Creep Life Prediction of Modified 9Cr-1Mo Steel under Multiaxial State of Stress

AbstractCreep life prediction of modified 9Cr-1Mo steel under multiaxial state of stress has been carried out in the present investigation. Creep tests were carried out on smooth and notched specimens of modified 9Cr-1Mo steel in the stress range 150 - 230MPa at 873K. The creep rupture life was found to be higher in the presence of notch than that of smooth specimens indicating ‘notch strengthening’ behaviour. The extent of strengthening tends to saturate for relatively sharper notches. Finite element analysis was used to estimate the variation of stresses across the notch throat plane. As the stresses varied across the notch throat plane, the stresses at the skeletal point were used for estimating the representative stress. The models proposed by Cane, Hayhurst and Nix were examined for creep life prediction under multiaxial state of stress. The von-Mises stress was found to predominantly govern the creep rupture life of the steel. The creep rupture life has been predicted based on Cane's model using finite element analysis and continuum damage mechanics

Efficient representation of texture details in medical images by fusion of Ripplet and DDCT transformed images

Purpose: To evaluate and compare the performance of Ripplet Type-1 transform and directional discrete cosine transform (DDCT) and their combinations for improved representation of MRI images while preserving its fine features such as edges along the smooth curves and textures.Methods: In a novel image representation method based on fusion of Ripplet type-1 and conventional/directional DCT transforms, source images were enhanced in terms of visual quality using Ripplet and DDCT and their various combinations. The enhancement achieved was quantified on the basis of peak signal to noise ratio (PSNR), mean square error (MSE), structural content (SC), average difference (AD), maximum difference (MD), normalized cross correlation (NCC), and normalized absolute error (NAE). To determine the attributes of both transforms, these transforms were combined to represent the entire image as well. All the possible combinations were tested to present a complete study of combinations of the transforms and the contrasts were evaluated amongst all the combinations.Results: While using the direct combining method (DDCT) first and then the Ripplet method, a PSNR value of 32.3512 was obtained which is comparatively higher than the PSNR values of the other combinations. This novel designed technique gives PSNR value approximately equal to the PSNR’s of parent techniques. Along with this, it was able to preserve edge information, texture information and various other directional image features. The fusion of DDCT followed by the Ripplet reproduced the best images.Conclusion: The transformation of images using Ripplet followed by DDCT ensures a more efficient method for the representation of images with preservation of its fine details like edges and textures.Keywords: Ripplet, Directional discrete cosine transform (DDCT), Peak signal to noise ratio, MSE (mean square error), SC (structural content), MD (maximum difference), NCC (normalized cross correlatio

Analysis of Hysteresis Loops of 316L(N) Stainless Steel under Low Cycle Fatigue Loading Conditions

AbstractLow cycle fatigue tests were carried out on 316 L(N) stainless steel at room temperature employing strain amplitudes ranging from ± 0.3 to ±1.0% and a strain rate of 3×10−3s−1. The material showed initial hardening for a few cycles followed by prolonged softening, saturation and final failure. The fatigue life was found to decrease with increase in strain amplitude. The analysis of stable hysteresis loops showed non-Masing behaviour for this material. The elasto-plastic response of the material under cyclic loading was characterized taking into account isotropic and kinematic hardening occurring during cycling. The material parameters were obtained from the experimental hysteresis loops and cyclic stress response of the material. Finite element analysis of elasto-plastic deformation was carried out to obtain the stabilized hysteresis loop and cyclic stress response of the material. The predicted hysteresis loops showed good agreement with experimental results. The low cycle fatigue life prediction was carried out based on plastic strain energy dissipation with cycling

Evaluation of Particulate Matter Pollution in Micro-Environments of Office Buildings—A Case Study of Delhi, India

High level of particulate matter in an office building is one of the prime concerns for occupant’s health and their work performance. The present study focuses on the evaluation of the distribution pattern of airborne particles in three office buildings in Delhi City. The study includes the Assessment of PM10, PM2.5 and PM1 in the different indoor environments, their particle size distribution, I/O ratio, a correlation between pollutants their sources and management practices. The features of buildings I, II, and III are old infrastructure, new modern infrastructure, and an old building with good maintenance. The results indicate that the average concentrations of PM10, PM2.5, and PM1 are found in the range of 55–150 μg m−3, 41–104 μg m−3 and 37–95 μg m−3, respectively in Building I, 33–136 μg m−3, 30–84 μg m−3 and 28–73 μg m−3, respectively in Building II and 216–330 μg m−3, 188–268 μg m−3 and 171–237 μg m−3, respectively in Building III. The maximum proportion of the total mass contributed by PM0.25–1.0 i.e., up to 75%, 86%, and 76% in the meeting room of Building I, II and III, respectively. The proportion of ultrafine particles was found higher in the office area where the movement was minimum and vice versa. The higher I/O indicates the contribution of the presence of indoor sources for ultra-fine and finer particles. Further, possible strategies for indoor air pollution control are also discussed

Successful use of intra-aortic counter pulsation therapy for intractable ventricular arrhythmia in patient with severe left ventricular dysfunction and normal coronary arteries

Intra-aortic balloon pumps (IABP) are commonly used in the setting of an acute myocardial infarction that is complicated by cardiogenic shock or mechanical complications such as a ventricular septal defect or papillary muscle rupture. IABP has also been shown to be useful in patients with refractory and hemodynamically unstable ventricular arrhythmias and refractory post-myocardial infarction angina. We report a case in which IABP was used in a patient with dilated cardiomyopathy and normal coronary arteries, who presented with persistent, recurrent and refractory ventricular tachycardia. His ventricular tachycardia settled immediately with the use of IABP therapy. He subsequently had an implantable defibrillator. The use of IABP is associated with favorable changes in the left ventricular wall tension and reduction in afterload, which could reduce the excitability of the myocardium, thus making it less prone to arrhythmias. The use of IABP is relatively safe and should be considered in patients with refractory ventricular arrhythmias, even if it is not associated with ischemia. (Cardiol J 2010; 17, 4: 401-403

Skuteczne leczenie komorowych zaburzeń rytmu serca za pomocą kontrapulsacji wewnątrzaortalnej u pacjenta z ciężką dysfunkcją skurczową lewej komory i angiograficznie prawidłowymi tętnicami wieńcowymi

Kontrapulsacja wewnątrzaortalna (IABP) jest powszechnie stosowaną metodą leczenia zawału serca powikłanego wstrząsem kardiogennym lub mechanicznymi uszkodzeniami, takimi jak: pęknięcie przegrody komorowej lub mięśnia brodawkowatego. Pacjenci odnoszą również korzyść ze stosowania IABP w opornych na leczenie i hemodynamicznie niestabilnych komorowych zaburzeniach rytmu i w niepoddającej się terapii dławicy pozawałowej. W prezentowanym doniesieniu przedstawiono przypadek kliniczny pacjenta z kardiomiopatią rozstrzeniową i angiograficznie prawidłowymi tętnicami wieńcowymi. U chorego wystąpił uporczywy, nawrotowy i niepoddający się leczeniu częstoskurcz komorowy. Po zastosowaniu IABP częstoskurcz natychmiast ustąpił. W konsekwencji pacjentowi wszczepiono kardiowerter defibrylator. Stosowanie IABP przynosi pożądane obniżenie naprężenia ściany lewej komory i obciążenia następczego (afterload). Zmiany te mogą zmniejszać pobudliwość komórek miokardium i w konsekwencji prowadzą do zmniejszenia ryzyka wystąpienia arytmii. Leczenie za pomocą IABP jest relatywnie bezpieczne i należy je rozważyć u chorych z opornymi na terapię komorowymi zaburzeniami rytmu serca, również tymi niezwiązanymi z niedokrwieniem. (Folia Cardiologica Excerpta 2010; 5, 6: 371–374

Solar radiation estimates at Meerut workplace

19-25The research is concerned with the assessment and analysis of solar radiation in a workplace with longitude 77.706 (77°43' east) and latitude 28.984 (28°59' north) located in western Uttar Pradesh and the National Capital Region of India. Solar radiation energy which varies according to geographical location and weather conditions and also depends on the variation in components of solar radiation such as global and diffused components. Every year from June to September except the rainy season, the spreading components of solar radiation are more and there is a significant amount of solar energy available in this area. This work estimates the variation in solar components of complete solar radiation and the possible availability of solar radiation energy, may play an important role in reducing the electrical energy crisis in the Meerut region

Audit of Bilateral Simultaneous Cochlear Implantation in Pediatric Population: South Indian Study

Objective: To conduct a medical audit of bilateral simultaneous cochlear implantation (CI) in patients with severe prelingual sensorineural hearing loss (SNHL).Methods: A medical audit of a tertiary care ear, nose, and throat center in Southern India was conducted on data collected from January 2007 to December 2014. All cochlear implantees 6 years, sequential bilateral CI, revision cases, abnormal or malformed cochlea, and children with global developmental delay in milestones. Subjective outcome scores used were Category of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR).Results: The CAP and SIR results showed that 20% of implantees achieved peak scores of 7 and 5, respectively. Mean CAP and SIR scores at 12 months were 5.4 and 3.1, respectively.Conclusion: The present study supports the claim that bilateral CI in severe prelingual bilateral SNHL is better than unilateral and recommends that bilateral CI should be the standard of care in children