Numerical simulation of tangential flow flameless combustion process

Rapid industrialization and changes in life style cause a teremendous increase in energy consumption. Fossil fuels are the most common energy source in the world. Increasing of fuel consumption cuased more pollutant formation and resources depletion. In this project flameless combustion has been investigated as a reliable solution to this problem. Many studies has been carried out on different setup of flameless burners. In this thesis a new setup has been studied that is tangential fuel-oxidizer arrangement of inlets. This study shows that changing in the arrangement of inlets from co-axial to tangential will increase the efficiency of the lab scale combustor upto 14% and caused reduction of emissions and in particular NOx formation upto 55%. Also it has been concluded that the maximum temperature of flameless combustion in this new setting is higher by about 12%. Additionally this maximum temperature occurs near the wall of the combustor despite of co-axial flow which its highest temperature occurs at the center line. This phenomena helps improving of combustion efficiency. Because the most application of this kind of burners are in the boilers and the pipes which carry water to be heated are installed near the wall of boilers this issue can be considered as a big advantages of tangential flow flameless combustion process rather than co-axial one

Gaussian-shaped Optical Frequency Comb Generation for Microwave Photonic Filtering

Using only electro-optic modulators, we generate a 41-line 10-GHz Gaussian-shaped optical frequency comb. We use this comb to demonstrate apodized microwave photonic filters with greater than 43-dB sidelobe suppression without the need for a pulse shaper.Comment: 3 pages, 4 figure

Comparing the Coronal Flaring Efficacy of Five Different Instruments Using Cone-Beam Computed Tomography

Introduction: Fearless removal of tooth structure during canal preparation and shaping has negative effects on the prognosis of treatment. On the other hand, sufficient pre-enlargement facilitates exact measurement of the apical size. The present in vitro study aimed to compare the efficacy of Gates-Glidden drills, K3, ProTaper, FlexMaster and RaCe instruments in dentin removal during coronal flaring using cone-beam computed tomography (CBCT). Methods and Materials: A total of 40 mandibular molars were selected and the coronal areas of their mesiobuccal and mesiolingual root canals were randomly prepared with either mentioned instruments. Pre- and post-instrumentation CBCT images were taken and the thickness of canal walls was measured in 1.5- and 3-mm distances from the furcation area. Data were analyzed using the one-way ANOVA. Tukey’s post hoc tests were used for two-by-two comparisons. Results: At 1.5-mm distance, there was no significant difference between different instruments. However, at 3-mm distances, Gates-Glidden drills removed significantly more dentin compared to FlexMaster files (mean=0.18 mm) (P<0.02); however, two-by-two comparisons did not reveal any significant differences between the other groups. Conclusion: All tested instruments can be effectively used in clinical settings for coronal pre-enlargement.Keywords: Cone-Beam Computed Tomography; Coronal Flaring; Coronal Pre-Enlargement; Root Canal Treatment; Root Canal Preparatio

Materials selection for hip prosthesis by the method of weighted properties

Process of materials selection for an artificial part, which is planted in vivo, has been always a vital procedure. Production and construction requirements for implants would involve a wide variety of considerations from mechanical specifications to medical limitations. From mechanical point of view, it is desired the implant exhibits mechanical properties of the missing bone as close as possible to reduce the risk of failure and provide a high level of comfort to the patient. The most bolded medical trait that prostheses must possess is the quality of biocompatible being; meaning that, they have to be accepted by the body’s living organisms. In this paper, five common biocompatible materials as candidates for hip prostheses production namely, 316L St Steel (cold worked, ASTM F138), Co–28Cr–6Mo (cast, ASTM F75), Ti–6Al–4V (hot forged, ASTM F620), Zirconia (ceramic, 3Y-TZP) and Alumina (ceramic, ZTA) are selected and evaluated by the method of weighted properties, in order to narrow down the search to find the candidate which best fit the real bone’s mechanical traits. For the analysis, six attributes were considered and weighted against each other namely, elastic modulus, yield strength, tensile strength, fatigue strength, corrosion rate and density. From the results, alumina and stainless steel show highest performance indexes but as it is discussed, due to the importance of biocompatibility required in practical, materials ranked on position 4th and 5th which are respectively of cobalt and titanium alloys–although are less mechanically similar to the real bone, are the most desirable choices in the industry. It will be concluded that in the process of materials selection for implant

Fertility Rate and Sperm DNA Fragmentation Index following Varicocelectomy in Primary Infertile Men with Clinical Varicocele: A Prospective Longitudinal Study

Background: Varicocele is one of the most common treatable causes of male infertility, and its treatment may bebeneficial for fertility. This study aimed to evaluate fertility rate and DNA fragmentation index (DFI) following varicocelectomyin primary infertile men with clinical varicocele.Materials and Methods: This prospective longitudinal study was conducted on primary infertility men, in a tertiarycenter from December 2018 to December 2019 with one-year follow-up. Data of the semen parameters, DFI (%), andfertility rate were gathered before, as well as 4 and 12 months after undergoing varicocelectomy. For data analysis,SPSS software and analytical test were used.Results: Out of 76 patients who were analyzed, 22 (29%) became fertile and 54 (71%) remained infertile. Semenparameters and DFI (%) were improved significantly following varicocelectomy (P<0.001). Smoking history, occupationalheated exposure, body mass index (BMI), and infertility duration were determined as predictors associatedwith fertility status (P<0.05).Conclusion: Although varicocele repair improved the DFI, the fertility rate was achieved in less than one-third ofpatients; it seems that the other parameters, such as the history of smoking, occupational heated exposure, overweight,and duration of infertility should be considered as predictors of fertility status, in primary infertile men who are a candidatefor varicocelectomy

Comb-Based Radio-Frequency Photonic Filters with Rapid Tunability and High Selectivity

Photonic technologies have received considerable attention for enhancement of radio-frequency (RF) electrical systems, including high-frequency analog signal transmission, control of phased arrays, analog-to-digital conversion, and signal processing. Although the potential of radio-frequency photonics for implementation of tunable electrical filters over broad RF bandwidths has been much discussed, realization of programmable filters with highly selective filter lineshapes and rapid reconfigurability has faced significant challenges. A new approach for RF photonic filters based on frequency combs offers a potential route to simultaneous high stopband attenuation, fast tunability, and bandwidth reconfiguration. In one configuration tuning of the RF passband frequency is demonstrated with unprecedented (~40 ns) speed by controlling the optical delay between combs. In a second, fixed filter configuration, cascaded four-wave mixing simultaneously broadens and smoothes comb spectra, resulting in Gaussian RF filter lineshapes exhibiting extremely high (>60 dB) main lobe to sidelobe suppression ratio and (>70 dB) stopband attenuation.Comment: Updated the submission with the most recent version of the pape

Estimates, trends, and drivers of the global burden of type 2 diabetes attributable to PM2.5 air pollution, 1990-2019 : an analysis of data from the Global Burden of Disease Study 2019

Background Experimental and epidemiological studies indicate an association between exposure to particulate matter (PM) air pollution and increased risk of type 2 diabetes. In view of the high and increasing prevalence of diabetes, we aimed to quantify the burden of type 2 diabetes attributable to PM2.5 originating from ambient and household air pollution.Methods We systematically compiled all relevant cohort and case-control studies assessing the effect of exposure to household and ambient fine particulate matter (PM2.5) air pollution on type 2 diabetes incidence and mortality. We derived an exposure-response curve from the extracted relative risk estimates using the MR-BRT (meta-regression-Bayesian, regularised, trimmed) tool. The estimated curve was linked to ambient and household PM2.5 exposures from the Global Burden of Diseases, Injuries, and Risk Factors Study 2019, and estimates of the attributable burden (population attributable fractions and rates per 100 000 population of deaths and disability-adjusted life-years) for 204 countries from 1990 to 2019 were calculated. We also assessed the role of changes in exposure, population size, age, and type 2 diabetes incidence in the observed trend in PM2.5-attributable type 2 diabetes burden. All estimates are presented with 95% uncertainty intervals.Findings In 2019, approximately a fifth of the global burden of type 2 diabetes was attributable to PM2.5 exposure, with an estimated 3.78 (95% uncertainty interval 2.68-4.83) deaths per 100 000 population and 167 (117-223) disability-adjusted life-years (DALYs) per 100 000 population. Approximately 13.4% (9.49-17.5) of deaths and 13.6% (9.73-17.9) of DALYs due to type 2 diabetes were contributed by ambient PM2.5, and 6.50% (4.22-9.53) of deaths and 5.92% (3.81-8.64) of DALYs by household air pollution. High burdens, in terms of numbers as well as rates, were estimated in Asia, sub-Saharan Africa, and South America. Since 1990, the attributable burden has increased by 50%, driven largely by population growth and ageing. Globally, the impact of reductions in household air pollution was largely offset by increased ambient PM2.5.Interpretation Air pollution is a major risk factor for diabetes. We estimated that about a fifth of the global burden of type 2 diabetes is attributable PM2.5 pollution. Air pollution mitigation therefore might have an essential role in reducing the global disease burden resulting from type 2 diabetes. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd.Peer reviewe

Estimates, trends, and drivers of the global burden of type 2 diabetes attributable to PM2.5 air pollution, 1990-2019 : An analysis of data from the Global Burden of Disease Study 2019

Background Experimental and epidemiological studies indicate an association between exposure to particulate matter (PM) air pollution and increased risk of type 2 diabetes. In view of the high and increasing prevalence of diabetes, we aimed to quantify the burden of type 2 diabetes attributable to PM2·5 originating from ambient and household air pollution. Methods We systematically compiled all relevant cohort and case-control studies assessing the effect of exposure to household and ambient fine particulate matter (PM2·5) air pollution on type 2 diabetes incidence and mortality. We derived an exposure–response curve from the extracted relative risk estimates using the MR-BRT (meta-regression—Bayesian, regularised, trimmed) tool. The estimated curve was linked to ambient and household PM2·5 exposures from the Global Burden of Diseases, Injuries, and Risk Factors Study 2019, and estimates of the attributable burden (population attributable fractions and rates per 100 000 population of deaths and disability-adjusted life-years) for 204 countries from 1990 to 2019 were calculated. We also assessed the role of changes in exposure, population size, age, and type 2 diabetes incidence in the observed trend in PM2·5-attributable type 2 diabetes burden. All estimates are presented with 95% uncertainty intervals. Findings In 2019, approximately a fifth of the global burden of type 2 diabetes was attributable to PM2·5 exposure, with an estimated 3·78 (95% uncertainty interval 2·68–4·83) deaths per 100 000 population and 167 (117–223) disability-adjusted life-years (DALYs) per 100 000 population. Approximately 13·4% (9·49–17·5) of deaths and 13·6% (9·73–17·9) of DALYs due to type 2 diabetes were contributed by ambient PM2·5, and 6·50% (4·22–9·53) of deaths and 5·92% (3·81–8·64) of DALYs by household air pollution. High burdens, in terms of numbers as well as rates, were estimated in Asia, sub-Saharan Africa, and South America. Since 1990, the attributable burden has increased by 50%, driven largely by population growth and ageing. Globally, the impact of reductions in household air pollution was largely offset by increased ambient PM2·5. Interpretation Air pollution is a major risk factor for diabetes. We estimated that about a fifth of the global burden of type 2 diabetes is attributable PM2·5 pollution. Air pollution mitigation therefore might have an essential role in reducing the global disease burden resulting from type 2 diabetes