Calculation of maximum surface settlement induced by EPB shield tunnelling and introducing most effective parameter

This study aims to predict ground surface settlement due to shallow tunneling and introduce the most affecting parameters on this phenomenon.Based on data collected from Shanghai LRT Line 2 project undertaken by TBM-EPB method,this research has considered the tunnel's geometric,strength,and operational factors as the dependent variables.At first,multiple regression(MR) method was used to propose equations based on various parameters.The results indicated the dependency of surface settlement on many parameters so that the interactions among different parameters make it impossible to use MR method as it leads to equations of poor accuracy.As such,adaptive neuro-fuzzy inference system(ANFIS),was used to evaluate its capabilities in terms of predicting surface settlement.Among generated ANFIS models,the model with all input parameters considered produced the best prediction,so as its associated R~2 in the test phase was obtained to be 0.957.The equations and models in which operational factors were taken into consideration gave better prediction results indicating larger relative effect of such factors.For sensitivity analysis of ANFIS model,cosine amplitude method(CAM) was employed; among other dependent variables,fill factor of grouting(n) and grouting pressure(P) were identified as the most affecting parameters.     

Preparation of tungsten oxide nanoporous thin film at carbon ceramic electrode for electrocatalytic applications

The electrodeposition of nanoporous tungsten oxide (WO₃) on the surface of carbon ceramic electrode (CCE) was described. The morphology of the WO₃ modified electrode was characterized by scanning electron microscopy and X-ray diffraction. The modified electrode was utilized as an electrochemical hydrogen peroxide sensor in a low potential with a high sensitivity and selectivity. The role of supporting matrix on the sensitivity of modified electrode was studied. The detection limit of 0.26 μM (S/N = 3) and the sensitivity of 16.8 A M⁻¹ cm⁻² were compared with some other metal oxides hydrogen peroxide sensors. The modified electrode has exhibited good reproducibility, long-term stability and negligible interference of some inorganic and biological compounds.     

Kenaf‐bast‐fiber‐filled biodegradable poly(butylene succinate) composites: Effects of fiber loading,fiber length,and maleated poly(butylene succinate) on the flexural and impact properties

Poly(butylene succinate) (PBS) filled kenaf bast fiber (KBF) composites were fabricated via compression molding. The effects of KBF loading on the flexural and impact properties of the composites were investigated for fiber loadings of 10–40 wt %. The optimum flexural strength of the composites was achieved at 30 wt % fiber loading. However, the flexural modulus of the composites kept increasing with increasing fiber loading. Increasing the fiber loading led to a drop in the impact strength of about 57.5–73.6%; this was due to the stiff nature of the KBF. The effect of the fiber length (5, 10, 15, and 20 mm) on the flexural and impact properties was investigated for the 30 wt % KBF loaded composites. The composites with 10‐mm KBF showed the highest flexural and impact properties in comparison to the others. The inferior flexural and impact strength of the composites with 15‐ and 20‐mm KBF could be attributed to the relatively longer fibers that underwent fiber attrition during compounding, which consequently led to the deterioration of the fiber. This was proven by analyses of the fiber length, diameter, and aspect ratio. The addition of maleated PBS as a compatibilizer resulted in the enhancement of the composite's flexural and impact properties due to the formation of better fiber–matrix interfacial adhesion. This was proven by scanning electron microscopy observations of the composites' fracture surfaces. The removal of unreacted maleic anhydride and dicumyl peroxide residuals from the compatibilizers led to better fiber–matrix interfacial adhesion and a slightly enhanced composite strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Progression from Graphene and Graphene Oxide to High Performance Polymer-Based Nanocomposite: A Review

In this article, various types of carbon nanofiller and modification of graphene oxide and graphene for the preparation of polymer-based nanocomposites are reviewed. Recently, polymer/graphene and graphene oxide-based materials have attracted tremendous interest due to high performance even at low filler content. The property enhancement is due to the high aspect ratio, high surface area and excellent electrical, thermal and mechanical properties of nanofiller. Different techniques have been employed to fabricate polymer/graphene and graphene oxide nanocomposite with uniform dispersion due to fine matrix/nanofiller interaction. Here we discuss the structure, properties and preparation of these nanocomposites.     

Strain‐rate‐dependent mechanical properties of polypropylene separator for lithium‐ion batteries

The mechanical integrity of battery separators is critical for battery safety and durability. A comprehensive study of strain‐rate‐dependent tensile and puncture properties of a polypropylene lithium‐ion battery separator is presented here with a new model. Due to anisotropy of the polymeric membrane, tensile testing was conducted for different directions. Results showed that tensile strength and elastic modulus were increased 1000% and 500%, respectively, for different directions. It was also demonstrated that tensile strength changed 10 to 25% with strain rate (1.67 × 10^?4 to 1.67 × 10^?1 s^?1) for different directions. An equation was obtained for the first time for flow stress versus strain rate at varied tensile directions with respect to machine direction. Moreover, puncture testing was performed and it was shown that puncture strength was increased 140% with increasing strain rate from 0.25 to 250 mm min^?1. Two failure modes were also observed in puncture samples. Finally, Eyring's model was used to calculate activation enthalpy of the porous polypropylene separator. © 2020 Society of Chemical Industry     

Influence of Different Additives on the Interaction of Quinolone Antibiotic Drug with Surfactant: Conductivity and Cloud Point Measurement Study

Conductometric and cloud point (CP) measurement studies have been performed to investigate the interaction of tetradecyltrimethylammonium bromide (TTAB) and Triton® X-100 (TX-100) with ciprofloxacin hydrochloride (CFH) in different solvents over the temperature range of 295.15–315.15 K. CFH is used for the treatment of various bacterial infections. The observed critical micelle concentration (CMC) values of TTAB were found to be reduced in the presence of electrolytes (Na₂SO₄/Na₃PO₄), and this reduction proceeds with the elevation of salt concentration. The order of the CMC of TTAB follows the trend: > >. The observed CMC values of TTAB were found to increase with increasing temperature and decrease with increasing concentration of CFH in aqueous medium. The values of Gibbs free energy of micellization () for the TTAB/TTAB + CFH mixture were found to be negative, implying spontaneous micellization. The estimated CP of TX-100 decreases with increasing concentration of TX-100 in aqueous medium. The CP values first decrease with increasing concentration of CFH and then increase at higher concentration of CFH almost in all cases investigated. The values of free energy of clouding were found to be positive in all cases studied implying that phase separation of TX-100 was nonspontaneous. The other thermodynamic parameters associated with the micellization of TTAB and the phase separation of TX-100 were estimated and explained.     

A comparative study on citrate sol-gel and combustion synthesis methods of CoAl2O4 spinel

CoAl₂O₄ spinel was successfully synthesized by combustion synthesis method using glycine and urea by 1:1 molar ratio as fuels and sol-gel process using citric acid as a chelating agent. The as-synthesized powders were calcined at desired temperatures to obtain CoAl₂O₄ spinel as a single phase. X-ray diffraction, thermogravimetric, and differential thermal analysis results revealed that the formation of CoAl₂O₄ spinel in combustion method needs 300°C higher temperatures than those of sol-gel. Scanning electron microscopy and transmission electron microscopy analysis results revealed that “sol-gel spinel” had nanometric particle size which was smaller than those of “combustion spinel.” Temperature programed reduction with hydrogen and Fourier transform infrared spectroscopy results declared that there was a little residual cobalt oxide in combustion spinel while there is no oxide resided in “sol-gel spinel.” Consequently, the sol-gel method has more benefit in synthesizing spinel with sulfate precursors than combustion.     

Reuse of waste sludge from papermaking process in cement composites

Papermaking sludge (PS), a waste residue from the pulp and paper processing, has brought great pressure on the environment because of large quantities that are produced in paper mills. This work was carried out to explore the possibility of making PS/cement composite products using solid waste of PS. Boards measuring 350 × 270 × 12 mm³ were manufactured using PS contents of 40, 50, and 60 wt%, adhesive dosages of 0, 10, and 15 wt%, and 0 and 5 wt% of calcium chloride as an accelerator. At least three replications were fabricated for each treatment, and some mechanical and physical properties of the boards were evaluated. Test results showed that the bending and internal strengths of the specimens decreased with an increase in the PS content, and the maximum values were obtained at PS loading of 40 wt%. The negative influence of PS content on the mechanical properties can be explained by the reduced bonding ability because of weaker PS compared with cement. Screw withdrawal values were up to 22.7 kPa. Water absorption and thickness swelling of cement mortar considerably increased with increased content of PS, with a corresponding reduction of bulk density. In general, all properties of the boards were improved when the adhesive and calcium chloride contents were increased. The results showed that an increase in board density improved the mechanical and physical properties. Finally, results showed that PS has good potential for recycling and utilization in developing value‐added building components. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Naphtha derived from polyolefins

Conversion of polyolefins (HDPE, LDPE and PP) into feedstock naphtha was investigated by hydroliquefaction process. Hydroliquefaction experiments were carried out under cold hydrogen pressure of 5 MPa at the temperatures between 375 and 450 °C in absence and presence of catalyst. Two types commercial catalysts were used, a hydrocracking catalyst (DHC-8) and a hydrogenation catalyst (HYDROBON). The effect of temperature and catalyst type on product yields and composition of gas and liquid products was investigated. The temperature was the main effect in hydroliquefaction. DHC-8 showed good cracking activity, but it gave the liquid product containing high olefin content same as thermal run. Although HYDROBON catalyst produced the sufficient amount of liquid (and naphtha fraction) at the higher temperature, it gave the liquid product with very low olefin content. The naphtha fractions obtained from polyolefins under the optimal hydrocracking conditions were analyzed by PIONA instrument to determine the hydrocarbon groups. PIONA analysis showed that the naphtha obtained from hydroliquefaction over HYDROBON catalyst could be used as a petrochemical feedstock. However, the naphtha obtained in presence of DHC-8 catalyst, which is to be used a feedstock, was needed further hydrogenation treatment.     

Design of a dual function buried channel waveguide for pulse compression and dispersion compensation in two different wavelengths for the purpose of optical integration

Silicon - Optical pulse compression and dispersion compensation are two important applications in optical systems. The present paper proposes a dual function buried channel waveguide to be used in...