Attitude Control of a Quadrotor with Optimized PID Controller

A new approach to control, stabilization and disturbance rejection of attitude subsystem of quadrotor is presented in this article. Analytical method is used to tune conventional structure of PID controller. SISO approach is implemented for control structure to achieve desired objectives. The performance of the designed control structure is evaluated through time domain factors such as overshoot, settling time and integral error index, and robustness. A comparison is done between designed controller and back-step controller applied to main model of quadrotor. The results of simulation show the effectiveness of designed control scheme.

Prediction of representative deformation modulus of longwall panel roof rock strata using Mamdani fuzzy system

Deformation modulus is the important parameter in stability analysis of tunnels, dams and mining struc- tures. In this paper, two predictive models including Mamdani fuzzy system （MFS） and multivariable regression analysis （MVRA） were developed to predict deformation modulus based on data obtained from dilatometer tests carried out in Bakhtiary dam site and additional data collected from longwall coal mines. Models inputs were considered to be rock quality designation, overburden height, weathering, unconfined compressive strength, bedding inclination to core axis, joint roughness coefficient and fill thickness. To control the models performance, calculating indices such as root mean square error （RMSE）, variance account for （VAF） and determination coefficient （R^2） were used. The MFS results show the significant prediction accuracy along with high performance compared to MVRA results. Finally, the sensitivity analysis of MFS results shows that the most and the least effective parameters on deformation modulus are weatherin~ and overburden height, respectively.

Development of a time-dependent energy model to calculate the mining-induced stress over gates and pillars

Generally, longwall mining-induced stress results from the stress relaxation due to destressed zone that occurs above the mined panel. Knowledge of induced stress is very important for accurate design of adjacent gateroads and intervening pillars which helps to raise the safety and productivity of longwall mining operations. This study presents a novel time-dependent analytical model for determination of the longwall mining-induced stress and investigates the coefficient of stress concentration over adjacent gates and pillars. The model is developed based on the strain energy balance in longwall mining incorporated to a rheological constitutive model of caved materials with time-varying parameters. The study site is the Tabas coal mine of Iran. In the proposed model, height of destressed zone above the mined panel, total longwall mining-induced stress, abutment angle, induced vertical stress, and coefficient of stress concentration over neighboring gates and intervening pillars are calculated. To evaluate the effect of proposed model parameters on the coefficient of stress concentration due to longwall mining, sensitivity analysis is performed based on the field data and experimental constants. Also, the results of the proposed model are compared with those of existing models. The comparative results confirm a good agreement between the proposed model and the in situ measurements. According to the obtained results, it is concluded that the proposed model can be successfully used to calculate the longwall mining-induced stress. Therefore, the optimum design of gate supports and pillar dimensions would be attainable which helps to increase the mining efficiency.

Assessment of dairy products consumed on the Arakmarket as determined by heavy metal residues

Dairy products are nutritious drink and can play a significant part in a healthy diet. The safety of dairy products decreases with increasing concentration of toxic compounds and environmental pollutants (especially heavy metals). In the present study, the contamination of Al, Sn, As, Cd, Hg and Pb in dairy products (pasteurized milk, yogurt, yogurt drink, cheese) consumed in Arak, Iran, 2013 was evaluated using inductively coupled plasma mass spectrometry (ICP-SFMS) method. To meet the aim, 60 samples of 5 different brands, consisting of pasteurized milk, yogurt, yogurt drink, cheese (n = 15) were selected and analyzed for heavy metals content. 100% of the samples were positive regarding the total average and range concentration of Al, Sn, As, Cd, Hg and Pb in dairy products was 168.25 ± 92.2 (30.6 - 356.5), 5.9 ± 4 (1.1 - 16), 3.2 ± 1.95 (0.4 - 8.1), 4.55 ± 2.6 (0.6 - 10.6), 23.15 ± 10.4 (6.8 - 50.2) and 15.4 ± 8.53 (3.1 - 40.2) μg/kg, respectively. 28.3% (17 of 60 samples) of dairy products samples had lead (Pb) greater than EU limit and national Iranian standard (20 μg/kg). Statistical analysis indicated except about As in pasteurized milk and cheese there was no significant difference between products in terms of heavy metals content.

Potentially Toxic Element Concentration in Fruits Collected from Markazi Province(Iran): A Probabilistic Health Risk Assessment

Objective This study was conducted to evaluate the concentration of potentially toxic elements(PTEs)such as arsenic(As),cadmium(Cd),mercury(Hg),and lead(Pb)in fruit samples collected from Markazi Province,Iran.A probabilistic health risk assessment due to ingestion of PTEs through the consumption of these fruits was also conducted.Methods The concentration of PTEs in 90 samples of five types of fruits(n=3)collected from six geographic regions in Markazi Province was measured.The potential health risk was evaluated using a Monte Carlo simulation model.Results A significant difference was observed in the concentration of PTEs between fruits as well as soil and water samples collected from different regions in Markazi Province.The order of PTE concentration in the soil and water samples was as follows:Pb>As>Hg>Cd.Furthermore,the highest level of transfer factor for Cd and Hg correlated with the grape.The estimated daily intake for adults and children was lower than the recommended tolerable daily intake.Conclusion The population in Markazi Province,Iran,is not at considerable noncarcinogenic or carcinogenic risk due to the ingestion of PTEs through the consumption of the examined fruits.

An Empirical Study on Microbial Load and Acidity in Raw Milk Produced in Malayer and Nahavand Cities, Iran 2012

Milk is very susceptible for growth and development of many microorganisms because it is rich in nutrients and has suitable condition. Thus, it is very vital to respect sanitary conditions at all stages of production and transport of raw milk. The objective of the present investigation was to determine the total bacterial, and acidity in raw milk from milk collection centers in Malayer and Nahavand cities. 52 milk samples were collected from 13 centers in summer 2012 and were analyzed according to standard methods. None of the raw milk samples under investigation, had superior or grade 1 quality. Only 7.7% of the samples were classified as raw milk with grade 2 quality and 92.3% were non-standard. The mean of microbial total count in base was 3.8 × 107 CFU/ml and average acidity in the samples was 0.163. The city of Tochqhaz and Aliabade-Damagh has the lowest and the highest microbial total count. In general the result of this study showed unsatisfactory conditions of milk in the milk collection centers of the Malayer and Nahavand cities.

An Empirical Study on Aflatoxin Occurrence in Nuts Consumed in Tehran, Iran 2013

By definition, “aflaxions” refer to a group of chemically toxic fungal metabolites, which are generated by specific species of genus Aspergillus. The species flourish on some of raw foods. This research is an attempt to assess aflatoxin contamination in nuts (Fig, Almond, Hazelnut, Walnut, Pistachio and Sunflower) available in Tehran city market in 2013. The assessments were done using ELISA method. To this end, 200 samples including Fig (n = 30), Almond (n = 25), Hazelnut (n = 25), Walnut (n = 40), Pistachio (n = 40), Sunflower (n = 40) were collected and analyzed regarding contamination with aflatoxin. The result of the tests was positive for 96.5% (193 samples) with total average concentration of 1.68 μg/kg (0 - 6 μg/kg). Moreover, in 6% (12 samples) of the cases, contamination exceeded the EU limits (4 μg/kg), while 100% of the samples met the legal limits of National Standard of Iran (15 μg/kg). In spite of contamination of majority of the cases, none was at hazardous level as the condition for growth of mycotoxin fungus or antioxidant activity in the nut was not suitable in Tehran (humidity level).

Manganese toxicity in the central nervous system: Decreeing of catecholamine in rat’s brains

Manganese is an essential metal in human that functions in many enzymes. In contrast excessive exposure to Mn results in neurotoxicity. Accumulation of manganese damages central nervous system and causes Parkinson disease like syndrome called manganism. Mn neurotoxicity has been suggested to involve an imbalance in catecholamine neurotransmitters. It hypothesized that Mn can obstruct catecholamine synthesis pathway by inhibition of Tyrosine hydroxylase. Previous studies demonstrated that chronic and acute dose of Mn has different possible effects on catecholamine synthesis. It’s assumed that an acute dose of manganese can kill dopaminergic cells. Therefore, we focused the effect of Mn in catecholamine concentration on the rat’s brain by MnCl2 injection intraperitoneally and analyzed their brains after the time interval. This study used different acute doses in short time courses and different chronic doses at different exposing times to investigate which of them (exposing dose or time) is more important in Mn toxic effect. Measurement of catecholamine concentration performed by fluorescence assay in acidic and oxidant environment.