A highly efficient engineering tool for three-dimensional scramjet flowfield and heat transfer computations

The SIMPLE-based parabolic flow code, SHIP3D, was under development for use as a parametric design and analysis tool for scramjets. Some capabilities and applications of the code are demonstrated, and a report on its current status is given. The focus is on the combustor for which the code was mostly used. Recently, it was also applied to nozzle flows. Code validation results are presented for combustor unit problems involving film cooling, transverse fuel injection, and nozzle test. A parametric study of a film cooled or transpiration cooled Mach 16 combustor is also conducted to illustrate the application of the code to a design problem

Comparison of Partial Recording Protocols in Disease Assessment among Periodontitis Patients in a Central Indian Population

Objectives: Partial recording protocols may be used for the purpose of assessing periodontal disease extent and severity in epidemiological studies. As there is very little data at present regarding the reliability of any partial examination methods among Indian populations, as an initial study, an attempt was made to determine the reliability of 9 different protocols in estimating the extent and severity of periodontal disease among periodontitis patients in a central Indian population. Study Design: Probing depths (PD) and clinical attachment levels (CAL) were recorded in 85 periodontitis patients on 6 sites on all the teeth excluding the third molars. Nine partial recording protocols (PRP) were compared with the full-mouth examination. Intra-class correlation coefficients (ICC) were calculated for mean PD, mean CAL, and percentage of sites with various thresholds of PD and CAL to determine the agreement between the PRP and the full-mouth examination. The sensitivity of different PRP for defining prevalence of sites with PD ≥6 and ≥7 mm and CAL ≥7 and ≥8 mm was also determined. Results: For all the tested PRP, the ICCs were consistently >0.9. The methods involving examination of 4 sites/ tooth slightly over-estimated the disease extent and severity in comparison with the full-mouth examination as well as PRP involving examination of 6 sites/tooth. Conclusions: The findings of the present study suggest that the tested PRP are in good agreement with the fullmouth examination. However, further studies need to be conducted with an improved methodology in a larger sample of subjects from the general population

Patterns of Periodontal Destruction among Smokeless Tobacco Users in a Central Indian Population

Background: Findings of studies testing the association between smokeless tobacco (SLT) use and periodontal health have shown varying results in different populations. Considering the high prevalence of SLT use in India, the present study was conducted to understand the pattern of periodontal destruction within different areas of the dentition among SLT users. Methods: Age, gender, oral hygiene habits, the frequency and duration of SLT consumption, the type of SLT product used, and the site of retention of the SLT product in the oral cavity were recorded among 90 SLT users. Probing depth (PD), recession (REC), and clinical attachment loss (CAL) at SLT-associated and non SLT-associated teeth of the mandibular arch were compared based on the site of retention of the SLT product, the type of product used, and the duration of the habit. Results: REC and CAL were significantly higher at the SLT-associated zones compared to non SLT-associated zones and at both interproximal and mid-buccal sites of SLT-associated teeth. Among individuals who had the habit for more than 5 years and also among those who had the habit for 5–10 years, PD, REC, and CAL were significantly higher at SLT-associated teeth than at non SLT-associated teeth. Significantly greater periodontal destruction was observed at SLT-associated teeth among khaini users and gutkha users. Conclusions: Smokeless tobacco consumption resulted in greater destruction of periodontal tissues. The severity of periodontal destruction at SLT-associated sites differed depending on the type of smokeless tobacco used, the site of retention of the SLT, and the duration of the habit

Performance Analysis and Optimisation of an Oil Natural Air Natural Power Transformer Radiator

AbstractIn Power transformers are inevitable components in alternating current generation, transmission, distribution and utilization systems. Lifespan and performance of power transformer are dependent on cooling system employed for dissipation of heat generated during its operation. In this paper numerical simulation of an oil natural air natural power transformer radiator was performed to determine its cooling capacity. In addition, optimum spacing between sections and optimum length of sections of radiator were also determined. An optimised radiator design was proposed and was simulated to determine its cooling capacity. The proposed radiator design was found to 14% more efficient than existing design in terms of cooling capacity for same material cost. The control volume method has been used to resolve the continuity, the momentum and the energy equations in steady state