4,515 research outputs found
Ranking social bookmarks using topic models
Ranking of resources in social tagging systems is a difficult problem due to the inherent sparsity of the data and the vo- cabulary problems introduced by having a completely unre- stricted lexicon. In this paper we propose to use hidden topic models as a principled way of reducing the dimensionality of this data to provide more accurate resource rankings with higher recall. We first describe Latent Dirichlet Allocation (LDA) and then show how it can be used to rank resources in a social bookmarking system. We test the LDA tagging model and compare it with 3 non-topic model baselines on a large data sample obtained from the Delicious social book- marking site. Our evaluations show that our LDA-based method significantly outperforms all of the baselines
Experimental L-band SST satellite communications/surveillance terminal study. Volume 4 - Aircraft antenna studies
Antenna requirements for supersonic transport satellite communications syste
MCC level C formulation requirements. Shuttle TAEM targeting
The level C requirements for the shuttle orbiter terminal area energy management (TAEM) guidance and flight control functions to be incorporated into the Mission Control Center entry profile planning processor are described. This processor is used for preentry evaluation of the entry through landing maneuvers, and includes a simplified three degree-of-freedom model of the body rotational dynamics that is necessary to account for the effects of attitude response on the trajectory dynamics. This simulation terminates at TAEM-autoland interface
MCC level C formulation requirements. Shuttle TAEM guidance and flight control, STS-1 baseline
The TAEM guidance and body rotational dynamics models required for the MCC simulation of the TAEM mission phase are defined. This simulation begins at the end of the entry phase and terminates at TAEM autoland interface. The logic presented is the required configuration for the first shuttle orbital flight (STS-1). The TAEM guidance is simulated in detail. The rotational dynamics simulation is a simplified model that assumes that the commanded rotational rates can be achieved in the integration interval. Thus, the rotational dynamics simulation is essentially a simulation of the autopilot commanded rates and integration of these rates to determine orbiter attitude. The rotational dynamics simulation also includes a simulation of the speedbrake deflection. The body flap and elevon deflections are computed in the orbiter aerodynamic simulation
Plane strain fracture toughness and mechanical properties of 5Al-2.5Sn ELI titanium at room and cryogenic temperatures Final report
Plane strain fracture toughness and mechanical properties of titanium alloy at room and cryogenic temperature
Plane strain fracture toughness of 2219-T87 aluminum alloy at room and cryogenic temperatures
Tensile strength, yield strength, and plane strain fracture toughness of aluminum alloy at room and cryogenic temperature
Eric W. Rood Administration Center- Fire Protection and Life Safety Analysis
A Fire Protection & Life Safety Analysis was conducted in order to fulfill the requirements for the degree of Master of Science in Fire Protection Engineering. The Fire Protection & Life Safety Analysis consisted of a prescriptive and performance-based analysis of the Eric Rood Administration Center (Rood Center).
The prescriptive based analysis was conducted to determine if the Rood Center adhered to the applicable codes and standards. It utilized the 2013 California Building and Fire Codes and the 2012 Life Safety Code (NFPA 101). Other NFPA codes that were referenced included the 2013 edition of NFPA 13, Standard for the Installation of Sprinkler Systems, the 2013 edition of NFPA 72, National Fire Alarm Signaling Code, and the 2015 edition of NFPA 2001, Standard on Clean Agent Fire Extinguishing systems.
The prescriptive based analysis examined four portions of the building’s fire protection system: Egress Analysis & Design, Fire Detection & Alarm Notification, Water-based Fire Suppression, and Structural Fire Protection
Deficiencies were found in the building’s fire detection and notification systems, as well as the inspection, testing, and maintenance of said systems. The building’s primary fire alarm system has photoelectric smoke detectors installed in only portions of the building. The bulk of the detectors are installed in the exit corridors with typically only one detector per department. While the number of smoke detectors in most departments is lacking, some departments don’t have any at all. The first floor has only 23 smoke detectors, while the second floor has only 16. Based on coverage-area-per-detector calculations alone, the first floor should have a minimum of 56 detectors and the second floor should have a minimum of 58. One of the departments in the building that does have smoke detectors, has only local detectors (they are not connected to the building’s fire alarm control panel (FACP)). Two of the fire scenarios in the performance based analysis indicated the fires were detected within 10 seconds of ignition. In the other two fire scenarios, the fires were not detected until 73 seconds and 107 seconds into the simulations respectively. Examining the building’s notification systems revealed several issues as well. Three of the notification devices types currently in use in the building are listed in the FACP’s manual as not compatible. Similar to the detection system, there are not enough notification appliances (audio or visual) throughout the building to ensure proper coverage. Inspections and tests are not done to confirm proper audible and/or visual levels in the building during an active alarm.
The performance based analysis examined how the building’s fire protection system would react to a fire, and whether occupants would have enough time to escape to safety. A computational fluid dynamics modeling program, Fire Dynamics Simulator (FDS), was used to estimate the available safe egress times (ASET) for four different fire scenarios throughout the building. Those values were then compared with the required safe egress times (RSET) calculated in the prescriptive based analysis for each fire scenario.
The original RSET values were calculated for the departments affected by the fire scenarios. The fire models were analyzed and the ASET values were determined when conditions either first became untenable, or when all the occupants had exited the building; whichever came first. The conditions in the building became untenable before people could evacuate the building in all four fire scenarios (RSET \u3e ASET). In some situations, conditions became untenable seconds after the fire alarm was activated, and several minutes before evacuations were complete.
The performance based analysis determine that the arrangement of the dead end hallway off the second floor lobby was especially problematic as it could cause the occupants to be trapped in the event of a fire. Two fire scenarios were examined, one with the fire in the dead end hallway, and another with the fire in the main lobby. In both cases, the conditions in the building became untenable long before the occupants would have been able to escape the hallway, let alone the building
Cryptorchidism In Swine
In a previous issue the cryptorchidism of the horse was discussed, with its probable mode of inheritance. The same anomaly is known in other animal species as well, being perhaps most frequent in the horse, with swine, cattle and sheep following in that order
Drivers of distribution trends and success: Consumers, technology, competition, EU
Hungary's domestic markets and export markets are growing. Entry into a unified European market is rapidly approaching. What are the things in the area of distribution to which Hungarian firms should be paying attention to enable them to prosper in these growing markets? This presentation will discuss: infrastructure drivers; consumer drivers; technology drivers including paperless systems for ordering, payment, and shipping; European integration; electronic commerce; structural changes, organization and competition in vertical distribution systems
Hernia and Its Heredity
Hernia is the protrusion of an organ, or part of an organ or other structure, through the wall of the cavity normally containing it. While the term applies to other regions of the body, in farm animals it refers to defects in the abdominal wall, unless otherwise qualified, and is the protrusion of a viscus, or viscera, through a natural or abnormal opening in the abdominal wall over which the skin remains intact. Rupture is its every-day synonym, and perhaps is a more widely used term than the more correct hernia
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