Assessment of a common nonlinear eddy-viscosity turbulence model in capturing laminarization in mixed convection flows

Laminarization is an important topic in heat transfer and turbulence modeling. Recent studies have demonstrated that several well-known turbulence models failed to provide accurate prediction when applied to mixed convection flows with significant re-laminarization effects. One of those models, a well-validated cubic nonlinear eddy-viscosity model, was observed to miss this feature entirely. This paper studies the reasons behind this failure by providing a detailed comparison with the baseline Launder–Sharma model. The difference is attributed to the method of near-wall damping. A range of tests have been conducted and two noteworthy findings are reported for the case of flow re-laminarization

Parallel implementations for solving matrix factorization problems with optimization

During recent years, the exponential increase in data sets' sizes and the need for fast and accurate tools which can operate on these huge data sets in applications such as recommendation systems has led to an ever growing attention towards devising novel methods which can incorporate all the available resources to execute desired operations in the least possible time. In this work, we provide a framework for parallelized large-scale matrix factoriza- tion problems. One of the most successful and used methods to solve these problems is solving them via optimization techniques. Optimization methods require gradient vectors to update the iterates. The time spent to solve such a problem is mostly spent on calls to gradient and function value evaluations. In this work, we have used a recent method, which has not been used before for matrix factorization. When it comes to parallelization, we present both CPU and GPU implementations. As our experiments show, the proposed parallelization scales quite well. We report our results on Movie- Lens data set. Our results show that the new method is quite successful in reducing the number of iterations. We obtain very good RMSE values with signi cant promising scaling gures

Using HPM for approximating the instability of narrow bio-sensor used in bio-electronic, biology and cancer detection

Recently biosensors become one of the most components in evaluating live systems and medical applications. These applications are detection of cancers, DNA, tumors, cells, bio-enzymes etc. In this paper, we investigate the instability of narrow bio nano electro mechanical system (bio-NEMS) sensor. The proposed HPM is employed to solve nonlinear constitutive equation of cantilever beam-type bio-sensor. An analytical solution is obtained in terms of convergent series with easily computable components. The basic design parameters such as critical cantilever tip deflection of the bio-sensor are comp uted. The analytical results agree well with numerical solutions and those from the literature. © IDOSI Publications, 2012

The prevalence and predicting factors of pulmonary thromboembolism in patients with exacerbated chronic obstructive pulmonary disease

Introduction: The risk of pulmonary thromboembolism (PTE) in patients with exacerbated chronic obstructive pulmonary disease(e-COPD) is higher than in non-COPD states. The study aimed to evaluate the prevalence and the parameters that are critical forfinding the incidence of PTE in patients with e-COPD. Material and methods: This cross-sectional study was performed on 68 consecutive patients with the e-COPD, referred to thePulmonary Disease Department at the Shariati Hospital in Tehran between 2013 and 2014. In addition to collecting data on thehistory of disease and physical examination, arterial blood sampling, spirometry, electrocardiography and echocardiography wereperformed for all patients. All subjects underwent computed tomography pulmonary angiography (CT-PA) as a method of choicefor diagnosing PTE. Results: Out of 68 cases, five (7.4%) had CT angiography findings suggesting PTE. These patients were all male and had a highermean age (79 vs. 65 years), lower mean systolic blood pressure (88.36 vs. 118.33 mmHg), and a higher mean heart rate (133.12vs 90.33 beats/min), compared to e-COPD patients without PTE. Arterial blood gas analysis in individuals with PTE demonstrateda lower HCO3 (2.33 vs. 9.44 mEq/l) and PCO2 (44.35 vs. 51.43 mm Hg) levels. The mean left ventricular ejection fraction (LVEF)was lower in patients with PTE (34.14 ± 4.49% vs. 46.94 ± 8.27%). Conclusion: The prevalence of PTE in our series of patients with e-COPD was 7.4%. According to the study results, male gender,advanced age, hypotension, tachycardia, and respiratory alkalosis are factors indicating possible PTE among subjects with e-COPD

Assessment of a common nonlinear eddy-viscosity turbulence model in capturing laminarization in mixed convection flows

Laminarization is an important topic in heat transfer and turbulence modelling. Recent studies have demonstrated that several well-known turbulence models, failed to provide accurate prediction when applied to mixed convection flows with significant re-laminarization effects. One of those models, a well-validated cubic non-linear eddy-viscosity model, was observed to miss entirely this feature. This paper studies the reasons behind this failure by providing a detailed comparison with the baseline Launder-Sharma model. The difference is attributed to the method of near-wall damping. A range of tests have been conducted and two noteworthy findings are reported for the case of flow re-laminarization

Parallelized preconditioned model building algorithm for matrix factorization

Matrix factorization is a common task underlying several machine learning applications such as recommender systems, topic modeling, or compressed sensing. Given a large and possibly sparse matrix A, we seek two smaller matrices W and H such that their product is as close to A as possible. The objective is minimizing the sum of square errors in the approximation. Typically such problems involve hundreds of thousands of unknowns, so an optimizer must be exceptionally efficient. In this study, a new algorithm, Preconditioned Model Building is adapted to factorize matrices composed of movie ratings in the MovieLens data sets with 1, 10, and 20 million entries. We present experiments that compare the sequential MATLAB implementation of the PMB algorithm with other algorithms in the minFunc package. We also employ a lock-free sparse matrix factorization algorithm and provide a scalable shared-memory parallel implementation. We show that (a) the optimization performance of the PMB algorithm is comparable to the best algorithms in common use, and (b) the computational performance can be significantly increased with parallelizatio

The Association between Myocardial Perfusion Scan and Electrocardiographic Findings among Patients with Myocardial Ischemia

Introduction: The aim of this study was to determine the consistency of Electrocardiography (ECG) and myocardial perfusion scan findings of patients with myocardial ischemia at Firoozgar and Hazrat-Rasool hospitals.Methods: Electrocardiogram of 80 patients undergoing myocardial perfusion scans was analyzed. All patients had a stable angina. All patients with bundle branch blocks and history of MI and coronary bypass or angiography were excluded. Overall, 120 patients were evaluated with single photon emission tomography/myocardial perfusion imaging for ischemia and 80 patients had a positive test.Results: Forty-five percent of patients were female and 55% were male. The average age of patients was 61.48 years. Sixty-one patients (76.25%) had normal ECG and 19 patients (23.75) had pathological changes in their ECG. Eleven patients had ST segment depression and 6 patients had T wave inversion. Furthermore, 21 patients (26.25%) had lateral wall ischemia in their myocardial perfusion scan and 13 (16.25%) patients had septal wall ischemia. The ECG changes in male patients and hypertensive cases were more prominent.Conclusions: This study showed that ST-T changes (ST depression and T inversion) in the ECG are more suggestive of accuracy of myocardial ischemia and ECG

Phantom Tumor of the Lung

Background: Localized interlobar effusions in congestive heart failure (phantom or vanishing lung tumor/s) are uncommon but well-known entities.Case Report: The patient is a 60-year-old male with a history of dyspnea and surgical removal of kidney stonein 1 year ago.Results: In chest-X-ray prior to the surgery an olive-shaped homogenous density, with a size of 30 mm × 20 mm in the right lung have been detected. Computed tomography (CT) scan has been performed, and a homogenous mass with a well-delineated border in major fissure of the right lung and mediastinal lymphadenopathy had been detected. Serial CT scans revealed mass enlargement. In Ct guided, Transthoracic biopsy fluid collection along the major fissure of the right lung had been detected. Biopsy of mediastinal lymph node silicoanthracotic changes with focal hyaline fibrosis had been shown.Conclusions: The diagnosis of the phantom tumor must be considered in any patient with congestive heart failure and lung mass. In this patient, there was no history of congestive heart failure which shows that phantom tumor could happen in non-chronic heart failure patients. Although the accurate diagnosis of the phantom tumor with imaging modalities in patients without congestive heart failure is very difficult but at least this diagnosis must be considered in a patient with a lung mass in the major fissure of the lungs

Występowanie i czynniki predykcyjne zatorowości płucnej u chorych na przewlekłą obturacyjną chorobę płuc w okresie zaostrzenia

WSTĘP: Ryzyko zatorowości płucnej (ZP) u chorych na przewlekłą obturacyjną chorobę płuc (POChP) w okresie zaostrzenia jest wyższe niż u osób niechorujących na POChP. Celem badania była ocena częstości występowania zatorowości oraz parametrów krytycznych związanych z ryzykiem ZP u chorych na POChP w okresie zaostrzenia. MATERIAŁ I METODY: Przeprowadzono badanie przekrojowe u 68 kolejnych chorych na zaostrzenie POChP, kierowanych na Oddział Chorób Płuc Szpitala Shariati w Teheranie w latach 2013–2014. U wszystkich chorych zebrano dane z wywiadu dotyczące przebiegu choroby oraz przeprowadzono badanie przedmiotowe, wykonano gazometrię krwi tętniczej, spirometrię, elektrokardiografię oraz echokardiografię. U wszystkich chorych przeprowadzono angiografię tomografii komputerowej jako metodę z wyboru w diagnostyce ZP. WYNIKI: Zmiany wskazujące na ZP w badaniu angio-TK stwierdzono u pięciu chorych (7,4%). Byli to wyłącznie mężczyźni, o wyższej średniej wieku (79 v. 65 lat), niższym średnim ciśnieniu skurczowym (88,36 v. 118,33 mm Hg), oraz wyższej średniej częstości pracy serca (133,12 v. 90,33 uderzeń/min), w porównaniu z chorymi na zaostrzenie POChP bez cech zatorowości płucnej. U chorych z zatorowością płucną wykazano niższe stężenia HCO3 (2,33 v. 9,44 mEq/l) i PCO2 (44.35 v. 51.43 mm Hg). Średnia wartość frakcji wyrzutowej lewej komory (LVEF, left ventricular ejection fraction) była niższa u chorych z cechami ZP (34,14 ± 4,49% v. 46,94 ± 8,27%). WNIOSKI: W badanej grupie chorych na zaostrzenie POChP zator płucny rozpoznano u 7,4% badanych. Uzyskane wyniki wskazują, że płeć męska, starszy wiek, niskie ciśnienie tętnicze, tachykardia, zasadowica oddechowa są czynnikami związanymi z ryzykiem zatorowości płucnej u chorych na POChP z cechami zaostrzenia.WSTĘP: Ryzyko zatorowości płucnej (ZP) u chorych na przewlekłą obturacyjną chorobę płuc (POChP) w okresie zaostrzenia jest wyższe niż u osób niechorujących na POChP. Celem badania była ocena częstości występowania zatorowości oraz parametrów krytycznych związanych z ryzykiem ZP u chorych na POChP w okresie zaostrzenia. MATERIAŁ I METODY: Przeprowadzono badanie przekrojowe u 68 kolejnych chorych na zaostrzenie POChP, kierowanych na Oddział Chorób Płuc Szpitala Shariati w Teheranie w latach 2013–2014. U wszystkich chorych zebrano dane z wywiadu dotyczące przebiegu choroby oraz przeprowadzono badanie przedmiotowe, wykonano gazometrię krwi tętniczej, spirometrię, elektrokardiografię oraz echokardiografię. U wszystkich chorych przeprowadzono angiografię tomografii komputerowej jako metodę z wyboru w diagnostyce ZP. WYNIKI: Zmiany wskazujące na ZP w badaniu angio-TK stwierdzono u pięciu chorych (7,4%). Byli to wyłącznie mężczyźni, o wyższej średniej wieku (79 v. 65 lat), niższym średnim ciśnieniu skurczowym (88,36 v. 118,33 mm Hg), oraz wyższej średniej częstości pracy serca (133,12 v. 90,33 uderzeń/min), w porównaniu z chorymi na zaostrzenie POChP bez cech zatorowości płucnej. U chorych z zatorowością płucną wykazano niższe stężenia HCO3 (2,33 v. 9,44 mEq/l) i PCO2 (44.35 v. 51.43 mm Hg). Średnia wartość frakcji wyrzutowej lewej komory (LVEF, left ventricular ejection fraction) była niższa u chorych z cechami ZP (34,14 ± 4,49% v. 46,94 ± 8,27%). WNIOSKI: W badanej grupie chorych na zaostrzenie POChP zator płucny rozpoznano u 7,4% badanych. Uzyskane wyniki wskazują, że płeć męska, starszy wiek, niskie ciśnienie tętnicze, tachykardia, zasadowica oddechowa są czynnikami związanymi z ryzykiem zatorowości płucnej u chorych na POChP z cechami zaostrzenia

Advanced oxidation of formaldehyde in the aqueous solutions using UVC/S2O82- process: Degradation and mineralization

Background: As a human carcinogen, formaldehyde is a toxic chemical imposing adverse effects on public health and environment. Due to its high reactivity, colorless nature, sustainability, purity in commercial forms, and low prices, the production and consumption of this compound has expanded vastly in industries. Methods: In this study, a UVC photoreactor with a total volume of 120 mL was used and operated in a rotary mode. To determine the residual concentration, high-performance liquid chromatography (HPLC) device was applied whose detector was set at a wavelength of 355 nm and equipped with C18 column (with dimensions of 25 × 4.6 mm i.d, and particle size of 5 μm). Total organic carbon (TOC) was determined using a TOC analyzer. Results: The optimal condition in this study was obtained at pH=3 and formaldehyde concentration of 350 mg, so that the removal of formaldehyde and TOC was 98.2% and 95.1%, respectively, after 35 minutes reaction time. The formaldehyde removal efficiency was assessed in the presence of methanol (MeOH), tert-butyl alcohol (TBA), and salicylic acid (SA) scavengers, and it was indicated that SO4 •- radicals were the most effective factors in formaldehyde destruction. By increasing the concentrations of MeOH, TBA, and SA to 2.5 g/L, the degradation efficiency of formaldehyde dropped from 98.02% to 69.78%, 64.68%, and 45.14%, respectively, at 35 minutes reaction time. The removal of formaldehyde in the presence of nitrate was significantly reduced and it had a significant effect on the removal of formaldehyde. Conclusion: In this study, the removal of formaldehyde was investigated in the presence of various anions including bicarbonate, carbonate, chloride, sulfate, and nitrate. According to the results, the UVC/S2O8 2- process is a convenient and cost-effective method for the removal of formaldehyde. Keywords: Formaldehyde, Advanced oxidation, Bicarbonates, Carbonates, Sulfates, Nitrate