Novel Linear Piezo-resistive Auxetic Meta-Sensors with Low Young's Modulus by a Core–Shell Conceptual Design and Electromechanical Modelling

Production of piezo-resistive auxetic sensors is usually carried out through mixing and coating methods. Although these methods are beneficial, Young's modulus of mixed sensors becomes high because of using a high percentage of sensing elements while the durability of coated sensors gets low due to the separation of sensing elements from the sensor surface. This article presents a new core–shell metamaterial model to address the mentioned problems. The shell and the core are produced of polydimethylsiloxane (PDMS) rubber and a mixture of PDMS/graphite powders (73.45 wt% graphite powders), respectively. A finite element model is developed via COMSOL software to predict the electromechanical behaviors of the created sensor and verified by an experimental study. Scanning electron microscope imaging is conducted to detect the separations of the graphite particles. The main important feature of this meta-sensor is to possess a linear sensitivity due to having zero Poisson's ratio. The advantage of this method is that Young's modulus of the sensor does not decrease (unlike the mixing method), and the sensor-coated particles do not separate from the sensor after a while (unlike the coating method). The introduced model has advantages that promote potential applications such as using sensory gloves to detect, for instance, human hand movements.     

Comprehensive energy and economic transient analysis of an off-grid hydrogen car-integrated zero energy building

Clean Technologies and Environmental Policy - In this study, for the first time, an off-grid zero-energy building with hydrogen energy storage integrated with two hydrogen cars is simulated and...     

Quantitative filter forensics: Size distribution and particulate matter concentrations in residential buildings

We applied filter forensics, the analysis of dust from the heating, ventilation, and air-conditioning (HVAC) filters, to measure particle size distribution in 21 residences in Toronto, Canada over a year. Four filters with different nominal efficiencies (Minimum Efficiency Reporting Value (MERV) 8–14 from ASHRAE Standard 52.2) were deployed in each residence each for three months, while the effective filtration volumes (the product of flow rate, runtime, and in-situ filter efficiency) were characterized over each filter lifetime. Using extraction and laser diffraction, we found that approximately 90% of the volumetric distributions were >10 µm and the volume median diameter (VMD) ranged from 23.4 to 75.1 µm. Using quantitative filter forensics (QFF), total suspended particle (TSP) concentrations ranged from 2.9 to 823.7 µg/m³ (median = 89.8 µg/m³) with a moderate correlation with the content of TSP on the filters (in terms of g) and with the TSP effective filtration volume (m³) indicating the importance of both filter forensics and HVAC metadata parameters to QFF concentration estimates. There was no strong correlation between PM₁₀ or PM_2.5 concentrations and hourly airborne particle number concentrations measured by low-cost sensors suggesting an evaluation of QFF is warranted, particularly for the exploration of smaller particles.     

Effects of the porous medium and water-silver biological nanofluid on the performance of a newly designed heat sink by using first and second laws of thermodynamics

The aim of this numerical investigation is to evaluate the laminar forced convection of biologically synthesized water-silver nanofluid through a heat sink (HS) filled with porous foam (PHS) using first and second laws of thermodynamics. The impacts of inlet velocity (V = 0.5–3 m·s⁻¹) and volume fraction of nanofluid (φ = 0–1%) on the performance metrics of HS are assessed and the outcomes are compared with those of the non-porous HS (NHS). The outcomes revealed that for both the PHS and NHS, the increase of V causes an intensification in convection coefficient, pumping power, and entropy generation due to fluid friction, while the maximum CPU temperature, thermal resistance, and entropy generation due to the heat transfer reduces by boosting V. Also, it was found that the augmentation of V results in intensification in convection coefficient, pumping power, overall hydrothermal performance, and frictional entropy generation, while the opposite is true for maximum CPU temperature, thermal resistance, and thermal entropy generation. Furthermore, it was reported that, except for φ = 0.5%, the overall hydrothermal performance of NHS is better than that of PHS, while PHS has better second-law performance than NHS in all the studied cases. Also, it can be concluded that the best hydrothermal performance for PHS belongs to φ = 1% and V = 0.5 m·s⁻¹, while for NHS, these values are 1% and 2 m·s⁻¹.     

Transient response of porous inhomogeneous nanobeams due to various impulsive loads based on nonlocal strain gradient elasticity

International Journal of Mechanics and Materials in Design - Transient vibration responses of a porosity-dependent functionally graded nanobeam under different impulsive loadings have been...     

A FinBOX Based Ge FinEHBTFET: Design and Investigation

Silicon - In this work, we propose a Germanium Fin Buried Oxide (FinBOX) Fin Electron-Hole Bilayer Tunnel FET (FBF-EHBTFET) structure. The proposed structure eliminates the gated underlaps and...     

Preparation of synthesized sulfide polymer through phase-transfer catalyzed polycondensation of ethylene dibromide and sodium tetrasulfide: characterization,thermal and rheological properties

Sulfide polymers were obtained through the interfacial polymerization of sodium tetrasulfide and ethylene dibromide. The polymerization process was carried out under interfacial condition using two phase-transfer catalysts: methyl-tributyl ammonium bromide and methyl-tributyl ammonium chloride. The polymer characteristics were examined by attenuated total reflectance- fourier transform infrared spectroscopy, elemental analysis (CHNS/O) and X-ray diffraction methods. Thermal characteristics were investigated by differential scanning calorimetry and thermogravimetric analysis methods. The rheological behavior of the synthesized sulfide polymer during curing reaction, and isothermal time dependency of elastic storage modulus, G^′, at different temperatures and constant shear frequency was studied using a stress-controlled rheometer. Moreover, the solvent resistance of synthesized polymer was investigated through the swelling method.     

Investigation of Mechano-chemical Properties of the Effects of Nanoparticles in Artificial Stone Produced

Silicon - The aim of this study is to produce artificial stone from the sludge of stone cutting factories, its properties are increased by adding nano-fillers. The results show reduced the water...