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Wyświetlanie 1-5 z 5
Tytuł:
Microstructure Development of Spark Plasma Sintered Ti-Nb Alloy by Heat Treatment
Autorzy:
Haq, M. A.
Abbas, S. F.
Eom, N. S. A.
Kim, T. S.
Lee, B.
Park, K.-T.
Kim, B. S.
Powiązania:
https://bibliotekanauki.pl/articles/355593.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
TiNb alloy
Spark plasma sintering
Heat treatment
Microstructure
β-phase titanium
Opis:
The β-phase Titanium (β-Ti) alloys have been under the spotlight in the recent past for their use as biomedical prosthetic materials owing to their excellent properties such as low elastic modulus, high corrosion resistance and tensile strength. Recently, Niobium (Nb) has gained a lot of attention as a β-phase stabilizing element in Ti alloys to replace Vanadium (V) due to its excellent solubility in Ti, low elastic modulus and biocompatibility. In this work, low cost Ti-20Nb binary alloy has been fabricated via powder metallurgy procedures. The blended powder mixtures of Ti and Nb were sintered at 900°C for 20 mins by the Spark Plasma Sintering (SPS) with an applied uniaxial pressure of 40 MPa. The heating rate was fixed at 50°C/min. The sintered alloy was subject to heat treatments at 1200°C in vacuum condition for various time durations. The characterizations of microstructure obtained during this process were done using FE-SEM, EDS and XRD. By increasing heat treatment time, as understood, the volume of residual Nb particles was decreased resulting in accelerated diffusion of Nb into Ti. Micro hardness of the alloy increased from 340 to 355 HV with the increase in β phase content from 30 to 45%. The resultant alloys had relatively high densities and homogenized microstructures of dispersed lamellar β grains in α matrix.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 3; 1429-1432
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling and simulation of an ideal plug flow reactor for synthesis of ethyl oleate using homogeneous acid catalyst
Autorzy:
Barno, Suondos K.A.
Rashid, Sarmad A.
Abbas, Ammar S.
Powiązania:
https://bibliotekanauki.pl/articles/2034051.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kinetics
simulation
ethyl oleate
product distribution
back-mixing
kinetyka
symulacja
oleinian etylu
dystrybucja produktu
mieszanie wsteczne
Opis:
The production of ethyl oleate, by homogenous acid esterification of oleic acid with ethanol, have discussed experimentally and via computational simulation in a plug flow reactor. An innovative simulation model has developed to predict the esterification reaction performance in an ideal plug flow reactor. The amount of H2SO4 acid catalyst, the initial molar ratio of alcohol to oleic acid, ethanol concentration, reaction temperature, and esterification time have examined their effects on ethyl oleate production and the conversion of oleic acid. Then the simulation extended to examine the esterification reaction kinetics and determine the reaction rate coefficients. The simulation results demonstrate that the increasing of H2SO4 acid, initial molar ratio of ethanol to oleic acid, ethanol concentration, and reaction temperature improved the productivity of the ethyl oleate and reduced the reactor space-time. The kinetics results illustrated that the reaction sensitivity to the temperature unchanging by using higher ethanol concentration and alcohol to oleic acid initial ratio. Lastly, the experimental yields at different conditions were slightly higher from those simulating with average values of 93.62 and 92.29%, respectively, indicating that the phenomenon of back-mixing cannot be ignored in esterification reactors, especially with a relatively high retention time within the reactor.
Źródło:
Chemical and Process Engineering; 2021, 42, 1; 53-68
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis of influential factors associated with rural crashes in a developing country: a case study of Iran
Autorzy:
Sheykhfard, Abbas
Haghighi, Farshidreza
Abbasalipoor, Reza
Powiązania:
https://bibliotekanauki.pl/articles/2173931.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
rural roads
severity of crashes
crashes
injury-fatal crashes
logit model
crash data collected
drogi wiejskie
ciężkość wypadków
awarie
wypadki śmiertelne
model logiczny
Opis:
Road traffic deaths continue to rise, reaching 1.35 million in recent years. Road traffic injuries are the eighth leading cause of death for people of all ages. Note that there is a wide difference in the crash rate between developed and developing countries and that developed countries report much lower crash rates than developing and underdeveloped countries. World Health Organization reports that over 80% of fatal road crashes occur in developing countries, while developed countries account for about 7% of the total. The rate of road crashes in developing countries is higher than the global average, despite some measures reducing deaths over the last decade. Numerous studies have been carried out on the safety of urban roads. However, comprehensive research evaluating influential factors associated with rural crashes in developing countries is still neglected. Therefore, it is crucial to understand how factors influence the severity of rural road crashes. In the present study, rural roads in Mazandaran province were considered a case study. The Crash data collected from the Iranian Legal Medicine Organization covers 2018 to 2021, including 2047 rural crashes. Dependent variables were classified as damage crashes and injury-fatal crashes. Besides, independent variables such as driver specifications, crash specifications, environment specifications, traffic specifications, and geometrical road specifications were considered parameters. The logit model data indicate that factors associated with driver and crash specifications influence rural crashes. The type of crashes is the most critical factor influencing the severity of crashes, on which the fatal rate depends. The findings suggested that implementing solutions that minimize the effect of the factors associated with injury and death on rural roads can reduce the severity of crashes on rural roads that share the same safety issues as the case study. Further studies can also be conducted on the safety and mechanics of the vehicle by focusing the research on the types of vehicles and the sources of the damage.
Źródło:
Archives of Transport; 2022, 63, 3; 53--65
0866-9546
2300-8830
Pojawia się w:
Archives of Transport
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sporadoceratid ammonoids from the Shotori Range (east-central Iran) - a case of putative gigantism caused by hydraulic sorting?
Autorzy:
Korn, Dieter
Ghaderi, Abbas
Devaere, Léa
Hairapetian, Vachik
Khanehbad, Mohammad
Belka, Zdzisław
Powiązania:
https://bibliotekanauki.pl/articles/949758.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Late Devonian
Famennian
Iran
ammonoids
body size
conodonts
dewon
famen
amonoidy
rozmiar
konodonty
Opis:
The Shotori Range of east-central Iran (east of Tabas) has yielded Famennian ammonoid assemblages dominated by the family Sporadoceratidae. Four genera Maeneceras Hyatt, 1884, Iranoceras Walliser, 1966, Sporadoceras Hyatt, 1884 and Erfoudites Korn, 1999 are represented. The conodont assemblage of one sample containing Iranoceras revealed an Upper marginifera Zone age. The ammonoid assemblages are characterised by comparatively large specimens; they reach conch diameters of 300 mm (including the body chamber) and the mean size is larger than 100 mm. The preservation of the material from the Shotori Range and size comparison with sporadoceratid assemblages from the Anti-Atlas of Morocco and the Rhenish Mountains of Germany suggest that hydraulic sorting has resulted in a bias towards large conchs, explaining the size distribution, rather than latitudinal differences. The new species Maeneceras tabasense is described; the genus Iranoceras is revised with a new description of the two species Iranoceras pachydiscus (Walliser, 1966) and Iranoceras pingue (Walliser, 1966).
Źródło:
Acta Geologica Polonica; 2019, 69, 1; 27-49
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Predicting and minimizing the blasting cost in limestone mines using a combination of gene expression programming and particle swarm optimization
Autorzy:
Bastami, Reza
Bazzazi, Abbas Aghajani
Shoormasti, Hadi Hamidian
Ahangari, Kaveh
Powiązania:
https://bibliotekanauki.pl/articles/1853861.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kopalnia wapienia
wybuch detonacyjny
regresja nieliniowa
blasting cost
limestone mine
gene expression programming
non-linear multivariate regression
particle swarm optimization algorithm
environmental impacts
Opis:
Blasting cost prediction and optimization is of great importance and significance to achieve optimal fragmentation through controlling the adverse consequences of the blasting process. By gathering explosive data from six limestone mines in Iran, the present study aimed to develop a model to predict blasting cost, by gene expression programming method. The model presented a higher correlation coefficient (0.933) and a lower root mean square error (1088) comparing to the linear and nonlinear multivariate regression models. Based on the sensitivity analysis, spacing and ANFO value had the most and least impact on blasting cost, respectively. In addition to achieving blasting cost equation, the constraints such as frag-mentation, fly rock, and back break were considered and analyzed by the gene expression programming method for blasting cost optimization. The results showed that the ANFO value was 9634 kg, hole dia-meter 76 mm, hole number 398, hole length 8.8 m, burden 2.8 m, spacing 3.4 m, hardness 3 Mhos, and uniaxial compressive strength 530 kg/cm2 as the blast design parameters, and blasting cost was obtainedas 6072 Rials/ton, by taking into account all the constraints. Compared to the lowest blasting cost among the 146-research data (7157 Rials/ton), this cost led to a 15.2% reduction in the blasting cost and optimal control of the adverse consequences of the blasting process.
Źródło:
Archives of Mining Sciences; 2020, 65, 4; 835-850
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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