Application of the EM algorithm for the multitarget/multisensor tracking problem

Caption title.Includes bibliographical references (p. 27-29).Supported by the Laboratory for Information and Decision Systems, Massachusetts Institute of Technology. DAAH04-95-1-0103Karl J. Molnar, James W. Modestino

Investigation related to multispectral imaging systems

A summary of technical progress made during a five year research program directed toward the development of operational information systems based on multispectral sensing and the use of these systems in earth-resource survey applications is presented. Efforts were undertaken during this program to: (1) improve the basic understanding of the many facets of multispectral remote sensing, (2) develop methods for improving the accuracy of information generated by remote sensing systems, (3) improve the efficiency of data processing and information extraction techniques to enhance the cost-effectiveness of remote sensing systems, (4) investigate additional problems having potential remote sensing solutions, and (5) apply the existing and developing technology for specific users and document and transfer that technology to the remote sensing community

High-Velocity Clouds in the Nearby Spiral Galaxy M 83

We present deep HI 21-cm and optical observations of the face-on spiral galaxy M 83 obtained as part of a project to search for high-velocity clouds (HVCs) in nearby galaxies. Anomalous-velocity neutral gas is detected toward M 83, with 5.6x10^7 Msolar of HI contained in a disk rotating 40-50 km/s more slowly in projection than the bulk of the gas. We interpret this as a vertically extended thick disk of neutral material, containing 5.5% of the total HI within the central 8 kpc. Using an automated source detection algorithm to search for small-scale HI emission features, we find eight distinct, anomalous-velocity HI clouds with masses ranging from 7x10^5 to 1.5x10^7 Msolar and velocities differing by up to 200 km/s compared to the HI disk. Large on-disk structures are coincident with the optical spiral arms, while unresolved off-disk clouds contain no diffuse optical emission down to a limit of 27 r' mag per square arcsec. The diversity of the thick HI disk and larger clouds suggests the influence of multiple formation mechanisms, with a galactic fountain responsible for the slowly-rotating disk and on-disk discrete clouds, and tidal effects responsible for off-disk cloud production. The mass and kinetic energy of the HI clouds are consistent with the mass exchange rate predicted by the galactic fountain model. If the HVC population in M 83 is similar to that in our own Galaxy, then the Galactic HVCs must be distributed within a radius of less than 25 kpc.Comment: 30 pages, 23 figures; accepted for publication in ApJ. Some figures have been altered to reduce their siz

LIMO-Velo: A real-time, robust, centimeter-accurate estimator for vehicle localization and mapping under racing velocities

Treballs recents sobre localització de vehicles i mapeig dels seus entorns es desenvolupen per a dispositius portàtils o robots terrestres que assumeixen moviments lents i suaus. Contràriament als entorns de curses d’alta velocitat. Aquesta tesi proposa un nou model d’SLAM, anomenat LIMO-Velo, capaç de corregir el seu estat amb una latència extremadament baixa tractant els punts LiDAR com un flux de dades. Els experiments mostren un salt en robustesa i en la qualitat del mapa mantenint el requisit de correr en temps real. El model aconsegueix una millora relativa del 20% en el KITTI dataset d’odometria respecte al millor rendiment existent; no deriva en un sol esce- nari. La qualitat del mapa a nivell de centı́metre es manté amb velocitats que poden arribar a 20 m/s i 500 graus/s. Utilitzant les biblioteques obertes IKFoM i ikd-Tree, el model funciona x10 més ràpid que la majoria de models d’última generació. Mostrem que LIMO-Velo es pot generalitzar per exe- cutar l’eliminació dinàmica d’objectes, com ara altres agents a la carretera, vianants i altres.Trabajos recientes sobre la localización de vehı́culos y el mapeo de sus en- tornos se desarrollan para dispositivos portátiles o robots terrestres que asumen movimientos lentos y suaves. Al contrario de los entornos de carreras de alta velocidad. Esta tesis propone un nuevo modelo SLAM, LIMO-Velo, capaz de corregir su estado en latencia extremadamente baja al tratar los puntos LiDAR como un flujo de datos. Los experimentos muestran un salto en la solidez y la calidad del mapa mientras se mantiene el requisito de tiempo real. El modelo logra una mejora relativa del 20% en el conjunto de datos de KITTI Odometry sobre el mejor desempeño existente; no deriva en un solo escenario. La calidad del mapa de nivel centimétrico todavı́a se logra a velocidades de carrera que pueden llegar hasta 20 m/s y 500 grados/s. Us- ando las bibliotecas abiertas IKFoM e ikd-Tree, el modelo funciona x10 más rápido que la mayorı́a de los modelos de última generación. Mostramos que LIMO-Velo se puede generalizar para trabajar bajo la eliminación dinámica de objetos, como otros agentes en la carretera, peatones y más.Recent works on localizing vehicles and mapping their environments are de- veloped for handheld devices or terrestrial robots which assume slow and smooth movements. Contrary to high-velocity racing environments. This thesis proposes a new SLAM model, LIMO-Velo, capable of correcting its state at extreme low-latency by treating LiDAR points as a data stream. Experiments show a jump in robustness and map quality while maintaining the real-time requirement. The model achieves a 20% relative improvement on the KITTI Odometry dataset over the existing best performer; it does not drift in a single scenario. Centimeter-level map quality is still achieved under racing velocities that can go up to 20m/s and 500deg/s. Using the IKFoM and ikd-Tree open libraries, the model performs x10 faster than most state-of-the-art models. We show that LIMO-Velo can be generalized to work under dynamic object removal such as other agents in the road, pedestrians, and more.Outgoin

Study of fault-tolerant software technology

Presented is an overview of the current state of the art of fault-tolerant software and an analysis of quantitative techniques and models developed to assess its impact. It examines research efforts as well as experience gained from commercial application of these techniques. The paper also addresses the computer architecture and design implications on hardware, operating systems and programming languages (including Ada) of using fault-tolerant software in real-time aerospace applications. It concludes that fault-tolerant software has progressed beyond the pure research state. The paper also finds that, although not perfectly matched, newer architectural and language capabilities provide many of the notations and functions needed to effectively and efficiently implement software fault-tolerance

A comparison of airborne and ground-based radar observations with rain gages during the CaPE experiment

The vicinity of KSC, where the primary ground truth site of the Tropical Rainfall Measuring Mission (TRMM) program is located, was the focal point of the Convection and Precipitation/Electrification (CaPE) experiment in Jul. and Aug. 1991. In addition to several specialized radars, local coverage was provided by the C-band (5 cm) radar at Patrick AFB. Point measurements of rain rate were provided by tipping bucket rain gage networks. Besides these ground-based activities, airborne radar measurements with X- and Ka-band nadir-looking radars on board an aircraft were also recorded. A unique combination data set of airborne radar observations with ground-based observations was obtained in the summer convective rain regime of central Florida. We present a comparison of these data intending a preliminary validation. A convective rain event was observed simultaneously by all three instrument types on the evening of 27 Jul. 1991. The high resolution aircraft radar was flown over convective cells with tops exceeding 10 km and observed reflectivities of 40 to 50 dBZ at 4 to 5 km altitude, while the low resolution surface radar observed 35 to 55 dBZ echoes and a rain gage indicated maximum surface rain rates exceeding 100 mm/hr. The height profile of reflectivity measured with the airborne radar show an attenuation of 6.5 dB/km (two way) for X-band, corresponding to a rainfall rate of 95 mm/hr

Integrated out-of-hours care arrangements in England: observational study of progress towards single call access via NHS Direct and impact on the wider health system

Objectives: To assess the extent of service integration achieved within general practice cooperatives and NHS Direct sites participating in the Department of Health’s national “Exemplar Programme” for single call access to out-of-hours care via NHS Direct. To assess the impact of integrated out-of-hours care arrangements upon general practice cooperatives and the wider health system (use of emergency departments, 999 ambulance services, and minor injuries units). Design: Observational before and after study of demand, activity, and trends in the use of other health services. Setting: Thirty four English general practice cooperatives with NHS Direct partners (“exemplars”) of which four acted as “case exemplars”. Also 10 control cooperatives for comparison. Main Outcome Measures: Extent of integration achieved (defined as the proportion of hours and the proportion of general practice patients covered by integrated arrangements), patterns of general practice cooperative demand and activity and trends in use of the wider health system in the first year. Results: Of 31 distinct exemplars 21 (68%) integrated all out-of-hours call management by March 2004. Nine (29%) established single call access for all patients. In the only case exemplar where direct comparison was possible, cooperative nurse telephone triage before integration completed a higher proportion of calls with telephone advice than did NHS Direct afterwards (39% v 30%; p<0.0001). The proportion of calls completed by NHS Direct telephone advice at other sites was lower. There is evidence for transfer of demand from case exemplars to 999 ambulance services. A downturn in overall demand for care seen in two case exemplars was also seen in control sites. Conclusion: The new model of out-of-hours care was implemented in a variety of settings across England by new partnerships between general practice cooperatives and NHS Direct. Single call access was not widely implemented and most patients needed to make at least two telephone calls to contact the service. In the first year, integration may have produced some reduction in total demand, but this may have been accompanied by shifts from one part of the local health system to another. NHS Direct demonstrated capability in handling calls but may not currently have sufficient capacity to support national implementation