Modeling and simulation of continuous fiber-reinforced ceramic composites

Finite element modeling framework based on cohesive damage modeling, constitutive material behavior using user-material subroutines, and extended finite element method (XFEM), are developed for studying the failure behavior of continuous fiber-reinforced ceramic matrix composites (CFCCs) by the example of a silicon carbide matrix reinforced with silicon carbide fiber (SiC/SiCf) composite. This work deals with developing comprehensive numerical models for three problems: (1) fiber/matrix interface debonding and fiber pull-out, (2) mechanical behavior of a CFCC using a representative volume element (RVE) approach, and (3) microstructure image-based modeling of a CFCC using object oriented finite element analysis (OOF). Load versus displacement behavior during a fiber pull-out event was investigated using a cohesive damage model and an artificial neural network model. Mechanical behavior of a CFCC was investigated using a statistically equivalent RVE. A three-step procedure was developed for generating a randomized fiber distribution. Elastic properties and damage behavior of a CFCC were analyzed using the developed RVE models. Scattering of strength distribution in CFCCs was taken into account using a Weibull probability law. A multi-scale modeling framework was developed for evaluating the fracture behavior of a CFCC as a function of microstructural attributes. A finite element mesh of the microstructure was generated using an OOF tool. XFEM was used to study crack propagation in the microstructure and the fracture behavior was analyzed. The work performed provides a valuable procedure for developing a multi-scale framework for comprehensive damage study of CFCCs --Abstract, page iv

PRACTICAL IMPLEMENTATION OF FOUR QUADRANT OPERATION OF THREE PHASE BLDC MOTOR WITH DIFFERENT LOADS

Brush Less Direct Current (BLDC) motors are attaining higher priority in industrial automation, computers, aerospace, military, household appliance and traction applications because of its high efficiency, high power density and low maintenance cost. This makes the control of BLDC motor in all the four quadrants very vital. To control a BLDC machine, it is generally required to measure the speed and position of rotor by using the sensor. Using the measured value of rotor position, each inverter phase acting at precise time will be commutated. This paper deals with the digital control of three phase BLDC motor in all four quadrant operation. The motor is controlled in all the four quadrants without any loss of power; in fact energy is conserved during the regenerative period. This energy is stored in a battery storage system during regenerative period and can be fed back to the inverter mains during shortage of supply from the source. The FPGA controller is implemented which is more advantageous over other conventional controllers as it is computationally intensive, highly parallelizable tasks, best in class accuracy, reliability and maintenance. A PI controller in closed loop configuration is used for speed control. The torque ripple in each quadrant operation is also reduced using a closed loop operation with the aid of a low pass filter. The operation modes of the proposed system are simulated using MATLAB and results are validated

Cross sectional study on prevalence and medication adherence of hypertension and diabetes in a tertiary care hospital in Karimnagar, India

Background: The study aimed to assess the prevalence of Hypertension (HTN), Diabetes mellitus(DM) and other diseases along with comorbid conditions, disease complications and also to assess medication adherence in a tertiary hospital in Karimnagar, Telangana, India.Methods: A Cross sectional study is performed by analysing a total of 500 patient’s individual case safety reports (ICSR). Prevalence of Hypertension and Diabetes along with most prescribed drugs are analysed. Medication adherence is analysed by using Morisky Medication adherence questionnaire scale (MMAS-4).Results: Patients with past history of DM, HTN and other diseases which was found to be 245 (49%) patients. Patients with highest disease prevalence were found to be with HTN (56.73%), DM (31.83%) followed by other diseases like asthma (8.57%), Cerebrovascular accident (4.89%) etc., Total of 66 Patients were ruled out with comorbid diseases. Patients with HTN+DM (47) were found to be highest followed by DM+HTN+CVA (4). MMAS-4 revealed 208 patients were using medication out of 245 patients with previous history. According to MMAS-4 most of the patients were with medium adherence (76). Prevalent drug used for HTN include Amlodipine and for DM Telmisartan+Hydrochlorthiazide.Conclusions: The study revealed that almost half of the admitted patients were with HTN and DM. The patients were counselled properly to adhere strictly to the prescription. Medication adherence to HTN and DM was found to be good in this study. Since the disease complications were also ruled out, the health care professionals are recommended to spread awareness on DM and HTN and disease management in order to control disease and improve health outcomes

A prospective observational study on incidence of adverse drug reactions in a tertiary care teaching hospital: a pharmacovigilance study

Background: An adverse drug reaction (ADRs) is determined as response to a drug that is noxious unintended excludes therapeutic failures, overdose, drug abuse, noncompliance, and medication errors. The main aim of the study is to detect, understand and report ADR’S.Methods: This study is prospective observational study conducted for 6 months in in-patient setting in a tertiary care hospital. Naranjo’s, WHO causality scale, Siegel scale, Schumock and Thornton scale are used to assess ADR. Graph Pad Prism and SAS software’s are used.Results: Data was collected from a total of 1000 patients of which 121 (12.1%) patients were effected with 150 ADRs. Among 121 patients AdrAd was 60.66% and AdrIn was 39.33%. Of 121 patients 97 patients with single ADR, 28 patients with 2 ADRs, 10 patients were with three ADRs. ADR onset divides acute (10%), Latent (39%) and sub-acute (51%). ADR occurred are recovered (54%), Recovering (13%). Naranjos scale interprets definite (0.9%), probable (50.9%), possible (42.97%). According to WHO scale certain (2.7%), unlikely (2.7%), possible (38.84%). Hartwig and Siegel scale results are mild (12.4%), moderate (66.12%) and severe (12.4%). Schumock and Thornton preventability results are definitely (25.45%), probably (68.18%) and not preventable (6.36%).Conclusions: Every health care professional should be aware of the Pharmacovigilance principles and also should be aware of suspected ADR reporting form of PVPI. By applying the above scales it is easy for health care professionals to assess an ADR

Analysis of Geotagging Behavior: Do Geotagged Users Represent the Twitter Population?

Twitter’s APIs are now the main data source for social media researchers. A large number of studies have utilized Twitter data for diverse research interests. Twitter users can share their precise real-time location, and Twitter APIs can provide this information as longitude and latitude. These geotagged Twitter data can help to study human activities and movements for different applications. Compared to the mostly small-scale data samples in different domains, such as social science, collecting geotagged data offers large samples. There is a fundamental question whether geotagged users can represent non-geotagged users. While some studies have investigated the question from different perspectives, they did not investigate profile information and the contents of tweets of geotagged and non-geotagged users. This empirical study addresses this limitation by applying text mining, statistical analysis, and machine learning techniques on Twitter data comprising more than 88,000 users and over 170 million tweets. Our findings show that there is a significant difference (p-value \u3c 0.001) between geotagged and non-geotagged users based on 73% of the features obtained from the users’ profiles and tweets. The features can also help to distinguish between geotagged and non-geotagged users with around 80% accuracy. This research illustrates that geotagged users do not represent the Twitter population

Visualización en tres dimensiones, los mapas de amenaza volcánica educan al ciudadano común

Even the most reliable volcanic hazard map will be of little use, unless it is presented in terms that are useful to politics, emergency management officials and citizens. The Volcanic Hazard Map of the Nevado del Ruiz Volcano (Colombia), was superimposed on Landsat TM 5 data and digital elevation models, in order to generate perspective views for making the volcanic hazard situations comprehensible to the common people.This 3-D visualization methodology could be used with any volcanic hazard map available. The products generated help to improve the communication between volcanologists and people not familiar with volcanoes, in order to avoid confusion, misunderstanding and strained relations between scientists and persons responsible for the public welfare, during any volcanic emergency crisis.Hasta el mapa de amenaza volcánica más confiable, será de poca utilidad si es presentado de una forma que no lo haga útil para políticos, oficiales que manejan situaciones de emergencia y ciudadanos comunes. Se realizó la superposición del Mapa de Amenaza Volcánica del Volcán Nevado del Ruiz (Colombia), sobre imágenes Landsat TM y modelos digitales de elevación, para generar vistas en perspectiva que hagan comprensibles para el público en general, las situaciones de amenaza volcánica.Esta metodología de visualización en tres dimensiones, podría utilizarse en cualquier mapa de amenaza volcánica disponible. Los productos generados ayudan a mejorar la comunicación entre vulcanólogos y gente no familiarizada con los volcanes, para evitar confusiones, malos entendidos y malas relaciones entre científicos y personas a cargo de la seguridad pública, durante cualquier crisis de emergencia volcánica. &nbsp

Effects of in vitro metabolism of a broccoli leachate, glucosinolates and S-methylcysteine sulphoxide on the human faecal microbiome

Purpose: Brassica are an important food source worldwide and are characterised by the presence of compounds called glucosinolates. Studies indicate that the glucosinolate derived bioactive metabolite sulphoraphane can elicit chemoprotective benefits on human cells. Glucosinolates can be metabolised in vivo by members of the human gut microbiome, although the prevalence of this activity is unclear. Brassica and Allium plants also contain S-methylcysteine sulphoxide (SMCSO), that may provide additional health benefits but its metabolism by gut bacteria is not fully understood. Methods: We examined the effects of a broccoli leachate (BL) on the composition and function of human faecal microbiomes of five different participants under in vitro conditions. Bacterial isolates from these communities were then tested for their ability to metabolise glucosinolates and SMCSO. Results: Microbial communities cultured in vitro in BL media were observed to have enhanced growth of lactic acid bacteria, such as lactobacilli, with a corresponding increase in the levels of lactate and short-chain fatty acids. Members of Escherichia isolated from these faecal communities were found to bioconvert glucosinolates and SMCSO to their reduced analogues. Conclusion: This study uses a broccoli leachate to investigate the bacterial-mediated bioconversion of glucosinolates and SMCSO, which may lead to further products with additional health benefits to the host. We believe that this is the first study that shows the reduction of the dietary compound S-methylcysteine sulphoxide by bacteria isolated from human faeces

The Metabolic Fate of Glucoraphanin in F344 Rats

129 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005.Broccoli is the richest dietary source of the potent isothiocyanate, sulforaphane (SF). Sulforaphane has been shown to have multiple mechanisms to fight cancer. However, sulforaphane is present in broccoli as its precursor, glucoraphanin (GP). Previous studies have reported that humans do not have the enzyme to hydrolyze GP to SF and are dependent on an endogenous plant enzyme, myrosinase. Most cooking methods inactivate myrosinase. Thus when humans consume cooked broccoli they are dependent on gut microbes to hydrolyze GP to reap the health beneficial effects of SF. Relatively little is known about the hydrolysis products formed as results of bacterial action on GP and the factors that affect the conversion of GP to bioactive sulforaphane in the gut. Thus, the over all goal of this research project was to elucidate the metabolic fate of the glucosinolate, GP. We developed methods to purify GP from broccoli seed to conduct metabolism studies using rats. Rats were given purified GP by gavage or by intra-peritoneal (ip) injection; urine and feces were collected and were analyzed for metabolites using HPLC, GC and MS techniques. An important finding was that GP is absorbed when given orally and some of it is excreted unchanged in the urine. Enterohepatic recycling of absorbed GP was identified through bile analysis. A fraction (x %) of an oral GP dose was converted to SF and its metabolites. In addition to SF we also found the reduced and oxidized forms of SF, erucin and erysolin, respectively, as N-acetyl cysteine conjugates in the urine. Slightly less than half of the GP given ip was found in urine either unchanged or as its reduced from, glucoerucin. Further investigation of GP metabolism was conducted using an in vitro fermentation model. Erucin nitrile was identified as one of the fermentation product of GP. These studies show low bioavailability of dietary isothiocyanates, suggesting that there may be ways to improve bioavailability for better utilization of cruciferous vegetables in improving the public health.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Study of Bird Strikes Using Smooth Particle Hydrodynamics and Stochastic Parametric Evaluation

One of the major threats to aviation safety is the in-flight impact of birds. Aircraft windshields are highlyvulnerable to damage and hence need a certification for a proven level of impact resistance. Bird-strike experimentsare expensive; therefore, explicit numerical modeling techniques are particularly important for the study of thisproblem. This research relies mainly on the theory of hydrodynamic impact and addresses basic shock-waveequations. It uses a smooth particle hydrodynamics approach and conducts a numerical simulation using a contact-impact coupling algorithm. Thefinite-element model has been verified by comparison with available experimentalfindings. Additionally, the work adopts a design-of-experiments approach, factorial design, to predict economicallythefactors thatsignificantlyaffect the pressure responsein bird-strike analysis.Theparametersinvestigated includeimpact velocity, bird mass, bird aspect ratio, porosity, and obliquity of impact. The results show that the velocity ofimpact and the interaction between porosity and obliquity have the greatest pressure response in a bird-strikeanalysis