 9DOF Inertial Measurement Unit (IMU) and dry EEG electrodes. A haptic device, such as vibrotactile motor, is integrated to the helmet in order to alert the operator when computed risk level (fatigue, high stress or error) reach a threshold. Once the risk level of accident breaks the threshold, a signal will be sent wirelessly to stop the relevant machine tool or process

    Statistics of counter-streaming solar wind suprathermal electrons at solar minimum : STEREO observations

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    Previous work has shown that solar wind suprathermal electrons can display a number of features in terms of their anisotropy. Of importance is the occurrence of counter-streaming electron patterns, i.e., with "beams" both parallel and anti-parallel to the local magnetic field, which is believed to shed light on the heliospheric magnetic field topology. In the present study, we use STEREO data to obtain the statistical properties of counter-streaming suprathermal electrons (CSEs) in the vicinity of corotating interaction regions (CIRs) during the period March–December 2007. Because this period corresponds to a minimum of solar activity, the results are unrelated to the sampling of large-scale coronal mass ejections, which can lead to CSE owing to their closed magnetic field topology. The present study statistically confirms that CSEs are primarily the result of suprathermal electron leakage from the compressed CIR into the upstream regions with the combined occurrence of halo depletion at 90° pitch angle. The occurrence rate of CSE is found to be about 15–20% on average during the period analyzed (depending on the criteria used), but superposed epoch analysis demonstrates that CSEs are preferentially observed both before and after the passage of the stream interface (with peak occurrence rate >35% in the trailing high speed stream), as well as both inside and outside CIRs. The results quantitatively show that CSEs are common in the solar wind during solar minimum, but yet they suggest that such distributions would be much more common if pitch angle scattering were absent. We further argue that (1) the formation of shocks contributes to the occurrence of enhanced counter-streaming sunward-directed fluxes, but does not appear to be a necessary condition, and (2) that the presence of small-scale transients with closed-field topologies likely also contributes to the occurrence of counter-streaming patterns, but only in the slow solar wind prior to CIRs

    Measurement of the Target-Normal Single-Spin Asymmetry in Quasi-Elastic Scattering from the Reaction 3^3He(e,e)^\uparrow(e,e^\prime)

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    We report the first measurement of the target single-spin asymmetry, AyA_y, in quasi-elastic scattering from the inclusive reaction 3^3He(e,e)^{\uparrow}(e,e^\prime) on a 3^3He gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A non-zero AyA_y can arise from the interference between the one- and two-photon exchange processes which is sensitive to the details of the sub-structure of the nucleon. An experiment recently completed at Jefferson Lab yielded asymmetries with high statistical precision at Q2=Q^{2}= 0.13, 0.46 and 0.97 GeV2^{2}. These measurements demonstrate, for the first time, that the 3^3He asymmetry is clearly non-zero and negative with a statistical significance of (8-10)σ\sigma. Using measured proton-to-3^{3}He cross-section ratios and the effective polarization approximation, neutron asymmetries of -(1-3)% were obtained. The neutron asymmetry at high Q2Q^2 is related to moments of the Generalized Parton Distributions (GPDs). Our measured neutron asymmetry at Q2=0.97Q^2=0.97 GeV2^2 agrees well with a prediction based on two-photon exchange using a GPD model and thus provides a new, independent constraint on these distributions

    The European Union in the World — A Community of Values

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    These are momentous times in Europe. The Euro has been successfully introduced, the enlargement negotiations are approaching their climax, and the European Convention (“Convention”) is moving towards the drafting of a constitution for a new, continent-wide political entity. At the same time, unrest is manifest, particularly in two areas. On the one hand, many of our citizens, and not just the political elites, are dissatisfied with Europe\u27s performance on the world stage and are concerned about the maintenance of peace and security within the Union. In these areas they would like to see a strengthened, more effective entity-- “more Europe.” On the other hand, their disenchantment with the long reach of European Union (“EU” or “Union”) regulation in the first pillar area of economic policy is growing. The feeling of loss of local control over their destiny and a vague feeling of potential loss of identity within an ever more centralized polity is palpable. Here, they want “less Europe.” In the outside world, change is also the order of the day. The ice-sheet of bipolarity, which overlaid and hid the complexity of international relations during the Cold War, is breaking up at an ever-increasing speed and revealing a world in which two paradigms are competing to become the underlying ordering principles for the new century. The traditional paradigm of interacting Nation States, each pursuing its own separate interests, with alliances allowing the small to compete with the large, is alive and well, and its proponents like Machiavelli or Churchill continue to be in vogue in the literature of international relations and the rhetoric of world leaders. At the same time, there is a school of thought which points to the growing economic and ecological interdependence of our societies and the necessity for new forms of global governance to complement national action. It is also becoming abundantly clear that the concept of a “Nation State” is often a fiction, positing as it does an identity between the citizens of a State and the members of a culturally homogenous society. For both reasons, the concept of the Nation State as the principal actor on the world stage, is called into question. The experience of the Union with the sharing of State sovereignty is clearly related to the second paradigm and also to the EU\u27s firm support for the development of the United Nations (“U.N.”) as well as other elements of multilateral governance. It would hardly be wise to suggest that any foreign policy, and certainly not that of the EU, should be based only on this paradigm. Given the recurrent threats to security, which seem to be part of the human condition expressed by some as the “inevitability of war”--the defense of territorial integrity; action against threats of aggression; and resistance to crimes against humanity such as genocide--the ability to conduct a security policy based much more on the old paradigm of interacting interests will continue to be required. That the EU needs to develop such a capability will be taken here as a given. Such a crisis-management capability will be essential to the Union, but will be distinguished here from the more long-term elements of foreign policy, which can be thought of as being designed to reduce the need for crisis management in the context of a security policy to a minimum. The crisis-management area of policy will not be treated further here. The thesis of this Essay is that the same set of political concepts can serve as a guide to the future internal development of the EU and as the basis of such a long-term foreign policy. Furthermore, it suggests that neither should be seen in terms of the balancing of interests but rather, as the expression of a small list of fundamental values. The list is as follows: (1) the rule of law as the basis for relations between members of society; (2) the interaction between the democratic process and entrenched human rights in political decision-making; (3) the operation of competition within a market economy as the source of increasing prosperity; (4) the anchoring of the principle of solidarity among all members of society alongside that of the liberty of the individual; (5) the adoption of the principle of sustainability of all economic development; and (6) the preservation of separate identities and the maintenance of cultural diversity within society. These values can be seen as the answer to the question posed both, by citizens of the Union and by our fellow citizens of the world: “What does the EU stand for?” In exploring these values we should, however, remember that in the real world there will be occasions on which Realpolitik will intrude and the interest-based paradigm will prevail

    The Proton Elastic Form Factor Ratio at Low Momentum Transfer

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    High precision measurements of the proton elastic form factor ratio have been made at four-momentum transfers, Q^2, between 0.2 and 0.5 GeV^2. The new data, while consistent with previous results, clearly show a ratio less than unity and significant differences from the central values of several recent phenomenological fits. By combining the new form-factor ratio data with an existing cross-section measurement, one finds that in this Q^2 range the deviation from unity is primarily due to GEp being smaller than the dipole parameterization.Comment: 5 pages, 2 figure

    Low Q^2 measurements of the proton form factor ratio mupGE/GMmu_p G_E / G_M

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    We present an updated extraction of the proton electromagnetic form factor ratio, mu_p G_E/G_M, at low Q^2. The form factors are sensitive to the spatial distribution of the proton, and precise measurements can be used to constrain models of the proton. An improved selection of the elastic events and reduced background contributions yielded a small systematic reduction in the ratio mu_p G_E/G_M compared to the original analysis.Comment: 12 pages, 5 figures, archival paper for proton form factor extraction from Jefferson Lab "LEDEX" experimen
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