Longitudinal jerk and celeration as measures of safety in bus rapid transit drivers in Tehran

Abstract

Traditionally, analysis of individual differences in road traffic crash risk has relied on after the fact crash data. Nowadays with the help of technologies like GPS, new measures are developed to assess driving risk, inferred from naturalistic driving behaviour of drivers. In this study, two main ways of modelling driver behaviour in naturalistic driving research were discussed and compared to each other. For this purpose, 176 Bus Rapid Transit (BRT) drivers were investigated during their normal driving on Tehran BRT routes. Their speed was continuously recorded by a smart phone app from which was derived deceleration, jerk and celeration measures. Analysis showed that all of the proposed measures had positive correlations with culpable crashes and that one of the jerk variables yielded the highest correlation. Measurements of speed derivatives like jerk and celeration can help to identify dangerous driving styles in public transportation and reduce the number of crashes. Although the results of this study are encouraging, further studies for longer periods are needed to improve the reliability of the measures.     

Doping effects of Co on exo-hydrogenated narrow single-walled carbon nanotubes

Density functional theory (DFT) calculations with the generalized gradient approximation (GGA) were employed for a systematic study of electronic structure and morphologic characteristics of bare and exo-hydrogenated Co-doped single walled carbon nanotubes (CNTs). Two internally and one externally doping configurations for the cobalt adatoms were investigated. Binding energies, bond lengths and angles, under full and half converge of the adsorbed hydrogen atoms were calculated for both cases. Effect of hybridization between the Co-3d and the H-s orbitals showed that the exo-hydrogenated CNTs with full and half coverage cases would be stable in the internally doped Co atom systems; whereas, the stability of the hydrogenated systems under externally doped Co adatom was not trivial. In general, for the externally Co-doping, the Co atoms can act as additional adsorbents so the amount of total adsorbed hydrogens could be varied substantially; whereas, for the internally Co-doping the nature of the exo-hydrogenation (being atomic or molecular) shows nanotube's chirality dependent.     

Milk Thistle Seed Oil Constituents from Different Varieties Grown in Iran

In this study, fatty acids, phytosterol classes and tocopherols composition of Milk thistle seeds oil were determined at four varieties grown in Ardebil-Iran. The four varieties consisted of two modified foreign varieties—Budakalaszi (originally from Hungary) and the CN-seed variety (originally from England) and two native varieties, namely Khoreslo and Babak Castle. The oil content of the seeds ranged from 26 to 31%. Among the fatty acids, linoleic acid had the highest percentage (50–54%) followed by oleic acid (23–29%) and palmitic acid (7–8%). This is the first detailed report on the phytosterol classes of milk thistle seeds oil. The 4-Desmethylsterol class was predominant (1,800–2,200 μg/g) followed by 4,4′-dimethylsterols (50–85 μg/g) and 4-monomethylsterols (26–35 μg/g). The α-, β-, γ-, and δ-tocopherols ranged from 187 to 465, 10 to 51, 9 to 12, and 18 to 80 μg/g oil, respectively. Based on the results obtained, the extracted oil from milk thistle seeds are rich in essential fatty acids, sterols and vitamin E and can be an attractive candidate for use in food preparation mixed with other vegetable oils or alone.     

Microencapsulation of disperse dye particles with nano film coating through layer by layer technique

Throughout the past ten years, comprehensive understanding of fundamental and applied research has focused on functional coating and specifically on microencapsulaion. In this study, weak polycation poly(allylamine hydrochloride) and strong polyanion poly(sodium styrene sulfonate) were used for fabrication of nano film through layer by layer technique on the surface of disperse dye particles. Then micron‐sized particles were surrounded by poly(urea formaldehyde) using in‐situ polymerization. Chemical structure, surface morphology, and size distribution of these novel microcapsules were characterized by Fourier transform infrared spectrometry, differential scanning calorimetry, optical microscopy, and scanning electronic microscopy. Size and surface morphology of the microcapsules can be optimized by selecting proper weight ratio of urea to formaldehyde and core to shell material type, and amount of surfactant and agitation rate. This technology demonstrated good capability in several applications in textile industry, such as dying fabrics because of saving huge amount of water and showing slow‐release property of dye without using dye assistant agents. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fabrication of a porous wall and higher interconnectivity scaffold comprising gelatin/chitosan via combination of salt-leaching and lyophilization methods

A novel gelatin/chitosan scaffold with higher porosity and interconnectivity was designed through salt-leaching/lyophilization (SLL) method. The properties of the fabricated scaffolds were compared with conventional scaffolds, which are obtained by thermally induced phase-separation (TIPS) method. The scaffolds made by phase-separation method have high tensile strength, but suffer from less channel interconnectivity, pore uniformity and also low surface porosity. The microstructure, porosity, phosphate-buffered saline (PBS) solution absorption and tensile strength of the prepared scaffolds by SLL method were studied. In this work, SLL as a two-step technique is introduced for creating porosity to improve both channel interconnectivity and pore uniformity for water-soluble polymers in comparison with the TIPS method. The SLL technique includes two mechanisms: the first, leaching of mixed sodium chloride crystals and particles created during recrystallization of the dissolved NaCl and the second, phase separation during lyophilization at the pore walls. These two steps in porosity formation lead to special pore morphology, which is more suitable for cell culturing because of higher interconnectivity and rich surface porosity in comparison with the phase-separated scaffolds. The prepared scaffolds, using this technique with different salt/polymer ratios and salt crystal size, have 91?C97% porosity and 94?C190???m mean pore size with tensile strength of 72?C215?kPa and PBS solution absorption between 12.4 and 19 times dry weight. The pore size of scaffolds prepared using the SLL method could be adjusted independently of polymer solution concentration. These scaffolds have a great potential in skin tissue engineering application.     

Geochemical characteristics of upper Jurassic carbonate reservoir bitumen in the Eastern Kopeh-Dagh,NE Iran

Geochemical characteristics of solid bitumen in Upper Jurassic carbonate reservoir are investigated. Aromatic maturity parameters indicate peak to late oil window level of maturity for the bitumen samples. Regular sterane distributions, conical variable (CV), plots of δ¹³C_Sat versus δ¹³C_Aro and Pr/nC₁₇ against Ph/n_C18, predominance of C₂₃ tricyclic terpane, ratios of steranes/hopanes and C₂₃/C₂₁ tricyclic terpane indicate charging from clastic-rich anoxic marine source rocks. Ratios of C₂₉/C₃₀ hopane, Ts/Ts+ Tm, C₂₄ tetracyclic terpane/C_20-26 tricyclic terpanes and plot of C₂₂/C₂₁ versus C₂₄/C₂₃ tricyclic terpanes show influences of carbonate/marl facies. All these would throw crucial guiding light on the interpretation of the future exploration.     

Effect of cosolvent and addition of catalyst (HZSM‐5) on hydrothermal liquefaction of macroalgae

The present study aimed to evaluate the effect of the direct liquefaction of macroalgae in an autoclave reactor (50 mL) possessing water and ethanol as cosolvent. The reaction conditions such as duration, temperature, algae/solvent ratio, the composition of cosolvent (ethanol‐water) on product distribution, and bio‐oil characterization were studied. The optimum conditions such as 300°C of temperature, 45 minutes of reaction time, 75% of ethanol, and algae to solvent ratio of 4/40 g/mL supported the bio‐oil yield of 46.75% with a conversion rate of 95.5%. The composition and concentration of the compounds in the bio‐oil produced under various doses of catalyst were described using GC‐MS. The bio‐oil characterization showed that the esters were most predominant in hydrothermal liquefaction with a catalyst (HZSM‐5) compared with hydrothermal liquefaction in the absence of the catalyst.