Sharif Digital Repository

Graphene oxide nanoribbons (GONRs) were synthesized using an oxidative unzipping of multi-walled carbon nanotubes. The interactions of the GONRs with various concentrations of fetal bovine serum or human plasma serum indicated that the GONRs were functionalized substantially by the albumin originated from the two different protein sources. Then, concentration-dependent cytotoxicity of the protein-functionalized GONRs on human epithelial cells was studied. Although the GONRs with concentrations ≤50 μg/mL did not exhibit significant cytotoxicity on the cells (with the cell viability >85%), the concentration of 100 μg/mL exhibited significant cytotoxicity including prevention of cell... 

Gamma-ray observations in the low and medium energy range (0.1-100 MeV) with sufficiently sensitive telescopes will provide unique insights into many outstanding high-energy astrophysics questions. The University of California, Riverside (UCR) Tracking and Imaging Gamma-Ray Telescope (TIGRE) Compton gamma-ray telescope uses multilayers of silicon strip detectors to, for the first time, track the Compton electron and CsI(Tl)-photodiode detectors to measure the scattered photon energy. By combining the Compton telescope's inherent imaging capability with improved background discrimination, a larger field-of-view and improved spectral and spatial resolutions, a significant improvement in... 

In this study, numerical computations are performed with the main purpose of shedding light on the mixing characteristics in an innovative T-shaped micromixer equipped with a twisted structure. A 3-D model is presented and verified to mix two miscible fluids in a single phase. By considering different geometrical cases, the proposed T-mixer is compared using the standard T-mixer (Base case) running in the same operational conditions. Furthermore, the impacts of variation in the geometry of twisted design are scrutinized for Re (Reynolds number) in the extent of 1≤Re≤500 with the focus of obtaining a significant mixing quality for flow through the micromixer. MI (Mixing index), PI... 

Adiabatic quantum algorithms are characterized by their run time and accuracy. The relation between the two is essential for quantifying adiabatic algorithmic performance yet is often poorly understood.We study the dynamics of a continuous time, adiabatic quantum search algorithm and find rigorous results relating the accuracy and the run time. Proceeding with estimates, we show that under fairly general circumstances the adiabatic algorithmic error exhibits a behavior with two discernible regimes: The error decreases exponentially for short times and then decreases polynomially for longer times.We show that the well-known quadratic speedup over classical search is associated only with the... 

Drying of green peas in a Fluidized Bed Dryer (FBD) with inert particle, heated by combined sources of hot air and InfraRed (IR) radiation, has been experimentally and theoretically studied. For this purpose, an experimental set up was constructed. This setup was composed of a cylindrical bed dryer containing some inert particles which are fluidized by hot air. Some infrared lamps were also placed around the bed for heating assistance. A sample of green pea was hung in the fluidized bed and its moisture content, surface and central temperature were measured with time. A mathematical model, based on the two layers concept of penetration and conduction was also proposed for this process. The... 

A sequential implicit numerical method based on discrete-fracture model and the Galerkin Finite Element method, for time-dependent coupled fluid flow and geomechanics problems in fractured subsurface formations is presented. Discrete-fracture model has been used to explicitly represent the fracture network inside porous media. The Galerkin Finite Element method with adaptive unstructured gridding is implemented to numerically solve the spatially three-dimensional and time-dependent problem. The presented method is validated with previously obtained solutions. Two problems are numerically solved by applying the presented methodology in a three-dimensional fractured petroleum reservoir under... 

In this paper we study and evaluate the performance of a spectral-phase encoded optical CDMA (SPE-OCDMA) system using advanced receiver structures based on second harmonic generation (SHG) effect imposed in a Thick or Thin crystal. This receiver structure is employed as the nonlinear pre-processor prior to the conventional low-speed photodetector. In our performance evaluation amplified spontaneous emission (ASE) of the optical amplifiers, receiver front end thermal noise and photodetector shot noise which are effective in low power conditions, and multiple access interference (MAI) noise which is the dominant source of noise in high power conditions in any coherent OCDMA communications... 

In this work, we address peak power and maximum temperature in multi-core Mixed-Criticality (MC) systems. In these systems, a rise in peak power consumption may generate more heat beyond the cooling capacity. Additionally, the reliability and timeliness of MC systems may be affected due to excessive temperature. Therefore, managing peak power consumption has become imperative in multi-core MC systems. In this regard, we propose an online peak power management heuristic for multi-core MC systems. This heuristic reduces the peak power consumption of the system as much as possible during runtime by exploiting dynamic slack and Dynamic Voltage and Frequency Scaling (DVFS). Specifically, our... 

In modern multi-core Mixed-Criticality (MC) systems, a rise in peak power consumption due to parallel execution of tasks with maximum frequency, specially in the overload situation, may lead to thermal issues, which may affect the reliability and timeliness of MC systems. Therefore, managing peak power consumption has become imperative in multi-core MC systems. In this regard, we propose an online peak power and thermal management heuristic for multi-core MC systems. This heuristic reduces the peak power consumption of the system as much as possible during runtime by exploiting dynamic slack and per-cluster Dynamic Voltage and Frequency Scaling (DVFS). Specifically, our approach examines... 

In modern multicore mixed-criticality (MC) systems, a rise in peak power consumption due to parallel execution of tasks with maximum frequency, specially in the overload situation, may lead to thermal issues, which may affect the reliability and timeliness of MC systems. Therefore, managing peak power consumption has become imperative in multicore MC systems. In this regard, we propose an online peak power and thermal management heuristic for multicore MC systems. This heuristic reduces the peak power consumption of the system as much as possible during runtime by exploiting dynamic slack and per-cluster dynamic voltage and frequency scaling (DVFS). Specifically, our approach examines... 

Users often have very specific visual content in mind that they are searching for. The most natural way to communicate this content to an image search engine is to use key-words that specify various properties or attributes of the content. A naive way of dealing with such multi-attribute queries is the following: train a classifier for each attribute independently, and then combine their scores on images to judge their fit to the query. We argue that this may not be the most effective or efficient approach. Conjunctions of attribute often correspond to very characteristic appearances. It would thus be beneficial to train classifiers that detect these conjunctions as a whole. But not all... 

Beside their worldwide abundance, oil recovery from fractured carbonate reservoirs is commonly low. Such reservoirs are usually oil-wet, thus, waterflooding leads into early breakthrough and low recovery due to the high conductivity of the fracture network, negative capillary pressure of the matrix and, consequently, the poor spontaneous imbibitions of water from fractures into the matrix during the course of waterflooding. In such problematic reservoirs, changing the wettability of the matrix toward water-wetness can improve spontaneous imbibition by changing the sign and, thus, the direction of capillary forces, resulting in an improvement of waterflood efficiency and, consequently, oil... 

This paper deals with the mixed convective heat transfer of nanofluids through a concentric vertical annulus. Because of the non-adherence of the fluid-solid interface in the presence of nanoparticle migrations, known as slip condition, the Navier's slip boundary condition was considered at the pipe walls. The employed model for nanofluid includes the modified two-component four-equation non-homogeneous equilibrium model that fully accounts for the effects of nanoparticles volume fraction distribution. Assuming the fully developed flow and heat transfer, the basic partial differential equations including continuity, momentum, and energy equations have been reduced to two-point ordinary... 

This paper is devoted to the characterization of an extended family of continuous-time autoregressive moving average (CARMA) processes that are solutions of stochastic differential equations driven by white Lévy innovations. These are completely specified by: 1) a set of poles and zeros that fixes their correlation structure and 2) a canonical infinitely divisible probability distribution that controls their degree of sparsity (with the Gaussian model corresponding to the least sparse scenario). The generalized CARMA processes are either stationary or nonstationary, depending on the location of the poles in the complex plane. The most basic nonstationary representatives (with a single pole... 

In this work, we implement a relatively new analytical technique, the exp-function method, for solving nonlinear special form of generalized nonlinear (2 + 1) dimensional Broer-Kaup-Kupershmidt equation, which may contain high nonlinear terms. This method can be used as an alternative to obtain analytic and approximate solutions of different types of fractional differential equations which applied in engineering mathematics. Some numerical examples are presented to illustrate the efficiency and reliability of exp method. It is predicted that exp-function method can be found widely applicable in engineering  

Ultrasonic motor working with coupled in-plane and out-of-plane vibration modes of rectangular plate is proposed and experimentally investigated. Thanks to its unique configuration, proposed motor provides large contact area between stator and rotor of motor which can reduce wear and enhance motor life-time. The proposed motor is designed using finite element method and according to the design, a prototype is fabricated and its working characteristics such as speed, normal and driving force and working frequency are measured. Overall dimension of designed prototype is 49 × 14 × 2 mm, working frequency of motor is 49.6 kHz, no-load speed and stall force of motor are 122 rpm and 0.32 mN m at... 

The growth of process industries has escalated the probability of loss containment scenarios of hazardous materials that can be tackled via process safety schemes. For preliminary design stage, the inherent scheme is more promising to generate sustainable process designs. For this purpose, various process routes are typically compared to recognize the safer one via numerous indexing methods to eliminate routes with hazardous materials. However, these indices lack in accommodating the equipment characteristics and the underutilization of process and chemical characteristics. Specifically for chemical characteristics, the toxicity aspect has not been engaged for process route selection in... 

Regarding the importance of rheological properties of water based drilling fluids, the effects of silica nanospheres, multiwall carbon nanotubes (MWCNTs) and two types of their hybrid, i.e. H1 (80 wt.% silica nanosphere/20 wt.% MWCNT) and H2 (50 wt.% silica nanosphere/50 wt.% MWCNT) on the viscosity and density of distilled water were investigated. According to the results, viscosity and density of the nanofluids increased with the concentration, while they were reduced by increasing the temperature. At high concentrations, the least increase in the viscosity of distilled water by adding the nanomaterials is related to H2 (8.2% increase at 1.0 wt.%). Likewise, the optimum operating... 

Among all proposed structures for optical networks, the optical packet switching (OPS) scheme, due to its practical implementation of IPs in an optical configuration and the consequent advantages, is a prizeworthy candidate for being employed in metropolitan area network and local area network communication levels. One of the few problems frequently met using the OPS structure in the fiber-optics realm is the lack of optical buffers, thus deteriorating the system's flexibility and quality of service. For example, optical label switching networks that have been developed recently based on the generalized multiprotocol label switching protocol, profoundly suffer from this setback which is...