90 research outputs found

    Investigation of the Fire Effects on Some Physico-Chemical Characteristics of Soil (Case Study: Miankaleh Rangeland, Iran)

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    Fire is one of the ecological factors that can have positive and negative effects on ecosystem processes. Nevertheless, prescribed burning is considered to be an important tool for grassland management, particularly to manipulate the balance between grasses and shrubs (Scheintaub et al. 2009). In Iran, for example, Khodagholi et al. (2001) in the Samirom rangelands of Isfahan Province suggest that fire reduces the shrubs cover and production and leads to the expansion of grasses. Sharifi and Imani (2006) showed that in the semi-steppe of Khalkhal Province shrub cover decreased in contrast to permanent grasses after fire was applied. However, others report that fire can reduce production and plant diversity due to affects on the range soil properties. This research investigated the effects of fire on some soil physico-chemical characteristics in the Miankaleh rangeland in northern Iran

    Evaluation of Microbial Resistance Pattern in Children with Urinary Tract Infection in Bushehr between 2017 and 2018

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    Background and Aim: Urinary tract infection is one of the most common childhood illnesses that can lead to complications such as hypertension and kidney failure. The aim of this study was to evaluate microbial resistance and sensitivity and to determine the relationship between urinary tract abnormalities and prior antibiotic use with microbial resistance. Methods: This is a descriptive-analytic study on 90 patients with a positive urine culture. Urine culture samples were taken using one of the sampling methods (midstream clean catch, catheterization, urine bag, suprapubic aspiration) and ultrasonography was requested for all patients to evaluate urinary system abnormalities. Also, a history of prior antibiotic use was asked and recorded. Results: Of all patients, 55.6% showed E.coli and 44.4% showed other bacteria in urine culture. 97.7% of patients' cultures were sensitive to imipenem, 82.2% to nitrofurantoin, and 77.8% to cefixime. 65% of patients' cultures showed resistance to nalidixic acid, 56.7% to co-trimoxazole, and 38.9% to ceftriaxone. There was a significant relationship between cefixime and amikacin antibiotic resistance with abnormal ultrasound and there was a significant relationship between antibiotic resistance to cefixime, ceftriaxone, co-trimoxazole, and duration of prior antibiotic use (p-value <0.05). Conclusion: The most common pathogen in UTI was E.coli. The highest sensitivity was to imipenem, nitrofurantoin, and cefixime, and the highest resistance was to nalidixic acid, co-trimoxazole, and ceftriaxone. There was a relationship between urinary tract abnormalities and prior antibiotic use with microbial resistance, so it is suggested to use kidney ultrasound in all patients with urinary tract infection

    Experimental Investigation of Asphaltene Content Effect on Crude Oil/CO2 Minimum Miscibility Pressure

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    Minimum Miscibility Pressure (MMP) is regarded as one of the foremost parameters required to be measured in a CO2 injection process. Therefore, a reasonable approximation of the MMP can be useful for better development of injection conditions as well as planning surface facilities. In this study, the impact of asphaltene content ranging from 3.84 % to 16 % on CO2/heavy oil MMP is evaluated. In this respect, slim tube miscibility and Vanishing Interfacial Tension (VIT) tests are used. Regarding the VIT test, the Interfacial Tension (IFT) is measured by means of two methods including pendant drop and capillary apparatuses, and thereafter the MMP measurement error between slim tube and VIT methods are calculated. Based on the results, by increasing the asphaltene content, the measured MMP by slim tube method increases linearly while that by VIT follows no clear trend. The results also indicate that there is an asphaltene content range within which the MMP error between slim tube and VIT tests is minimized. IFT measurement by pendant drop and Capillary Glass Tube (CGT) methods show that by increasing asphaltene content up to 10.15 %, IFT declines, whereas for further increase in content, IFT increases because of the irregular dispersion of asphaltene in oil droplets

    Mineral Content in Some Species of Leguminosae in Bandar Torkaman Plain Rangelands, Iran

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    Improving the forage quality and balance of their minerals in rangeland ecosystems is important for rangeland managers to improve livestock productivity (Mohamed et al. 2003; Epstein and Bloom 2005). This research investigated the amount of several minerals; Calcium (Ca), Phosphorus (P), Potassium (K) and Magnesium (Mg), in some important species of Leguminosae including Medicago sativa, Trifolium repens, Trifolium pratense and Lathyrus pratensis, that are grazed by livestock in the Bandar Torkaman plain rangelands in north of Iran

    An Investigation of the Wiener Approach for Nonlinear System Identification Benchmarks

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    We evaluate the effectiveness of the Wiener model structure in modeling of the given benchmark problems. Two different approaches are proposed for parameter estimation. The results are compared for three problems, i.e. Silver Box, Wiener-Hammerstein, and Wiener-Hammerstein with noise. The aim is to evaluate the capability of the algorithms on the other benchmark problems in future works as well

    A Data-Driven Statistical Approach for Monitoring and Analysis of Large Industrial Processes

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    Monitoring and fault detection of industrial processes is an important area of research in data science, helping effective management of the plant by the remote operator. In this article, a data-driven statistical model of a process is estimated using the principal component analysis (PCA) method and the associated probability density function. The aim is to use the model to monitor and detect the incurred faults in the industrial plant. The experimental data are collected by finding the suitable subsystems of a Recycle Gas in Ethylene Oxide production process, and a subset of nine variables are extracted for further statistical analysis of the system. The performance of the developed model for monitoring purpose is evaluated by using faulty and close to faulty inputs as the new test data

    Comparison of chromosomal instability of human amniocytes in primary and long-term cultures in AmnioMAX II and DMEM media: A cross-sectional study

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    Background: The genomic stability of stem cells to be used in cell therapy and other clinical applications is absolutely critical. In this regard, the relationship between in vitro expansion and the chromosomal instability (CIN), especially in human amniotic fluid cells (hAFCs) has not yet been completely elucidated. Objective: To investigate the CIN of hAFCs in primary and long-term cultures and two different culture mediums. Materials and Methods: After completing prenatal genetic diagnoses (PND) using karyotype technique and chromosomal analysis, a total of 15 samples of hAFCs from 650 samples were randomly selected and cultured in two different mediums as AmnioMAX II and DMEM. Then, proliferative cells were fixed on the slide to be used in standard chromosome G-banding analysis. Also, the senescent cells were screened for aneuploidy considering 8 chromosomes by FISH technique using two probe sets including PID I (X-13-18-21) & PID II (Y-15-16-22). Results: Karyotype and interphase fluorescence in situ hybridization (iFISH) results from 650 patients who were referred for prenatal genetic diagnosis showed that only 6 out of them had culture- derived CIN as polyploidy, including mosaic diploidtriploid and diploid-tetraploid. Moreover, the investigation of aneuploidies in senesced hAFCs demonstrated the rate of total chromosomal abnormalities as 4.3% and 9.9% in AmnioMAX- and DMEM-cultured hAFCs, respectively. Conclusion: hAFCs showed a low rate of CIN in two AmnioMAX II and DMEM mediums and also in the proliferative and senescent phases. Therefore, they could be considered as an attractive stem cell source with therapeutic potential in regenerative medicine. Key words: Human amniotic fluid cells, Chromosomal instability, Pseudomosaicism, Amniocentesis, Replicative senescence

    Machine-learning approach for fault detection in brushless synchronous generator using vibration signals

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    In order to maintain continuous production and to avoid the maintenance cost increment in power plants, it is important to monitor the condition of equipment, especially the generator. Regarding the impossibility of direct access to rotating diodes in brushless synchronous generators, the condition monitoring of these elements is very important. Here, a novel fault detection method is proposed for the diode rectifier of brushless synchronous generator. At the first stage of this method, the vibration signals are recorded and feature extraction is performed by calculating the relative energy of discrete wavelet transform components. Multiclass support vector machine (MSVM) is used for classification, and the best mother wavelet and number of decomposition level are chosen based on classification performance. To enhance the performance of the classification, a modified sequential forward subset selection approach is included by which the best statistical features are selected. In this approach, besides selecting the best subset of statistical features, the classification parameter is tuned according to the selected subset to achieve the best performance. The result of the proposed method is eventually compared with those results of classification performance using conventional subset selection. Experimental results show that the proposed method can detect rectifier faults effectively
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