Background: Changes have been seen in the age structure of the population due to a steady rise in life expectancy and reduction in fertility. Aim: To know the morbidity pattern of the elderly in urban population of Mysore, delineate the common health conditions affecting the elderly and evaluate the differences in the morbidity pattern between the young old and old old. Material and Methods: This community based Cross sectional study was carried out at the field practice area of Urban Health Centre, JSS medical college, Mysore. The study population comprises of all geriatric population aged 60 years and above who were residing in the study area for at least one year. 526 study subjects were used for the study. Results: Most of the system disorders were found to be almost equally distributed among elderly men and women. Disorders of oral cavity were more prevalent among aged males (40.6%), while diseases of skin were more prevalent among aged females (10.0%). Most common disorder reported among elderly were diseases of the eye (51.7%) followed by endocrine, nutritional and metabolic diseases (38.4%). Conclusion: Awareness among the elderly population should be created for regular medical checkups to ensure prevention and early detection of the chronic diseases. It is also essential to have geriatric units with specialised professionals along with subsidized health care services in order to address geriatric morbid conditions in a proper manner.

This article deals with the design, simulation, and analysis of a 10‐watt capacity thermoacoustic refrigerator using short‐stack boundary layer approximation assumptions and dimensional normalization technique. The variation of stack diameter with average gas pressure and cooling power is studied. The theoretical evaluation of quarter‐wavelength and one‐fifth‐wavelength resonator using helium gas is discussed for an operating frequency ranging from 300–500 Hz in the steps of 50 Hz. For the optimized stack, a 38.5% improvement in the stack performance for a 10‐watt cooling power quarter‐wavelength hemispherical‐ended resonator operating at 350 Hz frequency resulted in a 13.5% improvement in the coefficient of performance (COP) compared to published results. The resonator design is tested with DeltaEC software with 2% and 3% drive ratios using helium, hydrogen, neon, air, and carbon dioxide as working gases and the results are discussed. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(7): 577–591, 2014; Published online 3 October 2013 in Wiley Online Library (http://wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.21094

This paper deals with the design and analysis of a quarter-wavelength, 10 W capacity, thermoacoustic refrigerator using short stack boundary layer approximation assumptions. The effect of operating frequency on the performance of the refrigerator is studied using dimensional normalization technique. The variation of stack diameter with average gas pressure and cooling power is discussed. The resonator optimization is discussed and the calculation results show a 9% improvement in the coefficient of performance and 201% improvement in power density for the optimized quarter-wavelength resonator compared to published optimization studies. The optimized resonator design is tested with DeltaEC software and the results show better performance compared to past established resonator designs.

The design and optimization procedure for a loudspeaker driven 10-W cooling power thermoacoustic refrigerator components with a temperature di®erence of 120 K has been discussed using the linear thermoacoustic theory. The resonator losses are proportional to surface area and the optimum diameter ratio of small and large resonator tubes for minimum heat loss for a quarterwavelength hemispherical ended resonator design is discussed. The hemispherical ended resonator design is further analytically optimized to increase COP, cooling e®ect at cold heat exchanger and power density by decreasing total resonator surface area and volume. An alternate convergentdivergent resonator design is proposed which is found to be more e±cient compared to previous published designs. Resonator designs are tested with DeltaEC software, which predicts a lowest temperature of À48 C and À47 C for the improved hemispherical and convergent-divergent resonator designs, respectively. Theoretical results are in good agreement with DeltaEC results.

This paper presents a design of moving coil loudspeaker for a 10 W cooling power thermoacoustic refrigerator. An electrical model is presented which simulates the behavior of the loudspeaker. The gas spring system for matching the frequency of the commercially available loudspeaker with the frequency of the acoustic resonator tube for maximizing electro-acoustical efficiency of the loudspeaker is discussed. The optimum back volume for the gas spring system is found to be 59.7 cc, which is about 1.9% of the total resonator volume when the loudspeaker frequency and the acoustic resonator frequency is made equal at 400 Hz with a moving mass of 20 g. The effect of force factor Bl on loudspeaker performance is discussed. Analysis results shows that for better performance of a refrigerator, the loudspeaker should be chosen to have a large force factor and small values for electrical and mechanical resistances. The refrigerator system is tested with DeltaEC software and its results are in good agreement with an electrical model results.