Numerical modeling of fluid flow, heat, and mass transfer for similar and dissimilar laser welding of Ti-6Al-4V and Inconel 718

AbstractMost of the researches published on the numerical modeling of laser welding are looking at similar welding, mainly due to the difficulty of simulating the mixing phenomenon that occurs in dissimilar welding. Furthermore, numerical modeling of dissimilar laser welding of titanium and nickel alloys has been rarely reported in the literature. In this study, a 3D finite volume numerical model is proposed to simulate fluid flow, heat, and mass transfer for similar and dissimilar laser welding of Ti-6Al-4V and Inconel 718. The laser source was simulated by volumetric heat distribution, which considers the effects of keyhole and heat transfer on the workpiece. The heat source parameters were calibrated through preliminary experiments, by comparing the simulated and experimental weld pool shapes and dimensions. The model was used to simulate both homogenous and dissimilar laser weldings of Ti-6Al-4V and Inconel 718, and a systematic comparison was carried out through a number of selected experiments. The effects of three distinct levels of laser power (1.25 kW, 1.5 kW, 2.5 kW) on temperature distribution and velocity field in the welds pool were analyzed. Results highlighted the effects of Marangoni forces in the weld pool formation. Furthermore, in order to analyze the mass transfer phenomenon in dissimilar welding, species transfer equations were considered, demonstrating the important role played by the mass mixture in the weld pool formation. Finally, a high level of agreement between simulations and experiments—in terms of weld pool shape and dimensions—was observed in all cases analyzed. This proves the ability of the proposed numerical model to properly simulate both the similar and dissimilar welding of Ti-6Al-4V and Inconel 718 alloys

A constructability assessment model based on BIM in urban renewal projects in limited lands

One of the most significant concerns in urban development today is the organization of areas of cities that have become run-down over time. In order to complete previous constructability studies in other fields of construction, the current study evaluates constructability based on BIM, specifically in the context of the Tehran limited land renewal project. The motivation for this study is the current difficulties facing renewal designs for limited lands, and the lack of a quantitative constructability model for urban renewal projects in Iran. This paper aims (1) to discuss the design elements that should be considered in the design phase of urban renewal projects; (2) to identify the factors that may affect constructability; and (3) to propose a framework for assessing urban renewal designs by considering constructability factors using building information modeling (BIM). To meet these needs, this paper investigates constructability factors and their relative importance, considering the design elements that should be acknowledged in limited land renewal, using a multicriteria techniques. Some 28 constructability factors are identified through a literature review, and based on 52 responses received from a questionnaire survey, the factors are ranked using pairwise comparisons of the analytic hierarchy process (AHP). The final constructability factors that are identified through the technique for order preference using the similarity to ideal solution (TOPSIS) method are standard dimensions, safety, simplification of structure, resource intelligence and alignment, and skilled labor availability. The contribution of this research to the body of knowledge is, firstly, the development of constructability factors for measuring the constructability of urban renewal designs, and secondly, the introduction of BIM as a most beneficial tool for assessing the constructability of the proposed designs. In using the constructability assessment framework and identifying the trade-offs between the constructability of renewal projects in the limited areas of urban spaces, design alternatives become more feasible

Subjective and simulation-based analysis of discomfort glare metrics in office buildings with light shelf systems

Glare is a kind of physiological phenomenon that influences occupants’ visual comfort. Discomfort glare scenes in comparison to other levels of glare have been difficult to estimate and need accurate and reliable metrics. In contemporary architecture, the glass façade is so popular since it can remarkably minimize energy consumption in buildings and maximize daylight utilization as a natural energy. However, it is necessary to consider occupants’ visual discomfort due to the daylighting glare risks during the initial stage of design. Since the measured glare metrics should have an acceptable correlation with the human subject data study, the agreement on the glare indices is complicated. This paper presents a comparison between subjective and simulation-based analysis of discomfort glare metrics in offices with a light shelf system. The discomfort glare metrics considered in this study include Daylight Glare Index (DGI), CIE Glare Index (CGI), Visual Comfort Probability (VCP), Unified Glare Rating (UGR), and Daylight Glare Probability (DGP). The parallel comparison was conducted by using simulation and questionnaire surveys to determine which criteria are more useful under different conditions. According to the findings, DGP yields the most reliable results in different levels of glare based on the subjective analysis and VCP has the lowest accuracy in each stage. UGR also has the highest accuracy rate for evaluating perceptible glare, DGI is applicable for assessing imperceptible glare, and CGI can be an acceptable index for approximating intolerable glare. The study results significantly reduce the complexity of the problem and can provide useful guidance for designers to select the most reliable glare metric based on climatic conditions

بررسی کارایی بیومس قارچ آسپرژیلوس ترئوس در حذف کروم (VI) از محلولهای آبی: مطالعات ایزوترم و سینتیک جذب

Background and Aims: Chromium (VI) is one of the very toxic heavy metals and is known as a carcinogenic, mutagenic and teratogenic agent. In this study, the ability of dead Aspergillus Terreus fungus biomass in the removal of chromium (VI) from aqueous solutions was investigated.Materials and Methods: The suspension of AspergillusTerreus was cultivated in Potato Dextrose Agar and Potato Dextrose Broth mediums. The biomass was then boiled in 0.5 N NaOH solution. The ability of obtained biomass to absorb Chromium (VI) was studied with respect to various variables including time (15 to 120 min), pH (3 to 11), chromium (VI) concentration (20 to 120 mg/L) and absorbent dosage (0.1 to 0.8 g). Chromium concentration was determined using an atomic absorption of. All ethical issues and citations were taken into consideration in conducting the study.Results: Results showed that the maximum removal of chromium (89%) was obtained at contact time 90 min, pH=7, chromium concentration 20 mg/L and adsorbent dosage 0.6 g. The adsorption isotherm was best fitted by Freundlich with a high correlation coefficient (R2=0.952). Furthermore, the adsorption kinetics fitted well to the pseudo-first-order model with a correlation coefficient of 0.9775.Conclusion: The results of present study indicated that the studied variables have an incredible effect on sorption efficiency, as in the optimum condition, the biomass of AspergillusTerreus obtained an acceptable efficiency and adoration capacity compared to other adsorbents. So, this compound can be introduced as a practical natural adsorbent for chromium removal and also other heavy metals form aqueous solutions.زمینه و اهداف: یکی از فلزات بسیار سمی در فاضلابهای صنعتی کروم شش ظرفیتی (VI) میباشد که بعنوان یک عامل کارسینوژن، موتاژن و تراتوژن شناخته میشود. در این مطالعه توانایی بیومس مرده تولید شده از قارچ آسپرژیلوس ترئوس در حذف کروم (VI) از محیطهای آبی مورد بررسی قرار گرفت  مواد و روشها: سوسپانسیون قارچ آسپرژیلوس ترئوس در محیط های کشت پوتیتو دکستروز آگار و پوتیتو دکستروز براث کشت داده و سپس در محلول 0.5نرمال NaOH جوشانده شد. توانایی جذب بیومس حاصل برای متغیرهای زمان 15) تا 120 دقیقه(، 3) pH تا (11، غلظت کروم 20)(VI) تا  (120 mg/L و دوز جاذب 0.1) تا 0.8g) مورد بررسی قرار گرفت. از دستگاه جذب اتمی مدل Varian جهت سنجش کروم(VI) استفاده شد. موازین اخلاقی در انجام این پژوهش و استفاده از منابع رعایت گردید یافته ها : نتایج نشان داد که فرآیند جذب در زمان تماس 90 دقیقه، pH برابر با 7 ، غلظت آلاینده20 mg/L و دوز جاذب 0/6 g، دارای راندمان حذف برابر با 89 درصد میباشد. همچنین فرآیند جذب از ایزوترم فرندلیخ با R2=0.952 و سینتیک شبه درجه اول با R2=0.9775 پیروی می نماید. نتیجه گیری: نتایج نشان داد که متغیرهای مورد مطالعه اثر قابل توجهای در راندمان جذب دارند، بطوریکه در شرایط بهینه، بیومس قارچ آسپرژیلوس ترئوس دارای راندمان و ظرفیت جذب قابل قبولی در حذف کروم (VI) در مقایسه با سایر جاذبها است. در نتیجه میتوان این ترکیب را بعنوان یک جاذب طبیعی جهت حذف کروم (VI ) و سایر فلزات سنگین از محیطهای آبی معرفی کر

Indicator bacteria community in seawater and coastal sediment: the Persian Gulf as a case.

Abstract BACKGROUND: The aim of present work was to assess the concentration levels as well as vertical distribution of indicator bacteria including total coliform, fecal coliform, Pseudomonas aeruginosa, and Heterotrophic Plate Count (HPC) in the marine environment (seawater and coastal sediments) and evaluate the correlation between indicator bacteria and some physicochemical parameters of surface sediments as well as seawaters. METHODS: A total number of 48 seawater and sediment samples were taken from 8 stations (each site 6 times with an interval time of 2 weeks) between June and September 2014. Seawater and sediment samples were collected from 30 cm under the surface samples and different sediment depths (0, 4, 7, 10, 15, and 20 cm) respectively, along the Persian Gulf in Bushehr coastal areas. RESULTS: Based on the results, the average numbers of bacterial indicators including total coliform, fecal coliform, and Pseudomonas aeruginosa as well as HPC in seawater samples were 1238.13, 150.87, 8.22 MPN/100 ml and 1742.91 CFU/ml, respectively, and in sediment samples at different depths (from 0-20 cm) varied between 25 × 103 to 51.67 × 103, 5.63 × 103 to 12.46 × 103, 17.33 to 65 MPN/100 ml, 36 × 103 to 147.5 × 103 CFU/ml, respectively. There were no statistically significant relationships between the indicator organism concentration levels with temperature as well as pH value of seawater. A reverse correlation was found between the level of indicator bacteria and salinity of seawater samples. Also results revealed that the sediment texture influenced abundance of indicators bacteria in sediments. As the concentration levels of indicators bacteria were higher in muddy sediments compare with sandy ones. CONCLUSION: Result conducted Bushehr coastal sediments constitute a reservoir of indicator bacteria, therefore, whole of the indicators determined were distinguished to be present in higher levels in sediments than in the overlying seawater. It was concluded that the concentration levels of microbial indicators decreased with depth in sediments. Except total coliform, the numbers of other bacteria including fecal coliform, Pseudomonas aeruginosa and HPC bacteria significantly declined in the depth between 10 and 15 cm

Non-alcoholic fatty liver disease is not independent risk factor for cardiovascular disease event : a cohort study

There are no consistent results between previous studies for an independent association between non-alcoholic fatty liver disease (NAFLD) and cardiovascular disease (CVD) events. To determine if there is an independent association between NAFLD and CVD events. In the present study, valid outcome data of 4808 subjects were available for phase 2 of our cohort study. These subjects had been followed up for seven years from phase 1, beginning in 2009-2010 to phase 2 during 2016-2017. Simple and multiple Cox proportional models were used to determine the association between NAFLD in the primary phase of the cohort and subsequent fatal and non-fatal CVD events during follow-up. The incidence of non-fatal CVD events in males with NAFLD was significantly higher ( = 0.004) than in males without NAFLD. A positive association was demonstrated between NAFLD and non-fatal CVD events in males (Hazard ratio = 1.606; 95%CI: 1.166-2.212; = 0.004) by the simple Cox proportional hazard model, but no independent association was detected between these in the multiple Cox models. No independent association was detected between NAFLD and CVD. It is likely that diabetes mellitus and age may be the principle mediators in this regard. [Abstract copyright: ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.

Whole Transcriptome-Based Skin Virome Profiling in Typical Epidermodysplasia Verruciformis Reveals α-, β-, and γ-HPV Infections

HPVs are DNA viruses include approximately 450 types that are classified into 5 genera (α-, β-, γ-, μ-, and ν-HPV). The γ- and β-HPVs are present in low copy numbers in healthy individuals; however, in patients with an inborn error of immunity, certain species of β-HPVs can cause epidermodysplasia verruciformis (EV), manifesting as recalcitrant cutaneous warts and skin cancer. EV presents as either typical or atypical. Manifestations of typical EV are limited to the skin and are caused by abnormal keratinocyte-intrinsic immunity to β-HPVs due to pathogenic sequence variants in TMC6, TMC8, or CIB1. We applied a transcriptome-based computational pipeline, VirPy, to RNA extracted from normal-appearing skin and wart samples of patients with typical EV to explore the viral and human genetic determinants. In 26 patients, 9 distinct biallelic mutations were detected in TMC6, TMC8, and CIB1, 7 of which are previously unreported to our knowledge. Additionally, 20 different HPV species, including 3 α-HPVs, 16 β-HPVs, and 1 γ-HPV, were detected, 8 of which are reported here for the first time to our knowledge in patients with EV (β-HPV-37, -47, -80, -151, and -159; α-HPV-2 and -57; and γ-HPV-128). This study expands the TMC6, TMC8, and CIB1 sequence variant spectrum and implicates new HPV subtypes in the pathogenesis of typical EV

Investigation on electroless Cu-P-micro/nanoSiC composite coatings

Copper-phosphorus (Cu-P) coatings composited with superfine silicon carbide (SiC) particles were prepared by electroless plating. The composition, morphology, structure and roughness of the composite coatings, with micro- and nanosize SiC particles were studied respectively by energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and atomic force microscopy (AFM). It was shown that SiC particles are codeposited homogeneously and Cu-P-SiC composite coatings have crystalline structure. Mechanical properties of coatings were studied by Vickers hardness and wear testers. Cu-P/nano-SiC composite coating showed higher microhardness and better antiwear performance than microsize SiC composite coatings. Corrosion resistance of the electroless Cu-P composite coatings on carbon steel was studied in 3·5 wt-% NaCl and 1M HCl solutions by potentiodynamic polarisation technique. The study revealed that the corrosion resistance increases with incorporation of nano SiC particles in the Cu-

Survey Electrocoagulation Process in Removal of Acid Blue 113 Dye from Aqueous Solutions

Background: Treatment of textile industry wastewaters, due to having color and many pollutants, is one of the most important environmental issues. Acid Blue 113 dyes because of having benzene ring, which is not biodegradable, is toxic and carcinogen. The main objective of this study was determination of electrochemical process efficacy for removal acid blue 113 from aqueous solutions by using aluminum electrodes in batch reactor. Methods: This study performed in lab-scale in batch reactor. The effect of different parameters such as voltages (10, 20, and 40 volt), electrode distance (0.5 and 1 cm), and electrolysis times (5 to 80 min) was investigated. Results: The results of experiments demonstrated that with applying voltage 40V, 0.5 cm distance between electrodes, electrolyte concentration equal to 5 g/l, and 20 minutes electrolysis time, the color and COD removal rate was 99 and 78%, respectively. By increasing voltage and reaction time and reducing distance between the electrodes, power consumption is reduced and also final pH and dye removal efficiency increased. Conclusion: According to the results, the best removal efficiency of dye was obtained after 20 minutes contact time on the electric potential of 40 V, which was 99%. This process is environmental friendly and can be economically acceptable. Therefore, it can be results that electrocoagulation process by using aluminum electrode is an efficient and suitable method for acid blue 113 dye removal from aqueous solutions