Free vibration analysis of double-viscoelastic nano-composite micro-plates reinforced by FG-SWCNTs based on the third-order shear deformation theory

Microsystem Technologies - In this paper, free vibration analysis of a double viscoelastic nano-composite plate system reinforced by functionally graded single-walled carbon nanotubes (FG-SWCNT)...     

Nanoscale mass nanosensor based on the vibration analysis of embedded magneto-electro-elastic nanoplate made of FGMs via nonlocal Mindlin plate theory

Microsystem Technologies - In the current paper, the sensitivity performance of functionally graded magneto-electro-elastic (FG-MEE) nanoplate with attached nanoparticles as a nanosensor is...     

Thermal comfort analysis of earth-sheltered buildings: The case of meymand village,Iran

Vernacular buildings are known for their localized passive settings to provide comfortable indoor environment without air conditioning systems. One alternative is the consistent ground temperature over the year that earth-sheltered envelopes take the benefit; however, ensuring annual indoor comfort might be challenging. Thus, this research monitors the indoor thermal indicators of 22 earth-sheltered buildings in Meymand, Iran with a warm-dry climate. Furthermore, the observations are used to validate the simulation results through two outdoor and indoor environmental parameters, air temperature and relative humidity during the hottest period of the year. Findings indicated that the main thermal comfort differences among case studies were mainly due to their architectural layouts where the associated variables including length, width, height, orientation, window-to-wall ratio, and shading depth were optimized through a linkage between Ladybug-tools and Genetic Algorithm (GA) concerning adaptive thermal comfort model definition and could enhance the annual thermal comfort by 31%.     

Strengthening RC Beams in Flexure Using New Hybrid FRP Sheet/Ductile Anchor System

This paper explores a new hybrid fiber-reinforced polymer (FRP) sheet/ductile anchor system for rehabilitation of reinforced concrete (RC) beams. The advantages of the proposed strengthening method is that it overcomes the problem of low ductility that is associated with brittle failure mode in conventional methods of strengthening beams using epoxy-bonded FRP sheets. The proposed system leads to a ductile failure mode by triggering yielding to occur in a steel anchor system (steel links) rather than by rupture or debonding of FRP sheets, which is sudden in nature. Four half-scale RC T-beams were tested under four-point bending. Three retrofitted beams were strengthened using one layer of carbon FRP sheet. The results of the two beams that were strengthened with the new hybrid FRP sheet/ductile anchor system were compared with the results from the beam strengthened with conventional FRP bonding method and the control beam. The results show the effectiveness of the proposed strengthening system in increasing flexural capacity and ductility of RC beams.     

A simplified thermodynamic modeling procedure for predicting asphaltene precipitation

In this work, a simplified thermodynamic modeling procedure for determination of the amount of asphaltene precipitation is presented. The onset of asphaltene precipitation in the presence of different solvents is predicted by applying the molecular solubility model. Since asphaltene molecular weight varies in different solvents, the molecular weight of asphaltene has been tuned by experimental data. The tuned molecular weight is used to predict the amount of precipitated asphaltene. The Flory–Huggins statistical thermodynamics theory is applied to derive the Gibbs free energy relationship. A necessary and sufficient condition is defined to minimize the Gibbs free energy relation. By solving the set of equations derived from the minimization, the weight percent of precipitated asphaltene has been determined. The advantage of this model is that one does not need to perform expensive and time consuming experiment in order to obtain molecular weight data. The other improvement of this model compared to the other models is the requirement of a minimum amount of experimental data to find the unknown parameters. It also has the advantage of obtaining solubility parameters through thermodynamics relationships rather than using the relation for regular solution when the asphaltene solution is a non-regular solution. The results of this model are in good agreement with the experimental data.     

Shear Strengthening of RC Beams with Externally Bonded FRP Composites: Effect of Strip-Width-to-Strip-Spacing Ratio

The results of an experimental and analytical investigation of shear strengthening of reinforced concrete (RC) beams with externally bonded (EB) fiber-reinforced polymer (FRP) strips and sheets are presented, with emphasis on the effect of the strip-width-to-strip-spacing ratio on the contribution of FRP (Vf). In all, 14 tests were performed on 4,520-mm-long T-beams. RC beams strengthened in shear using carbon FRP (CFRP) strips with different width-to-spacing ratios were considered, and their performance was investigated. In addition, these results are compared with those obtained for RC beams strengthened with various numbers of layers of continuous CFRP sheet. Moreover, various existing equations that express the effect of FRP strip width and concrete-member width and that have been proposed based on single or double FRP-to-concrete direct pullout tests are checked for RC beams strengthened in shear with CFRP strips. The objectives of this study are to investigate the following: (1)?the effectiveness of EB discontinuous FRP sheets (FRP strips) compared with that of EB continuous FRP sheets; (2)?the optimum strip-width-to-strip-spacing ratio for FRP (i.e., the optimum FRP rigidity); (3)?the effect of FRP strip location with respect to internal transverse-steel location; (4)?the effect of FRP strip width; and (5)?the effect of internal transverse-steel reinforcement on the CFRP shear contribution.     

Rigorous correlations for predicting the solubility of H2S in methylimidazolium-based ionic liquids

Two general and simple models, a group contribution correlation (model I) and an empirical relation (model II), were proposed to predict the solubility of H₂S in methylimidazolium based ionic liquids (ILs) over wide range of temperatures (303.15-363.15 K) and pressures (60.8-2016.8 kPa). The constants of the suggested functionality relations were found via the Nelder-Mead simplex algorithm. Both correlations were trained with 407 data points of H₂S solubility in 9 methylimidazolium based ILs and tested through 121 H₂S solubility data points of 3 different methylimidazolium based ILs to ensure generality. A comprehensive statistical evaluation showed that both suggested correlations are vigorous and have satisfactory error trends. The dataset was subjected to a statistical outlier diagnostic test and the validity of the database was confirmed. In addition, the sensitivity analysis revealed that the experimental data and both models have the same responses toward pressure and temperature, which indicates the reliability of the proposed correlations.     

A 56-nm CMOS 99-mm2 8-Gb Multi-Level NAND Flash Memory With 10-MB/s Program Throughput

A single 3.3-V only, 8-Gb NAND flash memory with the smallest chip to date, 98.8 mm², has been successfully developed. This is the world's first integrated semiconductor chip fabricated with 56-nm CMOS technologies. The effective cell size including the select transistors is 0.0075 mum² per bit, which is the smallest ever reported. To decrease the chip size, a very efficient floor plan with one-sided row decoder, one-sided page buffer, and one-sided pad is introduced. As a result, an excellent 70% cell area efficiency is realized. The program throughput is drastically improved to twice as large as previously reported and comparable to binary memories. The best ever 10-MB/s programming is realized by increasing the page size from 4kB to 8kB. In addition, noise cancellation circuits and the dual VDD-line scheme realize both a small die size and a fast programming. An external page copy achieves a fast 93-ms block copy, efficiently using a 1-MB block size     

Tribological behaviour of an elastomer aged in different oils

This paper presents the influence of aging the nitrile rubber, the most popular seal material, in various base fluids on sliding friction and abrasive wear. The lubricants used are synthetic esters, natural esters, different types of mineral base oils, poly-α-olefins and very high viscosity index oils. Friction has been studied for two directions of motion with respect to lay on the elastomer sample by using the SRV Optimol test machine. These findings show that as compared to all other lubricant formulations, ageing the elastomer in polyol ester leads to the maximum reduction of friction coefficient especially in perpendicular sliding to the initial lay on the surface. The abrasive wear studies were carried out by using a two-body abrasive wear tester against dry and lubricated elastomer. It was interesting to note that two-body abrasive wear of elastomeric material was higher during rubbing in presence of the fluids as compared to that in dry condition. Further, aging the elastomer in these base fluids especially in ester base fluids, results in more abrasive wear.