Sharif Digital Repository

A lubrication model is used to study dewetting of an evaporating thin film layer over a solid substrate with a nanometer-scale topography. The effects of the geometry of the topography, the contact angle, the film thickness, and the slippage on the dewetting have been studied. Our results reveal that the evaporation enhances the dewetting process and reduces the depinning time over the topography. Also it is shown that the depinning time is inversely proportional to the slippage and increasing the contact angle may considerably reduce the depinning time, while the film thickness increases the depinning time  

We show a methodology for how to construct Dirac points that occur at the corners of Brillouin zone as the Photonic counterparts of graphene. We use a triangular lattice with circular holes on a silicon substrate to create a Coupled Photonic Crystal Resonator Array (CPCRA) which its cavity resonators play the role of carbon atoms in graphene. At first we draw the band structure of our CPCRA using the tight-binding method. For this purpose we first designed a cavity which its resonant frequency is approximately at the middle of the first H-polarization band gap of the basis triangular lattice. Then we obtained dipole modes and magnetic field distribution of this cavity using the Finite... 

The production of robust joints after diffusion brazing necessitates the advanced understanding of phase transformations during the bonding process. This paper aims to investigate the solidification and the solid state precipitation during diffusion brazing of wrought IN718 nickel base superalloy using Ni-15Cr-4B (wt-%) filler alloy. It was found that intermetallics containing eutectic type microconstituents were formed in the joint centreline by solidification which is controlled by segregation behaviour of B and its low solubility in Ni rich solid solution. In addition, extensive Cr-Mo-Nb rich precipitates were formed in the substrate region by solid state precipitation induced by B... 

We investigate the time-dependent evolution of thin liquid films over inclined substrates using a multi-component lattice Boltzmann algorithm. Substrates with and without grooves are considered and the effects of the inclination angle on the dynamics and the coating of the substrates are studied. Our results indicate that the dynamics is enhanced and the ridge height and its displacement are increased by increasing the inclination angle. However, by increasing the inclination angle the maximum depth that can be successfully coated is reduced. Also, although for any given groove depth the width should be larger than a critical value for successful coating, the critical width decreases for... 

We have previously reported the results of plasmonic behavior of an Au nanodisk array in the far-field coupling regime under oblique illumination with transverse electric polarization. In this paper, those results are studied in more detail. Here, results for transverse magnetic polarization are also presented and discussed. In addition to the far-field coupling regime, the results for the near-field coupling regime are also reported. Effects of different parameters, such as substrate thickness and array periodicity on the shape of plasmon spectra are discussed. It will be shown that in the far-field coupling regime, the diffractive grating orders can have a major role in the behavior of the... 

This chapter is dedicated to a theoretical investigation of the electrical behaviour of inductors and transmission lines integrated on thin silicon wafers. Using electromagnetic simulations, it is shown that thinning a standard silicon substrate to ∼20-70 μm yields a ∼20-30% increase in the maximum quality factor and resonance frequency of typical integrated spiral inductors. This improvement is due to a higher spreading substrate resistance between the inductor and the physical ground. However, further improvement of the quality factor requires substrates thinned to several microns in order to reduce the effect of stray electric fields induced between different points on the conductor,... 

Since plasma is rich in many biomarkers used in clinical diagnostic experiments, microscale blood plasma separation is a primitive step in most of microfluidic analytical chips. In this paper, a passive microfluidic device for on-chip blood plasma separation based on Zweifach–Fung effect and plasma skimming was designed and fabricated by hot embossing of microchannels on a PMMA substrate and thermal bonding process. Human blood was diluted in various times and injected into the device. The main novelty of the proposed microfluidic device is the design of diffuser-shaped daughter channels. Our results demonstrated that this design exerted a considerable positive influence on the separation... 

One of the key factors in the assembly of nanoparticles and controlled construction of such systems is their positioning by a manipulation system. The response of clusters that are subjected to this process is of great importance. In this study, the behaviour of metallic nanoparticles during the manipulation process on an Au substrate is investigated using molecular dynamics. Two criteria are proposed for the evaluation of success in a pushing process regarding the intactness of a nanoparticle/substrate pair. The effects of cluster material, temperature and manipulation speed on the success of the process are investigated based on the simulation results  

Since plasma is rich in many biomarkers used in clinical diagnostic experiments, microscale blood plasma separation is a primitive step in most of microfluidic analytical chips. In this paper, a passive microfluidic device for on-chip blood plasma separation based on Zweifach–Fung effect and plasma skimming was designed and fabricated by hot embossing of microchannels on a PMMA substrate and thermal bonding process. Human blood was diluted in various times and injected into the device. The main novelty of the proposed microfluidic device is the design of diffuser-shaped daughter channels. Our results demonstrated that this design exerted a considerable positive influence on the separation... 

In this paper we have studied the motion of a nanocar and nanotruck on gold substrate using the classical molecular dynamics method. Analyzing the motion regime of the nanocar at different temperatures is one of the main goals of this paper. In the past years, similar molecules such as Trimmer, Z-car and nanotruck have been simulated by Konyukhov and Akimov. To increase the modeling accuracy in this paper we have used classical molecular dynamics contrary to previous works which used a rigid body molecular dynamics method. The result of our simulations were compared qualitatively to the experimental tests performed by Zhang et al. [12]. There was a good agreement between the results achieved... 

Using molecular dynamics, the behavior of nanoparticles during manipulation process is investigated in this paper. The system consists of a tip, cluster and substrate. The focus of the present research is on ultra-fine metallic nanoclusters. The system of concern is made of different transition metals. Two criteria have been proposed for evaluation of success in a pushing process. Such criteria describe the intactness of nanoparticle/substrate pair. The effects of cluster material and manipulation speed on the success of the process are investigated by atomistic simulations. Such qualitative simulation studies can evaluate the level of success of manipulation regarding different working... 

A facile hydrothermal method and subsequent electroactivation have been developed to fabricate three-dimensional (3D) CuO nanosheet arrays on the copper foil substrate, which can be used directly as a binder-free electrode for supercapacitor applications. Under optimum conditions, by using this facile method, a high capacitance of 125 mF/cm2 at a current density of 0.3 mA/cm2 is obtained. The prepared supercapacitor showed a good rate capability (46.4% capacitance retention, when the current density is increased to more than 30 times) and an excellent cyclability (more than 88% capacitance retention after 3000 cycles). © 2017 Elsevier B.V  

A miniaturized patch antenna is proposed and its radiation properties are experimentally investigated. A new metamaterial configuration based on circular spiral inclusion is used as the patch antenna substrate. The proposed antenna has not only a lighter profile but also a higher gain in comparison with its previously reported counterparts. It is shown that by using this new configuration a miniaturization factor of 3.1 can be realized. © 2017 Wiley Periodicals, Inc  

Network virtualization is a promising approach in which common physical resources are shared between service providers. Due to the substrate network limitations such as maximum available memory of each node of the substrate network as well as different service priorities and requirements, resource management in this setup is essential. On the other hand, SDN is bringing a considerable flexibility in resource management by introducing a centralized controller which can monitor all the substrate network states. In this paper, we propose a proactive admission control and dynamic resource management in SDN-based virtualized network in which the number of accepted high-priority virtual network... 

One-dimensional nanostructures of tin oxide nanotubes were fabricated by carbothermal evaporation at 900°C in air. The synthesized film was grown on Au-coated (100) Si substrate. Heterogeneous catalysis by Au/Sn droplets assisted the formation of the tin oxide nanotubes of less than 40 nm diameter at Sn vapor pressures around 1.4×10 -7 Pa. In order to reduce the nanotube diameter further, an increase in the Sn vapor pressure by changing the source materials' ratio seemed viable. © 2009 Springer-Verlag  

The emergence of textile-based wearable sensors as light-weight portable devices to monitor desired parameters, has recently gained much interest and has led to the development of flexible electronics on non-rigid substrates. The flexible biosensors may result in improved sports performance, to monitor the desired bodies for injuries, improved clinical diagnostics and monitor biological molecules and ions in biological fluids such as saliva, sweat. In addition, they could help users with different types of disorders such as blindness. In this context, new composite and nanomaterials have been found to be promising candidates to obtain improved performance of the textile based wearable...