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Characterization Studies of Reduced Graphene Oxide/Zinc Oxide Nanocomposites Synthesized by Hydrothermal Method
Get PDFReduced graphene oxide/zinc oxide (RGO/ZnO) nanocomposites were synthesized by facile hydrothermal method; this method consists of exfoliation of graphite with modified Hummer's method and synthesis of (RGO/ZnO) nanocomposites using hydrothermal method. X-ray diffraction, TEM and FT-IR spectroscopy were used for structure morphological characterization. Optical properties of the samples were studied by measuring their optical absorbance. It can be concluded from XRD analysis that there are improvements of crystallinity associated with the increase of the crystallite size, as well as the increase in both of the (Zn-O) bond length and unit cell volume with the increase of ZnO ratio in RGO/ZnO nanocomposites. The morphological studies confirmed that the scale of ZnO particles is large and the size distribution is not uniform in samples of RGO/ZnO and that most particles have average size of about 9 nm while some particles even have larger size. The optical absorption spectra show that the excitonic peak of the as-prepared samples is red shifted from 268 nm to 376 nm for reduced grapheme oxide (RGO) with the increase of ZnO ratio, and the optical band gap changes from 2.39 for pure RGO to 3.34 eV for pure ZnO. The effect of UV irradiation on the optical absorption nanocomposites at different UV doses was carried out using UV lamp
Outdoor Autonomous Landing of a Quadcopter on a Moving Platform using Off-board Computer Vision
Get PDF This paper presents a method that enables a quadcopter to perform autonomous landing on a moving platform using computer vision. In addition, the system implementation of the computer vision technique is presented. Unlike other researches, the camera is mounted on the moving platform instead of being installed on the quadcopter. Besides, the computer vision system is tested outdoor, and the results such as the performance and the accuracy are presented. In the stationary platform test, 5 out of 10 landings fall within 30 cm from the center. In the moving platform test, the maximum platform-moving speed for autonomous landing is 2 m/s. Hence, it is proven that this methodology is feasible. Lastly, the advantages and limitations of the computer vision technique proposed are discussed
Prediction of Roughness Heights of Milled Surfaces for Product Quality Prediction and Tool Condition Monitoring
Get PDFThe objective of this research is to predict the roughness heights of milled surfaces, which indicates product quality and tool conditions. Two experiments are carried out to evaluate relevant factors such as vibration, force, and surface roughness. The purpose of the first experiment is to find out the limits of the machining variables compared to the constraints of the materials. The purpose of the second experiment is to identify, collect, and compare how each factor affects product quality and tool conditions. Based on this study, the vibration, force, and surface roughness are good indicators for tool conditions. When the magnitudes of the vibration and force increase, the surface roughness also increases. The increase in surface roughness with constant cutting parameters indicates the degrading of product quality and the decrease of the tool life. Thus, the variables, such as vibration and forces, are used as the inputs, and the surface roughness is used as the output of neural networks. By optimizing the network variables, it has been found that a 4,4,8,1 neural network can achieve the least absolute error, and accurately predict the actual roughness heights collected from the experiment. The minimum error of the prediction of surface roughness is 0.11%, the average error is 2.11%, and the maximum error is 6.98%. The prediction of surface roughness of milled surfaces is very important for the product quality prediction and tool condition monitoring
Determining Effective Parameters on CO Concentration in Tehran Air by Sensitivity Analysis based on Neural Network Prediction
Get PDFOne of the most toxic pollutant gases produced by fossil fuels is carbon monoxide. Hence, the accurate and regular estimation and control of CO in the cities such as Tehran is inevitable. In this research, for the first time, CO concentration in ambient air was predicted based on 12 important urban and meteorological parameters by neural network. Also, the sensitivity analysis of the factors that effect on the concentration of carbon monoxide in Tehran was investigated based on the pollutant concentration predictive model. In this research, the daily statistical data of Tehran metropolis over the course of five consecutive years from 12 factors affecting the amount of carbon monoxide in Tehran, such as population, density, precipitation, temperature, urban traffic, wind speed, gasoil consumption, moisture, air flow, effective vision and air pressure was used. Based on this database, the artificial neural network with the best possible algorithm had been trained to predict this contaminant and root mean square error of model was equal to 2.54. Then, sensitivity analysis was done to find the most effective factor on the concentration of carbon monoxide, urban density and air pressure. In order to control this hazardous contaminant in urban management, these parameters should be taken into account. Based on the result, by preventing the construction of high towers in Tehran, wind speed average will increase and increasing in wind speed (25%) caused to reducing in carbon monoxide concentration (about 12%). Also, prevention of urban density (25%) will cause to prevention of increasing CO concentration (about 10%)
Evaluation of Essential Metals and Arsenic in Poultry Feeds and Litters of Different Poultry Farms
Get PDFThe current study was aim to evaluate the speciation of arsenic (total arsenic “TAs”, arsenite “AsIII” and arsenate “AsV”) and total contents of essential metals in the feeds and litters of branded poultry feed using farms (BPF) and non-branded poultry feed utilizing farms (NBPF) at Hyderabad Sindh, Pakistan. The TAs and essential metals determined by graphite furnace and flame atomic absorption spectrometry (GF and FAAS), respectively. Whereas, the AsIII and AsV separated by solvent extraction followed by GF-AAS. The high levels of sodium, potassium, and zinc were observed in branded poultry feeds whilst calcium and iron contents were higher in non-branded poultry feed. The contents of total arsenic in poultry feed samples of both branded and non-branded poultry feed utilizing farms were within the NRC permissible limits (30.0 mg/kg) except NBPF-1 and NBPF-4. Total As in all poultry litter samples were found under the permitted monthly average dose of As (41.0 mg/kg) for agronomical application expert poultry litter samples of BPF-1, NPBF-2, and NPBF-3. The daily accumulation of total As from feed to boilers were also studied
Effect of the Processing Temperature on the Degradation of Food Flavonoids: Kinetic and Calorimetric Studies on Model Solutions
Get PDFFood flavonoids have a high antioxidant activity that make them bioactive to fight oxidation. However, when they are used in different formulations, these bioactive molecules are often the subject of at least one heat treatment step such as cooking, pasteurization. To establish the sensitivity of these molecules to heat treatment, the kinetics of degradation of 4 flavonoid extracts were evaluated under isothermal and non-isothermal conditions. The flavonoids tested belong to the aglycon (eriodictyol and mesquitol) and glycosylated (rutin, naringin) forms. The glycosylated flavonoids have a higher stability than the aglycons. Among the glycosylated flavonoids, rutin is more sensitive to heat than naringin because of the different degree of hydroxylation between these 2 compounds. For the aglycon form, the sensitivity to heat varies depending on the absence or presence of a carbonyl group at the 4-position and a hydroxyl at the 3-position. The addition of 10% of propylene glycol causes an effect protector delaying the thermal degradation of flavonoids. Activation energies are also affected by both the flavonoid structure and the heat treatment system. The differences observed between the isothermal and non-isothermal conditions can be attributed to the difference in heating intensity that can generate a difference in the composition of the solution. The evolution of antioxidant activity of flavonoid solutions after heat treatment is different depending on the structure of the flavonoid studied
Forecasting Model Validation of Particulate Air Pollution by Low Cost Sensors Data
Get PDFEnvironmental pollution in urban areas may be mainly attributed to the rapid industrialization and increased growth of vehicular traffic. As a consequence of air quality deterioration, the health and welfare of human beings are compromised. Air quality monitoring networks usually are used not only to assess the pollutant trend but also in the effective set-up of preventive measures of atmospheric pollution. In this context, monitoring can be a valid action to evaluate different emission control scenarios; however, installing a high space-time resolution monitoring network is still expensive. Merge of observations data from low-cost air quality monitoring networks with forecasting models can contribute to improving significantly emission control scenarios. In this work, a validation algorithm of the forecasting model for the concentration of small particulates (PM10 and PM2.5) is proposed. Results showed a satisfactory agreement between the PM concentration forecast values and the measured data from 3 air quality monitoring stations. Final average RMSE values for all monitoring stations are equal to about 4.5 µg/m3
Determination of Five Phthalate Esters and Bisphenol A in Fruit Juice by Packed-nanofiber Solid Phase Extraction Coupled with Gas Chromatography
Get PDFPacked-nanofiber solid phase extraction (PFSPE) combined with gas chromatography-flame ionization detector (GC-FID) was developed for the simultaneous determination of five phthalate esters (PAEs) and bisphenol A (BPA) in fruit juice. The PAEs and BPA was concentrated by PFSPE using polystyrene- pyridine (PS-PD) nanofibers as the sorbent, followed determined by GC-FID. Under this modified procedure, satisfied recoveries in fruit juice sample ranging from 81.9% to 109.6% were obtained. And relative standard deviation values (RSD) were ranged from 1.9 % to 9.8% in orange juice sample. The limits of detection (LOD) and the limits of quantification (LOQ) of five PAEs and BPA were ranged from 0.02 μg/mL to 0.30 μg/mL and 0.06 μg/L to 1.10 μg/L, respectively. This established method was successfully applied to detect real fruit juice samples, which were collected in local supermarket. These results demonstrated the applicability of the established PFSPE-based extraction coupled with gas chromatography method for determination of PAEs and BPA in fruit juice products
Evaluation of Phenolic Compounds, Antioxidant and Antimicrobial Activities of Rice (Oriza Sativa. L.) Pedicle extract (In Vitro)
Get PDFIn this study, rice pedicle extracts (Oriza sativa. L.) were obtained by high pressure reactor using water, and sodium hydroxide at temperatures of 70, 90, 110 130 °C. The extracts were evaluated for total phenolic content, antioxidant activity and growth inhibition of Escherichia coli and Candida albicans. Their results were compared to Soxhlet extraction by using ethanol (95%v/v). The results showed that the use of different temperatures had a significant effect on the percentage of phenolic compounds, and the alkali method had a significant effect on the amount of phenolic compounds rather than water extraction (128.72 and 51.79 GA/g, respectively). The highest antimicrobial activity levels were obtained in ethanol extracts that the extracts have inhibitory effect on E. coli. None of extracts had inhibitory effect on Candida albicans. The results provided the evidence that the studied rice (Oriza sativa. L.) pedicle extract might be potential sources of phenolic compound, natural antioxidant and antimicrobial agents
An Update on Applications of Power Ultrasound in Drying Food: A Review
Get PDFUltrasound is sound waves with above the human hearing range frequency that is approximately 20 kHz. Application of power ultrasound in combination with other food processing methods including drying, is considered to be an emerging and promising technology. The use of novel non-thermal technologies, such as power ultrasound, is suitable to facilitate the drying of heat sensitive food materials. Ultrasound enhance heat and mas transfer which result in faster moisture removal during drying due to heating, vibration and synergistic effects. These effects could lead to product quality preservation in terms of color, texture, vitamin C and antioxidants content, by the use of milder drying conditions, and in some cases can promote better energy efficiency. In this article, after a brief review on the history of ultrasonic drying, different methods are categorized and combinations of ultrasound with novel drying methods and their effects on phytochemicals are discussed with the focus on the recently published articles. Studies showed that the quality of ultrasonically dried products was usually higher than conventionally dried products. However, the effect of ultrasonic drying on the texture and nutritional value of the products should be further investigated