Using Sensor Metadata Streams to Identify Topics of Local Events in the City

In this paper, we study the emerging Information Retrieval (IR) task of local event retrieval using sensor metadata streams. Sensor metadata streams include information such as the crowd density from video processing, audio classifications, and social media activity. We propose to use these metadata streams to identify the topics of local events within a city, where each event topic corresponds to a set of terms representing a type of events such as a concert or a protest. We develop a supervised approach that is capable of mapping sensor metadata observations to an event topic. In addition to using a variety of sensor metadata observations about the current status of the environment as learning features, our approach incorporates additional background features to model cyclic event patterns. Through experimentation with data collected from two locations in a major Spanish city, we show that our approach markedly outperforms an alternative baseline. We also show that modelling background information improves event topic identification

Goal-oriented optimal subset selection of correlated multimedia streams

10.1145/1198302.1198304ACM Transactions on Multimedia Computing, Communications and Applications3

Theoretical and Experimental Investigation of 30 K Single Stage GM-Type Pulse Tube Cryocooler

Presented at the 16th International Cryocooler Conference, held May 17-20, 2008 in Atlanta, Georgia.Theoretical modeling of thermodynamic performance plays an important role in the design and development of pulse tube cryocoolers. In the present work, a thermodynamic model of a GMtype double-inlet pulse tube cryocooler has been developed. It includes calculation of ideal refrigeration power, various losses, and hence net refrigeration power. An experimental setup was designed and fabricated to carry out experimental investigations on the GM-type double-inlet pulse tube cryocooler. Experiments were conducted, and the results obtained were used for comparison with the isothermal model developed in the present work. The effect of orifice valve opening, double-inlet valve opening, and frequency on the performance of cryocooler was studied in terms of net refrigeration power and no-load temperature

Design of Standing Wave Type Thermoacoustic Prime Mover for 300 Hz Operating Frequency

Presented at the 16th International Cryocooler Conference, held May 17-20, 2008 in Atlanta, Georgia.Thermoacoustically driven pulse tube cryocoolers are gaining significant interest in the recent time due to the key advantage of complete absence of moving components for the entire system. The present work gives a simple design procedure for a 300 Hz Standing Wave-Type Thermoacoustic Prime Mover having a parallel plate type stack. The necessary code is written in MATLAB for solving the Rott’s wave equation. The code is validated by comparing the results with those available in the literature. The work further reports the effect of operating and geometrical parameters on the performance of the standing wave-type thermoacoustic prime mover. The system performance, mainly in terms of acoustic power and pressure ratio, is influenced significantly by the operating and geometrical parameters. The operating parameters are heat input, hot end temperature, frequency, filling pressure. The geometrical parameters are the stack length, the stack position, the resonator length and the dimensions of the acoustic amplifier, etc