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Author(s): 

ASHRAFI S. | ALIEV N.

Issue Info: 
  • Year: 

    2012
  • Volume: 

    2
  • Issue: 

    3
  • Pages: 

    2750-2757
Measures: 
  • Citations: 

    1
  • Views: 

    183
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    17
Measures: 
  • Views: 

    158
  • Downloads: 

    385
Abstract: 

BACKGROUND: SODIUM SULFIDE (NA2S) IS THE MOST IMPORTANT AND APPLICABLE COMPOUND AMONG ALKALI AND ALKALINE EARTH SULFIDES. NA2S IS USED IN A PROCESS FOR PRODUCING POLY (PHENYLENE SULFIDE) AND POLYSULFIDE POLYMERS. IT ALSO IS USED IN REDUCTION OF POLYNITROAROMATICS AND IN ENGINE OILS [1]. IN THE LABORATORY, ANHYDROUS NA2S CAN BE PREPARED BY REACTION OF SULFUR WITH SODIUM IN ANHYDROUS AMMONIA OR IN DRY THF WITH A CATALYTIC AMOUNT OF NAPHTHALENE [2]:2 NA + S ® NA2SINDUSTRIALLY NA2S IS PRODUCED BY REDUCTION OF SODIUM SULFATE WITH CARBON, IN THE FORM OF COAL AT 700- 900OC [3]:NA2SO4 +2C®NA2S+2CO2METHODS: IN THIS RESEARCH WE WISH TO REPORT OPTIMIZED PROCESS FOR THE SYNTHESIS OF NA2S USING NA2SO4 AND COAL. RAW MATERIALS OF THE REACTION ARE GRINDED VERY WELL IN MORTAR WHICH PASS TROUGH SIEVE WITH MESH 100. THE MIX OF NA2SO4 AND COAL IS HEATED IN ELECTRICAL FURNACE. AFTER EVOLUTION OF CO2 AND CO BEGINS THE REACTION MASS BECOMES VERY FLUID ON FURTHER HEATING, IT BECOMES PASTY AND FINALLY SOLID. THE PRODUCED SODIUM SULFIDE THAT CONTAINS EXCESS CARBON, ASH COMPONENTS AND OTHER SOLID IMPURITIES IS LEACHED WITH WATER, AND THE UNDISSOLVABLE COMPONENTS ARE REMOVED BY FILTRATION. THE FILTRATE IS CONCENTRATED BY EVAPORATION AND SOLIDIFIES BY COOLING.RESULTS: OPTIMIZED WEIGHT RATIO OF NA2SO4 TO COAL WAS 3.94:1. BEST YIELD OBTAINED AT 800OC FOR 2 HOURS. IN LEACHING STEP WEIGHT RATIO OF WATER TO SOLID PRODUCT MASS WAS 2.4:1. PURITY OF THE EVAPORATED FINAL PRODUCT WAS 60% AND SOLIDIFICATION TEMPERATURE WAS 90OC.CONCLUSION: IN SUMMARY, WE FOUND AN ECONOMICAL AND LocalLY DEPENDENT PROCEDURE FOR PRODUCTION OF NA2S. THE FEATURES OF THIS METHOD ARE HIGH YIELDS, OPERATIONAL SIMPLICITY AND THE ENVIRONMENTALLY FRIENDLY METHOD.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    17
Measures: 
  • Views: 

    999
  • Downloads: 

    306
Abstract: 

BACKGROUND: TETRA SODIUM PYROPHOSPHATE (TSPP) WITH THE FORMULA NA4P2O7 IS USED AS A BUFFERING AGENT, AN EMULSIFIER, A DISPERSING AGENT, AND A THICKENING AGENT, AND IS USED AS A FOOD ADDITIVE. TSPP IS SOMETIMES USED IN DETERGENTS AND TOOTHPASTE AS ANTI-DEPOSITION AGENT [1]. THE CONVENTIONAL TSPP PRODUCTION METHODS INVOLVE A TWO STEPS REACTION: 1) NEUTRALIZATION OF PHOSPHORIC ACID WITH NA2CO3 AT 90-105OC FOR PRODUCING DISODIUM PHOSPHATE (DSP) AND 2) CONDENSATION OF DSP IN CALCINATION CONDITION [2].METHODS: IN THIS RESEARCH WE WISH TO REPORT OPTIMIZED PROCESS FOR THE SYNTHESIS OF TSPP USING PHOSPHORIC ACID AND SODIUM HYDROXIDE AS ROW MATERIALS. IN THE 1ST STEP, PHOSPHORIC ACID IS NEUTRALIZED TO DSP AS A MIDDLE PRODUCT THEN THE WATER OF THE REACTION IS EVAPORATED AND IN THE 2ND STEP DRIED DSP IS CALCINED TO TSPP. (FIGURE 1).RESULTS: THE NAOH/H3PO4 MOLE RATIO WAS 1.98/1 AT 98OC AND THE WATER CONTENT OF DRIED DSP WAS 6.0%. THE CALCINATION TEMPERATURE WAS 300-350OC. THE PURITY OF TSPP WAS 98%.CONCLUSION: IN SUMMARY, WE FOUND AN ECONOMICAL PROCEDURE FOR PRODUCTION OF TSPP BY A TWO STEPS METHOD. THE FEATURES OF THIS PROCEDURE ARE HIGH YIELDS, OPERATIONAL SIMPLICITY AND THE ENVIRONMENTALLY FRIENDLY METHOD. MEANWHILE, PRODUCTION OF TSPP IS DEPENDENT ON THE Local Conditions.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

GLADKOV A. | NIKITIN A.

Journal: 

VIRTUAL

Issue Info: 
  • Year: 

    621
  • Volume: 

    1
  • Issue: 

    1
  • Pages: 

    1-10
Measures: 
  • Citations: 

    1
  • Views: 

    202
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    1393
  • Volume: 

    11
Measures: 
  • Views: 

    503
  • Downloads: 

    0
Abstract: 

لطفا برای مشاهده چکیده به متن کامل (PDF) مراجعه فرمایید.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2000
  • Volume: 

    11
  • Issue: 

    3
  • Pages: 

    233-237
Measures: 
  • Citations: 

    0
  • Views: 

    335
  • Downloads: 

    139
Abstract: 

Krein [1] mentioned that for each PD equation we have two extreme operators, one is the minimal in which solution and its derivatives on the boundary are zero, the other one is the maximal operator in which there is no prescribed boundary Conditions. They claim it is not possible to have a related boundary value problem for an arbitrarily chosen operator in between. They have only considered Local Conditions and so their claim is justified, particularly, for partial differential boundary value problems of odd orders. By considering more general (non-Local and global) Conditions, we showed this is not necessarily true. With similarly general Conditions as considered in this paper one can define a boundary value problem for PDEs of odd order and also problems with Local Conditions will be a particular case of this general form. In this paper, a mixed problem for a parabolic equation with general Conditions is analytically investigated and, in a closed from, its unique solution is shown.

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Issue Info: 
  • Year: 

    2011
  • Volume: 

    11
  • Issue: 

    2
  • Pages: 

    199-213
Measures: 
  • Citations: 

    0
  • Views: 

    765
  • Downloads: 

    0
Abstract: 

Wind is the carrier of pollutants and any other gaseous or particle matters in the atmosphere. Stable atmosphere with low wind provides favourable Conditions for high contamination of pollutants in urban areas. The importance of mesoscale atmospheric flows in air pollution dispersion has been recognized in the past three decades and has been the focus of intensive research, both observational and numerical. Mesoscale or Local scale circulations are more prominent when the synoptic pressure gradients are weak, allowing horizontal temperature contrasts to develop, which in turn lead to mesoscale pressure perturbations. Tehran, a city which is situated at the southern foothills of the Alborz Mountain chain has an average elevation of 1500m, and covers an area of 864 km2. Alborz Mountains have a significant influence on the dynamics and thermodynamic modification of wind regime over the city. At the same time, the Urban Heat Island effect (UHI) can cause its own mesoscale flow, complicating an already complex Local scale flow. The topography and the urban fabric can cause slope flows, mountain flows, and valley flows amongst many other factors. Th is paper focuses on the use of state-of-the-art atmospheric numerical model – The Weather Research and Forecasting (WRF) – in an ideal situation to study the characteristics of the mesoscale flow systems that prevail over Tehran when air quality is unfavourable. So average sound of Radiosonde at Mehrabad station, for almost all the fair days of cold seasons from 2005 to 2008 was selected as an ideal initial condition and boundary condition with 10 × 10 km spatial and 12-hour temporal resolution. The simulations were carried out for a 3-day period in December 2005 when an aircraft , due to low visibility caused by high concentration of air pollution, crashed 2 miles away from the end of runway into an inhabited area. Three simulations were prepared. For the first experiment, called control run, we used the default urban setting of Tehran. In the second simulation, urban properties of Tehran were removed completely from the land-use fed to the model to investigate the effect of urban area on thermally induced circulation in Tehran. This simulation was called NoURB simulation. To investigate the role of the roughness in the urban area, a 3rd simulation was prepared. In this simulation, which was referred to as HiFric simulation, three urban categories were used, class 31 of USGS land use/land cover was used for "Low Intensity Residential", which included areas with a mixture of constructed materials and vegetation. These areas were most commonly included as single-family housing units in which the population densities were lower than those in high intensity residential areas. Class 32 of USGS represented "High Intensity Residential" which included highly developed areas where people resided in large numbers. Finally class 33 of USGS was used for "Commercial/Industrial/Transportation", which included infrastructures (e.g. roads, railroads, etc.) and all highly developed areas not classified as High Intensity Residential. The results indicated that urban areas near complex topography can increase transfer of material (pollution) and energy from boundary layer to the free atmosphere. Besides the ideal simulation, we investigated some observational aspects of the transition time by wind persistence charts. The results showed that we have a 2 to 3-hour lag time at the evening transition of northern and southern part of the city which could improve the pollution potential in this period. This fact may play an important role in Tehran megacity management.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    13
  • Issue: 

    1
  • Pages: 

    43-68
Measures: 
  • Citations: 

    0
  • Views: 

    144
  • Downloads: 

    10
Abstract: 

The central issue of the present paper is the study of the causes of the mother tongue decline in the Sahne city in Kermanshah province. The issue of language is beyond the dialect of people and is refer to the form of life and the matter of macroeconomic and political relations. From this perspective, the form of life and the language associated with it explain the praxis of the members of the society. The appropriate method of examining the problem should be able to analyze the justification of agents to their situation, that is why Grounded Theory is chosen as the method of this research and data analysis is taken from abduction reasoning. The results of the analysis introduced the categories of globalizing, modernizing, de-use of language, economic necessity and the government as the most important factors of Local language fading. In this essay the meaning of globalization is the globalizing of special type of economic relation that explain other categories role in the process of fading of languages.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2021
  • Volume: 

    52
  • Issue: 

    2
  • Pages: 

    67-82
Measures: 
  • Citations: 

    0
  • Views: 

    166
  • Downloads: 

    16
Abstract: 

Identifying the constraining factors of production and yield gap is very important. Therefore; this research was performed to identify the production constraining factors of Local rice cultivars. All management practices from nursery preparation to harvesting stages for 100 paddy fields of Local rice cultivars were recorded through field studies, in Sari, from 2015-2016. In the CPA, the actual and calculated potential yield were 4495 and 5703 kg/ha, respectively and the gap was 1221 kg/ha. The yield gap caused by number of top-dressing variables was 324 kg/ha, equal to 27% of the total yield gap. The yield gap related to previous year of legumes cultivation was 218 kg ha-1, equal to 18% of the total yield variation. Among the 10 variables entered in the CPA model, the effects of top-dress fertilizer application and its application frequency and foliar application were remarkable, which could compensate a significant part of the yield gap (444 kg/ha, 37% of total) in the farmers’ fields by managing these variables. According to boundary line analysis (BLA) finding, actual yield mean on the basis of optimal limit related to 12 variables under study was 5369 kg/ha, with 881 kg/ha yield gap . Mean relative yield and relative yield gap for 12 variables (transplanting date, seedling age, number of seedlings per hill, planting density, nitrogen and phosphorous per hectare, nitrogen before transplanting, harvesting date, lodging problem, pest problem, diseases problem and weeds problem) were 83.64 and 16.35 kg/ha, respectively. Based on the finding, it can be stated that the model precision is appropriate and can be applied for both estimation of the quantity of yield gap and determining the portion of each restricting yield variables.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    13
  • Issue: 

    1
  • Pages: 

    105-140
Measures: 
  • Citations: 

    0
  • Views: 

    170
  • Downloads: 

    18
Abstract: 

The present research studied the (causal, contextual, and intervening) Conditions, strategies, and consequences of violence in the lives of child wives in Chabahar city, conducted with a qualitative methodology based on grounded theory. For this purpose, in-depth semi-structured interviews were conducted with 28 child-married girls in Chabahar city who were selected through theoretical sampling and snowball method. The analysis of the data in the framework of the three-level open, axial and selective coding system showed that gendered inequality and discrimination, women's inferiority, men's value, the culture of silence and the culture of violence play a role in the experience of child-wives in terms of violence (causal Conditions), which leads to a type of increased, double violence for them (core category); violence that operates within the framework of the family institution, the main mechanism of which are previous traditions and rules, and the perpetrators of which are men and women who were themselves the victims of the same traditions and rules that they have, now, internalized and used again against their daughters. This increased violence happens in a context where patriarchy is widespread (contextual Conditions) and due to the generalized self-deprecation among child wives (intervening Conditions), they may attempt to escape, get separated, threaten, and commit suicide (strategies), and these actions have consequences such as symbolic, physical, and sexual violence and even social isolation (consequences).

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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