فهرست مطالب m.safaei

The speed sensor is one of the main components of the control and monitoring systems of rotational machines which is widely used in the aviation industry, railway, and automotive applications. Variable Reluctance Speed sensor (VRS) is a kind of magnetic sensor that has been traditionally employed for many different industrial measurements because of several well-known advantages, such as passive nature, non-contact operations, robustness, low cost, low sensitivity to dirt, and large-signal output. In this paper, a variable reluctance speed sensor is proposed. The design process of the proposed sensor is presented and both the magnetic and electrical models of this sensor are derived by assuming the effect of magnetomotive force caused by eddy current formed on the outer edge of the target gear at high frequencies. As a result, the proposed model can demonstrate the performance of the variable reluctance speed sensor at high frequencies very well. The proposed VRS is designed and simulated using MATLAB and Ansys Maxwell software to verify the theoretical results is constructed and tested. In this paper, a variable reluctance speed sensor is proposed and studied. The magnetic and electrical models of the proposed sensor are derived and the output voltage equation has been calculated as a function of the air gap length. The proposed VR sensor is simulated using 2D Finite Element Analysis software to identify the main parameters that influence the sensor output and also to verify the accuracy of the model. According to the simulation results, the output waveform quality will be affected by parameters such as air gap length, target gear material, the self-inductance of the VR sensor, and the load component values. In terms of the electrical model, we were able to simulate the effect of load resistance and capacitance on the sensor output.

Lower Cretaceous carbonate rocks (Taft and Abkouh formations) in the south of Yazd host lead, zinc and barite ore deposits. Diagenetic processes after deposition in these carbonates have caused the formation of these deposits. The main diagenetic processes affecting these sediments include compaction, brecciation, neomorphism, cementation, dissolution, dolomitization and replacement. The dolomitization and replacement process has led to the formation of lead, zinc and barite ore deposits. Hydrothermal fluids through the active and normal faults have provided the conditions for the formation of these deposits in the carbonate rocks of this area. The formation of the ore deposit occurred during two stages of mesogenesis and telogenesis. In the mesogenesis stage and in the burial conditions, first dolomite is formed and after the entry of hydrothermal fluids and supply of necessary elements, the replacement has created sulfide minerals. During the telogenesis stage, some parts of the formed sulfide deposits are re-exposed to meteoric fluids, leading to the formation of oxide ore deposits.

This experiment was conducted to study the effects of nucleotide supplementation on induced ascites and its effects on growth performance, blood metabolites, and expression of hypoxia-inducible factor 1α (HIF-1α) mRNA in Ross 308 broiler chickens. A total of 672 one-day-old Ross 308 broiler chicks were allocated to eight treatments with two levels of common salt in drinking water (0 and 2 g/lit) and four dietary supplemental levels of nucleotides (0, 0.5, 1, and 2 g/kg diet). Each treatment was included 7 replicates of 12 birds each. The experimental design was completely randomized in a factorial arrangement. In this study, 0.2% salt in drinking water induced ascites, decreased body weight (BW), and increased mortality, right ventricle (RV) weight as well as RV to total ventricles ratio (P < 0.05). Results showed that nucleotide levels of 0.05 and 0.1% significantly decreased RV weight and blood triiodothyronine (T3) concentration on 42 d. Interaction effects between salt and nucleotide supplement revealed that 0.1% nucleotide level in the salt group significantly reduced blood T3 concentration in comparison with non-nucleotide supplemented and normal water group. Feed intake, weight gain, feed conversion ratio, carcass characteristics, and the expression of HIF-1α mRNA in heart of broilers were not significantly affected by excess salt, nucleotide supplement, and their interaction. It was concluded that 0.5 g/kg dietary nucleotide supplementation decreased the ascites parameter of the RV/BW ratio in broiler chickens.

In this study, the feeding habits of blue swimming crab (Portunus segnis) in the Northeast Persian Gulf were investigated. A total of 722 specimens were collected using bottom trawl. The samples were transferred to the laboratory in order to further analysis after freezing. All individuals were dissected and their stomach was removed. The results showed the vacancy index of stomach (CV) was 34.5. This finding indicated that this species is a gluttonous crab. Also the analysis of their feeding habits showed that this species is carnivorous. The main items included crustaceans, fishes and mollusks. Their diet varied seasonally. Crustaceans were more important in summer whereas fishes and mollusks were more important during autumn and winter, respectively. The crustaceans included shrimps and other crabs. The dominant mollusks were the bivalves such as common name Marcina hiantina, Circentia callipyga, Tellina sp., Cardita bicolor and gastropods Cerithium erythraeonese, Atys sp. There were significant differences in feed items occurrence frequency between sexes.

Phlomis bruguieri Desf. (Lamiaceae) is a perennial herbaceous plant distributed in Iran, Turkey and Iraq. Despite medicinal potentials of this species, the current knowledge on its phytochemical constituents is limited. The aim of the present study was to investigate the phytochemical constituents of the essential oil and various extracts of this species.

Essential oils of the plant aerial parts were extracted by hydrodistillation and steam distillation methods and analysed using GC and GC/MS.Column chromatography with silica gel (normal and reversed phases) and Sephadex LH-20 were also used for the isolation of compounds from various extracts obtained from P. bruguieri aerial parts. The structures of isolated compounds were established by 1D and 2D NMR techniques.

By GC and GC/MS analysis, germacrene D (29.8%), apiole (20.7%) and myristicin (16.63%) were identified as the main compounds of hydrodistilled oil. Apiole (53.20%) and myristicin (34.87%) were also detected as the main compounds of the oil extracted by steam distillation method. Phytochemical analysis of the plant extracts resulted in the isolation and structural elucidation of  β-sitosterol (1), p-coumaric acid methyl ester (2), chrysoeriol 7-O-(3''-(E)-p-coumaroyl)-β-D-glucopyranoside (3), chrysoeriol 7-O-(3'',6''-di-O-(E)-p-coumaroyl)-β-D glucopyranoside (4), chrysoeriol 7-O-β-D-glucopyranoside (5), chlorogenic acid (6) and verbascoside (7).

the results of the present study introduce steam distilled oil of P. bruguieri as a new source of apiole and myristicin. Moreover, identification of coumaroyl flavone glycosides and cinammic acid derivatives from the aerial parts of this species highlighted the species as a good candidate for further biological and pharmacological studies.

The ability of green microalgae, Dunaliella salina for existence, growth, nitrat reductase activity and ammonium release in low light, ambient CO2 and saline condition was studied for a better understanding of it is biotechnological importance. Samples were cultivated in Johnson medium whit NaCl, 7.5, 15, 30 and 50% or without NaCl(control), 30◦C±1◦C, continious white light, 1500 lux, provided by fluorescent lamps and were aerated continiously using aquarium pumps. Based on the results of the present research, the best growth obtained in NaCl 7.5% for along term period, although in short term, a very high growth rate was obtained in NaCl 50% (Saturated salinity). Ammonium release was maximum in NaCl 50% and the nitrate reductase activity was minimum in the same salinity but there was no statistically significant correlation between ammonium release and nitrate reductase activity. The ability of Dunaliella salina in releasing high amount of ammonium and growth in low and high salinity makes it an important candidate as a new biofertilizer.

Cyanobacterium Nostoc sp. can be considered as an interesting microorganism for the ability of excretion buffering compounds. With respect to possible applied potential of this strain, this ability has been studied under limited irradiance. Soil samples were collected from paddy-fields during one year. At the first step, different acidities (pHs 5,7,9) were studied under limited carbon dioxide condition. Results showed that in all treatments, organism tends to enter logarithmic phase of growth until third day, but acidic condition cause sharp decline on growth after this. Highest specific growth rate belong to alkaline condition (pH 9). For the next step, two alkaline condition near to pH 9 (pHs 8.5 and 9.5), were selected to compare. Results showed that specific growth rate was significantly less than pH 9, and even continuous aeration couldn’t be able to enlarge specific growth rate. Pigment composition can be rearranged at different acidities and phycobilisome systems cause viability and growth under acidity fluctuations and limited irradiance in addition of low carbon dioxide concentration. Ammonium liberation showed the highest rate at pH 5 and day two too.