731 research outputs found

    A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam

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    A Short-Baseline Neutrino (SBN) physics program of three LAr-TPC detectors located along the Booster Neutrino Beam (BNB) at Fermilab is presented. This new SBN Program will deliver a rich and compelling physics opportunity, including the ability to resolve a class of experimental anomalies in neutrino physics and to perform the most sensitive search to date for sterile neutrinos at the eV mass-scale through both appearance and disappearance oscillation channels. Using data sets of 6.6e20 protons on target (P.O.T.) in the LAr1-ND and ICARUS T600 detectors plus 13.2e20 P.O.T. in the MicroBooNE detector, we estimate that a search for muon neutrino to electron neutrino appearance can be performed with ~5 sigma sensitivity for the LSND allowed (99% C.L.) parameter region. In this proposal for the SBN Program, we describe the physics analysis, the conceptual design of the LAr1-ND detector, the design and refurbishment of the T600 detector, the necessary infrastructure required to execute the program, and a possible reconfiguration of the BNB target and horn system to improve its performance for oscillation searches.Comment: 209 pages, 129 figure

    Pathfinder autonomous rendezvous and docking project

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    Capabilities are being developed and demonstrated to support manned and unmanned vehicle operations in lunar and planetary orbits. In this initial phase, primary emphasis is placed on definition of the system requirements for candidate Pathfinder mission applications and correlation of these system-level requirements with specific requirements. The FY-89 activities detailed are best characterized as foundation building. The majority of the efforts were dedicated to assessing the current state of the art, identifying desired elaborations and expansions to this level of development and charting a course that will realize the desired objectives in the future. Efforts are detailed across all work packages in developing those requirements and tools needed to test, refine, and validate basic autonomous rendezvous and docking elements

    Tracking interacting targets in multi-modal sensors

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    PhDObject tracking is one of the fundamental tasks in various applications such as surveillance, sports, video conferencing and activity recognition. Factors such as occlusions, illumination changes and limited field of observance of the sensor make tracking a challenging task. To overcome these challenges the focus of this thesis is on using multiple modalities such as audio and video for multi-target, multi-modal tracking. Particularly, this thesis presents contributions to four related research topics, namely, pre-processing of input signals to reduce noise, multi-modal tracking, simultaneous detection and tracking, and interaction recognition. To improve the performance of detection algorithms, especially in the presence of noise, this thesis investigate filtering of the input data through spatio-temporal feature analysis as well as through frequency band analysis. The pre-processed data from multiple modalities is then fused within Particle filtering (PF). To further minimise the discrepancy between the real and the estimated positions, we propose a strategy that associates the hypotheses and the measurements with a real target, using a Weighted Probabilistic Data Association (WPDA). Since the filtering involved in the detection process reduces the available information and is inapplicable on low signal-to-noise ratio data, we investigate simultaneous detection and tracking approaches and propose a multi-target track-beforedetect Particle filtering (MT-TBD-PF). The proposed MT-TBD-PF algorithm bypasses the detection step and performs tracking in the raw signal. Finally, we apply the proposed multi-modal tracking to recognise interactions between targets in regions within, as well as outside the cameras’ fields of view. The efficiency of the proposed approaches are demonstrated on large uni-modal, multi-modal and multi-sensor scenarios from real world detections, tracking and event recognition datasets and through participation in evaluation campaigns

    Identification of the time base in environmental archives

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    The second chapter handles the measurement. These are often collected with a Laser Ablation Inductively Coupled Mass Spectrometer (LA-ICP-MS) and the first problem we encountered was the calibration of this instrument. It is used to measure trace elements with an incredibly high spatial resolution. Of course, it has also some major disadvantages. One of these is that the laser, which is used to ablate the solid substrate, has a variable intensity. In addition several other internal instrumental parameters seem to vary over time in an unpredictable manner. Therefore, people use internal standards for more than twenty years. Such internal standards are elements whose concentration does not vary over the sample. Consequently,all variation detected in these internal standards must be due to artificial variation in the instrument. Because the drift of the instrument is reflected in the measurementofthe internal standard, all other concentrationscan be calibratedaccordingto this internal standard. This simple idea seems to work quite well. Unfortunately, the calibration algorithm does not take into account measurement noise in the signal of the internal standards. This is exactly the improvement that we made: imagine two internal standards, each consisting of the same drift pattern, and disturbed by a different noise pattern. A better approximation of the true drift pattern can be reached by the arithmetic mean of both internal standards.Hereinthe drift remains and the noise cancels out. This idea is further refined, so that the uncertainty on the internal standards can be taken into account as well, and an a priori and an a posteriori verification of the model used is given. Further, the myth of mass dependent internal standards is ruled out and finally a real world example is processed. An additional important property of the proposed calibration is that an internal quality check is performed, which warns the investigator if some artefacts or problems occurred during the measurement. The remaining part of this work is devoted to the reconstruction of time series. One of the major problems with data-processing of proxy records (e.g. stable isotope ratios of oxygen or carbon, or trace elements in shells, sponges, corals, sediment cores, etc ) is the dating of individual observations. All these proxy records are measured as function of a distance, while generally the time series are desired. Due to variations and differences in accretion rate, each record has its unique distance series, which cannot be compared with other records or models. Therefore, distance series are transformed into time series. However, this is only possible if additional information about the accretion rate is available. Unfortunately, this is mostly not the case and thus additional assumptions are necessary. Such assumption can be made about the signal and formally written down in the signal model. In addition,the concept of a time base distortion is introduced.As will be shown,this enables us to estimate variations in accretion rate. For this, we started from a previously estimated time base (if this is unknown, we initialize the time base assuming a constant accretion rate). Next, we allow this base to be distorted due to nonlinear accretion rates or hiatuses and we will show how such a distortion can be estimated. In the third chapter, we have illustrated how the time series can be reconstructed, assuming a periodic proxy-record. Therefore, the concept of time base distortions is introduced. First, we propose a model for variations in accretion rate. Next, we illustrate how this accretion rate can be identified and estimated in the Fourier spectrum of the proxy. This approach is compared with the widely used anchor point method in two manners: the assumptions made are compared and next the sensitivity of both methods w.r.t. stochastic noise is illustrated on a simulation. Three case studies are incorporated to validate the method and to illustrate its use

    Multi-target tracking and performance evaluation on videos

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    PhDMulti-target tracking is the process that allows the extraction of object motion patterns of interest from a scene. Motion patterns are often described through metadata representing object locations and shape information. In the first part of this thesis we discuss the state-of-the-art methods aimed at accomplishing this task on monocular views and also analyse the methods for evaluating their performance. The second part of the thesis describes our research contribution to these topics. We begin presenting a method for multi-target tracking based on track-before-detect (MTTBD) formulated as a particle filter. The novelty involves the inclusion of the target identity (ID) into the particle state, which enables the algorithm to deal with an unknown and unlimited number of targets. We propose a probabilistic model of particle birth and death based on Markov Random Fields. This model allows us to overcome the problem of the mixing of IDs of close targets. We then propose three evaluation measures that take into account target-size variations, combine accuracy and cardinality errors, quantify long-term tracking accuracy at different accuracy levels, and evaluate ID changes relative to the duration of the track in which they occur. This set of measures does not require pre-setting of parameters and allows one to holistically evaluate tracking performance in an application-independent manner. Lastly, we present a framework for multi-target localisation applied on scenes with a high density of compact objects. Candidate target locations are initially generated by extracting object features from intensity maps using an iterative method based on a gradient-climbing technique and an isocontour slicing approach. A graph-based data association method for multi-target tracking is then applied to link valid candidate target locations over time and to discard those which are spurious. This method can deal with point targets having indistinguishable appearance and unpredictable motion. MT-TBD is evaluated and compared with state-of-the-art methods on real-world surveillanceThis work was supported by the EU, under the FP7 project APIDIS (ICT-216023) and the Artemis JU and TSB as part of the COPCAMS project (332913)

    The Optical, Ultraviolet, and X-ray Structure of the Quasar HE 0435-1223

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    Microlensing has proven an effective probe of the structure of the innermost regions of quasars, and an important test of accretion disk models. We present light curves of the lensed quasar HE 0435-1223 in the R band and in the ultraviolet, and consider them together with X-ray light curves in two energy bands that are presented in a companion paper. Using a Bayesian Monte Carlo method, we constrain the size of the accretion disk in the rest-frame near- and far-UV, and constrain for the first time the size of the X-ray emission regions in two X-ray energy bands. The R-band scale size of the accretion disk is about 10^15.23 cm (~23 r_g), slightly smaller than previous estimates, but larger than would be predicted from the quasar flux. In the UV, the source size is weakly constrained, with a strong prior dependence. The UV to R-band size ratio is consistent with the thin disk model prediction, with large error bars. In soft and hard X-rays, the source size is smaller than ~10^14.8 cm (~10 r_g) at 95% confidence. We do not find evidence of structure in the X-ray emission region, as the most likely value for the ratio of the hard X-ray size to the soft X-ray size is unity. Finally, we find that the most likely value for the mean mass of stars in the lens galaxy is ~0.3 M_sun, consistent with other studies.Comment: 13 pages, 7 figures. Replaced with version accepted to Ap
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