Active Noise Control using Variable step-size Griffiths’ LMS (VGLMS) algorithm on Real-Time platform

This paper proposes implementation of Griffith’s Variable step-size algorithm for Active Noise Control (ANC) on ADSP-TS201 EZ-Kit Lite. The dual computational units and execution of up to four instructions per cycle which are special features over other processors are best utilized to generate an optimized code. The VGLMS provides improved secondary path estimation and computations involved are marginal as the same gradient is used for step-size computation and coefficient adaptation. The improved secondary path estimate, in turn improves the ANC performance. Further, variable step-size algorithm is used for the main-path to achieve faster convergence. Both for narrowband (fundamental and its harmonics) and broadband noise fields, for a duct the attenuation achieved is 25 dB and 15 dB respectively. The program execution time was only 1.25% for an input sampling rate of 1 KHz which indicates the utility of the special features of the processor considered. Further these features have enabled in bringing down the program memory requirement in the implementation of the algorithm

Preprocessing Solar Images while Preserving their Latent Structure

Telescopes such as the Atmospheric Imaging Assembly aboard the Solar Dynamics Observatory, a NASA satellite, collect massive streams of high resolution images of the Sun through multiple wavelength filters. Reconstructing pixel-by-pixel thermal properties based on these images can be framed as an ill-posed inverse problem with Poisson noise, but this reconstruction is computationally expensive and there is disagreement among researchers about what regularization or prior assumptions are most appropriate. This article presents an image segmentation framework for preprocessing such images in order to reduce the data volume while preserving as much thermal information as possible for later downstream analyses. The resulting segmented images reflect thermal properties but do not depend on solving the ill-posed inverse problem. This allows users to avoid the Poisson inverse problem altogether or to tackle it on each of $\sim$10 segments rather than on each of $\sim$10$^7$ pixels, reducing computing time by a factor of $\sim$10$^6$. We employ a parametric class of dissimilarities that can be expressed as cosine dissimilarity functions or Hellinger distances between nonlinearly transformed vectors of multi-passband observations in each pixel. We develop a decision theoretic framework for choosing the dissimilarity that minimizes the expected loss that arises when estimating identifiable thermal properties based on segmented images rather than on a pixel-by-pixel basis. We also examine the efficacy of different dissimilarities for recovering clusters in the underlying thermal properties. The expected losses are computed under scientifically motivated prior distributions. Two simulation studies guide our choices of dissimilarity function. We illustrate our method by segmenting images of a coronal hole observed on 26 February 2015

Reoperative valve surgery: A Retrospective analysis of last ten years

INTRODUCTION: Extensive advances have been made in cardiac valve surgery since the first artificial valve replacements of the early 1950s. Improved survival after the first operation has meant that more patients ultimately require a redo operation at the same site and the number of patients will continue to increase as the general population ages. This trend reflects many factors, such as the increased life expectancy of the population, the decreased overall mortality associated with valvular surgery, and the increasing use of bioprostheses which have limited durability because of structural dysfunction. Hence reoperations are an integral part of the cardiac surgeon’s current daily practice. Among heart valves case load, re-operations on prostheses represent between 2.5% and 17%. AIMS AND OBJECTIVES: 1. To retrospectively evaluate our experience in patients who underwent re-operative valve surgery in our institution between January 2000 and December 2009 (a period of ten years). 2. To study their manner of presentation, the reasons leading to reoperation, the type of surgery performed and operative techniques. 3. To identify the risk factors for early mortality and morbidity associated with these operations. 4. To study the incidence of late morbidity and functional class at last follow-up. MATERIAL AND METHODS: This is a retrospective study of patients who underwent re-operative valve surgery between January 2000 and December 2009 in the Department of cardiothoracic surgery. In this period, a total of 43 underwent a first reoperation for a new valve problem of the native/prosthetic valve. There were 5 operative (30 days) mortalities (11.62%). A retrospective review of the hospital inpatient and outpatient charts of the rest of the 38 patients for their age, sex, presenting symptoms, preoperative NYHA class, preoperative risk factors, echocardiogram reports and operative details including surgical approach, total aortic cross clamp time, total cardio-pulmonary bypass time, post operative need for inotropes and ventilation, number of days of ICU care, post operative complications and post operative follow up was performed.(See appendix for proforma of data collection). Six patients were lost in the follow-up. Patients who had undergone a previous open heart surgery for varied etiologies were included in the study. Coronary angiogram was done in all patients older than 40 years. CONCLUSION: In conclusion, we have shown in this small series that repeat heart valve surgery can be performed with an acceptable operative mortality that compares favorably with results in other published series. However, several categories of patients have an increased risk of death at reoperation. These include patients with higher NYHA class, surgical priority, presence of infective endocarditis, preoperative renal dysfunction, Presence of CCF, preoperative LV function, previous surgery, present indication for reoperation and total CPB time. In addition, the indication for reoperation, especially thrombosed valves or prosthetic valve endocarditis, carries an increased risk. It is important that patients with prosthetic valves undergo regular follow-up with assessment of valve function and should undergo earlier reoperation before severe ventricular dysfunction occurs. In spite of regular follow-up, it is noted that majority of patients present with severe symptoms at reoperation, which is a predictor of major adverse postoperative event, including death, after valve reoperation. Hence, surgery should be considered early in the management of recurrent or progressive cardiac disease before severe symptoms develop and compromise the outcome of reoperation. In patients undergoing re-operative surgery, our unit protocol is to establish cardiopulmonary bypass before resternotomy and this is a valid and reproducible option to render cardiac reoperations safer and more expeditious in the reentry phase. The absence of cannulae in the operating field makes the procedure more comfortable. The liberal use of this strategy is recommended in redo cases is recommended. In our experience, there was no single instance of catastrophic hemorrhage and also it results in decreased total operative times and also decreased need for blood transfusions. No patient experienced complications related to femoral cannulation. The Seldinger method allowed little vascular trauma and intraoperative patency of femoral vessels. Reoperative surgery continues to pose a significant challenge to the entire cardiothoracic team. Careful patient selection and assessment, a tailored strategy based on accurate risk stratification, and a team approach in the perioperative period can decrease the incidence of adverse events, reducing morbidity and mortality. Further minimization of the risk is obtained by strict adherence to sound basic surgical principles and techniques. Generally speaking, optimal planning for reoperation prior to deterioration to NYHA class III–IV levels and before unfavorable co-morbid conditions have arisen is imperative to ensure good outcomes. Following these guidelines in the modern era, elective reoperative surgery can be performed with results similar to those of the primary operation

Detecting Unspecified Structure in Low-Count Images

Unexpected structure in images of astronomical sources often presents itself upon visual inspection of the image, but such apparent structure may either correspond to true features in the source or be due to noise in the data. This paper presents a method for testing whether inferred structure in an image with Poisson noise represents a significant departure from a baseline (null) model of the image. To infer image structure, we conduct a Bayesian analysis of a full model that uses a multiscale component to allow flexible departures from the posited null model. As a test statistic, we use a tail probability of the posterior distribution under the full model. This choice of test statistic allows us to estimate a computationally efficient upper bound on a p-value that enables us to draw strong conclusions even when there are limited computational resources that can be devoted to simulations under the null model. We demonstrate the statistical performance of our method on simulated images. Applying our method to an X-ray image of the quasar 0730+257, we find significant evidence against the null model of a single point source and uniform background, lending support to the claim of an X-ray jet

Long Run Health Impacts of Income Shocks: Wine and Phylloxera in 19th Century France

This paper provides estimates of the long-term effects on height and health of a large income shock experienced in early childhood. Phylloxera, an insect that attacks the roots of grape vines, destroyed 40% of French vineyards between 1863 and 1890, causing major income losses among wine growing families. Because the insects spread slowly from the southern coast of France to the rest of the country, Phylloxera affected different regions in different years. We exploit the regional variation in the timing of this shock to identify its effects. We examine the effects on the adult height, health, and life expectancy of children born in the years and regions affected by the Phylloxera. The shock decreased long run height, but it did not affect other dimensions of health, including life expectancy. We find that, at age 20, those born in affected regions were about 1.8 millimeters shorter than others. This estimate implies that children of wine-growing families born when the vines were affected in their regions were 0.6 to 0.9 centimeters shorter than others by age 20. This is a significant effect since average heights grew by only 2 centimeters in the entire 19th century. However, we find no other effect on health, including infant mortality, life expectancy, and morbidity by age 20.

Reduction Behaviour of Iron Ore Pellets

Demand of sponge iron and pre-reduced pellets for the manufacture of different varieties of steel is increasing day by day and new solid reductants based sponge iron plans are being commissioned. In the existing blast furnace an increase in production by at least 25 to 35% can be achieved by using pre reduced iron ore. Pre-reduced iron ore pellets have been established as a good substitute for steel scrap in an electric arc furnace which enhances the productivity of the arc furnace. A lot of investigations have been carried out on direct reduction process of iron oxides by carbonaceous materials, but little work has been done on the characterization of properties and reduction behavior of iron ore of. In the present project work, an attempt has been made to study the reduction behavior and kinetics of iron ore fired pellets. The effect of different reduction parameters such as temperature (850-1000ºC), time (15-120 minutes.), mixing of particles of different sizes at different ratios for pellet preparation etc. on the reduction behavior of iron ore pellets. These form the subject matter of the thesis. First chapter gives the introduction about the subject. It speaks about the need of DRI industry, scope, present status and future planning of DRI industry in India, world wise DRI production, etc. It gives a general idea of raw materials quality required for producing DRI, especially in Rotary Kiln. The second chapter deals with the literature survey. The third chapter deals with planning of experiments, selection of raw materials, preparation of samples, preparation of iron ore pellets, experimental procedure , evaluation of reduction and activation energies, etc. The results obtained and the discussions made from these observations have been outlined in chapter four. The result for fired iron ore pellets indicated an increase in degree of reduction with increase in reduction temperature (850-1000ºC) and time. The reduction kinetics of Zenith iron ore pellets were studied in temperature range of 850-1000ºC. The data were fitted on a differential model and the activation energies of reduction of pellets were calculated. Analysis of swelling behavior was also done. Results obtained from chapter four have been summarized in chapter five. Lastly, these conclusions have been followed by the list of references