Active front-end rectifier modelling using dynamic phasors for more-electric aircraft applications

The More-Electric Aircraft (MEA) has become a dominant trend for next-generation aircraft. The Electrical Power System (EPS) on-board may take many forms: AC, DC, hybrid, frequency-wild, variable voltage, together with the possibility of novel connectivity topologies. To address the stability, availability and capability issues as well as to assess the performance of the power quality and transient behaviour, extensive simulation work is required to develop the EPS architectures. The paper develops a fast-simulation model of active front-end rectifiers based on the dynamic phasor concept. The model is suitable for accelerated simulation studies of EPS under normal, unbalanced and line fault conditions. The performance and effectiveness of the developed model have been demonstrated by comparison against time-domain models in three-phase and synchronous space-vector representations. The experimental verification of the dynamic phasor model is also reported. The prime purpose of the model is for the simulation studies of MEA power architectures at system level; however it can be directly applied for simulation study of any other EPS interfacing with active front-end rectifiers

Türkiye’de bulunan yoğun bakımlarda sabun, kağıt havlu ve alkol bazlı el dezenfektanı yeterli mi?: Phokai çalışması sonuçları

Introduction: Hand hygiene is one of the most effective infection control measures to prevent the spread of healthcare-associated infections (HCAI). Water, soap, paper towel and hand disinfectant must be available and adequate in terms of effective hand hygiene. The adequacy of hand hygiene products or keeping water-soap and paper towel is still a problem for many developing countries like Turkey. In this multicenter study, we analyzed the adequacy in number and availability of hand hygiene products.Materials and Methods: This study was performed in all intensive care units (ICUs) of 41 hospitals (27 tertiary-care educational, 10 state and four private hospitals) from 22 cities located in seven geographical regions of Turkey. We analyzed water, soap, paper towel and alcohol-based hand disinfectant adequacy on four different days, two of which were in summer during the vacation time (August, 27th and 31st 2016) and two in autumn (October, 12th and 15th 2016).Results: The total number of ICUs and intensive care beds in 41 participating centers were 214 and 2357, respectively. Overall, there was no soap in 3-11% of sinks and no paper towel in 10-18% of sinks while there was no alcohol-based hand disinfectant in 1-4.7% of hand disinfectant units on the observation days. When we compared the number of sinks with soap and/or paper towel on weekdays vs. weekends, there was no significant difference in summer. However, on autumn weekdays, the number of sinks with soap and paper towel was significantly lower on weekend days (p<0.0001, p<0.0001) while the number of hand disinfectant units with alcohol-based disinfectant was significantly higher (p<0.0001).Conclusion: There should be adequate and accessible hand hygiene materials for effective hand hygiene. In this study, we found that soap and paper towels were inadequate on the observation days in 3-11% and 10-18% of units, respectively. Attention should be paid on soap and paper towel supply at weekends as well

A rheological network model for the continuum anisotropic and viscoelastic behavior of soft tissue

The mechanical behavior of soft tissue demonstrates a number of complex features including nonlinearity, anisotropy, viscoelasticity, and growth. Characteristic features of the time-dependent and anisotropic behavior are related to the properties of various components of the tissue such as fibrous collagen and elastin networks, large proteins and sugars attached to these networks, and interstitial fluid. Attempts to model the elastic behavior of these tissues based on assumptions about the behavior of the underlying constituents have been reasonably successful, but the essential addition of viscoelasticity to these models has been met with varying success. Here, a new rheological network model is proposed using, as its basis, an orthotropic hyperelastic constitutive model for fibrous tissue and a viscoelastic reptation model for soft materials. The resulting model has been incorporated into numerical and computational models, and is shown to capture the mechanical behavior of soft tissue in various modes of deformation including uniaxial and biaxial tension and simple shear.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47943/1/10237_2004_Article_49.pd

Cost-effectiveness of six strategies for Helicobacter pylori diagnosis and management in uninvestigated dyspepsia assuming a high resource intensity practice pattern

<p>Abstract</p> <p>Background</p> <p>Initial assessment of dyspepsia often includes noninvasive testing for <it>Helicobacter pylori </it>infection. Commercially available tests vary widely in cost and accuracy. Although there is extensive literature on the cost-effectiveness of <it>H. pylori </it>treatment, there is little information comparing the cost-effectiveness of various currently used, noninvasive testing strategies.</p> <p>Methods</p> <p>A Markov simulation was used to calculate cost per symptom-free year and cost per correct diagnosis. Uncertainty in outcomes was estimated using probabilistic sensitivity analysis.</p> <p>Results</p> <p>Under the baseline assumptions, cost per symptom-free year was $122 for empiric proton pump inhibitor (PPI) trial, and costs for the noninvasive test strategies ranged from$123 (stool antigen) to $129 (IgG/IgA combined serology). Confidence intervals had significant overlap.</p> <p>Conclusions</p> <p>Under our assumptions for how testing for <it>H. pylori </it>infection is employed in United States medical practice, the available noninvasive tests all have similar cost-effectiveness between one another as well as with empiric PPI trial.</p

COLOR DEGRADATION KINETICS OF CARROT (DAUCUS CAROTA L.) SLICES DURING

The effect of temperature on color change kinetics of carrot slices was investigated during hot air drying. The color parameters for the color change of the foods were quantified by Hunter L (whiteness/darkness), a (redness/greenness) and b (yellowness/blueness) values. These values were also used for calculation of the total color change (Delta E). The color values (L, a and b) decreased, while Delta E increased during drying. Zero-and first-order kinetic models were applied to describe color change. Mathematical modeling color change kinetics indicated that both models were found to describe the L, a and b values adequately. However, Delta E followed zero-order kinetics

convective hot air dryer

The effects of drying temperatures on the drying kinetics of garlic slices were investigated using a cabinet-type dryer. The experimental drying data were fitted best to the Page and Modified Page models apart from other theoretical models to predict the drying kinetics. The effective moisture diffusivities varied from 4.214 x 10(-10) to 2.221 x 10(-10) m(2) s(-1) over the temperature range studied, and activation energy was 30.582 kJ mol(-1)

Characteristics of Persimmons

In this study, the effect of different pretreatments and three drying temperature (55, 65 and 75 degrees C) on the hot air drying characteristics and color of persimmon were investigated. As pretreatments, persimmons were immersed in 20% sucrose solution or dipped in water at 80 degrees C for 15 minutes. As a result, it was determined that dipped in water at 80 degrees C pretreatment was better than immersed in 20% sucrose solution pretreatment on the color characteristics of persimmons. However pretreatments, which immersed in 20% sucrose solution, decreased the drying time. A significant reduction of the increase in drying times ambient temperature, but the high temperatures caused by deterioration of the color characteristics were determined. Changes in the characteristics of each color in a drying process takes place in accordance with the first-order kinetic model were determined

A Study on Thermo-Mechanical Behavior of AA5754 Alloy (Tread and Plain Sheet) Produced by Twin-Roll Casting

Aluminum alloy AA5754 is used for many technical and industrial applications. Twin roll casting is unique among the casting processes in that it is a combined "solidification/deformation" technique. The simultaneous solidification and hot rolling produces characteristic microstructure with a fine cell size and intermetallic particle distribution with some residual structure. In the study, first AA5754 alloy (tread and plain sheet) strips were fabricated by using a twin-roll caster equipped with water-cooled steel-rolls. To reduce the thickness of the strip, cold rolling process was applied until strip thickness got 3 mm. After homogenization step the strips were cut in to smaller specimens and annealed at 260°C, 285°C, 310°C, 340°C, 370°C, 400°C, 430°C, 460°C, 490°C, 520°C for 3 hours to obtain the desired temper conditions. Mechanical properties were investigated after processes. Tensile, hardness and bending tests were applied to monitor the effect of annealing after cold rolling process

drying

Allicin is an organosulfur compound formed in garlics, and it is slightly yellow in colour and gives unique odour to garlic. Allicin has been known to have an antioxidant and antimicrobial activity, and it can react with thiol groups containing proteins. Allicin potential (AP) in Taskopru garlic slices and its loss were monitored during drying in a cabinet drier at three temperatures (50, 60 and 70 degrees C). Initial AP of fresh garlic samples was 10.91 +/- 0.15 mg/g on the basis of dry matter (dm), and it reduced significantly during drying (P<0.05). APs of garlic samples dried at 50, 60 and 70 degrees C for up to 480 minutes were 5.35 +/- 0.029, 4.32 +/- 0.13 and 3.95 +/- 0.26 mg/g dm, respectively (P<0.05). Loss of AP values determined during drying followed a second-order reaction. Drying temperature had a significant influence on the loss of AP in garlic slices. Activation energy for AP loss was 25.48 kJ/mol. Q(10) value was 4.18 for the drying temperature increase from 50 to 60 degrees C, and it reduced to 3.07 for the temperature increase from 60 to 70 degrees C. Therefore, the effect of the first temperature rise on AP loss was bigger than the second temperature rise.C1 [Doganturk, M.] Burdur Mehmet Akif Ersoy Univ, Grad Sch Nat & Appl Sci, Div Food Engn, Istiklal Campus, TR-15030 Burdur, Turkey.[Demiray, E.] Pamukkale Univ, Dept Food Engn, Fac Engn, TR-20070 Denizli, Turkey.[Gursoy, O.; Yilmaz, Y.] Burdur Mehmet Akif Ersoy Univ, Dept Food Engn, Fac Engn & Architecture, Istiklal Campus, TR-15030 Burdur, Turkey