Preparation, stability of Nano-fluid and the thermal conductivity of Graphene oxide/Water Nano-fluid with the aim of improving the thermal properties of water were experimentally studied. FESEM and ...XRD tests were used for characterization of nano-particles. After getting assured of the structure of nano-particles, a two-step method was applied to produce Graphene oxide/Water Nano-fluid. Optimal pH, DLS and TEM tests were used to determine the stability. The mass fraction range of the Nano-fluid in this study was 0–1.5%, and the thermal conductivity was measured in the temperature range of 20–60 °C according to ASTM D2717–95 standard. The results indicate that the Nano-fluid has the highest stability at optimum pH (pH = 8). The results of TEM and DLS tests show the sheet structure of the nano-particles and their Nanoscale dimensions in the base fluid, respectively. The thermal conductivity of the Nano-fluid in the study range indicates a significant increase and its maximum increase is 48.1%. Using the curve fitting method, a new correlational with high accuracy has been proposed. Finally, according to the results obtained, it can be said that the Nano-fluid, with respect to its thermal properties in the practical systems, is an appropriate alternative to water-based fluid.
The determination of the efficiency of adhesives applied in glued joints, through the analysis of the percentage of wood failure, is one of the main validation parameters for the quality of gluing ...techniques and adhesive. However, the subjectivity of the interpretation, performance, and visual acuity of the evaluators makes the methodology subjective. This research aimed to establish a method for evaluating the behavior of the glue line in glued joints, using freely available software and digital camera images. Shear samples of glued joints with polyvinyl acetate - PVAc, resorcinol formaldehyde - RF, and melamine formaldehyde - MF were evaluated using digital images obtained by a 16.1-megapixel camera. The images were pre-processed to enable vectorization in Inkscape software, version 1.1.2. Each image was vectorized and subjected to the measurement of the areas of the generated vector layers (glue line and wood). The validation process was performed by evaluating the accuracy of vectorization. Thus, the photograph of each sample and the vectorized image were imported into ImageJ software, version 1.53. To ensure the reliability of the proposed methodology, statistical analyses of the Kappa coefficient, global accuracy, user, and producer were applied. To evaluate the efficiency of the proposed method in relation to the conventional method provided in ASTM D5266-13, five evaluators analyzed the proportion of bond line and wood failure of the 10 samples submitted to the proposed methodology. Subsequently, a descriptive analysis of the data was carried out to evaluate the variability and subjectivity of the conventional analyses among the evaluators. It is noted that the proposed methodology achieved high efficiency in the analysis of the proportion of glue line and wood, and it can be assured by the accuracy tests performed. The research also showed that there was no agreement among the five evaluators using the conventional method. It is concluded that the proposed methodology meets the research objective, with high levels of accuracy, and confirms the subjectivity of the analyses performed with the conventional methodology. The results underscore the need for objective methodologies, employing computational techniques to reduce subjectivity in adhesive bond failure assessments, enhancing critical decisions in the selection of adhesives for industrial structural applications.
•A new methodology for forest planning was proposed.•We consider the main forest genetic materials used in Brazil.•The methodology showed 81% assertiveness.•The proposed methodology had high precision and zero execution cost.•The proposed methodology is feasible and can be adapted to any other area.
In the work reported in this paper, two ultrasonic leak detectors were designed and manufactured to detect pipe leaks remotely using a non-contact, non-destructive method. One ultrasonic leak ...detector module with a parabolic reflector (diameter 150 mm and focal length of 100 mm) and a second ultrasonic leak detection module with a conical horn guide (length 100 mm, angle 9.5°) were fabricated. After CAD design, the parabolic reflector was processed by 3D printing manufacturing method. The performance of these devices was tested and evaluated in an outdoor environment in accordance with the ASTM E1002–05 class II equipment verification standards. The field verification tests were conducted about 20 times. According to the evaluation of the test results, the average S/N (signal to noise) ratio of the ultrasonic leak detector with the parabolic reflector was about 4.97 dB, and the average leak detection S/N ratio of the ultrasonic leak detector with a conical horn guide was about 1.89 dB
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Worldwide, improper disposal of plastics is instigating environmental initiatives to combat plastics accumulation of in the environment and the world's oceans. ...Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposites with Miscanthus (Misc) fibres and distillers' dried grains with solubles (DDGS) were studied to ascertain if natural fibres and proteinaceous fillers can improve polyhydroxyalkanoate marine biodegradability. Using ASTM standard D7991-15, the biodegradation of PHBV, PHBV with Misc (15 and 25 wt%) and PHBV with DDGS (15 and 25 wt%) was performed in a simulated marine environment for the first time, as indicated by a literature survey. PHBV/Misc (85/15) and (75/25) biocomposites showed 15 and 25% more biodegradation compared to PHBV, respectively. Proteinaceous PHBV/DDGS (85/15) and (75/25) biocomposites showed 17 and 40% more biodegradation compared to PHBV, respectively. Furthermore, PHBV/Misc (75/25) and PHBV/DDGS (75/25) biocomposites were marine biodegraded in 412 and 295 days, respectively. In conclusion, proteinaceous fillers (DDGS) biocomposites have better marine biodegradability than miscanthus.
•A method for obtaining experimental equilibrium distillation curves is proposed.•The method utilizes time-resolved measurements of liquid and vapor temperature.•A derivative based method is used to ...determine a fuel's true initial boiling point.•Dynamic holdup is found to correlate with volatility and condenser bath temperature.
A method has been developed to determine experimental equilibrium distillation curves using a modified ASTM D86 distillation apparatus.The method determines accurate equilibrium initial boiling points and accounts for the dynamic holdup inherent in distillation curves measured in accordance with the ASTM D86 standard.In this work, the ASTM D86 distillation setup has been modified to simultaneously measure liquid and vapor temperature using two resistance temperature detectors (RTDs) and a data acquisition system has been employed to record temperature data at one-second time intervals for the duration of each distillation.Additionally, the time for each volume recovery point is recorded.The method presented here uses the time-resolved liquid temperature data to identify the true initial boiling point (IBP) of four fuel mixtures of known composition; the IBPs are within 2°C of the calculated equilibrium values.The time-resolved volume recovery information and the identified initial boiling point time are used to construct a volume evaporated versus time curve.The measured temperatures determined at the corresponding volume evaporated increments provide an experimental equilibrium distillation curve (EEDC). The EEDCs for the four fuel mixtures of known composition match the calculated equilibrium curves within a few degrees Celsius; a maximum mean absolute error of 2.2±1.4°C was observed.The dynamic holdup (volume difference between volume evaporated and volume recovered) associated with a distillation is found to correlate with the initial boiling point of the fuel being distilled and the temperature of the condenser bath used in the experiment.The method was also applied to measure EEDCs for a gasoline fuel and a diesel fuel, where the compositions were unknown, to investigate the differences between the EEDCs and the ASTM D86 distillation curves.The results highlight the large errors incurred when using ASTM D86 results to approximate equilibrium distillation curves.
Dozarea oxidului nitric, un biomarker relativ nou apărut, este o metodă neinvazivă, din ce în ce mai accesibilă clinicienilor utilizată mai ales în domeniul pneumologiei, unde este folosit în ...monitorizarea inflamaţiei arborelui respirator. Scopul acestei lucrări este prezentarea experienţei Clinicii de Pediatrie a Spitalului Filantropia Craiova legată de dozarea oxidului nitric şi patologia astmatică, rezultatul a celor 10 ani de experienţă cu analizorul portabil al aerului expirat. Am selectat trei dintre cele mai importante lucrări ale noastre, prezentate la Congresele ERS (European Respiratory Society).
•Waste cooking oil (WCO) was converted into biodiesel.•Alkali catalyzed trans-esterification was adopted.•A 94% FAME yield was achieved using 1% catalyst at 50 °C.•Acid pretreatment and alkali ...trans-esterification is viable for biodiesel production from WCO.
Biodiesel production from waste oils is an attractive option to produce biodiesel economically, but high free fatty acids (FFA) in waste oils are a serious bottleneck for the process of transesterification. Present investigation deals with the utilization of waste cooking oil (WCO) for the production of biodiesel. The acid value of WCO was 5.5 mg KOH/g which indicated high FFA content. The WCO was subjected to esterification using different acid catalysts (HCl, H2SO4 and H3PO4) and H2SO4 catalyzed reaction was found to be the most efficient since the FFA reduced up to 88.8% at 60 °C with 1:2.5 methanol to oil molar ratio. Transesterification was done in the presence of alkali catalyst (KOH) and Fatty acid methyl ester (FAME) yield was 94% in the presence of 1% catalyst at 50 °C. The biodiesel was characterized based on acid value, saponification value, iodine value, cetane number, specific gravity, viscosity, cloud point, pour point and calorific value. The Gas Chromatography (GC) analysis of synthesized biodiesel was also performed. Base on ASTM standards, alkali catalyzed transesterification was an efficient method to produce biodiesel form WCO. Results revealed that the waste cooking oils can be converted into biodiesel as an energy source along with environmental pollution reduction.
The main objective of this work was to investigate the effect of hybridization and the effect of chemical treatments on the mechanical properties of a novel intralaminar natural fibre hybrid ...composite. Jute, sisal and curauá fibres were selected as natural fibre reinforcements for the epoxy matrix based composites which were produced by hand lay-up technique. The total volumetric fraction used in the fabrication of the hybrid composites was 30% of fibres and 70% of epoxy resin. Tensile, flexural and impact tests were carried out according to ASTM standards to characterize the novel hybrid composites. It was found that the mechanical properties evaluated are significantly improved by addition of the natural fibres to pure jute based composites. The fibre treatments had different effects on the mechanical properties of the hybrid composites. For sisal reinforced hybrid composites, the alkaline treatment had a positive impact on the composite properties (tensile, flexural and impact), while for the jute + curauá hybrid composites the alkali treatment had a negative effect on the tensile and impact properties. The mixed (alkalization + silanization) treatment had a positive effect on the jute + curauá flexural properties, while decreased the flexural properties for the jute + sisal composite. A scanning electron microscopy (SEM) was used to examine the fracture surface of the tested specimens.
•Spaceborne total solar irradiance observations from various radiometers are compared.•A proxy model of total solar irradiance is developed to fill in observational gaps.•Proxy model used to select ...the most reliable irradiance data sources during 1976–2017.•A 42-year gapless total solar irradiance record is derived.•A revised value of the solar constant is proposed, lower than previous estimates.
A reevaluation of the solar constant is undertaken here to take into account the progress in space radiometry that has occurred since the early 2000s. Various sources of spaceborne total solar irradiance (TSI) observations are investigated here, including the long-term ACRIM and PMOD composites, as well as recent observations from the SORCE-TIM, TCTE-TIM, and PICARD-PREMOS instruments. A proxy model is constructed using daily data of sunspot number, radio flux at 10.7 cm, and MgII index, as predictors for TSI over the 42-year period 1976–2017. These daily estimates are used to fill in 9.7% of missing TSI observations during that period. By comparison with these proxy estimates, the PMOD composite appears generally more reliable than the ACRIM composite before 2003, and particularly before 1981. The 42-year time span is separated into nine periods, each defining the revised TSI daily values from one or more sources that are selected based on the trend of their resemblance with the proxy model. A final correction is added to emulate the highly accurate absolute calibration of PREMOS. Based on the resulting TSI reconstruction, a revised solar constant value of 1361.1 W/m2 is obtained, with a standard uncertainty of 0.5 W/m2. The revised solar constant is ≈5 W/m2 less than the previous values promulgated in ASTM and ISO standards. A revision of these standards is thus highly recommended.
Ti–6Al–4V is one of the most used commercial titanium alloys, in part due to properties that are desirable in high value sectors such as the aerospace industry, such as good strength-to-weight ratio ...and corrosion resistance. These are of importance in gas turbine engines and structural components, where titanium alloys complement heavier steel or nickel alloys. It is also a good candidate to be used in the manufacturing of prostheses, since it has good biocompatibility, but applications in other areas are limited due to its poor bulk wear resistance.
Conventionally processed Ti-6AL-4V is typically used, however additive manufacturing (AM) techniques such as electron beam melting (EBM) can also be applied to this alloy. These techniques are increasingly attractive across many industries because of geometrical freedom and control of mechanical properties, both key, for example, to the successful production of highly personalised prostheses and complex thermofluids channels in aerospace and automotive components. Parts produced by EBM are typically denser than those obtained by other AM processes, but still experience increased wear over their traditionally obtained equivalents, particularly in sliding, thus surface treatment is common.
This work compares the wear observed when specimens manufactured by either conventionally or EBM were subjected to abrasion via means of a dry sand-rubber wheel tribometer capable of testing to the ASTM G65 test method. The specimens and resulting wear scars were characterised (hardness, grain size, roughness) and details of the wear mechanism(s) identified. The EBM specimens exhibited much greater wear, over twice that of the conventionally obtained specimens, and feature significantly more scratches.
Although there are several studies variously considering two-body sliding wear and the efficacy of surface treatments of this type of alloy, this work addresses the paucity of information about the comparative abrasive wear performance of the alloy obtained via the two process routes.
•Compares the abrasive wear of titanium alloy (Ti-6AL-4V), obtained conventionally and by electron beam melting (EBM).•Abrasion testing was performed with a dry sand-rubber wheel tribometer to the ASTM Standard G65 test method.•EBM specimens exhibited much greater wear, twice that of the conventional specimens, with significantly more scratches.•Addresses the paucity of information about the abrasive wear performance of the obtained via these two process routes.
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