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Availability is an important characteristics of the repairable machines system performance and improvement of production planning and loading operation is an important part of the mine production cycle. In this paper an approach to calculate availability of open pit mine loading system based on Markov chain theory has proposed. Markov method is based on different modes of the system and the transition from a state to another. Therefor data analysis and failure and repair rate determination are significant. To illustrate the application of model, the Mishdowan iron mine data was used. Calculation of failure and repair rate indexes and availability of loading system has been determined using Markov chain model. Related statistical tests was used detecting the failure and repair behavior of system for higher degree of accuracy. Based on the results obtained, failure and repair rate for Newholland hydraulic excavator are 0.019 and 0.064 and for Komatsu hydraulic excavator are 0.017 and 0.047, respectively. Additionally, availability of hydraulic excavators of mine loading system is evaluated to be 93.3 percent.

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To evaluate the relationships between soil inorganic phosphorus P (Pi) fractions, the soil P test and plant parameters such as plant P uptake, dry matter yield, tissue P concentra-tion and relative yield, glasshouse experiments and chemical analyses were conducted on 13 calcareous soils from six agricultural and seven adjacent bushland (virgin soil) sites. Four rates of P (0, 15, 30, 60 mg/kg soil) were applied as reagent-grade KH2PO4 to the soils in a randomised complete block design with three replications. Perennial ryegrass (Lolium perenne cv. Roper) was grown and forage was harvested five times over a period of 210 days. Successive harvesting resulted in the depletion of plant available P as meas-ured by NaHCO3-extractable P, which coincided with the decrease in the plant dry matter yield and P uptake. After five harvests, the order of reduction in Pi fractions induced by cropping without added P was Ca10-P>Al-P>Ca2-P>Ca8-P>occluded-P>Fe-P for the vir-gin soils and Ca2-P>Al-P>Ca10-P>Ca8-P>Fe-P>occluded-P for the agricultural soils. The order of abundance of Pi fractions for P treated-soils was non-occluded Al and Fe phos-phate (Al-P+Fe-P)>secondary Ca-bound P (Ca2-P+Ca8-P)>acid-extractable P (Ca10-P)>occluded-P for both virgin and agricultural soils. Although a marked proportion of added P was transformed into less soluble Al and Fe phosphates, successive harvesting had depleted considerable percentages of these fractions. Highly significant (p<0.001) re-lationships were found for P uptake vs. Olsen-P, P uptake vs. Pi fractions (Ca2-P, Ca10-P, Al-P, Ca8-P, Fe-P) and Olsen-P vs. Pi fractions. NaHCO3-extractable P seems to be ade-quate for evaluating plant available P in calcareous soils. However, the closer relationship for the Fe-P fraction vs plant P uptake than for Olsen-P versus plant P uptake indicates that NaHCO3 may not provide the best estimate of plant available P for calcareous soils. Using stepwise regression analysis, it was found that the Ca2-P fraction was most predic-tive of P uptake (60%), total dry matter (68%), relative yield (74%) and Olsen-P (69%), followed by the Fe-P fraction.

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This study examined the nature and patterns of rice consumption in Nigeria, using Kwara State as a case study. The study methodology comprised a two stage sampling technique which was used to survey 110 rice consumer households across two villages and six towns in Kwara State. Analytical tools used in the study include descriptive statistics and the multinomial logit model. The major factors that significantly influence household preferences for either a combination of local and imported rice or the imported rice only to the local rice were the income of the head of household, household size and the educational status of the heads of household, the price per unit kilogramme of rice, however, was not a significant factor. This study therefore recommends that an effort should be made to increase rice production coupled with the provision of standard processing facilities. This will help to make the local rice sufficiently more competitive thereby increasing its demand.

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In this paper an efficient algorithm of system design with reliability approach is presented. Using this algorithm in subsystem designing of special systems may lead to systematically optimized design with reliability parameters attitude. By applying item tree parameters including general subsystem parameters into the algorithm and by knowing failure modes and the occurrence rate of each failure mode, the design may be improved and necessary reconsiderations can be applied in order to prevent or reduce the probability of failure mode. First some basic conceptual definitions including reliability, availability, capacity and failure rate is explained then various reliability analysis methods like Fault Tree Analysis (FTA), Failure Mode Effect Analysis (FMEA), Reliability Block Diagram (RBD) and Markov analysis is discussed. Reliability and availability distribution over different phases of unlocking and deploying mechanisms are illustrated using Windchill Solution. Subsequently the effect of the different ranges of failure rates of added components on reliability, availability and capacity of whole system is investigated. By analyzing the reliability and availability of system for different phases, it was found that the whole system is under stable situation at the end of each phase. Also results showed that the reliability, availability and capacity of whole system increased and reached a stable level by minimizing the failure rate of the redundant components.

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D-CODER is a fertilizer with a new slow-release mechanism consisting of an organo-mineral matrix that releases the nutrients only in the presence of growing plants. Pot and field experiments were carried out to study the release pattern of N from D-CODER. The experiments included grown and bare soil plots. The fertilizer treatments were D-CODER, ammonium nitrate (ANpreplant), and the control. A fourth treatment was added to the cultivated plots, consisting of splitting the ammonium nitrate application of 25% at preplant and 75% as top-dressing (ANsplit). In the bare soil pots, 35 days after the fertilizer application (DAFA), NO₃-N concentrations in the extracts of anion exchange membranes incubated in the soil for ANpreplant, D-CODER, and the control treatments were 118.5, 82.5 and 34.5 mg L^-1, respectively, suggesting that part of N from D-CODER had not yet been released. In the pots cultivated with ryegrass, 209 DAFA, N recoveries for D-CODER, ANpreplant, and control treatments were 0.94, 0.86 and 0.20 g pot^-1, respectively, suggesting that in the presence of the growing plants the release of N from D-CODER had not been restricted. Furthermore, soil NO₃-N levels in the bare soil plots of the field experiment were significantly higher in D-CODER (38.1 and 6.8 mg kg^-1 on November and March) in comparison to ANpreplant (26.3 and 5.1 mg kg^-1 on Nov. and March) treatments, suggesting that N from D-CODER was better protected from leaching. In the absence of growing plants, D-CODER provided some protection of N at least until 65 DAFA. In cultivated soils, it seemed less effective, particularly if the risk of nitrate leaching persisted for a long period of time. In these situations, a split application of N was a better strategy.

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Measuring total metal concentration of heavy metals cannot be a suitable indicator to evaluate their danger and human health risk. Their toxicity depends on their mobility and bioavailability. In the present study, sixty-five surface soil samples in the Bama zinc-lead mining and residential area were collected to assess metal bioavailability. Since the mine is near to the metropolitan area (Isfahan) and a village is located in vicinity of the mine, assessing potential adverse effects of the surface soil on human health is a crucial issue. Firstly, total concentration of metals, using acid digestion method (Pb, Zn, Cu, Mn, Fe and Cd) as well as L.O.I and carbonate contents were determined for precisely understanding on pollution condition. Enrichment factor was used to determine the accumulation or non-accumulation of metals at Bama mining area and its residential area, using Fe and Mn as references elements. Single extraction tests were conducted to reveal bioavailability and human bioaccessibility of metals, using EDTA and glycine as extractants. Moreover, Bioavailability risk assessment index (BRAI) was used to assess the risk of metal bioavailability/bioaccessibility. Based on BRAI, qualitative mapping of health risk distribution was presented, using ordinary kriging method. High concentrations and enrichment factor of Pb, Zn and Cd were determined at mining area. Their high concentrations in mining area may be due to Bama host rocks where significant contents of mentioned metals were accumulated. The amount of L.O.I was higher in mining area, indicating the ability of its soils to carry more polluted metals. Cu created no pollution and health risk due to its low total and bioavailable contents at study area. Based on single extraction methods, the absorption percent for the toxic metals were different. The highest percent of bioavailability and human bioaccessibility was allocated to Cd and the lowest was for Pb. Further, it was found that glycine extracted more amounts of metals in comparison with EDTA,Since pH is in lower values using glycine solution, greater amount of metals can be changed into solution forms due to acidic pH of glycine. So the single extraction test exhibited higher bioaccessible fraction of metals. Bioavailable and bioaccessible percent of toxic metals was higher in residential area as mineral soils are in poor condition. Pearson correlation coefficient showed that Pb, Zn, Cd and carbonate contents were highly correlated at residential area. This is expressing that the metals probably are bonded with carbonate at residential area, which may increase the possibility of their mobility and release under changing conditions. Based on EDTA extractant, BRAI index was calculated 3.46 and 4.2 for mining and residential area, respectively. Further, on the base of glycine extractant, result of BRAI was calculated 4.2 and 4.6 for mining and residential area, respectively. The calculated BRAI represent a high risk for human beings and plants in both the mining and residential areas. Moreover, results revealed that higher degree of bioavailability/bioaccessibility for the residential area in comparison with the mining area. It could be concluded the higher potential health hazard for the residence beside the mining area.

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Waterlogging and drought are severe constrains that limit maize seedling growth in tropical and subtropical regions. It is significant to determine the differences in morphological and physiological responses of maize to drought and excess soil water, with a view toward better breeding and field management. In the present experiment, different levels of soil water availability were initiated at the one-leaf (V1) stage of two maize cultivars (Denghai9 and Yidan629): Control (CK), Severe Drought (SD), Light Drought (LD), Severe Waterlogging (SW), and Light Waterlogging (LW). The results indicated that waterlogging had more discernible impact on the seedling growth of both cultivars than drought stress. The Relative Growth Rate (RGR) of shoots and roots, along with root length, volume, and surface area were all markedly decreased in both cultivars under waterlogging stress. The malondialdehyde content increased significantly in roots and leaves under waterlogging treatment. In both cultivars, SuperOxide Dismutase (SOD) was mostly activated in roots and leaves at the three-leaf (V3) stage by waterlogging stress, while the Catalase (CAT) activity apparently increased under drought stress. The activity of Peroxidase (POD) distinctly enhanced in both cultivars under drought and waterlogging stress. Ascorbate Peroxidase (APX) showed constant activity with prolongation of waterlogging stress, and Glutathione Reductase (GR) activity notably increased in roots under waterlogging conditions at the six-leaf (V6) stage. We concluded that SOD, POD, APX, and GR were the most important antioxidant enzymes under waterlogging conditions, whereas CAT and POD appeared to play key roles under drought stress.