90 research outputs found

    Active control of spray combustion

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    Effect of a forced dilution air jet on air-fuel spray mixing and emissions has been investigated. Temperature measurements have been made at a number of forcing frequencies in the range of 100-1100 Hz and blowing ratios between 6-15. Open-loop flame response to forcing has also been acquired by recording pressure and heat release spectra. The results show that the mean temperature field inside the flame can be altered due to jet modulation. Significant effects are observed by forcing at locations close to the dump plane. Enhancements in temperature of the order of 100–200 ˚C, and reduction in pattern factor of the order of 40% were observed. Substantial reductions in nitric oxide emissions can be obtained over a range of flow conditions. More rigorous burning can be obtained due to enhanced fuel air mixing. A multi-resolution technique is utilized to analyze temperature fields to decompose the response of different hierarchical scales to forcing. Forcing is found to have most impact on large-scale structures that are in the order of characteristic jet length scale. Bulk mixing is not the only factor that determines pollutant emissions level. Consequently, there exist select frequencies, which affect both emissions and mixing positively. An artificial intelligence based extremum-seeking algorithm is introduced to optimize the combustor behavior. The second part of this dissertation deals with syngas combustion. Stability of a pre-mixed gas turbine combustor is quite sensitive to fuel composition. Behavior of a premixed confined hydrogen enriched methane flame is studied with regard to thermo-acoustic instability induced flashback, emissions, flammability limits and acoustics over a range of conditions. Hydrogen addition extends the flammability limits and enables lower emissions levels to be achieved. Contrarily, increased RMS pressure fluctuation levels, and higher susceptibility to flashback is observed with increasing hydrogen volume fraction inside the fuel mixture. In addition, a semi-analytical model has been utilized to capture the flame holding and flashback dynamics utilizing G-equation. A limit cycle behavior in the flame front movement is observed due to a non-linearity in the feedback term. Experiments including phase locked radical imaging and PLIF measurements have been performed at varying fuel composition

    Transition Modeling for Low to High Speed Boundary Layer Flows with CFD Applications

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    Transition modeling as applied to CFD methods has followed certain line of evolution starting from simple linear stability methods to almost or fully predictive methods such as LES and DNS. One pragmatic approach among these methods, such as the local correlation-based transition modeling approach, is gaining more popularity due to its straightforward incorporation into RANS solvers. Such models are based on blending the laminar and turbulent regions of the flow field by introducing intermittency equations into the turbulence equations. Menter et al. pioneered this approach by their two-equation γ-Reθ intermittency equation model that was incorporated into the k-ω SST turbulence model that results in a total of four equations. Later, a range of various three-equation models was developed for super-/hypersonic flow applications. However, striking the idea that the Reθ-equation was rather redundant, Menter produced a novel one-equation intermittency transport γ-equation model. In this report, yet another recently introduced transition model called as the Bas-Cakmakcioglu (B-C) algebraic model is elaborated. In this model, an algebraic γ-function, rather than the intermittency transport γ-equation, is incorporated into the one-equation Spalart-Allmaras turbulence model. Using the present B-C model, a number of two-dimensional test cases and three-dimensional test cases were simulated with quite successful results

    Selçuk Üniversitesi Tıp Fakültesi Hastanesinde Çalışan Araştırma Görevlisi, Hemşire Ve Temizlik Personellerinin Hastane İnfeksiyonları Konusundaki Bilgi Düzeylerinin Ölçülmesi

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    Amaç: Hastane infeksiyonları konusunda hastane çalışanlarının bilgi düzeyini ölçmek için hazırladığımız anketi uygulayarak alınacak önlemlere katkı sağlanması amaçlanmıştır. Gereç ve Yöntem: Çalışmada hastanemizde görev yapan doktor araştırma görevlisi , hemşire ve temizlik personelinden oluşan gruba 22 sorudan oluşan anket uygulandı. Bulgular: Her bir gruptan 100 kişi olmak üzere ankete yanıt vermeyi kabul eden toplam 300 kişi çalışmaya dahil edilmiştir. Hastane infeksiyonları konusunda eğitim alan kişi sayısı temizlik personeli grubunda daha fazla olmasına rağmen tanımlama ve bilgiye dayalı sorularda daha çok yanlış yaptıkları saptanmıştır. Temizlik personellerinin eğitim düzeyinin düşük olması sorulara verilen yanıtı etkilediği gözlenmiştir. Tüm sorulara verilen doğru yanıtların incelenmesi sonucunda, ortalama bilgi düzeylerinin mesleklere göre dağılım puanları incelendiğinde hemşirelerin %73.1, doktorların %59.2 ve temizlik personellerinin ise %52.3 puan aldıkları görülmüştür. Üç grubun bilgi puan ortalaması %61.5 olarak bulunmuşturSonuç: Hastane infeksiyonları konusunda, hizmet içi eğitimin bilgi düzeyini artırdığı görülmüştür. Böylece hastane infeksiyonlarının yayılımının önüne geçmek için hastanede görev yapanlara, periyodik olarak yetersiz oldukları konularla ilgili eğitim verilmesinin önemi ortaya çıkmıştır. Bu konuda hastane yöneticileri ile infeksiyon kontrol komiteleri gerekli önlemleri alarak ve iç denetim yaparak uygulamadan kaynaklanan hataların önüne geçilmesi sağlanmış olacaktı

    Effects of Tooth Brushing and MouthWashing on Leaching Bisphenol A Levels From an Orthodontic Adhesive: An In Vitro Study

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    Objective: To assess the levels of bisphenol A (BPA) released from an orthodontic adhesive with respect to the effects of tooth brushing and mouth washing.Methods: Three groups, each containing fifteen adhesive samples were prepared. In Group 1, samples were polymerized according to manufacturer instructions. In Group 2, after the same polymerization protocol, each sample was brushed with a fluoride-containing toothpaste. For Group 3, samples were immersed in a mouth washing solution after polymerization. Later, all samples were placed into glass tubes containing 5 mL distilled water. High-performance liquid chromatography (HPLC) measurements were performed to assess the leaching amount of BPA. Intergroup comparison was performed by one way ANOVA test.Results: Mean amounts of BPA were found to be 0.2674 μg/L, 0.2692 μg/L, and 0.2705 μg/L, respectively. Only a significant difference was found between Group 1 and 3 (P < .01), revealing higher BPA levels with the mouth washing solution.Conclusion: Measurable amounts of BPA release were observed in all groups of orthodontic adhesive samples, but the detected amounts were below the toxic levels. From a clinical point of view, alcohol-containing mouth washing solutions might increase the amount of leaching monomer, since alcohol is solvent of BPA

    Disc Rehydration after Dynamic Stabilization: A Report of 59 Cases

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    Study DesignA retrospective study investigating decrease in the nucleus pulposus signal intensity or disc height on magnetic resonance imaging (MRI) and disc degeneration.PurposeAlthough a degenerated disc cannot self-regenerate, distraction or stabilization may provide suitable conditions for rehydration and possible regeneration. This study aimed to evaluate clinical outcomes and disc regeneration via MRI in a series of patients with degenerative disc disease (DDD) who underwent lumbar stabilization with a dynamic stabilization system (DSS).Overview of LiteratureA dynamic system provides rehydration during early DDD.MethodsFifty-nine patients (mean age, 46.5 years) who undedwent stabilization with DSS for segmental instability (painful black disc) between 2004 and 2014 were retrospectively evaluated. All patients underwent MRI preoperatively and 12 months postoperatively. Intervertebral disc (IVD) degeneration grades at the implanted segment were categorized using the Pfirrmann classification system. Patients were followed for a mean of 6.4 years, and clinical outcomes were based on visual analog scale (VAS) and Oswestry disability index (ODI) scores.ResultsSignificant improvements in back pain VAS and ODI scores from before surgery (7 and 68%, respectively) were reported at 6 (2.85 and 27.4%, respectively) and 12 months postoperatively (1.8 and 16.3%, respectively). Postoperative IVD changes were observed in 28 patients. Improvement was observed in 20 patients (34%), whereas progressive degeneration was observed in eight patients (13.5%). Thirty-one patients (52.5%) exhibited neither improvement nor progression. Single Pfirrmann grade improvements were observed in 29% of the patients and two-grade improvements were observed in 5%.ConclusionsOur observations support the theory that physiological movement and a balanced load distribution are necessary for disc regeneration. We conclude that DSS may decelerate the degeneration process and appears to facilitate regeneration

    Novel Foraminal Expansion Technique

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    The technique we describe was developed for cervical foraminal stenosis for cases in which a keyhole foraminotomy would not be effective. Many cervical stenosis cases are so severe that keyhole foraminotomy is not successful. However, the technique outlined in this study provides adequate enlargement of an entire cervical foraminal diameter. This study reports on a novel foraminal expansion technique. Linear drilling was performed in the middle of the facet joint. A small bone graft was placed between the divided lateral masses after distraction. A lateral mass stabilization was performed with screws and rods following the expansion procedure. A cervical foramen was linearly drilled medially to laterally, then expanded with small bone grafts, and a lateral mass instrumentation was added with surgery. The patient was well after the surgery. The novel foraminal expansion is an effective surgical method for severe foraminal stenosis

    New Mediterranean biodiversity records (March 2016)

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    In this Collective Article on “New Mediterranean Biodiversity Records”, we present additional records of species found in the Mediterranean Sea. These records refer to eight different countries mainly throughout the northern part of the basin, and include 28 species, belonging to five Phyla. The findings per country include the following species: Spain: Callinectes sapidus and Chelidonura fulvipunctata; Monaco: Aplysia dactylomela; Italy: Charybdis (Charybdis) feriata, Carcharodon carcharias, Seriola fasciata, and Siganus rivulatus; Malta: Pomacanthus asfur; Croatia: Lagocephalus sceleratus and Pomadasys incisus; Montenegro: Lagocephalus sceleratus; Greece: Amathia (Zoobotryon) verticillata, Atys macandrewii, Cerithium scabridum, Chama pacifica, Dendostrea cf. folium, Ergalatax junionae, Septifer cumingii, Syphonota geographica, Syrnola fasciata, Oxyu- richthys petersi, Scarus ghobban, Scorpaena maderensis, Solea aegyptiaca and Upeneus pori; Turkey: Lobotes surinamensis, Ruvettus pretiosus and Ophiocten abyssicolum. In the current article, the presence of Taractes rubescens (Jordan & Evermann, 1887) is recorded for the first time in the Mediterranean from Italy. The great contribution of citizen scientists in monitoring biodiversity records is reflected herein, as 10% of the authors are citizen scientists, and contributed 37.5% of the new findings.peer-reviewe

    Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

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    Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure &lt; 100 mmHg (n = 1127), estimated glomerular filtration rate &lt; 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation
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