Muon tomography measures the flux of cosmic muons crossing geological bodies to determine their density. The telescopes used to perform measurements are exposed to noise fluxes with high intensities ...relative to the tiny flux of interest. We give experimental evidences of a so far never described source of noise caused by a flux of upward going particles. Data acquired on La Soufrière of Guadeloupe and Mount Etna reveal that upward going particles are detected only when the rear side of the telescope is exposed to a wide volume of atmosphere located below the altitude of the telescope and with a rock obstruction less than several tens of meters. Biases produced on density muon radiographies by upward going fluxes are quantified, and correction procedures are applied to radiographies of La Soufrière.
Key Points
Experimental evidence for upward-going cosmic particle in the lower atmosphere
Upward‐going particles produce strong bias in density radiographies of volcanoes
We show how to remove bias in muon density radiographies of volcanoes
This letter presents a hybrid concentric tube robot which covers the middle ear volume for exhaustive ablation of residual cholesteatoma. The proposed robotic system combines a concentric tube robot ...and a wrist at the distal end, actuated by a tendon. We first introduce the surgical protocol through two access points (ear canal and few millimeters size hole through the mastoid), then derive the anatomical constraints and specify the robot tasks. Based on the robot model enriched with the optical fiber stiffness and on anatomical constraints, the robot parameters are determined as the ones among discretized sets that provide the maximal volume coverage. Experiments are conducted with a benchtop prototype on a 3D printed middle ear phantom to validate the wrist model with the optical fiber and the robot repeatability assessment. The wrist model achieved an root mean square error (RMSE) of <inline-formula><tex-math notation="LaTeX">1.33^{\circ }</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">R^2 = 96.8\%</tex-math></inline-formula>. The robot repeatability has an RMSE of 0.7 mm for distance errors and <inline-formula><tex-math notation="LaTeX">1.34^{\circ }</tex-math></inline-formula> - <inline-formula><tex-math notation="LaTeX">2.42^{\circ }</tex-math></inline-formula> - <inline-formula><tex-math notation="LaTeX">3.11^{\circ }</tex-math></inline-formula> for the angular ones. We finally demonstrated the ablation of cholesteatoma by the embedded optical fiber on the hybrid concentric tube robot prototype.
Usage of secondary cosmic muons to image the geological structures density distribution significantly developed during the past ten years. Recent applications demonstrate the method interest to ...monitor magma ascent and volcanic gas movements inside volcanoes. Muon radiography could be used to monitor density variations in aquifers and the critical zone in the near surface. However, the time resolution achievable by muon radiography monitoring remains poorly studied. It is biased by fluctuation sources exterior to the target, and statistically affected by the limited number of particles detected during the experiment. The present study documents these two issues within a simple and well constrained experimental context: a water tower. We use the data to discuss the influence of atmospheric variability that perturbs the signal, and propose correction formulas to extract the muon flux variations related to the water level changes. Statistical developments establish the feasibility domain of muon radiography monitoring as a function of target thickness (i.e. opacity). Objects with a thickness comprised between $\simeq$ 50 $\pm$ 30m water equivalent correspond to the best time resolution. Thinner objects have a degraded time resolution that strongly depends on the zenith angle, whereas thicker objects (like volcanoes) time resolution does not.
Large liquid-scintillator trackers for neutrino experiments Benussi, L; Bruski, N; D'Ambrosio, N ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2002, Letnik:
488, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Results are given on tests of large particle trackers for the detection of neutrino interactions in long-baseline experiments. Module prototypes have been assembled using TiO
2-doped polycarbonate ...panels. These were subdivided into cells of
∼1
cm
2
cross-section and
6
m
length, filled with liquid scintillator. A wavelength-shifting fibre inserted into each cell captured a part of the scintillation light emitted when a cell was traversed by an ionizing particle. Two different fibre-readout systems have been tested: an optoelectronic chain comprising an image intensifier and an electron-bombarded CCD (EBCCD); and a hybrid photodiode (HPD). New, low-cost liquid scintillators have been investigated for applications in large underground detectors. Testbeam studies have been performed using a commercially available liquid scintillator. The number of detected photoelectrons for minimum-ionizing particles crossing a module at different distances from the fibre readout end was 6–12 with the EBCCD chain and a mirror at the non-readout end; 4–10 with the HPD and no mirror. The light-attenuation lengths in the fibres were
∼9.4
m
with the EBCCD and
∼6.4
m
with the HPD. The detector response to electron showers has also been measured. After ten radiation lengths of lead, the transverse position of the incoming electron was determined with a precision of a few millimetres for electrons of
4
GeV
, and with a precision of 1.5–
2.0
cm
for electrons of
1
GeV
.
Latest developments in digital intelligent motion, as digital signal processors (DSPs), has strongly improved AC motor control performances. Application-specific-integrated circuit (ASIC) technology ...has changed the need for rapid process and low-cost processor. However, new technological problems appeared, requiring digital properties which need considering, such as quantization, sampling, word length and data types. The authors of this paper propose to study the quantization problems on ASIC-based direct torque control of an induction machine. They present a high level behavior model of the specific circuit and analyze the torque quantization errors. Finally, simulation results illustrate quantization influences on control performances with different data type solutions.
Breastfeeding is a topic of global concern, particularly in developing countries. The World Alliance for Breastfeeding Action (WABA) is a network of people working on a global scale to address and ...overcome challenges to breastfeeding. This study analyzed WABA's 2011 World Breastfeeding Week campaign, in an effort to assess the campaign's relative strengths and weaknesses, and to identify recommendations for future WBW campaigns. The research sought to determine the extent to which the WABA World Breastfeeding Week campaign 2011 achieved its goals of focusing on engaging and mobilizing youth, and which specific factors should be considered in developing future communication strategies aimed at promoting breastfeeding. Surveys and in-depth interviews with the target groups of the Penang campaign, secondary students from a local teacher's college, were used to collect data. Interviews also were conducted with WABA's 2011 WBW development team. Qualitative data were transcribed and summarized. The campaign was largely successful in increasing awareness, promotion, and discussion of breastfeeding among the students in Penang. Communication for Development and Diffusion of Innovations theories were used to explain the findings, while Social Marketing theory was used to put forward recommendations. Improvements for future campaigns should ensure that all activities are engaging, easily understood, and transferable from one context to another. Discrepancies in student and staff responses indicate that WABA also should conduct intensive audience analysis, including pre- and post-campaign research. WABA's website and social media presence was found essential to the development and success of future WBW campaigns. For future campaigns, WABA should draw from Social Marketing theory, and identify a desired "product," "price," and "place," followed by strategies for promotion and positioning of the product. Finally, a method of assessment of such strategies should be implemented.
The authors introduce a low-cost robotic system designed to enable the safe, objective and efficient visual inspection of tunnels. The device makes use of consumer-grade digital cameras and ...high-power LEDs in a rotating rig, carried by a lightweight aluminium frame which is designed to reduce vibrations during data capture. Within the paper, they share insight into features of the device's design, including lessons learned from trials of earlier prototypes and comparisons with alternative systems. Using field data gathered from a 2km utility tunnel, they demonstrate the use of the system as a means of visualising tunnel conditions through image mosaicing, cataloguing tunnel segments using barcode detection and improving the objectivity of visual condition surveys over time by the detection of sub-mm crack growth. They believe that the device is the first to provide comprehensive survey-quality data at such a low cost, making it very attractive as a tool for the improved visual monitoring of tunnels.
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