Defence Research Agency

About: Defence Research Agency is a based out in . It is known for research contribution in the topics: Synthetic aperture radar & Radar. The organization has 1211 authors who have published 1109 publications receiving 31542 citations.

A keyword selection strategy for dialogue move recognition and multi-class topic identification

Abstract: The concept of usefulness for keyword selection in topic identification problems is reformulated and extended to the multi-class domain. The derivation is shown to be a generalisation of that for the two class problem. The technique is applied to both multinomial and Poisson based estimates of word probability, and shown to outperform or compare favourably to various information theoretic techniques classifying dialogue moves in the map task corpus, and reports in the LOB corpus.

The Use of Interfacial Test Methods in Composite Materials Development

Abstract: Interfacial testing generates physical information about the fiber matrix interface in a variety of forms. In recent years, there has been considerable discussion about the reliability of the tests and the compatibility of the data generated. One question that has only marginally been addressed is what is required from interfacial test methods to support the rest of the composites community in the understanding and development of fiber-reinforced composite materials. In this paper, the requirements of composite developers and designers are evaluated and related to the information generated by existing test methods. Data are presented demonstrating the significant influence that interface has on macroscopic properties. The relationship of this type of data to interfacial test techniques currently used is also addressed. Those interfacial test methods in use fall into three basic types and each generates information under different loading conditions. An attempt has been made to correlate these conditions to failure processes that occur in full-scale composites. This has clarified where there are deficiencies in both the test methods used and the type of data required. If interfacial property evaluation in composite materials is to become an integral part of composite design, then there needs to be an improved correlation between data generated and end-user requirements.

Multi-dimensional HF modem performance characterisation

Abstract: A high frequency (HF) communications system designed to service modern information exchange requirements can have at its disposal a variety of data modem configurations for supporting traffic transfer These may vary in terms of user data rate, modulation and error control coding Coupled with a choice of communications channel, this presents a number of possibilities for conducting a communications link at any particular time To optimise system performance, with the aim of maximising user data rate and link availability and minimising link setup times, a channel and modem configuration should be selected and appropriately matched for each link to provide the best solution under prevailing channel conditions This process requires an appreciation of the variations in performance, and hence the relative merits, of the modem choices on offer This paper describes a technique which is under development and permits characterisation of modem performance across a range of possible channel conditions Consideration is given to the suitability of using this information in a channel and modem matching process

Device-Based Measures of Sedentary Time and Physical Activity Are Associated With Physical Fitness and Body Fat Content

Abstract: Introduction/Purpose: Physical activity and sedentary time may associate with physical fitness and body composition. Yet, there exists some observational studies that have investigated the associations of device-based measures of sedentary time and physical activity (PA) with cardiorespiratory fitness (CRF) and body composition but associations with muscular fitness (MF) are less studied. Methods: Objective sedentary time and physical activity was measured by a hip worn accelerometer from 415 young adult men (age: mean 26, standard deviation 7 years). Cardiorespiratory fitness (VO2max) (CRF) was determined using a graded cycle ergometer test until exhaustion. Maximal force of lower extremities was measured isometrically and lower body power was assessed using standing long jump (MF). Body composition was determined with bioimpedance method. Single and compositional approach was used in regression analysis. Results: Mean sedentary time was 707 (standard deviation 133) minutes per day (77 ± 8% of the wear time). Volumes of all PA intensities were positively associated with CRF and associations showed linearly increasing magnitudes with higher intensities in single regression models adjusted for age and smoking (p < 0.001). Similarly, PA intensities were positively associated with lower body MF, however, with weaker associations (p < 0.005). After further adjustment for resistance training, the associations remained significant. The associations of the relative distribution of time within sedentary behavior (SB), light intensity PA (LPA) and moderate-to-vigorous PA (MVPA) behaviors as a whole with using compositional analysis further revealed that within the composition MVPA and SB were positively associated with CRF and MF (p < 0.001), while LPA was not. In addition, within the composition, accumulated PA bouts lasting more than 3 min were consistently associated with CRF and MF, and with all body composition variables (p < 0.001), while sedentary time was associated with body fat percentage (p < 0.001). Conclusion: Promoting physical activity and reducing sedentary time may have positive influence on physical fitness and body fat content, and thereby may offer positive health effects. Physical activity of higher intensities may offer greater benefits.