Application of Compressive Sensing to Weather Radars

The capability and importance of weather radar are proven for hazardous weathers detection, monitoring, and prediction in both research and operations. Continuous efforts have been made in improving radar performance in terms of spatial and temporal resolutions, data quality, new capabilities, etc. On the other hand, compressive sensing (CS) theory has been developed for solving underdetermined problems using l1-norm minimization. It has been shown that CS is capable of reconstructing the sparse images from a limited number of measurements. In this work, CS is specifically applied to two weather radar problems of (1) refractivity retrieval using a network of radars, and (2) retrieving reflectivity and velocity from an imaging radar. In the first study, CS is proposed to improve the refractivity retrieval since the performance of a conventional constraint least squares method can be degraded significantly by the measurement noise and the limited number of high-quality ground returns. The application of CS to refractivity retrieval is formulated using a linear model and subsequently the feasibility is demonstrated and verified using simulations. In the second study, the problem of digital beamforming (DBF) is posed as an inverse problem and formulated using a linear model for both reflectivity and velocity estimation for CS. The application of CS is investigated using both simulation and real data. In simulations, the performance of CS is quantified and compared to the traditional Fourier beamforming and high resolution Capon beamforming for various conditions. The feasibility of CS to weather observations is further demonstrated using the data collected by the Atmospheric Imaging Radar (AIR), developed at the Advanced Radar Research Center (ARRC) of the University of Oklahoma, on 15 April 2012

Space-time assessing of the earthquake potential in recent years in the Eastern Anatolia region of Turkey

In this study, a statistical analysis is carried out to reveal the current earthquake potential in the Eastern Anatolia region of Turkey. For this purpose, a space-time assessing based on the recent changes in Gutenberg-Richter b-value, seismic quiescence Z-value, cumulative moment, annual probability and recurrence time of earthquakes is achieved. Temporal variation of b-value indicates that average b-value decreased from 1.25±0.02 between 2002 and 2010 to 1.08±0.02 between 2011 and 2015. A clear quiescence in the seismic moment in recent years may be a clue foretelling the occurrence of an intense event. Annual probability of the earthquakes between 3.5 and 4.0 magnitude levels exhibits a value equal to and larger than 30. Recurrence time of the earthquakes has a value between 2.0 and 3.0 years for magnitude level of 6.0, and a value between 6.0 and 7.0 years for magnitude level of 7.0. A significant decrease in b-value and clear quiescence anomalies in Z-value at the beginning of 2015 are observed in the several same regions. These areas cover the Central Anatolia Fault Zone, Malatya and Ovacık faults, the southeastern part of the Eastern Anatolia Fault Zone, and the junction of the Eastern Anatolia and Dead Sea Fault Zones. In these anomaly regions, a decreasing trend in b-value may be an indicator of stress increases and an increasing trend in Z-value may show the quiescence areas before the next earthquake occurrences. As a remarkable fact, these areas in the Eastern Anatolia region may be interpreted as one of the most likely locations for the major earthquakes in the future.En este estudio se realizó un análisis estadístico para evidenciar el potencial actual de terremotos en la región de Anatolia, al oriente de Turquía. Con este objetivo, se obtuvieron una evaluación espacio-temporal basada en los cambios recientes del valor b en la ley Gutenberg-Richter, el valor z de inactividad sísmica, el momento acumulado, la probabilidad anual y el tiempo recurrente de los terremotos. La variación temporal del valor b indica que este factor cayo desde 1.25±0.02, entre 2002 y 2010, a 1.08±0.02 entre 2011 y 2015. La clara inactividad en el momento sísmico de los años recientes podría ser una clave predictiva de la ocurrencia de un terremoto intenso. La probabilidad anual de terremotos de magnitud entre 3.5 y 4.0 muestra un valor igual o mayor a 30. El tiempo de recurrencia de terremotos tiene un valor de 2.0 y 3.0 años en la magnitud de nivel 6.0 y un valor entre 6.0 y 7.0 años para la magnitud de nivel 7.0. A comienzos de 2015 se observó una caída significante del valor b y claras anomalías en el valor z de inactividad en varias regiones. Estas áreas cubren la zona de la falla de Anatolia Central, las fallas Malatya y Ovacık, la parte sureste de la falla Este de Anatolia, y las zonas de intersección de la falla este de Anatolia con la falla del Mar Muerto. En estas regiones de anomalías, una tendencia a la baja en el valor b podría ser el indicador de un aumento de tensión, y una tendencia al alza del valor z podría mostrar las zonas de inactividad antes de la ocurrencia de próximos terremotos. Como un hecho remarcable, estas áreas en la región Este de Anatolia pueden ser calificadas como unas de las más propensas a sufrir terremotos mayores en el futuro

An Application Of The Aftershock Probability Evaluation Methods For Recent Albania Earthquakes Based On Gutenberg-Richter And Modified Omori Models

In this study, an assessment on the aftershock occurrence probability based on the combination of Gutenberg-Richter and modified Omori formulae is made in order to forecast how many large aftershocks should follow small main shocks and in order to evaluate aftershock probability that a randomly chosen event is greater than or equal to a certain magnitude of aftershock. For this purpose, we made an application of aftershock probability evaluation methods to nine aftershock sequences in which occurred Albania between 2004 and 2009 with magnitude level between 4.5 and 5.0

THE EFFECTS OF A SOCIAL LEARNING NETWORK ON STUDENTS’ PERFORMANCES AND ATTITUDES

Despite the widespread use of Social Learning Networks (SLNs), there is little research on the effectiveness of these sites in related literature. Therefore, there is a need for studies investigating but use of SLNs in educational environments and their effects on learners’ academic achievements. In this study, the purpose was to investigate the effects of use of Edmodo, a leading SLN site, on students’ performances and attitudes towards online learning according to certain variables. In line with this purpose, using the pretest-posttest method, an experimental study with a control group was carried out with 79 learners taking the courses of Special Teaching Methods in the department of Computer Education and Instructional Technologies in the Education Faculty of a university in Turkey. In addition to face-to-face courses given to the experimental group students, various activities related to the course (group works, individual assignments, discussions) were carried out under the guidance of the course teacher via Edmodo. As for the control group students, they carried out the activities in class environment without using Edmodo. The results revealed that students who used Edmodo were more successful than those who did not. Based on this result, it could be stated that Edmodo had positive contributions to learners’ academic achievements.  Article visualizations

Takayasu Arteritis Initially Mimicking Infective Endocarditis

Takayasu’s arteritis (TA) is a chronic inflammatory disease that affects large vessels, predominantly the aorta and its main branches, leading to vessel wall thickening, fibrosis and stenosis. Cardiac and vascular symptoms are also commonly present at disease onset. In TA with thoracic or abdominal involvement, although murmur can be present at physical examination, the pulse difference may be absent. Here, we report a case of TA who initially resembled infective endocarditis and had widespread thoracic murmur

Active power loss minimization in electric power systems through chaotic artificial bee colony algorithm

Optimizacija reaktivne snage - Reactive power optimization (RPO) - osnovno je područje istraživanja u svrhu sigurnog i ekonomičnog rada energetskih sustava. RPO se može primijeniti za smanjenje gubitaka aktivne snage, reguliranje napona te za optimizaciju energetskih koeficijenata u energetskim sustavima. Funkcija ne-linearnog gubitka snage koristi se kao funkcija cilja koju treba smanjiti. U ovom se radu algoritam Kaotične umjetne kolonije pčela - Chaotic Artificial Bee Colony (CABC) - primjenjuje za smanjenje gubitka aktivne snage u energetskim sustavima. Rabe se kaotične mape kao što su logistička mapa i Henon mapa. CABS se primjenjuje na provjeravanim sustavima IEEE 6-sabirnice i IEEE 30-sabirnice i daju se rezultati. Provjerom rezultata ustanovilo se da primjena kritičnih vrijednosti stabilnosti dobivenih pomoću CABS može rezultirati dobrim potencijalnim rješenjima. Rezultati simulacije su obećavajući i pokazuju učinkovitost primijenjenog pristupa.Reactive power optimization (RPO) is a major field of study to ensure power systems for operating in a secure and economical manner. RPO can be used for decreasing of active power losses, voltage control, and for the optimization of the power coefficients in power systems. The non-linear power loss function is used as an object function that will be minimized. In this study Chaotic Artificial Bee Colony (CABC) algorithm is used to minimize the active power loss of power systems. Chaotic maps such as logistic map and Henon map are used against the random number generator. CABC is applied on the IEEE6-bus and IEEE 30-bus test systems and the results are shown. Accordingly, the results have been evaluated and observed that the stability critical values found by CABC can be used to produce good potential solutions. Simulation results are promising and show the effectiveness of the applied approach

Usefulness of the uric acid and CHA2DS2-VASc score in prediction of left atrial thrombosis in patients with mitral stenosis and sinus rhythm

Background: The risk of thrombus formation in the left atrium is known to be very high in patients with both mitral stenosis (MS) and atrial fibrillation (AF). However, that risk should not be ignored in patients with MS in sinus rhythm (SR). The aim of this study was to determine the clinical, echocardiographic, and biochemical factors that could have a determining role in the formation of a left atrial (LA) thrombus in patients with MS in SR. Method: A total of 207 consecutive patients with MS who underwent both transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) for diagnosis or to investigate the presence of a thrombus in the LA and appendage were enrolled in this study. Results: LA thrombus was detected in 21 of 207 patients. CHA2DS2-VASc score was not found to be a predictor of LA thrombosis in patients with MS in SR, despite the higher CHA2DS2-VASc scores observed in those patients. The mitral valve area and mitral valve gradient were not predictive of LA thrombus development; however, LA anteroposterior diameter (LAAPD) was found to be a predictor of LA thrombosis. Levels of high sensitivity-C-reactive protein and uric acid were higher in the patients with LA thrombosis, but only uric acid was found to be a predictor of LA thrombosis in multivariate analysis. Conclusions: A larger LAAPD and an elevated serum uric acid level were found to be independent predictors of LA thrombosis in patients with MS in SR.

Assessment of the relationship between a narrow fragmented QRS complex and coronary slow flow

Background: The coronary slow flow (CSF) phenomenon is a delayed antegrade progression of contrast agent to the distal branch of a coronary artery in the absence of obstructive coronary artery disease (CAD). A narrow fragmented QRS (fQRS) has been reported as a significant predictor of sudden cardiac death in patients with idiopathic dilated cardiomyopathy. The present study aimed to investigate the relationship between a narrow fQRS on the admission electrocardiogram (ECG) and CSF on coronary angiography. Methods: This study included 165 consecutive patients (112 CSF, 53 controls) who underwent first-time diagnostic conventional coronary angiography for suspected CAD. Coronary flow was quantified by thrombolysis in myocardial infarction (TIMI) frame count (TFC). The patients were divided into two groups according to the presence or absence of a narrow fQRS complex on the admission ECG. Results: Forty four patients were in the fQRS group (mean age, 52.97 ± 3.13 years). There was no difference between the two groups with respect to age, gender, body mass index, family history, hyperlipidemia, hypertension, or diabetes mellitus. The extent of CSF was significantly greater in the fQRS group compared to the non-fragmented group (p < 0.001). A significant correlation was also found between mean TFC values and fQRS (p < 0.001). On multivariate analysis, only CSF (p = 0.03) was a significant independent predictor for narrow fQRS, after adjustment for other parameters. Conclusions: The narrow fQRS is a simple, inexpensive, and readily available noninvasive ECG parameter that may be a new potential indicator of myocardial damage in patients with CSF.

Evaluation of left ventricular systolic asynchrony in patients with subclinical hypothyroidism

Background: The heart was very sensitive to fluctuating thyroid hormone levels. To assess intra-left ventricular (LV) systolic asynchrony in patients with subclinical thyroid dysfunction. Methods: Fifty patients with subclinical hypothyroidism and 40 controls were included. A diagnosis of subclinical hypothyroidism was reached with increased TSH and normal free T4. All subjects were evaluated by echocardiography. Evaluation of intra-LV systolic asynchrony was performed by tissue synchronization imaging (TSI), and four TSI parameters of systolic asynchrony were calculated. LV asynchrony was defined by these parameters. Results: All of the groups were similar in terms of demographic findings and conventional and Doppler echocardiograpic parameters except peak systolic velocity and early diastolic velocity. LV systolic asynchrony parameters of TSI including; standard deviation of Ts of the 12 LV segments (Ts-SD-12), maximal difference in Ts between any 2 of the 12 LV segments (Ts-12), standard deviation of TS of the 6 basal LV segments (Ts-SD-6), maximal difference in Ts between any of the 6 basal LV segments (Ts-6) were significantly lengthened in patients with subclinical hypothyroidism than controls (p < 0.001, p < 0.001, p < 0.001 and p < 0.001, respectively). The prevalence of LV asynchrony was significantly higher in patients with subclinical hypothyroidism than control. Conclusions: Patients with subclinical hypothyroidism present evidence of LV asynchrony by TSI. LV systolic asynchrony could be a warning sign of the early stage in cardiac systolic dysfunction in subclinical hypothyroid patients